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Author Topic:   How Many RPM?
George Gilliland
Dirt Full Roller

Total posts: 42
posted October 21, 2002 11:28 AM
Using a stock Chevy crank(cast), stock rods(remanufactured), Arp bolts, and pistons weighing the same as stock(hypereutectic), how high would you feel safe twisting it every week?

Dirt Forum Racer

Total posts: 96
posted October 21, 2002 01:25 PM
I've got a good motor with a rev limit of 6900 RPM .It's been running that way for 6 years now, Stock crank ,stock de-beamed rods ,ARP fasteners,TRW forged pistons.
I've been told that 7000 is the magic number for stock stuff anything over that ain't gonna last long ,All depends on how deep your pocket is above 7000.

Dirt Freak

Total posts: 250
posted October 21, 2002 01:41 PM
What is it exactly? 383 377 406 350? just wondering, I have a 406 that has almost all the same stuff

George Gilliland
Dirt Full Roller

Total posts: 42
posted October 21, 2002 03:54 PM
This is a 355 and I usually turn 7000-7200 RPM. I just wondered if I am too conservative. I guess the second question is if I upgraded the rods to chrome moly then what is the limit?

Dirt Maniac

Total posts: 125
posted October 21, 2002 04:10 PM
I try to keep my BALANCED 350 crankshaft in the 6900-7100 range on a weekly basis. I have turned it 7400 a few times without problems but wouldn't be comfortable with that very often.

Dirt Freak

Total posts: 253
posted October 21, 2002 08:57 PM
I've always ran around 6800 to 7000 with no problems. I think a little higher would be safe but this is just where I'm always geared at.

jhon hollomon
Dirt Roller

Total posts: 12
posted October 21, 2002 09:20 PM
Maybee it's just luck but i've tore up more aftermarket stuff than I have stock stuff.

Dirt Full Roller

Total posts: 50
posted October 22, 2002 11:42 AM
George, I don't think you really want to twist a motor higher than that with any rods. Yes, there are exceptions but for the most part, "I think" that 7400 is a max no matter what the parts. I run a 383 and a 421 both with Eagle steel cranks, Eagle H beam rods, fly weight pistons and usually run a 7000 chip. The less RPM's you run, the longer the motor will last. A set of gears are much cheaper than a new motor.

Dirt Roller

Total posts: 5
posted October 22, 2002 07:13 PM
we have a basicly stock throwback motor that sees 7400 on a regular basis, cast crank, X-rods, arp bolts, and CHEAP CHEAP speed-pro flat tops, no problems it has a season and a half of good hard laps

George Gilliland
Dirt Full Roller

Total posts: 42
posted October 23, 2002 08:47 AM
I have run about 37 nights this year on a single engine. I turned 7000-7200 rpm. The engine now needs to be rebuilt, it is getting some blow by and I am sure that the bearings have a good deal of wear on them. A lot of the cars that I run against turn 8000-8500 rpm and the only thing stock on theirs is the block. I was thinking if I could turn 7400-7500 rpm that it may help, beyond this is over the cam any way. But I do not want to get into reliablity problems, at the same time I do not want to be too conservative. Thank you for all of your input.

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