hot rod,

I was 1000 times out, I used the "g" instead fo "mg", thank you for correcting me.

For a moment it was interesting to follow this thread... now it becomes senseless.
My hope is that the majority of all I find on the web is real and not based on fantasy and nonsense as some statements I saw here.
Chemistry is not an opinion, neither physics.
Have fun with your cars guys! With or without WI...

Stefano

corrections on the fly
 

Richard, and Michael thanks for the double checks -- its not easy to whip out a mathmatical proof off the top of your head and keep all the details, factors, decimals, units etc. straight when your composing in stream of consciousness mode in one of these little message windows.

I've had a long term interest in chilled injection cooling and the complications it entails.

If you over cool the intake mixture you run into two problems. First you need to modify your ignition timing to account for the changes in burn time and fuel vaporization. In severe cases you may need to heat the fuel to get it to vaporize properly.

On first blush you would expect the power increase due to changing the mixture temperature and the change in charge density that results to give you a directly proportional power increase. In fact the change is closer to the square root of the change in absolute temperature due to several effects. The colder the air flow is the slower the sonic speed in the air mixture, so air flow into the cylinder is less during the early and late stages of valve lift with very cold air, when the valve opening becomes a critical flow orfice.

Assuming the pressure ratio is high enough to achieve critical flow. For air the pressure ratio across the orfice must exceed 1.89:1 to get critical flow.
As a result you don't see this effect at low boost and rpm because the pressure ratio across the valve never gets that high.

Second as the intake charge air gets colder it substantially increases the heat it gains passing through the intake manifold and past the hot intake valves, partially negating the cooling. If the intake air is hot enough it can actully loose heat to the intake manifold under high boost conditions with poor intercooling.

As most things with engines, its not as simple as it looks at first blush.

Larry

I kind of said it flippantly before, but if anybody is seriously thinking about this sort of thing - there's a better mousetrap:

nitrous oxide. It really disassociates into oxygen (and nitrogen), it supercools the intake charge, it's cheaper, it's proven, and a 35 shot dry setup is only a couple hundred dollars.

In my diesel application, it's for cooling a vehicle, pulling 15,000 lbs, that is working for more than 6 seconds. Nitrous has no application there.

Also, don't see how it is possible cheaper than, let's say, water, or WW fluid.

Have you tried nitromethane with water injection? it is like putting in methanol Plus nitrous all in one package.

supercools?

as in 'absolute zero' territory, or a figure of speech?

I had a friend who was mumbling about NOS and supercooling and the like, and he had mixed up degrees F with Celcious.
...as for the 'supercooling' effect of a tiny amount of nitrous liquid (IF it is liquid still!) in a torrent of hot incoming air...well it will be diluted more than you think mate.

And the latent heat of nitrous oxide is much lower than that of water. Even lower than petrol in fact.

...as for the 'cheaper' bit, I can't tell what other people's taps run, but mine run water :wink:

Figure of speech.. I should just say "cools".

I used nitromethane years ago for my radio controlled models...
Cool for that application but I think it lowers the octanes like hell if used with gas.

Thereis someone recently used it and got some interesting results:
http://www.aquamist.co.uk/phpBB2/vie...hp?p=3884#3884

It would be interesting if it used with water, it will balance out the flash point of the nitro and contribute something towards the speeding up the burn rate of a water injected setup.