sixshooter

iTrader: (12)

I disagree with your opinion. My opinion is that the best way to increase fueling on a direct injection car is with an aftermarket ECU and, if necessary, larger injectors. But I'm no engineer.

Back when I used to have carburetors it eCooled the charge so much we used to put the beer on top of the engine coming back from the store. But you had to be careful. With a really big carburetor the beer would sometimes freeze.

sparkybean

Right.

Reading the NACA papers was encouraging, a possible 70% increase in BMEP sounded bloody marvellous until i realised that their test engine was initially knock limited and the IAT's were held constant throughout the whole test. I am looking to lower IATs, knock is not (yet) a concern.

Reading further echo's the comments in this thread; water isnt a great intake charge cooler.

After this i started looking into meth/alky/water mixes, which DO cool the intake charge better than water but these solvents only do an average job (at best) of cooling the intke charge. They also screw up AFR's, are more expensive, require mixing, and generally still have nothing on a good intercooler.

Im not sure why i was so stuck on water injection to be honest. Too much time reading vendor websites and hoping for a magic bullet. I think i was also getting confused between IAT reduction and knock supression. Sure you can supress the knock and advance the timing, but as 18psi put it, I wont get any extra power with all that hot air going into the engine.

SO...

Looks like im getting an intercooler. Ill delve into that thread aidandj, thanks for the head start. Triple J, looks like you need to buy me a curry.

sparkybean

...Is it even worth me hanging onto my water injection setup for my power goals? While tuning for MBT sounds nice im sure i could be conservitive with the timing and run more boost.

Shame, im £250 down from this little excursion.

patsmx5

iTrader: (16)

In my experience, pure WI isn't going to help much. I've read way to many WI papers that say they will. If you run water/meth, then it could help, many have dyno graphs to prove it.

If I could do it over, and had the budget, I'd run dual fuel systems, gasoline for driving, something else for boost (E85 most likely). More weight and complexity, it's obvious, but it's the best of both worlds then.

deezums

iTrader: (3)

I don't know who originally said it, but god damn that's one hell of a Patsmx5 thing to do

patsmx5

iTrader: (16)

I know, I suck at making compromises... I own that.

Joe Perez

iTrader: (8)

5 or 6 years ago, I became hugely interested in the old NACA research papers which explored the injection of various liquids into piston engines at various locations. Got a whole 3-ring binder somewhere full of those articles.

Lots of different papers came to various conclusions based on differing methodologies. Some injected liquid directly into the combustion chamber at various timings, some metered liquid into the intake manifold at ratios varying with fuel, some explored the relationship of water-injection to power in the presence of varying IAT, etc. Some of the tests focused specifically on increasing ignition advance and MAP for maximum power on a turbosupercharged engine. Some focused on attaining maximum fuel economy. Some focused on allowing the use of lower-octane fuel.

All tests generally agreed that the use of water injection permitted great increases in knock-limited power, a result which I was never able to consistently replicate on my own car mostly because I'd run out of airflow (Greddy) and was already intercooled. That engine just refused to make much past 210 WHP no matter what I did.

From what I gather, the blending of alcohol with water was done principally to prevent the water from freezing solid. At 20,000 feet over Germany, this is a concern even during the summertime. Which brings me to this point:
I'm slightly curious about your statement here.

While decreasing IAT is generally desirable, isn't the primary goal of IAT reduction in a turbocharged engine to eliminate knock?

sparkybean

Very bad wording on my part. I am now looking to raise power by lowering IAT's (and thus reducing probability of knock) rather than just reducing knock with water injection while still having high IAT's.

Thanks for your input.

sparkybean

I even made this sick MSPAINT schematic... lol

patsmx5

iTrader: (16)

Then you need an intercooler. Good call on that, it's the better solution. If you try to push the absolute limits on pump gas, then water/meth injection could helpful.

Dust

Injecting water pre-turbo will cool the charge coming out of the turbo. It will work better than an alcohol. Depending on your IC location, and average speed, an IC might not be the best route.

deezums

iTrader: (3)

Way to contradict all the logical conclusions in this thread, I award you one eggplant.

sixshooter

iTrader: (12)

True.

If the intercooler is located behind the radiator or your speed will be less than 30mph then you are completely accurate.

concealer404

iTrader: (3)

No, what you saw was a Skyline running an HKS AIC or Greddy REBIC with a bunch of extra injectors put in for fueling under boost. Didn't have anything to do with "intercooling."

Full_Tilt_Boogie

iTrader: (1)

Back in the day they did a lot of stupid ****, even on expensive cars.

18psi

iTrader: (76)

but it "worked" right?
so it must be perfectly acceptable to use in 2015 right?
lol