RPM?

Rodram2002

Rodram2002

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May 8, 2007
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how much rpm can you get out of a 24 valve befor things start to break? I have valve springs taken care of. I'm thinking more of the bottom end. would 4500rpm be safe?
 
I turned a little less than 4 on mine on a regular bases with no ill effects.
 
I've turned 4000 a few times and it was smooth, but that is no load. I can only turn 3800 loaded. say a P-pumped 24 valve, would it hold 4500rpm ?:pop:
 
Rodram2002 said:
it would hold 4500 rpm, free rev or loaded?
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my buddies pulling truck, p-pumped 24v, shifts it a 5000rpm, and carries 38-4200 down the track:rockwoot:
 
RAMICATOR said:
my buddies pulling truck, p-pumped 24v, shifts it a 5000rpm, and carries 38-4200 down the track:rockwoot:
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did he build the bottom end at all?
 
If you have the air and fuel you can run down the track at 5k with out to much trouble on stock bottom end with any kind of luck. Over 5k the crank likes to wobble and do bad things to bearing and such. I have 1st hand knowledge on this as I have launched at over 5k and ran 5k with stock bottom end but only half a season that way.

ike
 
cool, I was thinking 4500free rev and 4000-4200 with a load when pulling the sled.
 
4100rpm is the terminal speed for the stock crank... Keeping it there for very long or trying to rev past it will severely shorten the fatigue life of the crank and probably stranded somewhere unconviently
128# crank isn't exactly balanced on the worlds most accurate machines...
A good balancing and shaving a bunch of weight off the fly weights would show a lot of improvement. You would be able to rev higher, and due to the lighter crank, faster than with a stock crank. Although I'm sure it doesn't do anything for the structural integrity of the crank either.
 
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Mountaineer said:
128# crank isn't exactly balanced on the worlds most accurate machines...
A good balancing and shaving a bunch of weight off the fly weights would show a lot of improvement. You would be able to rev higher, and due to the lighter crank, faster than with a stock crank. Although I'm sure it doesn't do anything for the structural integrity of the crank either.
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Are you sure that's sound advice? My crank came back from a reputable machine shop and the factory balance was perfect. There was nothing changed from the factory balance.
 
I think rings, bearings, and piston to wall clearance are more of a factor than a stock "out of balance" crankshaft. Not saying that an out of balance crankshaft is alright, but I think they are a lot closer than what a lot of people may think.

-Tom
 
joefarmer said:
Are you sure that's sound advice? My crank came back from a reputable machine shop and the factory balance was perfect. There was nothing changed from the factory balance.
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I also had my crank balanced buy a machine shop that balances rods and cranks for motors running 8+ rpm (gas) and he was shocked at how well the stock crank and rods were balanced they had to do very little work to get it true.
 
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