Something that I don't quite understand about Alky.

[Turbojorge]

I got the whole "cooling the air charge" part, but what I don't understand is how is the octane level rainsed? If it does not raise the octane level, then is cooler air the cause for higher boost?

Would any system that cools the air charge (alky, water, nos, propain) compensate for octane and allow you to run higher boost?

TIA

 

[turbo buicks]

i think its like when you mix 93 octane and xylene in a 3:1 ratio to get 100 octane. same principle here, just more alky in the cylinder so thats more octane.

 

[blackbuick87]

Alcohol has octane of ~ 115 octane, and water has infinite octane since it wont burn, so that is how your octane is raised

However since there is a lot more fuel than alcohol, the greatest benefit of alcohol injection is the cooling of the combustion chamber, not the increased octane. The alcohol is there to help facilitate combustion, since pure water can be tricky to tune, especially with only one or two jets

 

[Turbojorge]

But it is not really true that the cooler the ambient air, the more boost you can run even without alky. Is it?

If I made the air going into the trottle body cooler WITHOUT using a liquid (alky, water, etc) would I be able to run more boost?

 

[blackbuick87]

Yes with cooler air will allow more boost, as long as you can provide enough fuel also.

As the charge gets cooler, the air gets more dense and you have to add additional fuel to keep the same ratio

 

[Turbojorge]

Got it, thanks.

I'm working on something new for our cars. I'll let you guy's know soon if it works or not.

 

[BLACK6PACK]

Think of a deisel engine. They have no spark plugs. The air and fuel is ignited by compressing the air. Air gets hotter as its compressed. Deisels run at something like 20:1 compression once the air gets copressed enough and fuel is injected, boom spontainious combustion. Same thing with our cars. We are compressing the air with the turbo, and if we compress it too much boom, detonation. By cooling the air going into the engine, it has less chance to ignite before the spark plug fires.

 

[Turbojorge]

Thanks Brad. It does make alot of sense.