Race gas timing, hearing a different opinion.

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famous bob said:
hi octane race gas , burns slower than lesser gas...
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Octane and burn rate are not related. Here are two examples.

A Pro Stock engine with a top RPM of 10,500 uses fuel with a very fast burn rate. Why is that? Because at high RPM you don‘t have as much time to get the burn going so a high octane/slow burn rate fuel would require far more timing than a high octane/fast burn rate fuel.

If octane and burn rate were related, you’d see Pro Stock (and any other gasoline burning high RPM a engine) running total timing in the mid to high 40 degree range and they are nowhere near that.

Take your average street or street/strip car built on forums like this. What’s the RPM range of an engine like that? Idle to 4,000? and maybe, maybe 6,000 RPM every now and then when making a quick blast? Around here you have 91 octane. That’s the best you can get. That would mean if the lower octane fuel has a faster burn rate the total timing on these engines would be in the high 20’s. And it just doesn’t happen because burn rate and octane are not related.

Ill look and see if I can find a tech article from fuel blender and I’ll post it here.

There is a ton of confusion on this.
 
Pump Gas and Race Gas are just names. What is needed is are they oxygenated or 100% hydrocarbon fuels. That impacts Air/Fuel ratio which impacts performace significantly. Race gas with high aromatics can have a slower burn rate which may require more timing, but the Engine Masters video is correct for at least modern cylinder heads. Timing is a design parameter for heads to minimize NOx emissions. Less timing, less peak cylinder temperature, less NOx. Small Block Mopar engines with the spark plug more centrally located require less spark timing for peak power as the flame front has less distance to travel to cross the combustion chamber. B-Engines with the lower positioned spark plug (like SMC's) need more timing to account for the longer flame travel. The goal is to reach peak cylinder pressure just after TDC for peak performance and economy.
E10 and more importantly, E15, common pump gal, will require larger jetting to account for the oxygenates (ethanol) in the fuel. Switching to Race Gas w/o ethanol will be running rich without a jet change. Some race gas does contain ethanol, so you have to ask and/or tune for best power on the gas you run.
 
Rat Bastid said:
Octane and burn rate are not related. Here are two examples.

A Pro Stock engine with a top RPM of 10,500 uses fuel with a very fast burn rate. Why is that? Because at high RPM you don‘t have as much time to get the burn going so a high octane/slow burn rate fuel would require far more timing than a high octane/fast burn rate fuel.

If octane and burn rate were related, you’d see Pro Stock (and any other gasoline burning high RPM a engine) running total timing in the mid to high 40 degree range and they are nowhere near that.

Take your average street or street/strip car built on forums like this. What’s the RPM range of an engine like that? Idle to 4,000? and maybe, maybe 6,000 RPM every now and then when making a quick blast? Around here you have 91 octane. That’s the best you can get. That would mean if the lower octane fuel has a faster burn rate the total timing on these engines would be in the high 20’s. And it just doesn’t happen because burn rate and octane are not related.

Ill look and see if I can find a tech article from fuel blender and I’ll post it here.

There is a ton of confusion on this.
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B.S. , I know an 18 time national record holder that runs timing way up there, and dumped the clutch at 9500 ...most chevy guys run a lot of timing with hi octane gas ...
 
famous bob said:
B.S. , I know an 18 time national record holder that runs timing way up there, and dumped the clutch at 9500 ...most chevy guys run a lot of timing with hi octane gas
famous bob said:
B.S. , I know an 18 time national record holder that runs timing way up there, and dumped the clutch at 9500 ...most chevy guys run a lot of timing with hi octane gas ..
Click to expand...
Click to expand...

Did you read any of the above links? Some chevy’s take a lot of timing whatever a lot is
 
famous bob said:
if it has a slower burn time , you have to light it sooner , or it would be exploding late and rattle like hell close to tdc ...
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I agree. Your premise that octane and burn rate go together is wrong. That’s why I posted the links.
 
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