Max rpm before valve/studs upgrade

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Feb 19, 2011 | 01:48 PM

ClassA4x4

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From: Oak Hills (Cajon Pass Summit), Ca

Max rpm before valve/studs upgrade

What's the safe rpm limit for stock engine.

Feb 19, 2011 | 01:58 PM

ofcmarc

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From: 14mi North of North Pole

You start heading above 4000 you're gonna need the 60lb valve springs.

BC did a great (as always) write-up on the valve spring up grade. Look under performance in the sticky.

Feb 19, 2011 | 10:44 PM

mhuppertz

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From: Tijeras, New Mexico, 7,000ft up

Head studs are usually determined by boost pressure, not necessarily RPM. According to a Cummins engineer I spoke with, mechanical damage on a stock engine occurs starting about 5,000 RPM.

Feb 20, 2011 | 09:29 AM

KD93

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From: West Palm Beach, Florida

So to qualify Mark's answer, IIRC 35 psi is about the safe limit to run constantly before you'd need to stud the head.

Feb 20, 2011 | 09:42 AM

mhuppertz

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From: Tijeras, New Mexico, 7,000ft up

I would agree with that. I am at 40PSI and on 3,200 rpm blasts I lose a fair amount of antifreeze down the side of the block. Waiting for better weather (and a bottoming tap) to put my ARP's in.