water injection

[Greg Hermann]

>One person claimed that it actually helps clean the combustion chamber. Any
>one ever notice that after a car is over hauled that it gets faster and
>faster, that is because the coke insulates the chamber so instead of the
>heat giong into the water jacket it does some useful work. In addition does
>water not cause rusting? Water injection is just a reason for doing a poor
>job, if you want an engine to give 600 bhp and there is a chance you may
>blow it because it is being pushed to the limit, do not build it. Instead
>get an engine that will produce the power and not burst at the seams.
>Then if you still want to inject something with water in it, just design an
>engine to run an alcohol/ water mix
>
>
Hang on here--not gonna let you argue both sides!! F1 cars use coatings,
which keep the heat in the chamber, and far better than coke deposits.

If you run a low ash oil, like you should, and unleaded fuel, like you
should (not to please enviro GEEKS, but for better sustained performance),
you will be amazed how little coke you get in the chambers, even without
coatings. Been there and done that, getting 170 plus HP from 1648 cc's on
the (old) Amoco super premium gas (25 years ago). You could blow the soot
off the piston crowns and chamber surfaces with your breath (and no, my
name is not Monica!). No coke at all. Not even the white kind! The engine
was an Alfa.

Are you trying to tell me that lowering the peak combustion temps by nearly
1000 degrees F, as could be done with the right kind of water injection ,
will not reduce the amount of heat going into the water jackets by a
STRIKING amount?? Particularly when you consider that heat RADIATED by the
core of the flame kernel into the chamber walls varies with the FOURTH
power of the absolute temperature of the gas?? Somehow, I thing that this
saving would make a far bigger plus than a little bit of coke that proper
fuel and oil selection would avoid anyway!! And regardless of the reduction
in dreamed of Carnot efficiency! You are probably one of the folks who
would try to claim that polishing piston crowns and chambers makes no
difference to power output--cuz you apparently do not have a clue as to the
mechanisms of radiant heat transfer!

Plus, the main effect of coke deposits on power output is mostly due to
raising of effective compression ratio, not to heat insulation.  Coke is
not a particularly good insulator, plus it has a fairly high absorbtivity!

To borrow your own phrase, if you want a higher compression engine, build
it that way, and keep it clean so that the compression stays where you
meant it to be!!

Greg