924Board.org

[bruni]

Thanks, really interesting articles, amazing how much water you can put in without putting the fire out
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1982 931
1975 harley sportster

[Grenadiers]

Fascinating articles, one thing to remember though, or not, during the war, what was the average life-span of an aircraft engine? Maybe longevity wasn't a major concern. dave.
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'83 944 Track car.
'88 924S Track car.
'89 944 Turbo
2004 Winnebago Vectra monster RV
2012 Jeep Wrangler
2014 Kia Soul
2001 Ford F350 powerstroke

[tuurbo]

Yeah that's a really good point Dave and I didn't pay attention to any discussion (if there's been much) about the long term life of the engines.

I think they did have a concern for reliability while it was up and flying.

Thankfully, Porsche didn't make aircraft engines for the Allies (duck!).

They ran something like RON 80 back then, and with what I presume was a lot of lead it wasn't the same fuel as nowadays, which might account for lack of life, if it's true that they wore out. No synthetic oil then either. They probably used methanol or alcohol in their rads - don't think they had ethylene glycol back then, I don't know.

Working from sort of first guesses, barring any other dysfunctions that can come from using alcohol and water injection, the cooling effect should make the whole engine run harder without getting comparably hotter, when compared to no alcohol and water injection at all. Add to this the cleaner cylinders, which 'should' translate into less carbon to build up and ignite the gas/air, and you'll get less ping, which should combine with the cooler temperature to lengthen the life of the engine.

But if the alcohol and oil get together too much, I think that's a real problem for long term engine life. Surely they changed the oil after each run, but if the mix was off I can see there being room for some alcohol and water in the engine oil screwing up the viscosity, which would make things heat up quite a lot. Still, the temperatures of the head don't jive with that possibility - I got the impression the head was cooler. And I can't imagine them sending planes into the air without the mix (air, fuel, methanol, and water) being 'spot on' as the Brits say. I mean, they're the military, so they're doing everything completely by the book, with zero variation.
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1980 924 turbo, MSD, Meth. Inj, otherwise stock.

[bruni]

Well finally got around to fitting the water injection. After considering various options including multiple injectors and controllers i settled on a very simple system using cooling mist components, pump, nozzle, check valve ,pressure switch and relay. My objective was to be able to run 10lb boost on 95 octane fuel on full advance. At the moment I am using water only and fully meeting my objectives, subjectively performance is improved (no pinking) and pulling very strong. Will get around to measuring inlet temperatures soon
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1982 931
1975 harley sportster

[RC]

Cool.

Would you mind sharing a few details on your set up Bruni? What type of pump and pressure, nozzle details and position, what you used for tank and where it`s mounted. Have been thinking about H2O too and always good to get ideas from others.

An overall picture would be nice too.

[Kenodog]

Allied fighters,the Spitfire,Hellcat etc., did indeed have methenol injection. Pilots were told that it was to be used as a last resort for getting out of a life and death situation. In the Spitfire it was a lever on the left-hand side of the cockpit that,when pushed to the full forward position,would give the pilot 300 extra horsepower to either climb to safety or pull ahead out of trouble. It was to be used ONLY in case of emergency and if left on for more than a few seconds could possibly destroy the engine. In short Tuurbo,they didn't run anything other than gasoline for 99.99% of the engine's life.
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1979 Euro 931, Olive
1981 931, Sabine
1991 Ford Ranger XLT 4x4, Ricky
1996 Ford E-350 ex-FedEx Van
2014 Mazda CX-5 (Kinderwagon)
2019 KTM 790 Adventure
2024 KLX300
2024 KLX140

[tuurbo]

[bruni]

Fantastic old documents. I am sure than any increase in performance will have an effect on the life of an engine, however, I think it is worth considering the following.
Prior to fitting the water injection, my engine was experiencing detonation, this definitely will have a detrimental on engine life, admittedly I could of retarded the ignition and reduced the power output
I use my car only on the road, so the amount of time I use full throttle and full boost is minimill, cruising and about town is rarely on boost.

Turbo in my situation is there any advantage to adding alcohol or do I just stick with the water?
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1982 931
1975 harley sportster

[RC]

Although there`s some truth to Kenodog`s comment, remember that this was 70 years ago. Considering the technology, metallurgy, lubricants and particularly fuel available at the time, it is indeed an incredible achievement that these ancient aircraft performed as well as they did. The fuel was only around 80 octane and not even comparable to third world home brews today. Forced induction was not only necessary for take off power with heavy bomb load and fast climb rate but also at cruising altitude with low air density due to the lack of oxygen to support combustion.

Here`s another old doc and also some more modern literature.

http://www.not2fast.com/NACA/

http://www.rbracing-rsr.com/downloads/naca_H2O.pdf

http://www.not2fast.com/thermo/water_injection/

http://autospeed.com/A_107970/cms/article.html

http://www.autospeed.com/cms/A_110212/article.html?popularArticle

http://autospeed.com/cms/A_110369/article.html

http://www.autospeed.com/cms/A_110213/article.html

http://www.streetcommodores.com/images/tech/PDF/099-102%20POWR.pdf

ttp://www.rbracing-rsr.com/waterinjection.html

That last article may be slightly biased since the writer has a commercial interest however it contains much good information.

And not the real world I know but a useful piece of simple software to play with for a basic indication of the various options and outcomes.

http://www.not2fast.com/turbo/glossary/turbo_calc.shtml

[924guy]

anyone have any thoughts on dual port water injection where one nozzle injects pre turbo, and the second injects pre TB?
_________________
Eric
78 924
82 931 SE "smokey"
99' VehiCross
Y2K Honda Insight
http://www.cardomain.com/id/924Guy
Performance by Pasha

[ideola]

IMO, pre-turbo is a really bad idea because the water droplets can damage the fins on the compressor wheel.
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erstwhile owner of just about every 924 variant ever made

[RC]

Have no experience with it Eric but from my understanding is probably not a good idea. More so if you run through an IC where it will condense and loose cooling efficiency. May theoretically cool the compressor however high pressure as a water jet does damage, also thermal cycles may initiate metal fatigue and lead to cracking.

Theres good info to learn by the time you have read through those links. Know I wont be injecting into my blower, also with teflon coated rotors, after seeing this:
http://v6supercharged.com.au/workshop.asp?ProjectID=8

[tuurbo]

[Scorpio]

hey Tuurbo so if youre injecting 100ml/minute then you have to be "on boost" or around 20min to empty a 2 litre water/methanol tank...

20 minutes of "on boost" at say 7psi plus(or whatever your set boost entry point is) seems like a long time for a street car... ie how often do you need to top that water tank up?
_________________
1979 NA
MS1..EFI..
GARRETT T25 TURBO
BILSTEIN SHOCKS
GT BASED CUSTOM BODYKIT

Brisbane , Australia
Think mean think fast
all youll see is
my Porsches Arse!!!

[tuurbo]

My boost comes on at 1 PSI so it's on even longer. I notice this most when I'm at 70 mph the juice is on quite a lot. I have more than one tank but I think the one in the car is about 7 litres. I've tried the little 1 or 2 litre tanks but I believe bigger is better so I opted for a converted 1 gallon or whatever gas can. It just fits in the back of the vehicle. In fact I just bought another that is I think double - the next size up anyway. I can swap plastic yellow caps and the same pieces will thread onto the new can. I'll just take some black plastic-based spray product and paint the large red one flat black this spring.

I'm sure I don't change it more than every 3rd or maybe 4th tank of gas. I always check it when I fill up the car because it's on the right near the gas hole. I treat my car a bit like an old lady - I don't have long boost sessions because I've been trained to fear running the car hard - every time I do it with impunity something breaks. So I run it at full boost in 2nd, 3rd and 4th gears, on the very occasional night trip in the country, or during the day on on-ramps, but (a) only if everything is running right and (b) just until I find my place in traffic, then I just drive the same as everyone else. Or slower. The boost controller when I put the car up for the winter was at 12 PSI I think when she was sent to hibernate.

I don't know if that helps you gauge it any Scorp - my brother's tank is about as big as our 931 overflow tank and he tops his up every 2nd tank. His is on a lot because he's had serious heat issues with a very high compression setup.

I think the strategy in the industry is to make the small tanks to get you hooked on the product, then up sell you the larger units you will eventually want for big bucks. Some of these tanks are north of a hundred bucks.
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1980 924 turbo, MSD, Meth. Inj, otherwise stock.