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Originally Posted by 33outlawsst
(Post 4486100)
I dyno'd mine in full marine dress, CMI sweepers and tails that were going in the boat, why do it any other way ? because several, maybe most, of the shops are not set up to run wet exhaust, its really that simple.
Originally Posted by BenPerfected
(Post 4486182)
In all our dyno testing there was only about 15 HP difference using full length dyno headers and exhaust manifolds with 15" runners. It is pretty hard to beat the value of the Stainless Marine exhaust.
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Standard, single bolt pattern, I drilled the flange for the AFR's
Edit: mine are CMI not Stainless marine |
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That is interesting what haxby mentioned about seeing cams with more split, not being as affected as much by the poor exhaust setup.
Anyhow. Heres some 1600hp sterlings with Stainless Marine Gen 3's . |
So my 5 degree spit and exhaust sucks just wonderful lol
Originally Posted by MILD THUNDER
(Post 4486203)
That is interesting what haxby mentioned about seeing cams with more split, not being as affected as much by the poor exhaust setup.
Anyhow. Heres some 1600hp sterlings with Stainless Marine Gen 3's . |
3 Attachment(s)
Here's some dyno info on a 582 low rpm deal for a big white water jet boat. It shows a couple things. The first pic is with a custom cam 250 - 256 @.050 Dana exhaust with 2" divided riser extensions. The second is a few months later when we had to go through it because of reversion issues. I put a much smaller cam in it after running it in the boat and realizing that the pump was really inefficient over 4400rpm. 234 - 244 @.050. I believe the reason there is little change in peak torque rpm, is because the exhaust is holding it back and controlling the curve even more then the cam. Also, even though the engine ran at very low rpm, there was evidence of valvetrain instability with the bigger cam with higher lift. Second pic is with my dyno headers (which give very similar power numbers to E-tops) and last is with the Dana's back on, which is what the first one with the bigger cam was running too. I would agree with the gravel haulers suggestion that Tim's exhaust is more likely holding things back then the intake side of things. Oops, they posted in the wrong order. last one is 250-256, first one is smaller cam with headers, middle is with Danas. sorry
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So, in your opinion would I see anyone enough gain at the gps in a boat like mine if I bought headers?
Originally Posted by HaxbySpeed
(Post 4486211)
Here's some dyno info on a 582 low rpm deal for a big white water jet boat. It shows a couple things. The first pic is with a custom cam 250 - 256 @.050 Dana exhaust with 2" divided riser extensions. The second is a few months later when we had to go through it because of reversion issues. I put a much smaller cam in it after running it in the boat and realizing that the pump was really inefficient over 4400rpm. 234 - 244 @.050. I believe the reason there is little change in peak torque rpm, is because the exhaust is holding it back and controlling the curve even more then the cam. Also, even though the engine ran at very low rpm, there was evidence of valvetrain instability with the bigger cam with higher lift. Second pic is with my dyno headers (which give very similar power numbers to E-tops) and last is with the Dana's back on, which is what the first one with the bigger cam was running too. I would agree with the gravel haulers suggestion that Tim's exhaust is more likely holding things back then the intake side of things. Oops, they posted in the wrong order. last one is 250-256, first one is smaller cam with headers, middle is with Danas. sorry
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Originally Posted by HaxbySpeed
(Post 4486211)
Here's some dyno info on a 582 low rpm deal for a big white water jet boat. It shows a couple things. The first pic is with a custom cam 250 - 256 @.050 Dana exhaust with 2" divided riser extensions. The second is a few months later when we had to go through it because of reversion issues. I put a much smaller cam in it after running it in the boat and realizing that the pump was really inefficient over 4400rpm. 234 - 244 @.050. I believe the reason there is little change in peak torque rpm, is because the exhaust is holding it back and controlling the curve even more then the cam. Also, even though the engine ran at very low rpm, there was evidence of valvetrain instability with the bigger cam with higher lift. Second pic is with my dyno headers (which give very similar power numbers to E-tops) and last is with the Dana's back on, which is what the first one with the bigger cam was running too. I would agree with the gravel haulers suggestion that Tim's exhaust is more likely holding things back then the intake side of things. Oops, they posted in the wrong order. last one is 250-256, first one is smaller cam with headers, middle is with Danas. sorry
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https://www.youtube.com/watch?v=Y6EcyKygxTg
Just for fun...... full marine dress with Dana Marine manifolds. This was just getting it tuned. We eventually pulled it to 6500.
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Originally Posted by check300
(Post 4486269)
https://www.youtube.com/watch?v=Y6EcyKygxTg
Just for fun...... full marine dress with Dana Marine manifolds. This was just getting it tuned. We eventually pulled it to 6500.
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Oh we found quite a bit more torque before we were finished..:)
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