Re: Ice Intercooler

[Dave Dahlgren <ddahlgren@snet.net>]

Joe I can only tell you what I think happens as I have no real way to prove it
other than observation and intuition which is not all that scientific.
 Here goes.

You and I talked a while ago and I keep saying that I seem to find the largest
practical or at times survivable size for a nitrous system is about 50% of what
the engine makes off the bottle. I never did elaborate on that but will a little
now. Hope it makes sense to you.

I think the base HP of the engine describes the amount of air and fuel at
ambient temperatures and the relative amount of heat in BTUs during the
combustion of the fuel. With gasoline these are all at ambient or higher
temperatures so when you add the nitrous you have a certain number of BTUs that
you can reduce the intake charge temperature before you go too cold and the fuel
just becomes a liquid. At this point you have a mess on your hands as the fuel
has to be turned into something that can burn during compression and you don't
have much time for that to happen. The result i think is you get a variable
amount of fuel actually burned and the rest just passes through and is either
burned in the exhaust system or leaves as a vapor. This changes on a cycle by
cycle basis and once you start to not burn the fuel the temps first get hotter
then colder as you pass way too lean. At that point it might start to skip or
run so poor you shut it off. I had this happen with trying to run alky as both
the base fuel and the enrichment fuel for the nitrous. It just ran horrible.
With gasoline I seem to get to the point where it just goes lean and burns up if
i try to stay with a big hit for too long.. The limit of my courage currently is
25 to 40 seconds. I think for Bonneville you need the absolute best engine you
can build off the bottle and then add as little nitrous as you need to get the
job done if you want it reliable that is. Turk's car is a good example. He can
run the 150 hp plate system till he is tired of pouring gas in the tank with no
real problems. but that is 150 hit on 500 hp. Pretty tame. I have run his fogger
system on the dyno until it stabilized about 5 or 6 seconds..I don't think I
would want to run that much past 25 seconds though. So now he has to pick the
mile of interest drive up to it and pull the trigger. That is a 250 hp hit on a
565 hp engine just about 50%.

As far as fuels go I am no chemist and would gladly defer to anyone that is,
Rick Gold comes to mind, but I would think you would want a fuel with a very low
flash point and the ability to vaporize at very low temperatures( high vapor
pressure ???). Whether these translate to a good motor octane he would have to
answer. You basically need stable combustion in Antarctica weather conditions.

Dave

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