Torque & HP Open Discussion
Printed From: CorrectCraftFan.com
Category: General Correct Craft Discussion
Forum Name: General Discussion
Forum Discription: Anything Correct Craft
URL: http://www.CorrectCraftFan.com/forum/forum_posts.asp?TID=12164
Printed Date: May-07-2024 at 1:25am
Topic: Torque & HP Open Discussion
Posted By: 81nautique
Subject: Torque & HP Open Discussion
Date Posted: October-14-2008 at 1:39pm
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As we start to see all the discussion of winterizing it must be time to start talking about winter upgrades.
With the help of a few guys on the site(ReidP & TimB)and a program called Desktop Dyno I've made my decision and parts are ordered. Reid and I thought it would be interesting to post results of the sim dyno program for all to digest and maybe we could start a good informative thread regarding the gains/losses of certain known engine component upgrades. So this is not just about my project I decided to post the dyno results of a stock 351PCM engine first and then a few upgrades and what people could expect to get in return. We've also simulated a few other engines that guys are running as well as the 60mph Mustang so maybe we'll get into the 302 engine and a stroker or 2 later. Graph A is a 351 stock 240hp PCM 
Graph B is a 351 stock short block with GT40P heads. 
Graph C is my 351 is it sits now, 351 .030 over, 9.3:1 CR, Gt40P heads, .466 Lift cam, 1.7:1 roller rockers and a Performer intake. 
Graph D are the anticipated results of a top end upgrade. 351 .030 over, 9.8:1CR, RHS180CC heads, .466 Lift cam, 1.7:1 roller rockers and and Edelbrock RPM intake. The heads are being custom ported and intake/exhaust manifolds will be port matched but we don't have the flow data yet so these number are advertised flow rates. 
So study the data and ask away, if you have particular performance items that you want to ask about we can set up a dyno for your engine, I'll let you know what specs I need to set it up. ------------- You can’t change the wind but you can adjust your sails |
Replies:
Posted By: M3Fan
Date Posted: October-14-2008 at 2:23pm
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Can you specify MPI or TBI? I'd be curious to see what they show for the "GT40" MPI setup. ------------- 2000 SN GT40 w/99 Graphics/Gel 2016 SN 200 OB 5.3L DI https://forum.fifteenoff.com |
Posted By: 81nautique
Date Posted: October-14-2008 at 2:40pm
Can't get that specific Joel, the induction menu shows 4v carb and Fuel injection as the same. If you could find the CFM value for the fuel injection we could play around with it. I also don't have the specs for a stock 351PCM cam so if anybody has that info or has a few minutes to call PCM and get it that would make these numbers more accurate. ------------- You can’t change the wind but you can adjust your sails |
M3Fan wrote:Posted By: phatsat67
Date Posted: October-14-2008 at 4:54pm
| I had that on a floppy disk it was fun to play with. I used it all the specs that I put into my 360 thats in the car it seemed to be pretty accurate. |
Posted By: JoeinNY
Date Posted: October-14-2008 at 5:24pm
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Well this is torque and horsepower but in the vein of torque vs horsepower my guess is you would now need to run a smaller pitch prop to get you up to your max speed potential. Even if not by much pitch. All just conjecture at this point mind you...
Holding the prop the same for the moment I would guess your running in the 5200 to 5300 area (with your hightest speed prop) with your current setup which is about where your horsepower/torque graphs cross and not a bad all around place to be in terms of speed vs fuel economy. Lets say based on the graphs it takes you 325lb-ft of torque to turn your prop at your current high speed of 53 or so... Well if that remained the same at your new high speed the new setup could get you all the way to 6000 rpm 60 mph with the same prop, but my guess is that the torque required is actually going to go up with the additional speed due to the increased drag (mostly water but air as well) of the boat. My guess is with this theoretical prop it goes up about 12ftlb/mph in this range, why twelve well because it is about twice linear and there is an offset and yadda yadda I think twelve.. this number is extremely important and it would be good to really know it but I havent done the research... Anyway if its 12lb-ft your not going to be able to turn this prop past 55mph or 5500 or so as thats going to cross your new torque curve at that rpm. If the number is 20 or worse yet is not fixed but exponential then your not going to see more than another 1 to 1.5 with the same prop. Besides changes to the hull the only way to change change this number is with a smaller pitch or diameter prop. In an ideal performance world (gas mileage being the lost cause) you would want to shoot for a prop that got you to the 6000 rpm point (maybe 5900 to be conservative) while your speed should be theoretically the same as a prop that got you to 5600 or so your holeshot and mid range would improve without costing you on the top end. If you go with too small a pitch you will over shoot on rpm be past your maximum potential on the curve and simply be slow and use too much gas, holeshot wont even be great as you wont get enough bite.. Anyway this is a lot of rambling to suggest that proper propellor sizing is just as key to actually getting a boat to move. Hp vs Torque curves are a great tool to know if your prop is giving you all you can get ------------- http://www.correctcraftfan.com/diaries/details.asp?ID=1477 - 1983 Ski Nautique 2001 1967 Mustang 302 "Decoy" http://www.youtube.com/watch?v=cO5MkcBXBBs - Holeshot Video |
Posted By: TRBenj
Date Posted: October-14-2008 at 5:43pm
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Joe, good points but I'll go ahead and disagree with you on this one. Reid has found that by adding mods that increase breathing without increasing cubic inches (ie, top end mods that significantly improve hp and not torque, thereby shifting the hp curve to the right), the boat seemed to like the stock sized prop the best. Alan is doing the same thing- notice he is adding ~50hp, which I would guess would increase his max RPM by about 400. If memory serves, I believe youre correct that he's in the 5300 range now- so that would put him at ~5700 with the new upgrades. Thats right at the peak of the new hp curve- so whichever prop he likes now might still be the fastest when its all said and done. ------------- |
Posted By: Brktracer
Date Posted: October-14-2008 at 6:59pm
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Very interesting conversation, especially for a drag racer.
Granted I haven't spent much time tuning I'll have to agree with Joe. My boat will turn 5,300 RPM max. The cam I have should peak at about 5800 according to Comp. This cam has a more aggressive lobe (larger duration at .050") and higher lift than my last cam and it still maxs out at 5,300. I intentionally went larger on the cam in an attempt to improve the top end to no avail. A couple weekends ago I got bored and tried 2 carb spacers and 2 carbs to see if there was anything there. I tried a 750 dp, 650 dp, 4 hole 1" spacer, and open 1" spacer; all on the same day. All were within .5 mph on the gps! All ran, you guessed it, 5300 rpm. Frustrated, I decided having points triggering my MSD could be a problem. Maybe points "bounce" was causing the limitation. I found a new electronic prestolite on ebay to my door for $55! Installed the distributor and still turns 5300 RPM! Looking at the stock manifolds, the collector area is really small compared to what I would run on a similar car engine. I have experienced instances where the exhaust was so restrictive that an engine simply wouldn't turn any more RPM. We put on a nice set of headers and made a huge difference. In another case I had a small restriction in an exhaust system and after resolving it picked up .5 sec in the 1/4 mile. As you can probably tell, I'm beginning to doubt the efficiency of the Osco (PCM replacement) manifolds. Is anyone with a 351 turning more RPM than about 5,300 with the PCM manifolds? Any A/B test results with PCM vs Hi-Teks (since they're the only obtainable alternative)? Great topic for the fall! Matt ------------- http://www.correctcraftfan.com/diaries/details.asp?ID=3180 - 1976 Nautique |
Posted By: JoeinNY
Date Posted: October-14-2008 at 7:03pm
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I think it will go to the right because he has increased torque just not that far because it starts to fall off and because he is going to need more at the greater speed.
At the end of the day your going to need enough torque to turn the prop and drag is related to speed so more speed = more torque (given same slip and prop which in my opinion is not going to be the same I believe it will slip more) Reid gets a boat bouncing and then the torque per rpm isnt rising as much in fact it goes down. Alan's boat wont be as bad as yours or mine in terms of digging down the bow but its closer to ours than reid's after 53mph I would guess. I also maintain that mr pinkhams various fast boats all run signifcantly higher compression ratios than stock to go along with that better breating. That gives them both more torque and moves the curves left (similar to what alans new setup will do). I think the major difference will still be in how much more drag the boat experiences as it goes faster. Remote transmitting strain gauges on the drive shaft anyone? ------------- http://www.correctcraftfan.com/diaries/details.asp?ID=1477 - 1983 Ski Nautique 2001 1967 Mustang 302 "Decoy" http://www.youtube.com/watch?v=cO5MkcBXBBs - Holeshot Video |
Posted By: JoeinNY
Date Posted: October-14-2008 at 7:09pm
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Matt,
I believe Reid is working on an A/B type comparison for the hi-teks, my swap included a bunch of differences. Last time my engine was on a dyno (different setup than now but same heads and bottom end) my hp peak was at 4900-5000, I currently run 5300 with one prop and 4500 with the other so I hit both sides of the curve but miss the middle. I dont think the hi-teks were a huge improvement over the pcms, but dont doubt that they could be on some setups pushing more rpms. ------------- http://www.correctcraftfan.com/diaries/details.asp?ID=1477 - 1983 Ski Nautique 2001 1967 Mustang 302 "Decoy" http://www.youtube.com/watch?v=cO5MkcBXBBs - Holeshot Video |
Posted By: JoeinNY
Date Posted: October-14-2008 at 7:11pm
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Also, my hi-teks are a little odd and wont fit under a motor box but if someone wants to do an A/B comparison this fall (without the motor box on) I would lend them out for the cost of freight as I am pulling them for the winter anyway... ------------- http://www.correctcraftfan.com/diaries/details.asp?ID=1477 - 1983 Ski Nautique 2001 1967 Mustang 302 "Decoy" http://www.youtube.com/watch?v=cO5MkcBXBBs - Holeshot Video |
Posted By: TRBenj
Date Posted: October-14-2008 at 7:24pm
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Matt, all the aggressive cams and high-CFM carbs in the world wont do a whole lot of good if there are bottlenecks in the rest of the system. My bet is that your limiting factor was most likely the heads- though the exhaust and intake could have been playing a part as well. Remind us- what heads do you have on your boat?
Joe, not all of Reids boats bounce- and I would say that Alan's hull has more in common with the 16'5" Mustang than it does with my 19'6" tugboat. Those boats are still light and run bow high enough to outrun the laws of physics that drag us down so quick. Notice that the new powerband has him making 350lb-ft at 5700 RPM, where his current set up has him at that same level at just under 5k. I still maintain that the extra 50hp or so will get him close to another 400 RPM, and a good 2mph, maybe 3. ------------- |
Posted By: lewy2001
Date Posted: October-14-2008 at 9:40pm
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If thinking about Hiteks the Aussie$ is down to 0.65 us$ at the moment. Makes them much more attractive for you people than when it was 0.96
I would like to have someone do a direct comparison on the Hiteks vs PCM manifolds. If I ever were to replace my standard manifolds I think Hiteks would be on the shopping list. ------------- If you're going through hell, keep going http://www.correctcraftfan.com/diaries/details.asp?ID=2999" rel="nofollow - 89 Ski <a href="http://www.correctcraftfan.com/diaries/details.asp?ID=5685" ta |
Posted By: Brktracer
Date Posted: October-14-2008 at 10:34pm
Hey Joe, How much do you think those Hi-Teks weigh? (Matt wondering how much shipping would cost  ) You're going to laugh but I considered removing the cover and installing a set of car headers upside down for a test run to the end of the cove and back! 
Tim...it has stock heads with full port and polish and 1.94 / 1.60 valves, 9:1 compression, Performer RPM, 1.6 roller rockers, balanced, ARP rod bolts, etc. My first cam is this one but with 111 LSA: http://www.compcams.com/Cam_Specs/CamDetails.aspx?csid=870&sb=1 The current cam is this one except with 112 LSA: http://www.compcams.com/Cam_Specs/CamDetails.aspx?csid=878&sb=1 I wouldn't want to go any bigger on the cam than the second one as idle quality could become a concern. Unless of course it's a bigger engine! It is quite possible the heads have reached their full potential but I wouldn't think so? My current hypothesis is that the manifolds are limiting the exhaust flow. If I can disprove, it's got to be the heads! Matt ------------- http://www.correctcraftfan.com/diaries/details.asp?ID=3180 - 1976 Nautique |
Posted By: 81nautique
Date Posted: October-14-2008 at 11:30pm
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Well I'm getting back to the party late after a busy day but Joe you make a lot of sense although I'm leaning towards Tims thinking that I will be around 5700 and possibly pickup 3 mph. I also believe I will do that with the same prop I am running now as I have had that prop on since the stock motor was in the boat. After each set of mods to the motor I though I would have to adjust the prop but the only difference from 240 hp to my current setup was adding a little cup to it. The heads are being ported by Cam Research as he has worked with those heads before and insists he can massage them to produce more torque, that's also the reason we stayed with the 180cc runners so as not to hurt the torque. He will supply flow numbers once done and we'll plug the numbers in and see what difference there is.
Currently the boat turns 5300 and runs at 53mph. I do agree with the compression needs to get these things to turn, that was instantly obvious when I installed the gt40p heads as my CR went from 8.5 to 9.3. Thats why we're doing everything we can to bump up the cr by milling the heads to 54CC chambers and going with a thin a head gasket as I can find. We calculate the final CR to be 9.8:1 still short of where I think it should be but that was a fatal mistake in the beginning that we're trying to overcome short of putting in new pistons. ------------- You can’t change the wind but you can adjust your sails |
Posted By: 81nautique
Date Posted: October-14-2008 at 11:37pm
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Matt,
Several of us have had discussions about the PCM manifolds and the concensus is they may not be as constricting as they appear. Based on the results of those that have installed hiteks there seems to be a little disappointment to the performance improvements with that bolt on, not to say they're not worth it but the return may not have been as much as expected. With that said Reid seems adamant that the PCM risers are more of a problem than the manifolds themselves. I have a few ideas on that but need to do some more homework on alternatives first. Also if anyone replaces a set of PCM manifolds this winter because of rustout I would gladly pay to have them shipped to me so I could cut them open and get a cross section of them, I would expecially like to do that to a riser as well. ------------- You can’t change the wind but you can adjust your sails |
Posted By: 81nautique
Date Posted: October-14-2008 at 11:45pm
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Lastly I will be the first to admit that I am a rookie engine tuner, I've never felt experinced enough to interpret a plug chop confidently. Fully knowing my shortcomings there I am making an adapter that will sit between the manifold and the riser that will accept an air/fuel sensor. I've purchased an digital meter that will monitor A/F ratio at any rpm range and load so I can fully tune the engine in the spring. There's a good chance without it I will never get the engine tuned to perform near it's potential anyway. This will be a temporary meter so once dialed in it will be removed and I plan to make it available for anyone with PCM manifolds to borrow if they like. ------------- You can’t change the wind but you can adjust your sails |
Posted By: Brktracer
Date Posted: October-15-2008 at 12:18am
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Alan,
I'd be interested in borrowing your adapter when you're done. I have an Innovate LM-1 and Innovate LMA-2 for tuning my race car and would love to try it on the boat but never had a way to install it. I totally agree it would be interesting to cut the PCM manifolds and risers apart to see the inside. I chunked mine years ago when they were replaced. I was just thinking the other day that I'd love to have one back to cut open! The risers have a very small inlet and outlet. In fact, I'm betting the inlet is only about the same area as a couple exhaust ports. If I recall correctly the outlet is only about 2" diameter (inside). If the riser is the restriction that would be nice as it wouldn't be that difficult to fab a replacement. Anybody have an old manifold or riser for Alan or me to cut open? Maybe pictures of one cut open? Matt ------------- http://www.correctcraftfan.com/diaries/details.asp?ID=3180 - 1976 Nautique |
Posted By: 81nautique
Date Posted: October-15-2008 at 12:22am
Matt, Here's a graph based on your specs. Some of the input is guesswork but I think it's fairly close. Seems to match up pretty closely to a gt40 280 hp motor. Do you have flow data on the heads? Shoot me your email address and I'll send you a pdf of the report, if you want to change anything just let me know.
 ------------- You can’t change the wind but you can adjust your sails |
Posted By: Brktracer
Date Posted: October-15-2008 at 12:30am
I just pulled a spare riser gasket from my tool box and it measures 1 1/4" X 3". That's only 3.75 in^2. Usually on a similar engine in a car we run a 3" collector - 7.065 in^2!  It's fairly common to run a 2 1/2 exhaust system on similar engines which is 4.90 in^2.
The car that had an exhaust restriction I mentioned earlier picked up almost .5 sec in the 1/4 mile due to a 2 1/2" exhaust system with a pipe the installer shrunk to slip fit and weld together. No other changes except removing the restriction picked up almost .5 sec! Maybe we're on to something! 
Unfortunately, I don't have any flow data on the heads. Shoot me the report when you have a chance. brktracer@hotmail.com ------------- http://www.correctcraftfan.com/diaries/details.asp?ID=3180 - 1976 Nautique |
Posted By: Gary S
Date Posted: October-15-2008 at 2:01am
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Interesting thing to me is "the worlds fastest Mustang" my quotes,is that he's running basically stock exhausts with just some port matching.Maybe that accounts for why H&M's sound different.I would guess that the PCM's were not built for performance but for a way to get the exhaust out of the boat,fishing or skiing it didn't matter. Hiteks and to a lesser extent the H&M's I would guess,were made with performance 1st. I have to go now,I have to start locking my boat up ------------- http://www.correctcraftfan.com/diaries/details.asp?ID=1711&sort=&pagenum=1&yrstart=1966&yrend=1970" rel="nofollow - 69 Mustang HM SS 95 Nautique Super Sport |
Posted By: MaddMarxx
Date Posted: October-15-2008 at 3:19am
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Alan..Do you think you could run that program on my motor with what i have now plus the upgrades I am going to add soon, I think the CR is close to 9.75 now, its has 30 over with flat tops, 1.7 rockers, block is decked with a wiend stelth intake, with stock heads now but i am going to add a set of alum AFR 185s, and a cam with around 470 lift and a holly 715 cfm and a set of edelbrock manifolds and alum under drive pullys with a fluid dampner, my Brother has been telling me the heads and cam could add 75 to 100HP, I would like to see if your program agrees...thank you. ------------- |
Posted By: 81nautique
Date Posted: October-15-2008 at 10:06am
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Mark,
I can run one based on assumed CR but we could get a better report if you have all the details on the pistons and cam. Later today I'll post all the detailed info required to do a proper test but in the meantime we'll use some assumed numbers. Crazy busy day today so if I don't get to you til tomorrow hang in there I didn't forget you. ------------- You can’t change the wind but you can adjust your sails |
Posted By: SNobsessed
Date Posted: October-15-2008 at 11:00am
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I know this will get a chuckle out out you speed freaks, but I am wondering if an upgrade to GT40P heads would give any fuel
efficiency gain at 2500-3000 RPM range. It looks like the torque went up a little, as opposed to stock. Is it correct to assume that is with same fuel usage? We run at this midrange 95% of the time & I have all the power I need. ------------- “Beer is proof that God loves us and wants us to be happy.” Ben Franklin |
Posted By: 81nautique
Date Posted: October-15-2008 at 11:51am
Mark, are you saying you have 9.7:1 CR now or after the head change? Your stock heads probably have 65CC Chambers and the AFR185 will have 58CC. If thats the case it's going to push your 9.7 CR to 10.5:1 which the aluminum heads will like better than iron. You're going to be in the same situation as me with those big valves and will need to check for piston to valve clearance before bolting everything up. Do you have more detail on the cam? What I really need to do this right is the following info from the cam card: intake valve open=_____ intake valve closed=_____ exhaust valve open=______ exhaust valve closed=_____ specify if the above is at seat to seat or .o50 timing. Advertised duration and/or .050 duration(just specify which it is.) Those numbers are as important as the lift for the program to work. If you don't have actual cam info I'll substitute data from a few known cams like mine or trbenj's. Later AA ------------- You can’t change the wind but you can adjust your sails |
Posted By: 81nautique
Date Posted: October-15-2008 at 12:04pm
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Joe, A final note before I get to work today. A while back I set up a simple spread sheet to calculate prop, slip% based on known data including RPM, MPH, prop pitch, & trans ratio.
My boat currently runs 52.6 on GPS at 5300 rpm, with my 540 prop with the added cup that calculates out to 16.16% slip. If the slip percentage holds true and I could possibly turn the motor at 5700 the speed comes out at 56.5 mph. Several unknowns there such as will ssip stay the same and will the engine actually turn 5700. I think 5700 may be a stretch. If I change props to the 13x13 the spreadsheet shows it should only need to turn 5500 to get to 56.5 mph. Experience to date still leads me to believe that will be a challenge also. I firmly believe I will need exhaust work to do that and possibly a taller cam. ------------- You can’t change the wind but you can adjust your sails |
Posted By: Ben#155
Date Posted: October-15-2008 at 7:59pm
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[QUOTE=81nautique] Matt, Here's a graph based on your specs. Some of the input is guesswork but I think it's fairly close. Seems to match up pretty closely to a gt40 280 hp motor. Do you have flow data on the heads? Shoot me your email address and I'll send you a pdf of the report, if you want to change anything just let me know.
[/QUOTE
I tryed 3 inch headers but there was not much difference! I think stock manifolds has much torque and that is what you need. |
Posted By: reidp
Date Posted: October-15-2008 at 11:10pm
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Sorry I'm late. Couple of things from well up above. In regards to me thinking the risers could be a bottleneck, my thoughts were from this: My aluminum Barr manifolds on my blue '69 302 have 3-1/2" risers, and they perform very well comparitively. Port openings on the manifolds were enlarged by me, but mainly the outlets on the risers are larger, falling in line with what Matt above suggests as critical. On the PCMs, the outlets, just like the manifold-to-riser passage are significantly cut down.
These are some good and thought-provoking points above which will make for some really interesting conversation. Alan, I'd like to feed you some cam/head combo info for a good solid 302 build-up also. I'll try to do a PCM/HM/Hitek comparison some time in the not too distant future. ------------- ReidP /diaries/details.asp?ID=231&yrstart=1971&yrend=1975 - 1973 Mustang |
Posted By: 81nautique
Date Posted: October-16-2008 at 11:26am
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Mark,
Here are some graphs for engine both current and with the mods you mentioned, I also added one with the RHS heads I'm going to use. Without having the exact cam specs what I did was put together a stock 351 and then make your changes to it like CR and intake. There are no provisions in the program for marine exhaust so the reports I will email you are going to show stock exhaust with mufflers but the only other selections are open headers. All of the models so far have used the same exhaust options. There are no provisions in the program to add the underdrive pulleys. MM's 351 as it is currently, 9.7CR,stock cam, 1.7 rockers, stealth: 
MM's 351 with the AFR185,10.5 CR, .470 cam, 1.7 rockers, stealth: 
MM's 351 with the RHS180,10.5CR, .470 cam, 1.7 rockers, stealth: 
This one is a side by side: 
If you want anything changed just let me know, you might want to really take a good look at the RHS180 heads. I found that out of the box they flow better than the AFR and are less expensive although you'ld have to decide iron over aluminum. I think the real answer to your question is will a cam and head change add 75-100hp and it appears that it will. Better install some grab rails in that machine. ------------- You can’t change the wind but you can adjust your sails |
Posted By: GottaSki
Date Posted: October-16-2008 at 11:31am
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Now If someone were to comit to both fancy heads and hi-teks, that begs the question - "why stay with the hindrance of Windsor-style heads"
Quest for speed opens the door to make a clevor. The sb Hi-teks are the same price no matter the port arrangement, so its a chance to start fresh. Please use your calculator to see the potential in using CHI 3V heads. They are available in Alloy and Iron, and three different port volumes so the low end won't suffer as much as you think and the canted valves really boost breathing. Yes, different pistons are in order to optimize the whole package but that could be rationalized. I think its a worthy exercise. I predict you will be able to exceed the performance above and be able to keep the CR in a more practical range for pump gas. ------------- "There is nothing, absolutely nothing, half so much worthwhile as messing around with boats...simply messing." River Rat to Mole |
Posted By: 81nautique
Date Posted: October-16-2008 at 11:49am
AFR185/RHS180 flow comparison
 ------------- You can’t change the wind but you can adjust your sails |
Posted By: 81nautique
Date Posted: October-16-2008 at 11:53am
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GottaSki, I'll play around with that in the next few days but I'm sure I'll have some questions so stay tuned. ------------- You can’t change the wind but you can adjust your sails |
Posted By: Waterdog
Date Posted: October-16-2008 at 1:54pm
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Alan
I've been holding on to a set of cracked exhaust manifolds, to cut open. Would you cut it front to back, thru the center of the pipe plug holes on each end ? Just wondering what would be "best". ------------- - waterdog - http://www.correctcraftfan.com/diaries/details.asp?ID=3896&sort=&pagenum=2&yrstart=1978&yrend=1978" rel="nofollow - 78 Ski Tique |
Posted By: 81nautique
Date Posted: October-16-2008 at 2:41pm
That's what I was thinking of doing so we could get a look at the runners up to the riser. I also plan to port match mine when I get my heads in so I wanted to see how much material there is to work with. ------------- You can’t change the wind but you can adjust your sails |
Posted By: GottaSki
Date Posted: October-16-2008 at 3:05pm
most excellent. look forward to it. Likely those heads will like more cam lift than you are used to seeing. Most windsors reach deminishing returns above .45", but it appears the canted valves really open up and get away from the cyllinder wall from .45" on up and the flow continues to climb in earnest. ------------- "There is nothing, absolutely nothing, half so much worthwhile as messing around with boats...simply messing." River Rat to Mole |
Posted By: Waterdog
Date Posted: October-16-2008 at 5:56pm
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Alan
I'll get those exhaust manifolds out of the barn & put them in my work car. I'll cut 1 if I like it I'll cut the other the same and ship it to you. Probably just the inboard half to cut down on weight. Could you donate the cost of shipping to the club ( CCFan)? ------------- - waterdog - http://www.correctcraftfan.com/diaries/details.asp?ID=3896&sort=&pagenum=2&yrstart=1978&yrend=1978" rel="nofollow - 78 Ski Tique |
Posted By: 81nautique
Date Posted: October-16-2008 at 6:00pm
That will work Andy, do you have a bandsaw at your disposal? I wasn't really looking forward to tackling this with just a sawzall. ------------- You can’t change the wind but you can adjust your sails |
Posted By: Sabre002
Date Posted: October-16-2008 at 11:55pm
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This program is great I showed it to Reid a few years ago I have sense got a new version and you would not belive the thing it will let you toy with.
I have used it to build my LS1 and it was right were it said it would be. ------------- So what winks and f**k's like a tiger? www.facebook.com/sabre002 |
Posted By: Waterdog
Date Posted: October-17-2008 at 10:21am
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Alan
I pulled the manifolds out of the barn last night. Need to remove the risers and throw them in the trunk. We have a 20 in cut off saw at work for sectioning aircraft parts during engineering investagations. Maybe over the weekend I'll come in and cut them up. ------------- - waterdog - http://www.correctcraftfan.com/diaries/details.asp?ID=3896&sort=&pagenum=2&yrstart=1978&yrend=1978" rel="nofollow - 78 Ski Tique |
Posted By: 81nautique
Date Posted: October-17-2008 at 11:12am
Cool, I'm really interested to see how these things are shaped. Please send both halves if you can. I have a neighbor at my shop that does hydraulic flow testing for nuclear power plant cooling systems and started a conversation with him yesterday about the manifolds and he said once I remove mine for the upgrades he could help me set up a flow test on them. When I was in the window industry I had to take a sampling of each of our products to a test lab annually so we could have water and air infiltration tests performed for certification so I have a pretty good idea of whats going to be needed to do it. Should be fun putting the rig together. ------------- You can’t change the wind but you can adjust your sails |
Posted By: M3Fan
Date Posted: October-17-2008 at 11:44am
|
Although the riser area is a bit restrictive doesn't the length of the restriction become a factor as well? For example, an automotive header may be less restrictive at the collector but then you've got 2" exhaust going all the way back to the rear of the car with twists and turns, cats, mufflers, resonators, etc. With a lot of these boats you've just got 10 feet or so of 3" hose and nothing else to restrict flow after the riser. ------------- 2000 SN GT40 w/99 Graphics/Gel 2016 SN 200 OB 5.3L DI https://forum.fifteenoff.com |
Posted By: 8122pbrainard
Date Posted: October-17-2008 at 12:04pm
|
Joel, Very good point!! With some CFM figures, it's very easy to look on the graphs or calculate the restriction with different lengths and diameters of "tail" pipe. My graphs will show restriction in inches of water (manometer reading). I'll take a look to get a rough idea. The major unknown however will be the effect of the water in our wet exhausts. ------------- /diaries/details.asp?ID=1622" rel="nofollow - 54 Atom /diaries/details.asp?ID=2179" rel="nofollow - 77 Tique 64 X55 Dunphy Keep it original, Pete < |
Posted By: 81nautique
Date Posted: October-17-2008 at 12:08pm
While flow of the exhaust system is one concern another major factor that will not be overcome with stock manifolds is that they are considered a Non Tuned design meaning no pulse or suction waves are produced so there is absolutely no scavenging effects to help evacuate exhaust gases from the cylinder. You would need to get into a header/collector design and I don't believe even the hiteks fall into this catagory as they are not long enough. So restriction may not be as big a detriment as overall design. Let's not forget about the water in those 3" pipes and the effect it may have as well. ------------- You can’t change the wind but you can adjust your sails |
Posted By: 81nautique
Date Posted: October-17-2008 at 12:34pm
|
Thinking about this exhaust a little more, without scavenging, the engine is relying solely on the exhaust stroke of the piston to push the gases out of the cylinder. This also has an impact on the engines ability to refill the cylinder with a fresh charge of intake mix. Scavenging in combination with valve overlap could be the biggest factor in get air/fuel and spent gases through our engines. Scavenging creates the pulse and overlap allows the intake and exhaust valves to be open at teh same time using the pressure of the outflowing gasses to draw in fresh air/fuel mix. If that effect is being limited then the focus should still be on the exhaust.
Seems to me we need water jackets headers for a ski boat. ------------- You can’t change the wind but you can adjust your sails |
Posted By: Hollywood
Date Posted: October-17-2008 at 12:37pm
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Alan, what has gotten into you? You can still ski, plenty of "golden" years to do all that engine stuff. ------------- |
Posted By: 81nautique
Date Posted: October-17-2008 at 12:58pm
I don't know man, been hanging around with these motorheads for a couple of years and I'm hooked. Don't worry though, I still get Amped to go skiing but the head ringers seem to take longer to go away. Ended my last footin run of the year sunday with a big crash and the birdies didn't go away for an hour and I limped around until wednesday.!!!  ------------- You can’t change the wind but you can adjust your sails |
Posted By: 81nautique
Date Posted: October-17-2008 at 1:08pm
|
ok, last post for this morning, I gotta get out and make a living.
I took the last dyno on my engine with the new mods and then ran another one but replaced the stock exhaust and mufflers with short tube headers and mufflers. The results are below and quite dramatic. My engine on the left and the Header engine is on the right.  ------------- You can’t change the wind but you can adjust your sails |
Posted By: Brktracer
Date Posted: October-17-2008 at 4:54pm
Amen! ...still thinking of trying a set of headers!
Any predictions? ------------- http://www.correctcraftfan.com/diaries/details.asp?ID=3180 - 1976 Nautique |
Posted By: JoeinNY
Date Posted: October-17-2008 at 5:02pm
Matt, I dont think the hiteks weight is prohibitive to shiping, someone here has the number it is in the 10-20 lb each range. I will try and pull out my dyno sheet and get specifications to alan here so we can run mine and see how close we can get to what the dyno measured... lots to talk about here but I am late for a meeting... ------------- http://www.correctcraftfan.com/diaries/details.asp?ID=1477 - 1983 Ski Nautique 2001 1967 Mustang 302 "Decoy" http://www.youtube.com/watch?v=cO5MkcBXBBs - Holeshot Video |
Posted By: RainDog
Date Posted: October-18-2008 at 11:44am
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Alan,
Would your buddy be willing to flow a Hi-Tek header as well? It would be interesting to see if it flows any better and by how much. ------------- http://www.correctcraftfan.com/diaries/details.asp?ID=1868&sort=&pagenum=1 - 62 Classic http://www.correctcraftfan.com/diaries/details.asp?ID=5242&sort=&pagenum=1 - 2002 Super Air |
Posted By: 81nautique
Date Posted: October-18-2008 at 12:11pm
Steve if we can get a bench rigged up for very little money I'd be willing to test anything. The neighbor uses all digital monometers and he's not sure if the boss is going to let them be loaned out. Still working on it thought. I just picked up a set of HM manifolds on ebay last night so those will go on the list as well. ------------- You can’t change the wind but you can adjust your sails |
Posted By: 8122pbrainard
Date Posted: October-18-2008 at 12:20pm
I wish we had a means of measuring the resistance of our wet tube exhausts and then comparing them to the automotive exhausts. The water bouncing around in the "tail" pipe I'm sure adds up. ------------- /diaries/details.asp?ID=1622" rel="nofollow - 54 Atom /diaries/details.asp?ID=2179" rel="nofollow - 77 Tique 64 X55 Dunphy Keep it original, Pete < |
Posted By: Brktracer
Date Posted: October-18-2008 at 11:24pm
Alan: Glad you found some HM manifolds. I look for them periodically but have yet to see a set for sale. Any idea when you might test them? Pete: You make a great point about the water. I'm betting the amount of water we are pumping through the exhaust is overkill as well. But, that's probably not an area to fool around with unless we are very careful! Matt ------------- http://www.correctcraftfan.com/diaries/details.asp?ID=3180 - 1976 Nautique |
Posted By: 81nautique
Date Posted: October-19-2008 at 11:24am
I don't want to pull anything apart until all my parts are in and that looks like mid november. I wasn't sure I wanted to go with the HM's but they showed up with a low buy it now so I scooped them up. Hopefully this will also solve the taller valve cover issue that I had with the PCM's. Ofcourse before they go on I'll have to polish them!! ------------- You can’t change the wind but you can adjust your sails |
Posted By: boat dr
Date Posted: October-19-2008 at 12:24pm
|
Allen , give me a call . I may have some pieces to add to this maze.
Boat dr 1-318-386-2825 ------------- boat dr /diaries/details.asp?ID=4631 - 1949 Dart /diaries/details.asp?ID=1533 - 1964 American Skier |
Posted By: Luchog
Date Posted: October-19-2008 at 10:38pm
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how would the Commander manifolds flow comnpared to others? I'm about to buy an engine with these. My boat uses some square log type replacements. ------------- http://www.correctcraftfan.com/diaries/details.asp?ID=2095" rel="nofollow - 1980 Ski Nautique Commander 351W |
Posted By: JoeinNY
Date Posted: October-20-2008 at 1:39pm
I see no reason why the commanders (at least 3 inch outlet commanders) wouldnt flow as well or better than the holman moody ones. They are extremely similar manifolds without the up and down riser. I am also not convinced that the pcm manifolds aren't better or equal to both the commanders and the HM's, although they are much quieter. Absolute flow will not be the only determination. A lot of the marketing around the PCM pyramid design was related to the effective "runner" length of the PCMs' being much more equal between cylinders than the log style manifolds. It may all be bs but it is something to consider, logs definitely dont help with scavenging. The stock PCM configuration supports a lot of horsepower in the GT'40's and other later engines. The python engines do pretty well with PCM manifolds that dont look a heck of a lot different than the sbf ones. So my plan was to test my commanders vs hi-teks vs pcms on the same engine here in the fall (not a great test anyway because its not a stock displacement engine), but since my boat is down once again thats not going to happen. However I do have a set of commanders I could ship out with those hi-teks if someone really wants to get some water testing in... ------------- http://www.correctcraftfan.com/diaries/details.asp?ID=1477 - 1983 Ski Nautique 2001 1967 Mustang 302 "Decoy" http://www.youtube.com/watch?v=cO5MkcBXBBs - Holeshot Video |
Posted By: Mojo
Date Posted: October-20-2008 at 5:55pm
|
Magic,
I have the manifold in the shed. I'll bring it Thursday. Hope you can still make it for beers... Moj' ------------- 05' SV211 TE 73' Martinique had:96' SNOB had:76' Nautique had 77 Tique |
Posted By: MaddMarxx
Date Posted: October-21-2008 at 12:18am
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Maybe if I put this on my Boat I may be able to give Reid a run for his money!!
http://cgi.ebay.com/ebaymotors/4-71-blower-351w-hot-rod-street-rod-gasser-supercharger_W0QQcmdZViewItemQQ_trkparmsZ72Q3a1207Q7c66Q3a2Q7c65Q3a12Q7c39Q3a1Q7c240Q3a1318QQ_trksidZp3286Q2ec0Q2em14QQhashZitem180299181552QQitemZ180299181552 - 471 Blower ------------- |
Posted By: 81nautique
Date Posted: October-31-2008 at 12:24pm
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Well Andy(waterdog) has finished his monumental task of sectioning a PCM manifold and it is on it's way to me. I'll post a few pics once I get it and maybe we'll bump some life back into this thread.
I've started dismanteling my Holman Moody manifolds but they haven't been apart in 40 years and they're kicking my butt. Finally had to give in to the hacksaw and cut the risers off. It's obvious why these went in the trash as the internal mating surfaces were not sealing and this boat must have been hyrolocking with all that water leaking in. A trip to the machine shop to remove the studs(I gave up on that too) and resurface them and I'll be back on track. After that we'll make teh adapter plate for the A/F sensor, then get back to cleaning and polishing them up. Probably won't get to any flow comparison testing between the HM and the PCM for a while yet but it's still on the list. Doc, I 've had a pretty busy week and never did find the time to call so if you care to post your engine specs online here I'll run a dyno for you. ------------- You can’t change the wind but you can adjust your sails |
Posted By: 8122pbrainard
Date Posted: November-09-2008 at 1:58pm
|
The blatantly obnoxious advertising posting of the Hitek manifolds by Ash has gotten me thinking about their design again. Allen, I believe you made a comment that they really aren't a true "header" design and I certainly agree. The performance gains are probably due to the smoother and larger porting. It's a shame Hitek didn't carry the design farther with continuing the water jacketed exhaust tubes down the aft side and to a collector closer to the bilge duplicating a true header. Most of our engine enclosures have the room to do it. The only issue would be keeping the low side of the water jacket full before the collector. Certainly not a very difficult problem with a block off plate on the high side of the existing and then hosed to a bottom fill on the tail end. Up the tail end to another outlet hosed back to the far side of the collector.
As far as flow of the existing design, it's too bad Allen couldn't check them out with his flow bench he's building. I feel we should ask Ash to plug up all the ports on a set, strap them to his back as "water wings" and swim them over!! ------------- /diaries/details.asp?ID=1622" rel="nofollow - 54 Atom /diaries/details.asp?ID=2179" rel="nofollow - 77 Tique 64 X55 Dunphy Keep it original, Pete < |
Posted By: Andy
Date Posted: November-14-2008 at 1:38am
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I got my newest issue of Hot Rod mag tonight. Page 92 in big letters it reads "351 hop-up". They are stating 54 rear wheel horsepower with the Edelbrock top end "kit". It consists of Performer RPM XT heads, 1.6:1 roller rockers (crane parts,not included in the kit), Performer RPM intake, Performer link timing set, Rollin Thunder Cam, Edelbrock hydraulic roller lifters, and a shorter pushrod length.
Their dyno sheet showed 303.29 rwhp at 5700 RPM. |
Posted By: 81nautique
Date Posted: November-14-2008 at 11:44am
Thought I would repost these photos over here.
Still planning on doing some basic flow tests but I think that won't happen until January when I get a little free time. It will take me until then to complete the refurbishing of my HM manifolds anyway. The new heads shipped yesterday so I'm anxiously waiting for them to arrive. I'll post some pics and flow data once I get it then start pulling things apart after the first of the year. ------------- You can’t change the wind but you can adjust your sails |
Posted By: Waterdog
Date Posted: November-14-2008 at 12:00pm
|
Alan
I'm looking forword to seeing a picture of the exhaust ports. I talked to Scott at cam research and some other guys before I ported my GT 40p's. I think I got pretty close to what was recomended (for working this head for the first time). ------------- - waterdog - http://www.correctcraftfan.com/diaries/details.asp?ID=3896&sort=&pagenum=2&yrstart=1978&yrend=1978" rel="nofollow - 78 Ski Tique |
Posted By: JoeinNY
Date Posted: November-14-2008 at 3:01pm
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I did pull my hiteks and commanderstyle the other day if anyone wants them for testing purposes let me know. ------------- http://www.correctcraftfan.com/diaries/details.asp?ID=1477 - 1983 Ski Nautique 2001 1967 Mustang 302 "Decoy" http://www.youtube.com/watch?v=cO5MkcBXBBs - Holeshot Video |
Posted By: SNobsessed
Date Posted: November-14-2008 at 8:57pm
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Joe - Don't send your hiteks to 81 Nautique, otherwise we might get to see what's inside them too! ------------- “Beer is proof that God loves us and wants us to be happy.” Ben Franklin |
Posted By: Andy
Date Posted: November-19-2008 at 2:11am
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So heres a newB question for ya. When purchasing a cam can I get any cam advertised or is there a rot specific note I need to look for, or a specific place I should call, or a magic troll to put under my timing cover?
|
Posted By: Waterdog
Date Posted: November-19-2008 at 10:33am
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Andy
Give Cam Research a call 303-762-0022 There Ford guys. My reverse rotation (ski boat grind) cam & lifters was about $250. ------------- - waterdog - http://www.correctcraftfan.com/diaries/details.asp?ID=3896&sort=&pagenum=2&yrstart=1978&yrend=1978" rel="nofollow - 78 Ski Tique |
Posted By: Brktracer
Date Posted: November-19-2008 at 12:50pm
|
Comp cams can grind you one also. I think any specs other than stock will have to be custom ground.
Joe, I would love to try the manifolds but I have a big problem. Our lake is down about 25' now due to the drought. Tree tops are starting to poke up in various places so there's no way I'm taking the Nautique out. I would love to do some testing but can't until we get some serious rain! It's not looking good for this summer! 
Matt ------------- http://www.correctcraftfan.com/diaries/details.asp?ID=3180 - 1976 Nautique |
Posted By: TRBenj
Date Posted: November-19-2008 at 1:01pm
You'll find many Cam Research endorsements here. JoeinNY, Boat Dr, Alan (81Nautique), and myself all have used them in our boats. They only do Fords and they know their stuff. I think I was the first here to find them, but they had already done cams for a lot of ski boats. See if Comp or Crane even know what a Ski Nautique is! Before you call them, you'll want to have some details on hand. They'll need specific info on your other engine components (heads, intake, compression ratio, etc), and obviously need to know whether or not you have a reverse rotation motor in order to make a good recommendation. That $250 number sounds about right- and that price should include the break-in service that they offer. ------------- |
Posted By: Andy
Date Posted: November-20-2008 at 12:17am
| Thanks guys!! |
Posted By: 81nautique
Date Posted: November-20-2008 at 12:22am
|
The new heads came back from Cam Research today. We bought bare castings and had them ported, angle milled for smaller cc chamber, 5 angle valve job and they installed springs to match my cam and rpm operating range.
The old heads in the photos are stock castings from the original 81 engine before the rebuild, the gt40p are still on the boat for now. Enjoy!!! 
 ------------- You can’t change the wind but you can adjust your sails |
Posted By: Andy
Date Posted: November-20-2008 at 12:26am
| Holy holes there magicman!!! |
Posted By: Waterdog
Date Posted: December-16-2008 at 4:22pm
|
Bump to the top ------------- - waterdog - http://www.correctcraftfan.com/diaries/details.asp?ID=3896&sort=&pagenum=2&yrstart=1978&yrend=1978" rel="nofollow - 78 Ski Tique |
Posted By: 81nautique
Date Posted: December-16-2008 at 4:36pm
|
Funny you bumped this Waterdog, I finally got some time this weekend to gasket match the intake to the new heads. Needed to remove lots of material but they came out pretty good. The factory port castings are not very uniform and even if they matched up good enough they could use to have some of the casting lines removed so I've cleaned up as deep into the ports as I can get. I still have some drum sanding to do but the heavy work is done. Took about 4 hours to do the intake.
Exhaust manifolds are coming back from the machine shop later this week after having all mating surfaces machined. I'll gasket match them next. Biggest problem I see there is I don't think I'll be able to open them up enough to match the ports on the heads so the exhaust is still somewhat of an issue. Needed to remove almost an 1/8" of material 
Partially completed port matching  ------------- You can’t change the wind but you can adjust your sails |
Posted By: 79nautique
Date Posted: December-16-2008 at 5:25pm
|
Allen taper the cut when you do the exhaust, The flange is thick enough and it's much better to have a transition than a flat wall, think of it as adding a chamfer all around. Depending on how much needs removed and how deep you can go will drive the angle. ------------- http://www.correctcraftfan.com/diaries/details.asp?ID=756&sort=&pagenum=1&yrstart=1979&yrend=1979 - 79 nautique |
Posted By: 81nautique
Date Posted: December-16-2008 at 7:16pm
That's the plan Chris, problem is I'm switching over to Holman Moody manifolds and they are water jacketed all the way down to the block so there's just not much material fro removal and I'm concerned about cutting through. I'll go as far as I dare and then taper. Thanks ------------- You can’t change the wind but you can adjust your sails |
Posted By: 79nautique
Date Posted: December-16-2008 at 7:44pm
well that would be the first ones to do that because to do that then you also have to have the jacket around the mounting bolts and I doubt that they are. There should be plenty of wall thickness in the runners that mount to the heads, you don't need to open them up all of the way to the common passage just create a nice smooth transition and 1/2"-1" is more than enough ------------- http://www.correctcraftfan.com/diaries/details.asp?ID=756&sort=&pagenum=1&yrstart=1979&yrend=1979 - 79 nautique |
Posted By: 81nautique
Date Posted: December-16-2008 at 8:24pm
Lousy picture but all I have here on this computer. The arrows indicate the area on the bottom of the manifolds where the ports are water jacketed all the way to the head. Although I'm not sure how much I will have to remove yet I'll have to be careful, that's all.
The thickness of material between the bolt holes and the port "should" allow for a fair amount of opening but the stock ports on the HM and PCM manifolds are so much smaller than on these heads that I will have to settle for a happy medium. These ports are really designed for a nice set of headers but I'll make it work. ------------- You can’t change the wind but you can adjust your sails |
Posted By: MaddMarxx
Date Posted: December-17-2008 at 2:54am
|
Alan..Those heads look great, your Boat is going haul butt with them on it, What do they cost? And are you going to run the same Cam you are using now? ------------- |
Posted By: 81nautique
Date Posted: December-17-2008 at 9:12am
Mark, You can buy them assembled from Summit for less than $1000 but I got them bare through Cam research and had him do some porting and we milled them to get my compression up. He then did a 5 angle valve job and matched the springs to my cam. The porting wasn't mandatory but he talked me into it and I'm glad he did, he does very nice work. Take a look at the area around the valve guides compared to stock heads, it's amazing how much work went into that area to get it looking that nice. These same heads are available in aluminum if you want to go that route. I am staying with the cam that was in the boat, after installing the 1.7 roller rockers it will be at .488 lift. If I was starting from scratch I would change the cam out but I think this will be a runner as is. ------------- You can’t change the wind but you can adjust your sails |
Posted By: 79nautique
Date Posted: December-17-2008 at 11:06am
|
Allen I'm not so sure that the water jacket extends to the extent that you say it really doesn't appear that there is enough wall thickness for there to be a water jacket around them maybe on the backside in between the bolts could be a small pocket but theres no way it's all around the port. More like a straight cyclindrical shape otherwise the core needed for the casting to make the cavity doesn't make since and gets to thin and would never hold togther when the aluminum was poured in the mold. ------------- http://www.correctcraftfan.com/diaries/details.asp?ID=756&sort=&pagenum=1&yrstart=1979&yrend=1979 - 79 nautique |
Posted By: 81nautique
Date Posted: December-17-2008 at 11:35am
|
I wish I had them in front of me to take a look as I'm going from memory, I should have them back this weekend but you're probably right. I tend to be over-cautious with first time projects so I'm sure I'm over planning something that's fairly routine. Thanks for the help, I'll post some better pictures once I get going on them. I have the polishing just about done too, they certainly don't look like the above photo anymore. ------------- You can’t change the wind but you can adjust your sails |
Posted By: Brktracer
Date Posted: December-17-2008 at 11:58pm
|
Alan,
What diameter is the outlet on the HM manifolds (measured at the flange where the riser attaches)? Thanks, Matt ------------- http://www.correctcraftfan.com/diaries/details.asp?ID=3180 - 1976 Nautique |
Posted By: JoeinNY
Date Posted: January-02-2009 at 5:39pm
|
Well it's 2009 and time for everyone to get back to working on solutions to worlds most pressing issues like the massive deficit of 60 mph correctcrafts, so we better get this thread back on the first page. I took the opportunity to measure the exhaust ports on a couple manifolds over the holidays and thought I would share the results for reference. On the hiteks the opening is approx 1.29 inchs x 1.53 inches high the runners are big and smooth but have some dimpleing for the bolt heads. On my pcm manifolds that are ported as far as I would consider safe the openings are more peanut shaped. The port ended up about 1.45 high and near the top and bottoms 1.28 wide, however near the mounting holes they neck down to about 1.18. The runners are fairly smooth but restrict down quite a bit after the interface due to mounting bolt head dimples.
Alan, How big are the ports on the Rhs heads? ------------- http://www.correctcraftfan.com/diaries/details.asp?ID=1477 - 1983 Ski Nautique 2001 1967 Mustang 302 "Decoy" http://www.youtube.com/watch?v=cO5MkcBXBBs - Holeshot Video |
Posted By: eric lavine
Date Posted: January-02-2009 at 6:18pm
|
I think some work could be done to get some good clean fresh air in the engine boxes, it gets pretty hot in there and air is pretty restricted and i personally dont think the engines breath enough...thats me though, dollar for dollar it is cheap to get more air in the compartment ------------- "the things you own will start to own you" |
Posted By: JoeinNY
Date Posted: January-02-2009 at 9:50pm
While that might be an issue in some of these boats, particularly older examples it is not an issue in my 83, I have run it down the lake with no motor box and saw no significant change in performance, just louder and scarier. ------------- http://www.correctcraftfan.com/diaries/details.asp?ID=1477 - 1983 Ski Nautique 2001 1967 Mustang 302 "Decoy" http://www.youtube.com/watch?v=cO5MkcBXBBs - Holeshot Video |
Posted By: 81nautique
Date Posted: January-03-2009 at 12:03am
|
Thanks for bumping it Joe, I thought everyone lost interest!!!
I'll get the port dimensions on sunday and post them. I'm almost ready to start pulling the 81 apart, I've been waiting for all my parts to come in before touching it. I should have the HM manifolds back next week, they needed some machining and since it's being done as a favor I've had to be patient waiting for them. I'm not sure if I'll ever get to the flow testing as work has taken a few turns and I'm going to be fairly busy the next few months. I would still like to but's it not a priority right now. ------------- You can’t change the wind but you can adjust your sails |
Posted By: eric lavine
Date Posted: January-03-2009 at 11:51am
|
Joe, I think as you are running, the wind over the windshield creates a vacuum, so i dont think it would help with the cover up or down.
I was more on the lines thinking of forced fresh air from the front of the boat...it just seems the little venting they have now doesnt matter ------------- "the things you own will start to own you" |
Posted By: 81nautique
Date Posted: January-04-2009 at 7:16pm
|
Joe, The RHS exhaust ports are square at 1.34x1.34 Again I hope to have the manifolds back by the weekend so I'll measure the HM before and after porting.
------------- You can’t change the wind but you can adjust your sails |
Posted By: M3Fan
Date Posted: January-05-2009 at 12:50am
|
What's the logic in using the HM manifolds? Are they proven to flow better? ------------- 2000 SN GT40 w/99 Graphics/Gel 2016 SN 200 OB 5.3L DI https://forum.fifteenoff.com |
Posted By: jbear
Date Posted: January-05-2009 at 1:07am
No Way! Altho I have no idea what you guys are talking about...I sure do like the way you say it.. john ------------- "Loud pipes save lives" AdamT sez "I'm Canadian and a beaver lover myself"... |
Posted By: Gary S
Date Posted: January-05-2009 at 1:55am
Cool factor Joel Pure speculation on my part but they are 3" outlets, the Donzi guy's want them and Reid has them on the worlds fasest Mustang.
------------- http://www.correctcraftfan.com/diaries/details.asp?ID=1711&sort=&pagenum=1&yrstart=1966&yrend=1970" rel="nofollow - 69 Mustang HM SS 95 Nautique Super Sport |
Posted By: jbear
Date Posted: January-05-2009 at 2:01am
What more of a recomendation does a guy need? How was the last few days of forced OT? Looks like your weather is messy. Gonna call this week? john ------------- "Loud pipes save lives" AdamT sez "I'm Canadian and a beaver lover myself"... |
Posted By: JoeinNY
Date Posted: January-05-2009 at 3:33am
|
I agree they are cool, they polish up pretty, they are loud and they do save weight maybe not the best flowing but certainly close enough.
Thats a pretty wide port, not a whole lot of material between the mounting holes and the port to seal. However they are the same width as my current heads though and I have had more problems getting them to seal on the bottom than on the sides. ------------- http://www.correctcraftfan.com/diaries/details.asp?ID=1477 - 1983 Ski Nautique 2001 1967 Mustang 302 "Decoy" http://www.youtube.com/watch?v=cO5MkcBXBBs - Holeshot Video |
Posted By: 81nautique
Date Posted: January-05-2009 at 9:33am
Not to mention the PCM manifolds don't allow for taller valve covers without adding a spacer to move them outboard, which ofcourse doesn't exist so more backyard enginering required. Joe, I am concerned with sealing them up. Have you ever had any luck with the copper permatex hightemp sealant. ------------- You can’t change the wind but you can adjust your sails |
Posted By: 8122pbrainard
Date Posted: January-05-2009 at 9:52am
Alan, I'd like to comment on the copper high temp. It's a silicone and I'm not a big fan of any silicones! They have very poor adhesive qualities and really don't "wet out" on the surface. They only work when you have a large surface areas. I'd go with the "tried and true" Permatex non hardening (no. 2) Form-a-gasket. It's good for 400F. ------------- /diaries/details.asp?ID=1622" rel="nofollow - 54 Atom /diaries/details.asp?ID=2179" rel="nofollow - 77 Tique 64 X55 Dunphy Keep it original, Pete < |
Posted By: JoeinNY
Date Posted: January-05-2009 at 12:44pm
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I have used the paint on copper gasket sealant from permatex, and the 1372 non hardening similar to the number two pete suggests but rated to 600 f, but have never used the copper silicone type. Just bought some the other day though that I plan to use to install an recently repaired manifold on a grady white that's been hogging the back center bay of my shop for way too long, it's got nla gaskets and not the greatest surfaces for sealing. Some swear by the copper silicone and I haven't heard any complaints so it's good enough for a gw. If you have pretty good but narrow surfaces I would start with 1372 on both surfaces thin and uniform with a good gasket between. ------------- http://www.correctcraftfan.com/diaries/details.asp?ID=1477 - 1983 Ski Nautique 2001 1967 Mustang 302 "Decoy" http://www.youtube.com/watch?v=cO5MkcBXBBs - Holeshot Video |
Posted By: TRBenj
Date Posted: January-05-2009 at 2:30pm
Eric, I disagree- Ive skied on enough cold mornings to know that the windshield doesnt protect much beyond where the driver sits. The engine gets more fresh air than it could possibly use with the motorbox off. Ive driven mine plenty with it off and saw no difference in performance either- though it is louder and looks pretty cool. The venting from the factory must be sufficient, at least on most of our boats. I do see your point, though- my buddy has a pretty fast MC that picks up a good 2mph with the engine cover off- it must be starving for air with it on. Alan, cant wait to see everything bolted up! ------------- |
Posted By: eric lavine
Date Posted: January-05-2009 at 3:04pm
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Just shooting ideas out there, it seems some of the older boats have 1, 3" going to it' more or less observations ------------- "the things you own will start to own you" |
Posted By: Andy
Date Posted: January-07-2009 at 11:17pm
Have you considered a set of header flanges? I know some people who make them in Addison. How thick of a spacer would you need? http://www.victoryheaderflanges.com/ - Victory Header Flanges |