Rapid Robert
Well-Known Member
any thoughts on a good additive to search for?
race gas or pump non ethanol premium, which to use
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Rat Bastid
Dunamis Metron
Gator
Mopar or No Car
Well I tend to disagree with you on the lowest octane. In my HiPo 340 I am running 93 octane and when mixing 110 Sunoco racing fuel,1 gallon to 15 gallons of 93 my car comes alive.
We have tested this many times on the dyno on both 9:1 open and crate motors for IMCA type racing. 91-93 10% ethanol for most power. I'll post a more complete run down on this later when I have time.
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What cylinder heads and compression? For clarification, the lowest octane fuel that meets the octane demand of the engine at its optimal state of tune will make more power than a fuel that surpasses the engines actual octane requirement that has a slower burn rate and is harder to ignite. Anytime that an increase in fuel octane increases power it usually means that it is remedying some inaudible or intermittent detonation. Any 9:1 engine should run better on straight pump fuel than 110 octane. That is unless the fuel is heavily oxygenated and you’re able to operate at ethanol like F/A mixtures.
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TT5.9mag
Two atmospheres are better than one
Could not agree more. We ran a 418 Windsor on the dyno Tuesday. At 10:1, solid roller, aluminum afr heads it made 581hp. We mixed 2 gallons of 110 in because Brule wanted to for a test. Lost 3 hp.
Rat Bastid
Dunamis Metron
And that’s why you have to test. You just never know.
BTW 581 on 10:1 on pump gas is damned impressive.
TT5.9mag
Two atmospheres are better than one
It’s not every day you see someone post a picture of their project with Mr. Engine Masters tweaking on it…
TT5.9mag
Two atmospheres are better than one
Not my engine. It’s for another teams off road truck. I just got to be a small part of it. And any chance I get to sit in the dyno and listen to Brule talk I take. I learn so much from that guy. I go in to absorb mode. He’s forgotten more than most people will ever know.
Scody21
Just send it
It’s an experience for sure. The time I spend with my brother working on the vintage F1 / F2 / Atlantic cars and seeing him built the Cosworth DFV’s / DBG’s, etc. then running them on the dyno is impressive to say the least. Nothing like an 11k screaming 3 liter. It’s the same chilling and talking with The banned forever YR. His knowledge of push rod motors is awesome. We’re going to run my motor soon then make the changes run it again, then play with some fuel / tuning to see how the different fuels compare.
All else being equal, a higher octane fuel burns more slowly than a lower octane fuel & therefore requires more ign advance. This hurts power. So use the lowest octane fuel that your engine will tolerate.
j par
Well-hung Member
Radical cam??...
Rat Bastid
Dunamis Metron
Octane and burn rate are not related. Not even close. Most race fuels have a much quicker burn rate than pump gas. And it’s only a few that are as slow as pump gas.
same results here 11.4 compression adding 2 gallons sunoco 110 to the tank wakes the car up
Octane & burn rate are veeeery related with gasoline fuels. As I stated earlier in this thread, high octane fuel burns more slowly; that is how it avoids detonation, by burning slower & not spontaneously igniting. This information is freely available on the web among other places.
From D. Vizard in his Holley book, p.121.
' There is no performance value in a high octane fuel unless the engine's CR & thermal operating conditions dictate its need to stave off detonation. An 8.5 CR engine will, as often as not, produce a better output on a quality 87 octane fuel than a costly 110 octane race fuel.'
' There is no performance value in a high octane fuel unless the engine's CR & thermal operating conditions dictate its need to stave off detonation. An 8.5 CR engine will, as often as not, produce a better output on a quality 87 octane fuel than a costly 110 octane race fuel.'
Rat Bastid
Dunamis Metron
Here is just one tech article that touches on octane and flame speed. You can all ANY race fuel company and they will tell you octane and flame speed are NOT related.
Junk, garbage information is one reason why there are so many under achieving engines out there.
One more time. Octane and flame speed are NOT a related regardless of what you are on a forum.
https://www.rockettbrand.com/downloads/tech_bulletins/Tech-Flame%20Speed%20Octane%20&%20Power.pdf
Junk, garbage information is one reason why there are so many under achieving engines out there.
One more time. Octane and flame speed are NOT a related regardless of what you are on a forum.
https://www.rockettbrand.com/downloads/tech_bulletins/Tech-Flame%20Speed%20Octane%20&%20Power.pdf
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