Cam and valvetrain longevity....??? low duration high lift...
09-29-2016, 10:57 AM
#662
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Standard, single bolt pattern, I drilled the flange for the AFR's
Edit: mine are CMI not Stainless marine
Edit: mine are CMI not Stainless marine
Last edited by F-2 Speedy; 09-29-2016 at 11:35 AM.
09-29-2016, 11:56 AM
#665
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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
Last edited by HaxbySpeed; 09-29-2016 at 11:59 AM.
09-29-2016, 12:37 PM
#666
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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?
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
09-29-2016, 02:12 PM
#667
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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
09-29-2016, 03:38 PM
#668
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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.
09-29-2016, 03:55 PM
#669
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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.
