my dad and i were talking last night, and we were talking about the fuel i run while auto-xing, while at the track, and while i'm daily driving. i said from my experience, my car seems to run fine while on 91-93 octane as i just have a stock b16a. i thought my car may run better on 100+ octane although i've never tried race fuel simply because its not the easiest to get. now, he was telling me about his triumph motorcycles that he's had in the past. their compression was similar to that of a b16a (around 10.4:1) and he said with 100+ octane the bike's engine would make more noise, seem to get hotter, and the tailpipes would glow from the increased heat. now, obviously when there is a more efficient burn, an engine will make more power and thus create more heat, right? now i'm wondering if this increased heat would have an adverse affect on engine life, etc. meaning, the hotter and more power a motor makes, the shorter its engine life simply because its working harder and there is more stress on the internals of the motor.

just wondering what everyone elses experiences are with higher octane, and would like to know if my reasoning is simply incorrect.

 

octaine from race gas does one thing only........ reduce the risk of detonation, if u arent increasing the timing or boost pressure, then using race gas is stupid... HOWEVER it does burn hotter, hence why cast piston tops melt when using race gas.

 

Typically racing gasoline's actually burn cooler and require less fuel to burn efficient. Basically if you are running fine without detonation then there is no need for race gas.

You will probably lose power by adding race gas without leaning your car out a little because of the cooler burn.

 

Think of octane as a rating of how well the fuel resists combustion.

Its a two edge sword since high octanes will help during high pressure and temperatures scenarios by inhibiting unintended combustion but that inhibition will also work against motors with pressures and temperatures that do not require that octane.

That is the reason for the lower burn temps since it slows down the combustion rates and why you might need to lean out a mix of high octane fuel.

The bottom line is use whatever minimum octane your engine's circumstances require.

I would imagine your reliatively stock b16a with 10.5:1 compression can live just fine with 91 octane.

 

he's right, I actually noticed a decreas in power when using 110 with my current fuel pressure, droped the fuel pressure and gained 2-3 mph in the traps.

 

so consider 12.2:1 compression. what are your thoughts then...

considering the motor would be revved only to 8k.

i understand what you mean about higher octane...it kinda goes along with what my dad was saying.

 

DOH oh well....... maybe i was wrong.... but why do cars running race hate cast pistons? i thought it was cause of extra heat.........

 

I don't know what you are talking about... I run race gas alot and have cast pistons. I think when people are really using race gas alot they are ussually pushing the limits of tunning (in a good or bad way) and can tune to a piont where they either detonate(crack a piston), overheat (melt a piston) or over power (usually brake) the pistons. Forged pistons take more abuse, but alo of cast piston are really strong too.

Extra heat is not from the feul. It is from the tune. Too much timming and/or not enough feul can cause excessive heat.

 

What the hell kind of advice is that? My car only requires 87 octane. However I will be slow as you with no boost or timming.