Spade

iTrader: (26)

Building a procharged 370 LQ9 to be daily driven. What do you guys recommend for compression? I have seen anywhere from 9.5 to 10.1 for boost motors. Thoughts?

Detoxx03

iTrader: (14)

What fuel and what headunit? If 93 octane no lower than 10.0:1 and if e85 higher than that.

Spade

iTrader: (26)

91 is the best we have here. D1SC unit.

conan

iTrader: (5)

I'm running 10.1:1 compression on 91 octane, no problems. I wouldn't go any lower if I were doing it all over again as well. My car is 99% street car, part throttle and low RPM driving is nice and crisp.

What elevation are you at in NM ?

oscs

iTrader: (19)

On 91 I would keep it around 9.5 unless youre trying to break records. No reason in risking detonation. You want more power just turn the boost up. Remember, You can't "turn down" compression.

mOtOrHeAd MiKe

iTrader: (8)

Can you afford to put a meth injection kit on it?

If not, I would stay in the 9.5:1 range. Our LS2 is still at its factory 10.9:1 and I am running 30% ethanol and propane on top of 91 octane to compensate. Keep in mind that static compression ratio (pistons, heads, and HG thickness) is going to be higher than your dynamic compression ratio (valve events) - and this will impact your octane:knock tolerance.

Detoxx03

iTrader: (14)

Methanol with definitely help. Before I switched to e85 I was on 93 and ran 100% meth. Made a good 780 easily on the stock 10.7:1 compression. Now on the same compression on corn make almost 900 on less timing.

If no methanol then you can play it a little more conservative.

Bob@BruteSpeed

iTrader: (16)

9.5/1 is a good compromise for you with 91 octane. Bob

Spade

iTrader: (26)

Thanks for the input guys, I honestly have not looked at doing meth injection. Figured it would just be to much of a hassle and the fact I know very little about it. I would like to just fill the car up at the gas station and drive it around like I stole it and not worry to much about anything else.

Would 9.5/1 feel slouchy driving around if not in boost or do you think I really am not going to feel it much? To be honest I really don't know how much I would be out of boost anyways.

Bob@BruteSpeed

iTrader: (16)

A tank of meth usually last quite awhile as it is only used when deep into the throttle. Alky Control has one of the best kits you can buy, they're in Florida. Give Julio a call there and he'll answer any question you have.
9.5/1 doesn't feel weak down low to me. Bob

malibu9in

iTrader: (4)

Auto or stick?

Spade

iTrader: (26)

Sorry never did answer your question, 4200 feet

Detoxx03

iTrader: (14)

Stick

Monte4ever

iTrader: (2)

I run 9.5 comp and have real good bottom end grunt. I do have a 403 thou.

malibu9in

iTrader: (4)

What kinda clutch you running? Is the pedal hard? Gonna swap a clutch veeerryyy soon. Thx

conan

iTrader: (5)

I live at 6,300 and drive on a road that hits 7,500 daily. One more reason I chose to keep the compression up on my new motor, making power up here where planes fly is tough.

Like Bob said it takes quite a bit to burn through a tank of meth, so don't be afraid that its something you'll have to fill all the time. I have a 3/4 gal tank for my Snow meth kit and it lasted me all of last summer, about 1,200 miles of hard driving. You can also set what psi you want it to turn on at, so my pump doesn't even kick on until 4 psi. I would look in to a kit for your set up, it's worth the insurance for sure.

Detoxx03

iTrader: (14)

Mantic 9000 twin. Pedal feel is about the same as stock.

malibu9in

iTrader: (4)

thanks for rply

kingtal0n

iTrader: (1)

this!

Lots of people say "I wish I built it with a little less compression"

very few will say "damn I wish I had an extra half point of compression"

Spade

iTrader: (26)

I greatly appreciate the input folks.