Went to the machince shop to see what my final compression ratio on the motor is today and then asked him how big of a shot he felt his work could take. " 100 shot is pushing it becasue we didnt clearnce it"?. What the hell ive made severel pulls on 150 jets on the stock shortblock? My new longblock consists of this. 355ci,Stock crank turned and polished, eagle billet four bolt mains with arp studs, 6" forged Eagle h-beams with arp studs(block clearenced), srp forged flat tops,chromoly top ring, cc306, OEM timing set, Stock heads redecked with comp 918 springs and hardware,Comp 1.6 RR, TF guideplates,ls7 lifters,TF pushrods, felpro 1074 head gaskets, arp head bolts, lightly ported lt1 intake with 58mm TB. Final compression ratio is around 11.5:1. I was planning on ripping the 200's through this motor. What do you guys think?

 

if they set the rings up for NA use only I would take their advice ....I have a friend that destroyed a 385cid fully forged motor on a 100shot.

 

Was this something you discussed with him before he assembled the motor??? Presuming as Chopstix did that he was refering to the ring end gap. Ask him what the gap of each of the two rings are.

 

how!!!

 

The shortblock was set up for a max effort NA motor....on the 100 shot the cylinder pressure butted the ring ends together and broke the ring lands off 2 pistons.

 

The extra heat from the nitrous combustion also closes up the ring gap.

 

then he must have had 600whp na??

 

nope...only made mid 400's

A NA only motor is setup different than a nitrous or FI motor...regardless of the power you are going to make

 

Im going to call him in the morning to see exactly what rings and gap they used. To be honest im kind of bummed to only be running 100 pills through it, with stock heads ill be lucky to see 350rwhp NA so im prob looking at 440-460rwhp on the juice. I figured i would be able to run 200 through it and not think twice, I just hope this wasnt a $3,400 mistake.

 

whats a good end gap for nitrous?

.020 .024?

 

Depends on the bore. A 4.00" bore nitrous motor should have a top ring gap of approx .024"-.028". The 2nd ring should be approx .025"-.029"

 

again - Ring GAP
also side note - Piston to Wall

 

I have a little question while this thread is going to (sorry for this mild hijack) But do you need to buy nitrous specific gapped rings, or can any ring be gapped accordingly? Again sorry.

 

There are hardened rings especially suited for high boost/big nitrous applications. But for the typical combo any good moly ring with the correct gap will be fine.

Rich

 

Ok ring gap is .029"? I figure this should be fine, I know there is other factors involved but from what i understand ring gap is a biggie.