Compression Calculations

[IT_SS]

Does anyone have a formula to calculate static compression ratios for assembled engines? I figure X= bottom end compression and Y= top end compression, so X + Y = Total static compression????? or is it X(Y)/2?

I'm asking because in the next year or so I'll be starting my FI build, and I'm in the planning phase now and I want to make sure my numbers are right. The Lunati 395 Stroker Kit seems to be the direction I'm going in. The kit is offered in 3 different compressions :

8.7:1
10.4:1
12.2:1

In my mind, the 10.4:1 would be the wiser choice to use with say and LS head with these specs:

Combustion Chamber: 72cc
Intake Runner: 227cc
Exhaust Runner: 70cc
Intake Valve: 2.055"
Exhaust Valve: 1.57"
(Patriot Performance LQ9 Stage II)

Which advertise a drop from 10.1:1 to 9.0:1 on a stock LS1. So if X(Y)= Z, am I looking at a 9.5:1 compression?

I've also posted this on LS1Tech

[shady milkman]

its much more complicated..you need to know Bore,Stroke,Head Gasket Thickness,Deck Height,Piston Dome cc..like (-2 etc) ,Combustion Chamber of the heads

[shady milkman]

plus i doubt that stroker that is pushing the limits as is for a ls1..will be able to handle boost etc...why not go 402-08 or just do a 346ci with forged internals and boost the fuck out of it..

[IT_SS]

its much more complicated..you need to know Bore,Stroke,Head Gasket Thickness,Deck Height,Piston Dome cc..like (-2 etc) ,Combustion Chamber of the heads

plus i doubt that stroker that is pushing the limits as is for a ls1..will be able to handle boost etc...why not go 402-08 or just do a 346ci with forged internals and boost the fuck out of it..

I figured it would be, I'm looking @ the 395-6 CI forged internals because of the price, but if i keep the stock crank, i would just have to worry forged everything else.....hmmm

[shady milkman]

why not get a forged crank ? ..dont go half ass and cut corners when it comes to strokers or forging when going the FI route..YOU WILL BE SORRY~! and it will be expensive

[IT_SS]

why not get a forged crank ? ..dont go half ass and cut corners when it comes to strokers or forging when going the FI route..YOU WILL BE SORRY~! and it will be expensive

well, getting the forged crank justifies the 396 stroker, that's as high as an LS1 can go with out re-sleeving the block to my understanding. Im my mind, the goal is a 396 stroker twin turbo, no matter what tho, forged internals are a must!!!

[shady milkman]

well, getting the forged crank justifies the 396 stroker, that's as high as an LS1 can go with out re-sleeving the block to my understanding. Im my mind, the goal is a 396 stroker twin turbo, no matter what tho, forged internals are a must!!!

nice but pushing the limits of the already thinned walled ls1 then pushing pushing boost on top of it isnt the best idea..why not a 383 TT project..i think you will be much happier with that set up ..since you will have a little leeway for things

[IT_SS]

nice but pushing the limits of the already thinned walled ls1 then pushing pushing boost on top of it isnt the best idea..why not a 383 TT project..i think you will be much happier with that set up ..since you will have a little leeway for things

that has a bit of a sexy ring to it...383 twin turbo..... I just want to make sure i can hit 9.0:1-9.5:1....

[shady milkman]

that has a bit of a sexy ring to it...383 twin turbo..... I just want to make sure i can hit 9.0:1-9.5:1....

well you can always pick up a cheap lq4 and you will have nooo prob getting that ratio..just make sure you get a short/long block that is made for FI..for example the ls3 427 from texas speed is not made for fi at all..but the heads and cam make or break that set up

[IT_SS]

well you can always pick up a cheap lq4 and you will have nooo prob getting that ratio..just make sure you get a short/long block that is made for FI..for example the ls3 427 from texas speed is not made for fi at all..but the heads and cam make or break that set up

im either going to get the patriot performance LQ9 stage II or port a set of LS1 heads i have @ home......

[shady milkman]

im either going to get the patriot performance LQ9 stage II or port a set of LS1 heads i have @ home......

go big or go home..if your aiming for a TT dont take a shortcut on the heads..

[IT_SS]

patriot performance LQ9 stage II it is, now to start selling drugs....