... like putting pure race gas in a car that only “needs” pump 93 ?

Waste of money and lower performance?

Remember that Shell ad puffing putting premium into a car that only needs 87 ?

Yur thoughts?

Less power, waste of money. I have seen cars on the chassis dyno pick up power switching to lower octane. Gas doesn't "magically" make power, it has to be matched to the combination.

I have seen pistons coated with what looks like and feels like lead and was told that’s the result of running race fuel in an engine that doesn’t need it . Is there lead in race fuel??
[i][/i]

Years ago i use to run my 10.5.1 motor on 105 octane fuel ,thought it was more of a cushion than anything due to bad tuning.

Give it what it needs and dont over do it. In my 11.25:1 408 small block i ran 93 pump with 36* timing and raced it that way. I once tried 110 VP straight and lost 3 tenths. Another time i ran low on 93 at the track and bought the tracks Torco 110 and again lost 2-3 tenths, so give it what it wants and its usually less than you think in my experience. I ran a mix of race 100 no lead and pump last year at a T&T which was a 95 octane mix and seen no issues in my 12.5:1 511. I dont recommend that for everyone. I now have been running a mix of Dragon 110 and 93 Sunoco to give about 100 octane and it works real nice too and much safer.

You can hear too much octane in the exhaust note. Makes it soft and the engine is sluggish.

I agree, it will have a dead exhaust note and not clean sounding like when its right.

A friend tossed together a low compresion copy of his bracket motor. Can't remember how low but i think it was 8 something. Picked up .4 in the 1/4 going from race gas to 87 oct.

And the plugs will foul quicker with the lead buildup.

Octane is a measurement of the fuels ability to resist ignition under compression. It's ideal to use fuel with an octane rating that is just on the edge of combustion so when the spark plug lights the fuel is ready. Too high an octane rating means the fuel is harder to burn than it should be

Any additive* replaces fuel in the mixture, and lowers the energy content (BTU per gallon, etc.).

*Obviously, this does not include mixing fuels with higher octane ratings like toluene.

I would run 116 octane on my high boost stuff with the thought of being safe... Come to find out the fuel would burn so slow the EGT's were would be really high regardless of timing and A/F and it would spool the turbo like a turd compared to regular 93 octane. I think it would had been better to run something in the 108-110 range.

AG.

This.

Modern engines with close to 11:1 compression run just fine on 87 Octane and don't gain anything if you run rocket fuel.

Got a buddy of mine who has a 12 to 1 small block stroker with aluminum heads.
He insists his engine builder told him it requires112 fuel. Dont get that at all
I told him 110 is plenty for an aluminum headed 12 to 1 motor that might see 7k at most

He will kill alot of power with 112. 110 at most and i bet it wouldn't require than much either, but he will be safe with 110.

My hemi was built specifically to run on 93 pump gas when N/A. On VP 110 fuel it slows down about a tenth in the 1/4 and a little over 1 MPH. I didn't change anything other than the fuel.

I haven,t built a race motor, or raced a car since 1980, until now, so this thread is very interesting.I remember using Sunoco Cam 2 racing fuel, with great results, in a 13-1 big block Chevy.(not to be confused with Sunoco 260 premium pump gas). Does anyone here remember the octane rating of Cam 2? My current race motor is a 13-1 Mopar big block w/a solid roller.Trying to figure a safe starting point. Thanks for starting this interesting thread Doc Fiberglass. Bill

Several stations around here sell it at a pump. Its 110

WOW great topic, i tell peopl e all the time, they slow down a car with too much octane. Proved it with my sons car. Junkyard 360, went 11.48 on 110 , put 93 and it went 11.15

Now HERES a major convert ! ... into a majorly diff car !

St Pete Bill .. an ex CHeEzY Chebby guy into a 1961 Dodge Lancer !

I have my on a 61 meself.. but a 4 door !