I have -24cc dished pistons in my 383 that i had for my blower setup. I want to raise the compression ratio and run nitrous as i have removed the blower...can i keep the dished srp's and mill the heads to get the CR up or do i have to change the pistons...reason being i have to ship my crank/rods/pistons aprox 1500 miles to have rebalanced if i put new pistons in and its already balanced now...any ideas??

 

Short answer: Change the pistons.

 

ok...can i get some reasons why? not doubting you or anything but i figured that was the responde i was going to get but i'd like to learn why. I was probably going to change them anyway...thanks for the quick response.

 

I believe if you change the pistons, your balance will not be affected. Because dished pistons are heavier than flat tops. If your new pistons are lighter than your dished ones its not a problem.

 

You need different pistons, but what is the chamber size in your heads?

 

I went through this same situation. I looked and the KB flat top pistons for my aplicatin were about 75 grams heavier than the KB dished pistons I already had. I milled the heads to bump the compression up because new pistons and a rebalance were out of the question.

 

You can mill the heads and keep the pistons. You won't get the optimum SCR for your car, so you'll be low on the DCR, too more than likely. Nitrous works much better with higher compression. You might have to mill your intake to match the heads.

Even with lighter pistons, you should still rebalance for sure.

 

you need pistons and a balance.

We can't answer about milling the heads b/c you didn't state what the chamber size is now. Bit with a -16cc piston you would have to cut the hell out of the heads and they would pretty much be useless for anything in the future.

Plus the intake etc. will not line up and everything on the engine is pretty much going to only be able to be used on that exact enigine

 

You'd be better off selling the longblock and building another one.

 

i'm getting new pistons......
Thanks guys for the replies

 

best and ideal situation would be to get a set of flat top pistons (built to take nitrous) and of course the re-balance.

Another idea might be to keep those -24cc SRP pistons in there and get a set of small chamber cylinder heads to replace the big chamber AFR heads.
Those -24cc SRP's are good pistons and have the quench pad so it'd be a shame to have to ditch them. Just thinking out loud.

Karl Ellwein

 

Only thing is AFR heads flow numbers take a dive when the chambers are reduced thru milling. It's the wrong way to go for a NA engine, even tho it might work.

 

something like some GM LT4 or GM LT1's small chamber heads and have a good valve job and maybe pocket porting.

I would not mill the AFR heads. Agree!