jasoncoker

Hello All,

Here is a link to my website with my latest dyno results and a couple of H20 injection pics. Let me know what you think.

http://home.earthlink.net/~jasoncoker/dynoresults/

Sincerely,
j

NZ951

You actually made HP by adding water and not boost or timing? Thats pretty interesting, I have seen HP drop by just adding water! I guess the conversion to steam is cramming more oxygen in and the hydrogen is cooling in the state change.

jasoncoker

Dear NZ,

I think I gained HP b/c the K26 is so far out of its efficiency range at the higher boost levels that it really heats the air. The H20 vapor must have ameliorated this somewhat hence the extra power. This is just speculation on my part.

Sincerely,
j

NZ951

Still great to have some data on it...

jasoncoker

Oh, you just said that. Right, the whole latent heat of evaporation and all that.

NZ951

he he he yup, all good

Pity we dont have temp sensors in your valves and in the combustion chamber!

FSAEracer03

If you see a drop, then the kit/installer/user is at fault... or your car is getting near-ambient temperature charge air.

The theory behind water injection isn't that it simply allows more boost and increases knock capability. It drops the intake temperature by latent heat of vaporization... the heat it takes to boil the amount injected is the heat sucked out of the charge air/fuel. Heat removed from a system drops the temperature and therefore creates a denser charge. That alone is power. Also, the efficiency of combustion is now increased and flame propogation benefits. Knock count isn't the only bad side effect of heat, NZ. As far as the cooling due to the state change goes, both molecules cool.

Thanks for the info, Jason! Glad to see some are venturing into water injection successfully!

EDIT: I can't see the torque increase (the good stuff). My buddy's system got ~15hp gain from just water (no, it's not a cheap system) but saw a torque gain of almost 60lb-ft just from water addition on a bone stock 951!

NZ951

I think thats what I said, but in a sentence.

FSAEracer03

riiight

ibkevin

Chas

On the website it notes that you go way rich under injection. If water injection cools the air, so it is denser...giving the same injector duty cycle, wouldn't you go lean (more air, same amount of fuel)? Or am I thinking about this all wrong?

Are you spraying before or after the IC?

jasoncoker

Dear Chas,

You are right about colder air being denser. The problem arises b/c the water molecule takes up space in the charge mixture. Since water is such a stable molecule it does not split up into hydrogen and oxygen en route to the cylinder although it does undergo a phase change (liquid to gas=absorbs a lot of heat). Therefore, the water in the intake charge actually prevents some oxygen from entering the cylinder hence the richness. So this translates into less HP usually, but in my case the cooling effect more than compensates.

I am using a water/methanol washer fluid mixture, but the idea is more or less the same. My nozzle might be too big which would exacerbate the richness, and I can also tune it out. If I do that and something fails in my system, though, I could blow my HG before I realize the injection has stopped working.

I am injecting into the intercooler endtank on the "air out" side. Injecting before the intercooler creates a problem with the water vapor recondensing inside the intercooler as the air going through it is cooled.

Sincerely,
j

docwyte

I know with my old supercharged M3, using a 4mm jet for the aquamist was optimal. I'd imagine it'd be similar for the 951. What system are you using?

hally

snow stage 1 kit it says on the website.
great info j, keep it coming.
hey what triggers the H2O injection, a MAP sensor? what PSI for triggering did you find best?

NZ951

Hally, snow triggers off MAP. I would think given you cant adjust the quantity of water dynamically, and you should maintain a fuel proportion to water, then you should inject the water when the AF becomes stable. That may be 10psi for example, and most likely bewteen 8-12psi I would think.