Can Anyone give me an idea of what my compression would be. Stock LT1 castings, lets say I use a stock head gasket, and the block has the stock deck height?

I found a really good deal on a short block, but dont know about those pistons.

 

What stroke and bore?

 

sorry, 3.75 stroke, 4.020 bore. Im thinking it will be around 10.5:1

 

Yep I'd say with an undecked block and the piston setting .010 or so inthe hole you'll be right around 10.2 (given a 58 cc comb chamber).

 

Looks like your compression will be around 9.9:1 if you use a stock head gasket, assuming a 57cc chamber (I assume you were referring to your LE1 heads, not an actual stock casting. The LE1 heads should have a ~ 57cc chamber). You'd be better off running the Mr. Gasket head gasket, .026 installed thickness and a 4.100 bore. This would give you ~ 10.5:1.

You're referring to the LE1s and not an actual stock LT1 head right? If you really were referring to a stock LT1 head, your compression would be ~ 10.2 with the stock head gasket and ~ 10.8 with the Mr. Gasket head gasket.

 

Yeah, I am talking about my LE1 heads. Wouldnt they increase compression with the smaller combustion chamber? The heads have been milled .020". Im not sure of the deckheight on the block. I was just wondering what compression would be at its lowest with everything stock.

 

Please don't run -16cc pistons.... you give up so much free power by making the compression WAY too low. Just run a -5cc flat top. EVEN in a stroker.

Bret

 

I dont really want to much compression, I can only get 91 at the pump, and it gets pretty damn hot here.


How much of a power difference is there between 10.5:1 and 11.5:1. What would my compression be with a -5cc piston?

 

Actually we design the setups around the higher compression. Flat Top 383's especially. Ask Lloyd what his motor is.

The higher compression helps with the idle vacuum and driveablity along with giving you more power. It can be as much as 20hp.

Bret

 

Wont the extra compression hp gains be nixed from a less agressive tune? We have 6 months out of the year with 100* + days and only get 91 octane at the pump. I think thats what J Was trying to get at.

 

Why would you have to make the tune less aggressive? We have guys in TX with high 11's 383 strokers not going less aggressive on the tune.

Besides you only need to pull out timing on the bottom end, not the top end.

Bret

 

Thanks Bret

That was more of what I was looking for. With 91 being the max here would the point of compression be worth a couple less *'s of advance. I am assuming your going to say yes.

 

you will give up 4% by dropping your compression one full point from 11.5 to 10.5, but there are benefits to lower compression.

 

only benefit is a blower!

As for dropping back a couple of degrees, you should only have to do that at the low end of the RPM scale at the most.

Bret

 

When SRP advertises there compression at 11.8 with a 58cc head, is that with the block zero decked?