DJ's Z

iTrader: (10)

Okay...not much on "quench" properties of heads so...what would be a better scenario with a FI engine?

A larger combustion head say (72cc) with a less dish cc piston or

A smaller combustion head say (65cc) with more cc in the piston. Or does it really matter all that much with a pretty good amount of boost?

Both trying to acheive 9.5-10:1 compression.

With all else being equal of course...

FUroundeye

iTrader: (6)

I asked the same question about a week ago and the general concensus seemed to be larger cc head w/ less dish to the piston. Less dish = thicker piston = stronger piston.

OldBlue

iTrader: (3)

I'd probably say the 72cc, depending on you're cubic-inch and the amount of boost you plan on huffing!

DJ's Z

iTrader: (10)

If your already having a custom blower piston made for a paticular compression ratio why would that neccessarily mean it would be a "weaker" piston if the dish was a little more cc's. I was just curious how the differences would effect the quench property of the head. Which combination would be a better performer or would it really matter not being N/A motor? 408 with an ATI Procharger about 15lbs of boost...

eviltwins

Larger CC pistons = less material in the crown of the piston = potentially weaker piston.

I've always been told a dished piston will give you a better flame front and more power than a flat top, but I don't know if it varies much/at all for different sized dishes. Either way, if you're building an FI motor from scratch i'd shoot for lower than 10:1 compression.

turbo'd stang

I'd leave the piston down in the hole, run a smaller chamber and a flat top.

Inspector12

iTrader: (29)

A dished piston is just fine and a better way to lower the compression than heads are generally speaking. The strength on the crown of the piston is usually not an issue. It is usually the amount of material from the top of the piston to the top ring and the thickness of the ring lands inbetween the rings. If any detonation occurs this is usually the area that is taken out and not the crown. If you have that lean of a condition then the you can potintially burn a hole in there, but not likely if you have a good tunner and you are keeping and eye on the AF ratios like you are supposed to etc...I have been doing some reasearch so take my opinon for what you will and I think if you talk to any piston manufaturer they will tell you what I just did and to lower the compession with the piston mostly -25cc dish is not an issue with a 65 or 66cc chamber witch is pretty comon among head manufacuters and stock LS1 are @66cc etc... Talk to you later Dennis.
Jeff

DeltaT

iTrader: (5)

Why do you have the Vette covers on there?

That's a nice looking car, overall.

Jim

Inspector12

iTrader: (29)

Cause they clean up the engine bay a little by covering all the wireing and they are a direct fit. Just cause it isn't a vette doens't mean we cant use some of the same parts. I know you were asking DJ, but I used to run them before the SC so I was giving you my reasoning, and i am assuming his are simular reasons as most people have told me.

DJ's Z

iTrader: (10)

Thanks Jeff, couldn't have said it any plainer than that. Actually I wasn't even going to respond...At the time the photo shoot was done I just wanted to "clean" up the engine bay as much as possible, so I put them back on...at a few car shows I attended over the years (before anyone, gear heads excluded) knew anything about the LS1's, I couldn't tell you how many people said, "OH, look its got a Corvette motor in it" That alone made me keep them on until I planned on some custom ones...I just wouldn't raise my hood for the "regulars" or I'd hear a rash of **** from them...now go pick on someone else... BTW their for sale if you want to buy them...