[Cliff R]

Last outing at Norwalk I put in 5 gallons of race gas and the car slowed .04-.05 seconds. If your engine has the correct effective duration for lower octane, putting in higher octane and slowing down the burn rate also kills off some power.

This entire thing is about effective compression, cylinder filling abilities across the loaded RPM range, combustion efficiency, quench distance, BSFC, close control of timing/fuel curves and about a dozen other things right down to vehicle weight and torque converter efficiency that effect octane requirements.

It's WAY beyond just throwing in camshaft A into engine B, setting the timing by ear, and hoping you get good results and can get it to work on currently available pump fuel......FWIW.

Even with that said, at the end of the day if you are happy with the end results and found a way to get there, and can deal with the expense and limited availability of high octane fuel/additives in a street driven vehicle......good for you........Cliff

[TAQuest]

Originally Posted by Cliff R

Last outing at Norwalk I put in 5 gallons of race gas and the car slowed .04-.05 seconds.

That's obviously because you have it detuned for crappy fuel.

It doesn't take a rocket scientist to know that more octane has more power potential if tuned correctly for it.

[Formulajones]

Originally Posted by TAQuest

That's obviously because you have it detuned for crappy fuel.

It doesn't take a rocket scientist to know that more octane has more power potential if tuned correctly for it.

That is absolutely completely false.

If the engine is built properly, with the right camshaft and compression, it'll run perfectly fine on pump gas in all conditions without the need to detune.

I have several real world examples here, as Cliff does, and many others on the forum here.

I'm running an 11:1 compression engine with iron heads on 91 octane here, with 36 degrees total timing and it runs absolutely perfect on pump gas and is driven daily.

My bird is a stock RAIII 400 that has 10.13:1 compression and the stock 068 cam in it. Much like your claimed original 69 bird, very similar engine. It's not detuned at all, loves 34 degrees total timing and runs on 91 octane. With stock converter and only a 3.31 gear has gone 13.10 @ 104.5 mph. I drive this thing everywhere on pump gas, no additives.
Race gas does nothing for this car, I've tried it. If the engine doesn't need it, it's wasted money.

[TAQuest]

Originally Posted by Formulajones

My bird is a stock RAIII 400 that has 10.13:1 compression and the stock 068 cam in it. Much like your claimed original 69 bird, very similar engine. It's not detuned at all, loves 34 degrees total timing and runs on 91 octane. With stock converter and only a 3.31 gear has gone 13.10 @ 104.5 mph. I drive this thing everywhere on pump gas, no additives.
Race gas does nothing for this car, I've tried it. If the engine doesn't need it, it's wasted money.

I would ever do this with my concourse 69 numbers matching RAIII 400 Firebird Convertible. It's worth WAY too much to penny pinch like that. Better look at your plugs ….

[Formulajones]

Originally Posted by TAQuest

I would ever do this with my concourse 69 numbers matching RAIII 400 Firebird Convertible. It's worth WAY too much to penny pinch like that. Better look at your plugs ….

Plugs look perfect, no signs of detonation anyplace. Been racing and daily driving this combo going on 3 years now.

[Steve C.]

Pump Gas Versus Race Gas

Is Race Gas Worth Any Power On A Pump-Gas Street Engine? We Put It To The Test.

https://www.hotrod.com/articles/0901...pump-race-gas/


The problem running race gas is that if you don't have the compression to compress the fuel and air enough, you'll actually run SLOWER!

http://www.badasscars.com/index.cfm/...rod/prd427.htm

Everything You Need To Know About Octane
http://www.superchevy.com/how-to/car...w-about-octane




.

[NeighborsComplaint]

Originally Posted by Steve C.

Pump Gas Versus Race Gas

Is Race Gas Worth Any Power On A Pump-Gas Street Engine? We Put It To The Test.

https://www.hotrod.com/articles/0901...pump-race-gas/.

Those amateurs at Westech obviously don't have the hearing acuity of TAQuest. Neither does Cliff. He walks around with a book full of notes and timeslips and can't hear that his car is actually making more HP on race gas. lol

I have summarized the important steps to tuning by ear for performance and drivability below.

[NeighborsComplaint]

Sorry to the OP for derailing this thread momentarily. Hope you can locate the source of the noise.

[ta man]

Originally Posted by TAQuest

That's obviously because you have it detuned for crappy fuel.

It doesn't take a rocket scientist to know that more octane has more power potential if tuned correctly for it.

Not sure about that, for most here why would we want to "tune" for high octane..basically setting up our engines to have unmanageable higher compression ratios when readily available pump gas will get the job done running lower compression ratios.
If I remember correctly lower octane fuel actually produces more energy.

[Dragncar]

Originally Posted by TAQuest

That's obviously because you have it detuned for crappy fuel.

It doesn't take a rocket scientist to know that more octane has more power potential if tuned correctly for it.

Not true. High octane fuel has "less" energy in it not more. If you have a engine that will not ping/detonate on 91 octane pump gas with timing set for max power you will always make less power with race gas.
Always.
The only reason race gas makes more power is if the engine/combo has enough cylinder pressure to light off 91 octane before the piston gets to TDC'
It has been proven in laboratory's. There is more energy in 87 octane pump gas then 110 race gas. If you use a gallon of gas to simply burn it and head up a big vat of water the 87 octane does a better job of it. More heat is transferred.
A gallon of race gas has additives in it inhibiting the flash point. Raising it so the air/fuel does not light off before the piston gets to TDC due simply to the heat generated from compressing the molecules together.
The high CR engine "will" make more power in the end even if there is less energy in the fuel. Its simply because there is more cylinder pressure from the higher compression and the fuel needs the higher flash point to let it all happen like it is supposed to.
Simply put, the additives is a gallon of race gas, to make it race gas just takes up space. That "space" taken up is the difference in the race gas having less energy in a given gallon of gas.
I am a iron head pump gas racer and have proven it in my car and others at the track. A guy at the track ran a sbc 350 with 10-1 CR and aluminum heads. He used to mix 50/50 with 91 and race gas. He got all worried when he ran out of race gas during a big race to mix with. I told him not to worry and just run straight 91. He ran his best time ever that day.
Tuning by ear is the reason Butler sends out their street 455s with aluminum heads out at 9.9 CR. Less come back from the guys tuning it that do not know what they are doing.