Questions

[vershun]

Does higher octane gas typically burn slower than lower octane gas under the same conditions?

I've read different sites/articles and there's mixed information.

Most sites and some books say higher octane burns slower
Some say, higher octane burns faster than lower octane
Some say, octane doesn't affect burn rate, the additives do.

Ethanol burns faster than gas, right? And has lower peak temperatures than gas?
So a gasohol mix (E10,E85,etc) would burn faster than straight gasoline


The reason why AvGas burns slower than automotive gasoline is because of the Lead added to the fuel, and has nothing to do with the Octane rating?
edit:^I think that's incorrect.

So what does affect the burn rate of gas? O_o



Can running to high of an octane cause an incomplete burn? Worse emissions? Power loss? The effect of retarding ignition timing too much?
Here's a link to Dyno charts comparing lower octane with 100 octane.

http://www.team-integra.net/forum/di...&TopicID=50204


During the compression stroke, the spark plugs ignite the fuel mixture several degrees BTDC. So the gases expand while the piston is moving upwards correct? Wouldn't that cause a power loss?

How does Advancing Ignition Timing increase power output?
By raising the effective compression/increasing cylinder pressure?
So that would mean better mixing of fuel and air?
How does this better "thermal efficiency" work?


Thanks.
Hope to get some good answers.