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How Much HP / Boost Can a stock 420a lower end handle?

DKSTREET1990

Probationary Member
7
3
Feb 9, 2021
Arvada, Colorado
I have a fullly built head and am now considering building the lower end of the motor. money has become tight and was wondering how much boost and hp stock pistons and rods could handle.

thanks
 

dustyboner

DSM Wiseman
1,386
634
Mar 13, 2016
abq, New_Mexico
a low mileage engine will handle 8-9 psi for a little while as long as its tuned properly.
but
if your head is fully built, you might not wanna run boost on the stock bottom end. If you break a piston or rod, you could end up trashing it.
 

DKSTREET1990

Probationary Member
7
3
Feb 9, 2021
Arvada, Colorado
Thank you, I agree and I have the mega squirt 2 for tuning. Just don’t want to destroy it
 

BLACK'98DSM

Proven Member
2,583
826
Feb 9, 2019
Birmingham, Alabama
I've heard that 7 psi is what you can reliably run. The weak points in the bottom end are the ringlands.

I'd never boost or spray a 420a without it being built though.
 

DKSTREET1990

Probationary Member
7
3
Feb 9, 2021
Arvada, Colorado
Thank you for helping me out and I have decided to go ahead and build the Lower end before installing motor again
 
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