cheetha94607

with higher compression ratio(11:1-13:1+)would bigger injectors and fuel system stop detonation? the reason why im asking is because checking the forms it said that you would need a higher octane level. wouldnt adding more fuel have the same affect as changing your octane level?

302f150

nope[8D] do more reading. a lot more reading. higher octane means it resists detonation. dumping more fuel in will just make it run really rich.

cheetha94607

what is thehighest compression ratio can you go with 91 or 93 gas.

302f150

it depends on a lot, shape and size of combustion chamber, timing etc. newer celicas run like 11.5, obviously they use pump gas, but ive been told 10.5 is the highest you can run on pump gas. so you'd really have to ask someone who builds a lot of higher compression motors. high compression ratios are really hard on motors, you'd be better off to just get a cam or heads or something, it doesnt have that much of an effect on horsepower, maybe 10-15hp b/t 9.5:1-11.5:1. somebody correct me if im wrong

92civy

I know a guy that runs 11.3:1 with pump gas! To many veriable, and a good tune!

I plan to run 10.8:1 with PUMP GAS!

WhiteWindsor

My 357 is just a hair under 11.1 compression and i use 93 octane. That would be about the limit though. The tune is very important. I use carb so the most important thing for mine is the timing. I have my dizzy locked out 32. As soon as it starts and is idling it is 32 degree's and never changes. I could possibly run a couple more, but i'm not taking the chance.

gtpcoupe

my camaro has 10.75 and runs fine on pump fuel. my buddies TA runs 12.5 to 1 on pump with no probs. fords may be diff. but you shouldnt have any problems.

WhiteWindsor

Forgot to add that a good ign. system and using colder plugs are a must also.

mjr46

I ran 11 to 1 306 on 93 octane......the key is a good tune and ignition system but running aluminum heads helps alot to cause it will disapate heat better than cast iron thus allowing a higher compression to be run