Re: Water / Methanol Injection - for AMC -

[farna@xxxxxxx]

I checked some of this out. The Mother Earth News (MEN) article is promising, but old. I looked at all the kits available. Average price seems to be around $250. Part of the problem with something like the MEN described system is good atomization of the water into vapor. It can't be done except under pressure -- vacuum pulling water in leaves the droplets to large. So a high pressure pump is needed to spray the water in just like it's needed for fuel injection. Most systems use a 100 psi pump, which is $75-$100. 

Water injection (WI -- with or without methanol) would work very well for a turbo system when you can't run an intercooler, and costs would be about the same or cheaper than an intercooler installation, or where you really wanted to increase boost. In a normally aspirated engine there is very little gain. In a car with a knock sensor there MIGHT be some gain. The theory is since WI decreases combustion temp without a power loss, it will keep the knock sensor from turning timing down and there will be a slight power increase. Or if the vehicle requires premium fuel (which is due to compression) it can run regular with WI. 

WI would greatly benefit a 4.6L budget stroker engine. Almost any cam could be selected and the compression could be left at 9.7-10.2:1. there would be a cost savings on pistons of around $150 (getting the dishes machined), so the system will cost about $100 over engine build costs for an ~15-40 hp increase in power (depending on cam choice). Even for ~15 hp (using a stock 4.0L cam) that's not a bad cost per hp deal. That's $6.67 per hp -- discounting the $150 savings on pistons. Now 15 hp is a "guesstimate", but that's getting rid of the high overlap cam and running at least a point higher than stock compression. It may be more like a 20 hp gain. 

If you look at a stock engine, the cost situation is pretty high. Even assuming the same 15 hp gain (around 5 is more likely without a compression increase and/or cam change), the cost goes up to $16.67 per hp. The more likely 5 hp gain costs $50 per hp. 

Don't be confused by WI systems that inject water into the exhaust head pipe! Those are for TWO STROKE engines and don't have the same effect on four strokes. The expansion chamber on two strokes has a big effect on how the engine runs and at where (what rpm) peak performance is achieved. If I weren't familiar with two strokes I'd have been confused myself!


On September 28, 2005 Brien Tourville wrote:

> You may find this info useful:
> 
> A brief History:
> Water injection was evaluated scientifically in the 1930's by H.
> Ricardo who demonstrated that one can basically double the power
> output of an engine using water/methanol. The first widespread use
> was during WWII on supercharged and turbocharged aircraft. In 1942,
> the German Luftwaffe increased the horsepower of the Focke-Wulf 190D-
> 9 fighter aircraft from 1776HP to 2240HP using 50/50% water/methanol
> injection. The allies soon followed by fitting the P51 Mustang and
> other high performance aircraft with water/methanol injection.
> Following the war, the turboprop aircraft industry used
> water/methanol injection and called it the "automatic power reserve
> system (APR)" for use in hot or high altitude take off. It surfaced
> again in the 60's when GM used a system on the OEM turbo Corvair. It
> was used effectively in Formula 1 before being banned for adding too
> much power.
> 
> http://www.ww2guide.com/engines.shtml
> 
> http://www.motherearthnews.com/library/1979_September_October/Water_In
> jection_Wizardry
> 
> http://history.sandiego.edu/gen/st/~nbarham/history/history.html
> 
> www.kuratrading.com/PDF/WaterInj.pdf
> 
> http://www.rbracing-rsr.com/waterinjection.html
> 
> SPONSORED LINKS
> 
>              Brien.
>          NEW YORK
>    eagle registry #501
> 
> eagle kammback registry


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