63 dart 360 2bbl 9-1CR circle track. I can use either one. I wouldn't think pinging would be an issue tho I dont have quench. iirc there was something about race gas burning slower??? which should I use? thank you for your time. RR

91-92 pump is all you need, assuming a reasonable total mechanical in the 36 degree range. Any more is waste of money.

I tried race gas in my 10-1 pig. It actually slowed down. Best thing is if you can find some 91-93 No Alcohol. My car liked that the best but they quit selling it around me.

You'll need to test the jetting, valve lash, intake lobe centers and spark plug heat range and gaps to get it to run as fast as it can, especially on a dirt track
Focus on handling to start with and then when it won't go any quicker on the lap times focus on making more power and driving techniques

My wifes Challenger 360 is 9.0-1. I've used pump 93 to race. But It runs 87 on the street. Cam is 220@.050/110 lca. It gets beat on every time I drive it. Never an issue. Been together since 2004. Not sure it even needed 93.
Doug

Buy an engine program, I use performance trends, it will calculate a bunch of stuff besides HP and torque, Things like cranking compression and if it is prone to spark knock, and it will generate a timing curve to protect against spark knock, I have been using it for many years. If you put in good numbers, it is very accurate compared to what the engine makes on a real dyno, including those cranking compression numbers. And it depends on the specific gravity of the race fuel you use but usually yes the higher the octane the slower it burns.

Just out of interest, I was watching engine masters last night. They tried 87, 93, 109, 116 octane and E85 on a 530hp LS engine. Only the E85 made more power. The gasolenes made almost the same power (plus or minus roughly 3-4 hp IIRC) and needed the same timing.
The conclusion was if the engine runs optimal on the lower octane fuel, increasing fuel octane won't make any more power AND If the higher octane fuel makes optimal power at the same timing, It can't be burning slower.

good info! I got my work cut out for me. I'll work on the handling first. thanks guys. RR

I think that's a good point.

It's not that higher octane burns slower. (can't really have race fuel and slow burn with say 20,000rpm F1 cars for example) but if you look at specific energy or btu/lb.... pump fuel is a bit higher than race fuel in that regard.

So yes, if higher octane isn't needed......but used.....the result can be lower output, but for reasons other than burn speed. (which is rather similar between varying types of gasoline)

Pump 93. Anything more is a waste of money.

I watched the same Engine Masters. Very good tests. If it were me with only 9;1 I would run 87 . And to run E85 you will burn 20-25% more fuel and then you have corrosion problems.

That is all I run, and I get it from the same pump each week to insure consistency.

The only thing consistent about pump gas is it’s inconsistency.

Race gas additives displace gasoline, energy content per gallon goes down (HT Vizard).

I've read that high octane gas burns more slowly, but that's not the only anti-knock measure. Not all fuels have the same sensitivity (heat, physical shock, electrical current): you can drown a lit match in a bucket of kerosene. TNT (2,4,6-trinitrotoluene) is far more powerful than dynamite, but it won't explode if you hit it with bullet.
TEL (tetra ethyl lead) increased octane for Spitfires' Merlin engines 80 years ago, but kills the whales, or something.

Does that station get the same gas from the same refinery with the same gas year around? Or does it buy its fuel from the cheapest supplier they can by from? Do they have winter, spring, summer and fall mixes? We do have them, different mixes, out here on the west coast

I run 93 pump gas in all of my old classic cars on the street. I switch to VP NO2 at the track when on the spray in my 70 Challenger street/strip car.

I would run pump premium (92-93 octane).

To add to the other comments....
I have heard from a dyno operator, and others; that since pump gas can have 10% ethanol, if you jet for it, you might be able to make a little more power.
When I dyno tested a 10.3 CR big block Mopar with roller cam and 5800 rpm peak HP (stock heads, 496 CID), it made the same (+/-2) on pump premium and 112 race race.

Use pump low grade with 10% ethanol content and jet for it. That engine with a 2bbl will be starving for oxygen and ethanol carries in liquid oxygen. There is no need for anything above 89 octane with that low of compression and low cylinder filling. Take the same engine and put a good induction and exhaust on it that is tuned to fill the cylinders with resonance tuning and really good flow or even over fill them then you "might" have an excuse to run higher octane with the lower compression.

Just for info, this was also touched upon in the EngineMasters episode I mentioned previously, the oxygen effects of E10 are negligable. Though not tested at that time, the 10% of the 10% (1% by volume ??) makes no difference according to the previous experience of Mr Brule.

Got a link? I can't find it.

I imagine it making a lot bigger difference on some engines than on others, an oxygen deprived engine I would expect more difference especially with some additional cooling from the alcohol evaporation helping more air molecules get in by making the air denser. I know it would not be as big a deal as say E-85 but when races are sometimes won and lost by a handful of HP and the real kicker is that the money for fuel could then be used elsewhere I would say it is defiantly worth while.