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Originally Posted by BenPerfected
(Post 4506750)
Our 500 ci 3.80 stroke engines are 9.5 CR with Valako/Dart I.E. 308's ported to 320ci. We run 92-93 pump gas and have never had any signs of detonation including totally inspecting the recent complete rebuilds. The timing is locked at + 40 degrees and we have a very smooth valve train w/55mm cam cores. Total package gives us 780 HP @ 6800 RPM. Water conditions being reasonable, we regualrly make extended runs at 6000+RPM.
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28P Bravo 1 props.... 90+ MPH in 2' or less water.....balls are getting smaller :eekdrop:
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If running locked in timing it will be a bit less than a mechanical or digital curve... The lighter the boat the less difference mind you
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Originally Posted by abones
(Post 4506812)
these comp #s are a great starting point, but the real deal is to know your VE at operating RPM. I would that a 9.6 at 125% VE over a 10,0 at 95% VE of equal CID. Meaning the combination of parts in the build will ultimately determine your running CR and fuel requirements. Cam valve timing event, induction system and air flow volumes and speed, exhaust scavenging and so on. my point is static CR is no more then a good starting point.
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Doing a little reading on comp. ratio and came across this , kinda interesting
https://www.uempistons.com/index.php...ors&type=comp2 |
Originally Posted by BenPerfected
(Post 4506750)
Our 500 ci 3.80 stroke engines are 9.5 CR with Valako/Dart I.E. 308's ported to 320ci. We run 92-93 pump gas and have never had any signs of detonation including totally inspecting the recent complete rebuilds. The timing is locked at + 40 degrees and we have a very smooth valve train w/55mm cam cores. Total package gives us 780 HP @ 6800 RPM. Water conditions being reasonable, we regualrly make extended runs at 6000+RPM.
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