Advanced Engineering Tech - .020 in the hole too much

I'm at the middle stages of my motor build and just found out that my pistons are going to be in the hole .020. It works out ok for compression since I am trying to get it as low as I can, using the pistons in the hole .020 will lower my compression slightly to 8.64:1. Is there a max number they can be in the hole on a big boost motor?
Phil

steel rods?

steel rods?

Yep, Howards Billet Rods.

Yep, Howards Billet Rods.

that'll leave an awful lot of quench. could lead to detonation problems I would think.

Your 100% right but I am running BIG dished pistons, they don't have much of a quench pad anymore. Its a -28cc piston.

Is there a quench ring around the entire perimeter of the piston, or is it still a partial dish?

Jim

out of curiosity, how would combustion chamber design affect a compression height issue like this? would a smaller chamber solve the quenching issues, or would it need to be a very shallow chamber with no quench area? (I don't think any LS heads currently available have a chamber like that though)

Is there a quench ring around the entire perimeter of the piston, or is it still a partial dish?

Jim

The outside quench ring is about .350" or so. I can measure it to be exact.
Phil

out of curiosity, how would combustion chamber design affect a compression height issue like this? would a smaller chamber solve the quenching issues, or would it need to be a very shallow chamber with no quench area? (I don't think any LS heads currently available have a chamber like that though)

I've got a 72cc chamber with a -28cc dish. Not sure if you can go either way, the pistons have the biggest dish they offer. I probably could have gotten some pistons for a taller deck height.
Phil

Yep, Howard's Billet Rods.I don't want to scare you to bad, but I broke one of them rods right in half in less than 200 passes. Sawed my oil pan into, put a hole in my cross member and ruined a nice block, luckily didn't hit the wall. I've heard of a few more people that had a failure too. It was a rod failure and not a bearing seizure like most broken rods are, the half attached to the crank and the other half still attached to the piston still spun freely. That's the only rod I've broke in 22 years of drag racing.

They were called Power Detroit Rods when I bought them, rated 1000+ HP. They were from Competition Products and they look exactly like and have the exact same description but seem to be called Howards now. Maybe I'm wrong or they improved them now, hopefully they did.

What heads, and how do(es) the head quench area(s) match up to the piston. Right now I'm thinking that you have so little quench areas that what you have will be critical - have you thought of getting a .020" skim off the block? What's the end use, turbo?

Jim

Turbo, thats what we're debating shaving .020 or not.
Phil

I wouldn't be concerned with tightening up the quench distance, especially since you aren't running a reverse dome piston.

boost car I wouldnt be as overly concerned with quench as a NA motor

Thanks jeff, I kinda thought the same thing, we ended up decking the block .010 and using a .030 MLS gasket with a SS o ring(.006-.007) & reciever groove in the head. The pistons sit .010 in the hole. I still have my .040 quench and can deck the block another .005 to .010 if necessary.

theres a whole lot more mixing going on in 20 lbs of boost then sucking in stagnant air in some lame as 500 hp NA motor as WOTFMAn would say :)