10 to 1 compresion ratio engine gasoline

[EagleMark]

Does a 10 to 1 compresion ratio engine need to run 92 octane fuel?

[RobertISaar]

depends on how much advance you want to run :lol:

you can run a motor on moose urine, but you're going to have to retard the timing quite a bit to do so without detonation.

[Six_Shooter]

you can run a motor on moose urine,

That made me LOL.

[RobertISaar]

eventually, it runs down to 2 different methods of tuning for octane: the quick way and the thorough way.

quick: just run the best fuel you can get consistently, tune for that.

thorough: get the lowest grade of fuel you would consider running, tune for that, step up a grade, run more advance(since you should be able to), see if it gains any power/economy, if so, step up another grade, repeat. when you get to the point of increasing octane does not allow for more advance(or you're running so much that it hurts power), then you'll know at what point you'll be wasting money.

[EagleMark]

YEAH BUT THIS IS AN ORAGANAL mOPAR 6 pack engine, darn caps...

[Lucky]

The real issue is not strictly compression ratio - it is dynamic compression ratio AND combustion chamber design. A modern combustion chamber with a good quench area and some swirl to mix the air/fuel together can run low grade fuel at higher compression than an older design - like say a Hemi. Dynamic compression is mostly a function of cam profile - a 'rough' cam with lots of overlap and long duration effectively lowers the compression pressure in the cylinder.

That said - I never even considered paying for high octane fuel when I was younger and built Chevies with 10:1 to 12:1 with no problems. My cams always had lots of duration and my carbs were set a little rich though. It was pretty easy to hear a chevy knock for some reason. Usually just set the timing by ear for whatever it would take :D