06sierra5.3

iTrader: (7)

im looking for an lq9 to build to swap in place of my 5.3. i was told by Dave at WCCH that i should be running a combustion chamber around 72-74cc. im not sure what compression ratio this would give me. i was thinking, if i came across an lq4 for a decent price, can i make up for the dished pistons by using a smaller combustion chamber on the heads? like a 62-64cc

1. how do i figure out what my compression ratio will be with the combustion chamber? what would an lq4 ratio be with 64 cc heads?

2. for a daily driver, what would be too high of a compression ratio?

3. if i wanted to add 100 shot of nitrous down the road, how would i account for that? is there a rule of thumb how many compression points to drop for nitrous?

Derek @ EDO

iTrader: (73)

you dont drop compression for nitrous!

Nitrous LOVES compression!

I calculated 10.4:1 on 64cc

06sierra5.3

iTrader: (7)

haha sounds good

isnt 10.4 about where the lq9 is stock? id like to go a bit higher. can i run 11:1 reliably?

Zick

iTrader: (18)

LQ9 is 10.1:1 stock.
I ran about 11.5 w/ my LQ9 setup in my old 03'. Not sure what you mean by reliably. But with the right tuning you can run 11:1 just fine.

06sierra5.3

iTrader: (7)

it gets 120+ out here in the summer and we only hve 91 octane i dont want it pinging. i talked to richard at WCCH this morning. i think hes gonna help me pick my setup.

Zick

iTrader: (18)

Again with the right tuning anything is possible.
I was run on 87* octane with no detonation but I had to lower the timing by quite a bit.
It was definitely nice having HPT to be able to change my tune when I saw fit.

hirdlej

iTrader: (31)

For every 1cc lost, you'll gain about a tenth of a compression point. I obtained 10:1 compression out of my LQ4 using 64cc LS6 heads, and cometic .040" MLS headgaskets. That's with NO machine work on the heads. With the **** poor quality gasoline coming up the the near future, I wouldn't go much higher than that. Here's a good LS based compression calc to play with. http://www.c5frc.com/calculators/Com...Calculator.htm

06sierra5.3

iTrader: (7)

thatnks for the link. yeah ive noticed the gas in the last 5 years or so has become noticeably different in smell and texture. not lookin good.