Ski Nautique Y-pipe exhaust
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=42782
Printed Date: April-28-2024 at 7:24am
Topic: Ski Nautique Y-pipe exhaust
Posted By: gt40KS
Subject: Ski Nautique Y-pipe exhaust
Date Posted: May-13-2018 at 11:41pm
As part of the rebuilding process, I am getting rid of the inverta-flo and installing a y-pipe, straight through exhaust system. I know it's not very popular with most of the CCF folks, but let's face it, we all know I'm not your conventional CCF thinking guy.  Anyway, as such it's not an incredibly common topic. I've done my thread searching and read what there is out there and until recently I figured it was fairly straight forward. But something came up in a Fish Nautique thread recently that got me thinking so I thought I'd ask the group to get some input from those who may know a bit more. The question is if I need to be concerned about water reversion with no muffler or inverta-flo and the stock GT-40 risers? I'm thinking that the exhaust is well above the water line so I should be good, but a little more input would be appreciated. Thanks  ------------- JCCI 1995 Ski Nautique GT40 |
Replies:
Posted By: SNobsessed
Date Posted: May-14-2018 at 12:31am
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You might consider putting a flap on the outlet, to prevent a big wake from pushing in. ------------- “Beer is proof that God loves us and wants us to be happy.” Ben Franklin |
Posted By: gt40KS
Date Posted: May-14-2018 at 1:05am
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Thanks Chris. The boat had a flapper when I bought it. But I haven't inspected it very well, I may need to replace it. ------------- JCCI 1995 Ski Nautique GT40 |
Posted By: gun-driver
Date Posted: May-14-2018 at 2:04am
| You might as well leave the back seat out for the extra room as no one will want to sit in the back seat anymore, it's obnoxiously loud. I have straight hose/pipes on my '85 and I'm putting mufflers back in. Just say'in |
Posted By: Hollywood
Date Posted: May-14-2018 at 2:19am
| Riding around in the back seat of a ski boat is a crummy ride with or without muffler(s) |
Posted By: Riley
Date Posted: May-14-2018 at 9:07am
| Crummy ride in ski boat better than no ride in ski boat. |
Posted By: JoeinNY
Date Posted: May-14-2018 at 10:43am
Its not that uncommon at one point I am pretty sure the boat dr was selling a kit at my correct craft parts and race city marine also installed one or two IIRC. Search the older posts and you will probably find a picture, or give the boat dr a call. Keeping a flapper is not a bad idea. ------------- 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 |
gt40KS wrote:Posted By: gt40KS
Date Posted: May-15-2018 at 12:23am
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Thanks Joe - got the new Centek Y already and new 3 1/2" HD exhaust hose to make the connections. I was just curious if anyone had experienced any problems associated with reversion since it's basically just straight through pipes now. Searching the older posts as you suggested, most of the installs I've found don't appear to have anything more than I will have, save one that had in line mufflers. And though Paul may be right about it's ultimate sound level, I'll take my chances. I can always add something later if it's too loud for us.  ------------- JCCI 1995 Ski Nautique GT40 |
Posted By: Hollywood
Date Posted: May-15-2018 at 12:36am
| I am currently working on a pair of v hull boats both with log exhaust manifolds and no mufflers. I am heavily counting on my flappers to prevent reversion. |
Posted By: gun-driver
Date Posted: May-15-2018 at 1:24am
| Hollywood I had Edelbrock logs on my ‘85 with straight pipes no snails with no problems. I did have new exhaust flaps on the outside though. |
Posted By: TRBenj
Date Posted: May-15-2018 at 8:38am
| Reports of logs being susceptible to reversion (even combined with no mufflers or flaps) seem a bit exaggerated... otherwise, I’m not sure how so many of us with older boats configured that way have escaped this reversion epidemic for so long. |
Posted By: 8122pbrainard
Date Posted: May-15-2018 at 8:58am
Plus 1. I can honestly say I have never heard of a "reversion" issue even back in the days of logs, straight pipes, no snails and no flappers. My X55 is a good example. . ------------- /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: Hollywood
Date Posted: May-15-2018 at 11:23am
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I wouldn't be too concerned in flat bottom boats where the engine is higher up off the water. Someone like Gary or Ken might be able to find the spacers used even on PCM pyramid manifolds on the Fish. |
Posted By: Riley
Date Posted: May-15-2018 at 11:25am
| Is the engine lower in the water in a BFN? |
Posted By: Hollywood
Date Posted: May-15-2018 at 11:25am
| Yes. |
Posted By: 8122pbrainard
Date Posted: May-15-2018 at 11:33am
I didn't limit my statement to flat bottoms only. ------------- /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: Orlando76
Date Posted: May-15-2018 at 11:44am
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I still have logs and straight pipes and no problemo. ------------- Please support The Cystic Fibrosis Foundation 1976 Ski Nautique 351 Escort 1993 Ski Nautique purple and black 351 HO PCM |
Posted By: Hollywood
Date Posted: May-15-2018 at 11:47am
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I assume you're talking about a 70s ski nautique? If so, great, add another flat bottom boat to the list... |
Posted By: Riley
Date Posted: May-15-2018 at 11:56am
| If you're elbows are significantly closer to the waterline than they are in a flat bottom, why not get some proper elbows or PCM manifolds and avoid all that pain when your weekend suddenly turns to saving your engine because it filled up with water? |
Posted By: Hollywood
Date Posted: May-15-2018 at 12:05pm
| But I ski weekdays too... |
Posted By: Riley
Date Posted: May-15-2018 at 12:06pm
| Then you have plenty of time to have those cool looking logs. |
Posted By: TRBenj
Date Posted: May-15-2018 at 12:16pm
| The engine is lower relative to floor height in a v-hull like the Bfn but I bet the engine height relative to the water isn’t that much different. All that hull allows the a v-hull to float higher- the Bfn doesn’t dunk the chine by much, whereas the small flat bottoms float with the chine nearly a foot below the surface. |
Posted By: Gary S
Date Posted: May-15-2018 at 12:17pm
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I have a feeling this is more an urban legend,does anyone have actual experience getting water in? Someone somewhere probably had a problem with a high overlap cam and over the transom exhausts,some other guys had trouble with big sport fishing boats backing down when fighting fish and then PCM's marketing dept who would sell an engine for any type boat said that their pyramid style exhaust were better than the logs for that reason. We just don't back up hard,we spend most our time going forward. ------------- 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: Hollywood
Date Posted: May-15-2018 at 12:19pm
| So you don't have a v hull log setup nor have you measured. Thanks for your input TRB |
Posted By: Riley
Date Posted: May-15-2018 at 12:22pm
That's how photos of both boats look to me. What about the noise levels from lack of mufflers? |
Posted By: Orlando76
Date Posted: May-15-2018 at 2:19pm
I think my cousin’s brother’s first grade teacher’s landscaper SN had logs too. ------------- Please support The Cystic Fibrosis Foundation 1976 Ski Nautique 351 Escort 1993 Ski Nautique purple and black 351 HO PCM |
Posted By: throttle out
Date Posted: May-17-2018 at 9:13am
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Just an FYI I literally just did this conversion on my 89 using a Centek y-pipe. I fired it up for the first time yesterday and the sound difference is NO where near what I was expecting. At an idle sitting on the trailer it honestly would be hard to tell a difference, it is ever so slightly louder but more just sounds a bit different. At WFO it could be a completely different ball game but I won't know that for about a month yet as I'm replacing my interior. My buddy's got an 88 SN and his on the trailer is still much louder than mine at an idle, and sounds better as well. My boat slightly edges his out performance wise but man the 88 and older Nautiques sure do sound perfect lol. ------------- 1989 Ski Nautique 2001 351 PCM w/ 1-1.23 |
Posted By: gt40KS
Date Posted: May-17-2018 at 9:14pm
Good to hear real feedback from one that not only has done the conversion, but also seems to appreciate the throaty growl of a V8  ------------- JCCI 1995 Ski Nautique GT40 |
Posted By: throttle out
Date Posted: May-18-2018 at 9:12am
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I'll try to get a sound clip next chance I get. ------------- 1989 Ski Nautique 2001 351 PCM w/ 1-1.23 |
Posted By: Jonny Quest
Date Posted: May-18-2018 at 11:44am
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I love the throaty growl of a V-8 as much as the next guy -- but my hearing is not too good, so I need all the noise reduction available. I replaced my blown-out Inverta-Flo muffler with a new unit when I performed major surgery to the engine a couple of years ago. I wish I could quiet things down even more... JQ ------------- Current 2003 Ski Nautique 206 Limited Previous 2001 Ski Nautique Open Bow 1994 Ski Nautique Open Bow Aqua skiing, ergo sum |
Posted By: MNLakeSkier
Date Posted: May-27-2018 at 10:28am
| Throttle out- anyway you could post a pic? I have an 89 as well and am about to do the same and just want to make sure I route everything correctly. Many thanks! |
Posted By: 8122pbrainard
Date Posted: May-27-2018 at 10:50am
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Erik, I did some searching and found this picture. I'm sure there are other examples posted.
------------- /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: Goldcup101
Date Posted: May-27-2018 at 11:12am
I restored a bubbleback last year. It came from the PO with the Y-pipe which I've left as is. I would have bought a new hullhugger muffler until I saw the price! Noise doesn't seem too bad to me but I never heard it with a muffler.
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Posted By: 8122pbrainard
Date Posted: May-27-2018 at 11:26am
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http://www.centekindustries.com/product-category/fittings-connections/ys/" rel="nofollow - Centech fiberglass Y fittings ------------- /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: desertskier
Date Posted: May-27-2018 at 7:04pm
I did a muffler delete on our '89 about a year ago. My son uses it so I hadn't driven it until last weekend. I really like the way it sounds. Not too loud, slight drone while cruising but not bad and sounds great wide open. For some reason the '89 was much quieter than the '92. They both have the same muffler except the '89 has smaller diameter risers and less HP. I like the way the '92 sounds so I wouldn't delete the muffler but I'm glad I did it on the '89. The only issue I had was getting the muffler tubing to bend downward after the risers. It may have been the type of tubing I used. I can take some pictures but it will be a few weeks. |
Posted By: gt40KS
Date Posted: May-28-2018 at 1:37am
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I should finally have my engine by the end of the week next week (of course .... now that I'm swamped with work) and hopefully be able to get everything prepped and in the boat over the weekend. The exhaust will be close to the last part of the install, but I will definitely post some pics of the process then. ------------- JCCI 1995 Ski Nautique GT40 |
Posted By: throttle out
Date Posted: May-30-2018 at 8:51am
I don't have any photos of my boat but it looks identical to this.   ------------- 1989 Ski Nautique 2001 351 PCM w/ 1-1.23 |
Posted By: mspalatro
Date Posted: April-17-2019 at 12:37am
| I am looking to get rid of my inverta flo on my 1990 Nautique. Is there much of a performance gain to go straight dual vs y pipe?? I can see straight dual is a much bigger project. |
Posted By: JoeinNY
Date Posted: April-17-2019 at 10:48am
It will sound different, but it is very unlikely there would be any performance gain from going to straight duals with anything near a stock engine. Mostly likely you would see no difference, slight chance the duals would be slightly slower. ------------- 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: gt40KS
Date Posted: April-17-2019 at 9:29pm
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What Joe said. Sound would be a bit different - not really better, just different - with duals. Did mine last year with no mufflers and Y-pipe into the one 4" outlet and IMO it sounds awesome. If there were any performance gains to be had it would likely only be with a highly modified engine that is going to require a lot more flow than a single 4" will allow. A stock, standard 240 (260) hp 351 would not require 2 - 3" outlets and in fact as Joe pointed out, this could be a detriment. Couple this with the HUGE pia it would be to run duals in our era of boat. I'd stay with the single 4". ------------- JCCI 1995 Ski Nautique GT40 |
Posted By: mspalatro
Date Posted: April-17-2019 at 11:42pm
| The engine does have cam that is supposed to bring it up to 300hp. Everything else is stock. |
Posted By: gt40KS
Date Posted: April-18-2019 at 9:17pm
I'm running the Y-pipe system in mine with a modified GT-40 that is likely sitting at about 340-350 hp .... not thinking I need any more exhaust than I have with just the single 4" through the back. If she was supercharged as well then I'd be needing more - but that puts it well over 500hp. You have to remember that our boats are more or less straight pipes from the manifolds after eliminating the invertaflo - few bends and all very gradual, none sharp. ------------- JCCI 1995 Ski Nautique GT40 |
Posted By: mspalatro
Date Posted: April-18-2019 at 10:58pm
| I am going to with Y conversion. Looking through some old threads I saw there was a boat dr that sold the conversion kits. I checked his website and I don’t think he is still in business. Do you have any online recommendations to buy parts?? Also for the install, was there anything you had to take into consideration like the placement of the Y fitting?? And did you run hose right from Y to manifold or did you use additional fittings for bends?? |
Posted By: gt40KS
Date Posted: April-18-2019 at 11:02pm
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Check the other thread Michael - I have links there and some photos. No other fittings, just straight from the manifolds to the Y and the Y straight into the 4" hose to the exit. Do you have the 3" or the 3.5" exhaust risers? ------------- JCCI 1995 Ski Nautique GT40 |
Posted By: gun-driver
Date Posted: April-18-2019 at 11:04pm
Don’t know who sold you the cam, but you’re not going to get 40 extra ponies from just a cam, with stock heads and intake. |