Just had a motor built with forged internals. I had the builder mill the heads to up the compression a little. He came back with a compression that was 11.3:1. Will I be able to run 93 octane and be ok, or am I going to have to run a special high octane mix all the time...any input would be nice.
11.3:1 compression
- Thread starter Morningstar908
- Start date
It'll be fine on 93 as long as the tune is good.
That sounds awful high. Before you jump to conclusions find out how your builder calculated that comp ratio. You will need to know piston deck height at TDC for that cylinder, type of head gasket he used, and the volume of one combustion chamber measured in 'cc'.
whats stock compression??? thats seems like it would be a big jump but i dunno where you started to begin with
stock is 9.85:1...or so ive heard
Morningstar908 said:
CORRECT!
There are stock motors that have compression ratios well over 10 to 1. In fact, my trailblazer is 10.2 to 1 and it runs on 87 octane. 11.3 will not be a problem.
Last edited:
I have 11.5:1 pistons, and it pings bad on 91.....We dont have 93 in Cali, so I have to run Union 76 100 octane, at the low-low price of 7.06 a gallon:nonono: .....DA snake boy!!!!
couldnt you pull a little timing duane...or would it drastically alter performance???
that would alter performance drastically on Duane's motor.Morningstar908 said:
Last edited:
If it does ping with 93 octane...is there anyway to jack up the octane. Could you use an off the shelf octane booster instead of paying 6+ dollars per gallon for racing fuel?
maybe if you bought about 100 cans of it.
The stuff I use every now and then comes in a 4 bottle pack and says "Use one bottle per 20 gallons." I use all four when I am down to 1/4 quarter tank. Feels no different
Morningstar908 said:
I used to use this stuff called Torco, and it worked....However it left a thick redish-brick color residue on the spark plug insulator...So I stopped using it....DA snake boy!!!!
i have 11.3:1 compression and my car runs fine on amoco (bp) 93 octane. even in 105 degree weather in traffic 
na svt said:
LS1s are 10.5:1 stock and can run 87 all day long. The computer just pulls timing based on octane.
Doug said:i have 11.3:1 compression and my car runs fine on amoco (bp) 93 octane. even in 105 degree weather in traffic
Awesome! Now is that with a tune, or with the factory timing/fuel?
with a tune.
I ran 10.8:1 on factory timing and 93 for about a month and a half before I got it tuned. Didn't have problems with it. other than losing races cause I didn't have nitrous.
I ran 10.8:1 on factory timing and 93 for about a month and a half before I got it tuned. Didn't have problems with it. other than losing races cause I didn't have nitrous.
Doug said:
What were your numbers with 11.3:1...prior to N2O?
Doug...what were your numbers before nitrous with 11.3:1?
Users who are viewing this thread
