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Thread: What is the safe RPM range for a 434 Chevy engine

  1. #1

    What is the safe RPM range for a 434 Chevy engine

    Need to know how much to turn a high compression 434 chevy engine.
    I've been shifting at 6500 RPM and everything seems to be working great. I know there is more horsepower in turning more RPMS however since the engine is a stroker with long stroke I'm thinking maybe it would be better to shift at lower RPM's and let the torque from the engine work.
    I'm using a turbo 350 transmission without a transbrake to compete in the no electronics class.

  2. #2
    Senior Member RACING JUNKIE curtisreed's Avatar
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    There is now way anyone could give you a decent answer to your question with no knowledge of your heads, cam timing, carb size, compression, etc..... That said a big small block like that has to have some really good heads to turn a lot of rpm. You're talking big block cubic inch in a small block platform. Heads on these engines will go into choke pretty early compared to a 350ci engine.

    With that said, I would hope that it wouldn't peak under 6800 or so. Basically try raising your shift and see what it says on the time slip. Also, I don't know what rpm you are leaving at on the brake, but I have found that many times leaving at too high of an rpm like a SG car will slow you down. My car is quicker leaving at 3800 than it is leaving at 5500. It gets a run at the converter and uses the torque multiplication better in the early part of the run. Hope some of this helps a little.

    Curtis

  3. #3
    Senior Member RACING JUNKIE TheRabbit's Avatar
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    Being a 434 I would ASSUME it's a very well built motor. IF that's the case I'd run it to 7,200 then 7,400 then 7,600, etc and see what the time slip says. Well built small blocks usually have no problem turning 7,000 +.

  4. #4
    Senior Member RACING JUNKIE
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    Quote Originally Posted by curtisreed View Post
    Also, I don't know what rpm you are leaving at on the brake, but I have found that many times leaving at too high of an rpm like a SG car will slow you down. My car is quicker leaving at 3800 than it is leaving at 5500. It gets a run at the converter and uses the torque multiplication better in the early part of the run. Hope some of this helps a little.

    Curtis
    Curtis,
    How much time did you remove from your box to make up for the converter's ramp up time?
    Dave
    http://www.racingjunk.com/profile/343797
    "All that is necessary for the triump of evil is for good men to do nothing" Edmund Burke

  5. #5
    Senior Member RACING JUNKIE jmarksdragster's Avatar
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    I've spun my 4.25 stroke 461 SBC to 7900 regularly. Just depends on the parts you used.
    Mark Whitener
    http://racingfuelsystems.myfunforum.org
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    Good work isn't cheap, and cheap work can't be good.

  6. #6
    Senior Member RACING JUNKIE curtisreed's Avatar
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    Quote Originally Posted by oldandtired View Post
    Curtis,
    How much time did you remove from your box to make up for the converter's ramp up time?
    Dave, I don't box race. I was index racing on a pro tree.

    Curtis


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