[Diy_efi] injector advance

[frederic]

> > Yes, alcohol cools during intake, but several orders
> > of magnitude more (between the greatly increased
> > volume of fuel being delivered, and the lower heat of
> > vaporization) than gasoline ever can or will, so it's
> > not relevant to the conversation WRT gasoline.

When you compress a gas, the gas itself gets really hot.  Its not uncommon 
for supercharged/turbocharged intake air charges to reach the 300+ degrees 
range, well over the boiling point for isopropol as well as ordinary 
water.

And yes, both expand greatly as they go from a liquid state to a gaseous 
state, and absorb heat in the process.

The nifty thing about alcohol, is it burns.  Water, does not.  So the 
obvious advantage to injecting alcohol instead of water, is you enjoy the 
cooling properties while having opportunity to burn darn near everything 
that goes into the combustion chamber.

> > And water injection does not cool in the intake charge;
> > to the contrary, since water expands so greatly during
> > vaporization.....

Actually it does.

> > combustion chamber pressure before ignition.  Water,
> > even in vapor form, greatly slows the burn rate of the
> > mixture, allowing higher boost without detonation. 

This is also true.


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