Curiosity about rev limit
Thread Starter
Racer
Joined: Jun 2004
Posts: 265
Likes: 1
From: Columbia MD
Curiosity about rev limit
I am a bit of a noob when it comes to tuning and performance enhancement, but I am learning quickly by reading this forum. One thing I have not heard about around here is increasing the rev limit or redline, to say, 7000 RPM like the Z06. Perhaps it requires upgrades to internal engine parts? Maybe it requires better intake and exhaust to handle increased flow? If it could be done without too much trouble, seems like you could get increased area under the curve, thus more usable power. I have heard about this being done on other vehicles, but haven't heard about it here. I did a search for rev limit, and only found people that were afraid they hurt something from hitting the rev limit... 
Le Mans Master
Joined: Aug 1999
Posts: 5,411
Likes: 2
From: N Carolina 08 Z51 Coupe
push rod V8's usually make their power at low rpm's. Higher rpm's usually don't add much unless the motor is built for it, cam, springs, etc...
IMO, there is really no need for having to rev that high when so much is available down low..
IMO, there is really no need for having to rev that high when so much is available down low..
Safety Car
Joined: May 2000
Posts: 4,824
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From: Albuquerque NM
Horsepower = torque x rpm/5252. So the higher in rpm you make torque, the more horsepower you make, even without increasing the actual torque numbers. That's how F1 cars make such high horsepower from such small cubic inch motors, by reving them to the moon, 19,000 to 20,000 rpm.
Premium Supporting Vendor
Joined: Oct 2004
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From: Providing the most proven supercharger kits for your C5/6/7 609-752-0321
Cam profile will dictate the RPM band and thus the rev limiter. On a stock engine raising the rev limiter is not a good move because the car starts losing power at the stock limit already, and the springs were not designed to rev higher anyway.
Tech Contributor
Joined: Mar 2003
Posts: 12,094
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From: Colorado Springs, CO
St. Jude Donor '08-'09-'10-'11
The stock srpings are barely good enough for the stock cam. People who get S/C or TT should get better springs because the pressure hitting the back of the valve makes it harder to control even with the stock cam.
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Brett Foote
CF Senior Member
Joined: Feb 2006
Posts: 23,313
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From: Tucson Arizona
I didn't go-with the most radical cam but even my fully built Lingenfelter engine only goes to 6800 RPMs before bumping the rev-limiter (not 7000). IMO anytime you push a stock, cast-piston engine past its design tolerances you're asking for a problem.
Le Mans Master
Joined: Oct 2007
Posts: 6,149
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From: Greater Detroit Metro MI, when I'm not travelling.
The factory rev limiter is where it is because the cam/head/manifold configuration does not make much useful power above that RPM (mainly the cam, and it runs out a bit before redline actually).
Increasing the rev limit will first create valve float, so you need stiffer springs. Then you will either experience rod stretch or oiling issues, depending on the motor. With some stronger rods and adequate oiling you could rev the motor well beyond 7K, but it would require a very agressive cam and head porting to make useful power up there.
Race Director
Joined: Dec 2005
Posts: 11,299
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From: Carlsbad Ca
Le Mans Master
Joined: Oct 2007
Posts: 6,149
Likes: 11
From: Greater Detroit Metro MI, when I'm not travelling.
Why do V8 offerings from BMW, Audi and Mercedes Benz rev as high as 8250RPM in fully warrantied, bone stock trim while the Corvette will only to go 6500?
That would be a better question to start a discussion about stroke length, inertial loading, rod stretch, valve float, etc...
Team Owner
Joined: Nov 2006
Posts: 21,136
Likes: 212
From: Long Island New York
Reciprocating mass also plays a large part in keeping RPM down. It costs alot of money to make internal moving parts lightweight and strong enough to hold together when spun super fast.
