Bowtie Boy

...out of a 396 LT1. LE3 heads -5cc pistons, 3.875 stroke. Average gaskets needed. Not sure what else there is, I cant find a good calculator for this (and dont know what some of the things they ask are anyways). But if someone knows average that would be nice. I really want a procharged 396 down the road. I know that in stock form the LT1 compression isnt ideal for a supercharger. Sorry if I am leaving anything out I am starting to get deeper into things and learning as I go.

strokin93z

iTrader: (1)

To find out compression we need: Bore size, stroke, head gasket thickness, Combustion Chamber of the Head (cc's), The piston to deck clearance.

Guessing tho you may be around 12.1-6:1, We'll get a better idea of compression with all info.

Edit: With Heads at 52cc, Felpro 1074 gasket(.039), and a .020 for piston/deck clearance.(about avg) Your around 12.6:1

Bowtie Boy

Heads are 60cc
Am I looking at compressed thickness for the gasket?

strokin93z

iTrader: (1)

compressed thickness of a gasket should be somewhere from .020ish to .120ish.. The 4.330 etc numbers, i assume are the bore diameters. Im sure someone will be able to help a little more.

Edit: With the 60CC and this gasket-http://store.summitracing.com/partde...T&autoview=sku

Compression is at 10.3:1 Not sure if this optimal for a Blower in the future? I really dunno, just throwing numbers out.

James Montigny

iTrader: (13)

LE heads are usually 56cc, unless you asked for something different.

Yes, you want compressed thickness.

.051" stock
.039" felpro
.028" GM ("Impala")
.026" Mr Gasket

Bowtie Boy

I was just guessing I was looking at VRE heads and they flow about the same as LE...their chamber volume is 60cc I figured it would be the same?

VRE flow-60cc
197/280 E/I

LE
195/280

James Montigny

iTrader: (13)

Nope.

Bowtie Boy

Interesting! So how does something with 4cc more flow the same?

strokin93z

iTrader: (1)

Not sure, heres a site to check out. Compression Calc

For piston to deck, unless you know maybe stick with .025. That seems about average on LT1. Just play with the calculator and enter different combos.. Good Luck.

bombebomb

I was expecting a little lower compression, even with the stock heads using a dished piston.

Also 10:1 + compression is not ideal for a boosted set up.

kgkern01

iTrader: (10)

Because there are a LOT more things involved in the flow properties of a head than simply how many cc's are in the combustion chamber. Every company has different styles of their porting and machining. LE3 port job =/= VRE port job. Plus even with the same chamber volume there can be differences in the work done to the chambers depending on who does the work. You can very easily have a head with more or less cc's difference either smaller or larger flow more, or either could flow less, it depends on the work done, not just the volume of the chambers.

James Montigny

iTrader: (13)

You're suggesting that combustion chamber size has a huge impact on flow?

If you get us the numbers Strokin' asked for above, we can help you calculate CR.

I'm worried about your pistons in a F/I build, the dish is very small.
If you try to compensate with thicker head gaskets, they'll just blow out on you under load.