Torque & HP Open Discussion

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".

81nautique wrote: GottaSki, I'll play around with that in the next few days but I'm sure I'll have some questions so stay tuned.

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.

Waterdog wrote: 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)?

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.

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.

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.

M3Fan wrote: 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.

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.

Alan, what has gotten into you? You can still ski, plenty of "golden" years to do all that engine stuff.

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.

Brktracer wrote: Hey Joe, How much do you think those Hi-Teks weigh? (Matt wondering how much shipping would cost ) Matt

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...

RainDog wrote: 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.

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.

81nautique wrote: I just picked up a set of HM manifolds on ebay last night so those will go on the list as well.

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

Allen , give me a call . I may have some pieces to add to this maze.

Boat dr 1-318-386-2825

Luchog wrote: 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.

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...

Maybe if I put this on my Boat I may be able to give Reid a run for his money!!
471 Blower

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!!