Use Rev Limiter or Let Carbs Limit Revs?
08-04-2011 | 01:47 PM
#1
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From: Jackson, Mississippi
Use Rev Limiter or Let Carbs Limit Revs?
My engines started out as Gen VI 454 mags 1997. With the help of RMBuilder and new parts from the cams up I can turn 6100 rpm before the engines fall flat due to running out of carb (750 cfm). I have 6000 rpm rev limiters to go with my Performance Distributors (DUI). I intend to prop for 56-5800 rpm wot. I would like to forego the rev limiters just becasue it would be one less thing to fail. Do I need the rev limiters, if the carbs won't let it get over 6100 rpm? Opinions welcomed. Brian
08-04-2011 | 02:00 PM
#2
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From: MA
I would think motor will break past 6100 when not under load. Like when boat airs. This could be costly if you make a mistake and don't throttle back. Your valve float will sound similar to a rev limiter. But prob not get the same results. LOL .... 2¢ install rev lim
08-04-2011 | 02:13 PM
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From: Central IL / Green Bay, WI
Rev limiter...I have pics around somewhere of the 468 in my buddy's jet boat...no limiter..got some air at WFO, pump unloaded...cam came out in 5 pieces. Only good parts off the engine was one head, the intake, and the carb.
Cheap insurance.
Cheap insurance.
08-04-2011 | 03:10 PM
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From: Somewhere in Ohio
You need a rev limiter. I think you are misunderstanding that the carb size does not limit the revs. Your just out of horsepower at 5800 RPM. With no load, it will rev well past that, until she blows. If your carb was truly limiting your revs, you would not have enough power to even get on plane.
Hope this makes sense.
Hope this makes sense.
08-04-2011 | 03:20 PM
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From: Jackson, Mississippi
You need a rev limiter. I think you are misunderstanding that the carb size does not limit the revs. Your just out of horsepower at 5800 RPM. With no load, it will rev well past that, until she blows. If your carb was truly limiting your revs, you would not have enough power to even get on plane.
Hope this makes sense.
Hope this makes sense.
08-04-2011 | 03:44 PM
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From: Somewhere in Ohio
So when you open the throttle all the way in neutral, it will only hit 6100?
Have you tried them under load? The carb calculations are correct for that size engine, but 750cfm should give you enough Carb to make horsepower at 5800, not choke the engine off.
If they will only free rev to 6100 you either have an intake restriction, a rev limiter already installed, or a major tuning problem. Are you sure your throttle plates are opening all the way?
Have you tried them under load? The carb calculations are correct for that size engine, but 750cfm should give you enough Carb to make horsepower at 5800, not choke the engine off.
If they will only free rev to 6100 you either have an intake restriction, a rev limiter already installed, or a major tuning problem. Are you sure your throttle plates are opening all the way?
