Planning to go street 408 Twin Turbo but need some help here to decide which parts to combine from what I have available right now. As said its going to be used as a daily driver and occasional racing maybe.
1.Flat diamond pistons with 72cc 317 heads or with 65cc 243's? What CR with those combinations?
2.-28cc JE pistons with same heads; 72cc or 243's cc heads? What CR will get with those combinations?

 

How much boost are you planning to run and what fuel(s) ?

Use this calculator to get the ball park:
http://www.csgnetwork.com/compcalc.html

That's the one I use for a prelim calculation. This should get you what you want.

Off the top of my head i'm going to say o-ring it and run the larger combustion chambers. will be easy to run on pump and you can dial the boost way up for when running race fuel/meth

 

Sounds like you are trying to make some good steam.

What are your total HP goals(that includes glory runs)
What parts do you have?
What type of fuel are you planning on running?
4" Stroke?
6.125" rod?
4.030" iron block?
what size turbo's?

 

Thanks for your time. The project will be a 1954 Chevy truck (show, daily and occasional race vehicle). I have already: a 6.0L iron block; bored to .030; a 4 inches K-1 crankshaft, 6.125 compstar rods, as et of JE -28cc pistons and a set of Diamond racing flat top pistons, as et of 317 heads and a set of 243's. Turbos will be Precision turbos 62/66. Which combination of pistons and head should I use?

 

I'd run the flat-top's and 64cc 243's... Shoot for ~12:1 static compression and feed it premium gas and/or E85. Just get a good cam and a really good tune.

 

This is pretty much what I'm thinking. Being mainly a street vehicle I would choose the flat tops with the 72cc 317's.

 

Really?
Premium gas with a boosted setup? E85 for sure.

But I'd either go Flat tops with 317's. Or -28 with 243's. The latter is what I'd do because 91 is the best we get around here.

 

Any idea of the CR withe flat top with 317's and the -28cc with the 243's? Remember that will be a twin turbo set up so maybe too high CR is not desirable.

 

Use the link to the compression calculator. It seems the flat tops w/ 317's would be around 11:1 & the -28cc with 243's around 9:1.

Maybe a -15cc piston could be adequate.

 

LQ9's has flat top pistons with 317's ad I think that the CR doesn't reach 10:5:1 and GTO's with flat top pistons and 243's is about 10:5:1. Can you verify somehow your info? Will apreciate.

 

If those are the Diamond #11518 pistons, at 71-72cc on the heads you will be at 10.85:1-11:00:1.

The 28-29cc dish with the 64-65cc head would be about 9:1-9.2:1.

 

best combo for boost would be the dished with .020" wacked off the 243s
shoot for about 9.5:1 with LS9 head gaskets and head studs
This puts you right in the pump gas streetability range where the engine will still be responsive enough to kick the smaller turbos yet if you go E85 and say 12-14 lbs of boost you'll be safe and powerful. Easy 750 flywheel horse

 

Sure. It is better if you fill the details out. http://www.csgnetwork.com/compcalc.html

 

An lq9 doesn't have a 4" stroke. What fuel are you going to be running? I wouldn't run the -28cc on any motor really. A 9:1 just isn't necessary unless you are looking for huge numbers on pump gas only. But I also wouldn't run flat tops without E85.

 

http://www.ls1lt1.com/forum/crcalc.php This calculator is a little easier to me

 

I'm sure of that but I work in the health system so doesn't understand those things that maybe you consider simple. The thing is that this project will be mainly a show truck but with big heart. I have the -29cc JE pistons and the flat top Diamond pistons. Also has the 243's and the 317's. With those part that I have already. I would like to know, which parts would be the better combination.. I would like to be about 9:5:1 on compression. I would like to know which head gasket (thickness) would be the match for the combo. I need your advice but think that your are talking to a kid with no major knowledge about it. The block is an iron block with .030 bore, 4" crankshaft and 6.125 rods. Turbos that will be use are 62/66 typ.. No cam choose yet.

 

That was my point.

The JE pistons with the 243 heads will yield roughly 9.14:1 CR and is definitely not High in CR. That's using the MLS GM LS9 gasket at a .051" thickness.
I'd salvage as much deck thickness as possible and go without milling the heads. Plenty of people making gobs of power at this CR. And he'll have no problems spooling those turbo's like a switch in the lower RPMs. (IMO of course)

 

So what can I do with what I have right now?

 

Run the JE's with the 243's if you plan on running Premium gas.

That's what I'd do.

If you want more CR, mill the 243's down a little bit and/or use the Cometic Head gaskets that are .040" thick.