mean_greenZ

iTrader: (1)

what is the highest compression ratio to still be able to use 93 octane safely?

lilblackZ28

This does have to do with your ?, but what do you run in the 1/4 mile with what is one your sig.

socal

iTrader: (1)

i'm going to be running 12:1 when my motor get back thats about all you can do

1redta

I remember hearing 9.4 dynamic compression for 93 octane. you have to input your specific variables for your car into a calculator to figure this. Art

mean_greenZ

iTrader: (1)

i have no idea cause ive never taken it to the track. but i really want to see what it will run. im hoping it will do pretty good

ckyconan2003

iTrader: (2)

11.5:1 WILL run fine. 12:1 is pushing it, but it'll run, you may have issues though.

LT1Formula007

iTrader: (66)

Tony Shephard has a 397 stroker with nitrous running 9's and when he's off the bottle he's running 93 octane with 12.8:1 compression. It's all about the tune honestly. I've seen as high as 13.5:1 compression and supposedly had NO issues. Just make sure the tune is right......Don't expect to advance your timing all the way as far as you can and expect not to get detonation or spark knock.
James

sdm1234

iTrader: (8)

you'll have to set your cam up correctly for whatever compression you want. it's just like sportbikes running 12.2:1 compression and running 93 octane.

lilblackZ28

I bet it will run good.Do you drive it year round or just when it nice out?

FASTFATBOY

iTrader: (23)

I run 12.6 on Shell 93 octane


David

LT1Formula007

iTrader: (66)

+1 For Shell 93 octane....
I work for shell, and their gas is alot better than alot of the others....
But like I was saying earlier 12.8+ is safe. Don't be afraid of the compression issue, by going with lower compression your leaving power out on the table... Just my .02

James

Formula350

iTrader: (3)

Would it help to get it setup for E85 which is 105oc? I notice when I run around 65gas:35E85 I get more pep out of my car and it's just stock. There's a guy on here who's pretty knowledgable on E85, and since it's alcohol he's said you'll need to change over a few fuel components to account for this. Like fuel o-rings and I think even your fuel pump. Still though E85, 105oc and 30-80cents cheaper than even 87oc!

mean_greenZ

iTrader: (1)

i drive it every single day of the year unless its snowing or sleeting/freezing rain.
but yea its got almost 138k and it had 114k when i got it about a year and a half ago

and to everyone else thanks for the info. i want to run as high compression as i can on 93. cause that means more power!

and is the shell 93 really better than others? i usually go to hickory point or bp.

TT632

iTrader: (3)

You really need to know what your dynamic compression ratio is. Your motor only sees the full static compression if your intake valve closes at bottom dead center or before.

If you have a late closing intake valve (as with a big race cam) your piston could be a 1/4 of the way up the bore before the intake valve closes and your engine only captures 3/4 of the cylinders volume, ie your 12:1 motor has the dynamic compression ratio of 9:1 motor.

BADHAWK51

iTrader: (1)

I'm running 12.8:1 here. no issues on the dyno no detonation at all.

transamsam98

iTrader: (56)

speaking of compression and 383s does a run of the mill sbc 383 kit work in a lt1?

Puck

iTrader: (17)

Like stated, it heavily depends on the tune and the cam. The dynamic compression is the value to watch.

My bike is 13.3:1 and only recommends 90 octane(!).

infinitebird

iTrader: (11)

You can go high 12s easy like others have said. If you run into any trouble you can always retard timing a few degrees and that should clear up any problems.

thebufenator

iTrader: (2)

My car has 12.2:1
no knock, and that on 8 month old gas.

Its all in the cam and tuning. More compression == bigger cam with more overlap.

blackz93

iTrader: (2)

That's alot!