I am getting ready to install an alcohol injection system on my car and was wondering if anyone had suggestions on where to put the injector? I realize it needs to be after the turbo to prevent blade erosion. My injector system has variable pump speed and a selectable boost turn on point. I run an SAFC and have a TMO datalogger as well.
I wouldn't worry about the BOV unless it proves to be a problem (which it shouldn't). I would put it right after the intercooler, that way it will have more time to atomize and mix with the rest of the air before entering the plenum. This will ensure the most even distribution between all cylinders, after all, what good is the cooling effect if it's not equal in each chamber.
The only way to know for sure how evenly it is being distributed would be to run an egt in each runner. this obviously would be rather expensive. Just keep an eye on your knock count with the datalogger, that should be the next best thing.
By the way what system are you running? I havn't heard of a variable speed pump, does it actually pump more with higer boost or rpm or something? And like ecoli asked, are you using a nozzle or injector? How high of pressure does your pump go? the higher the better- as far as atomization is concerned.
Good luck. I'm planing for an alcohol injection setup in my car as well, I'm interested to here how well yours works out.
And another thing, As for what pressure it starts to turn on-
Well i'd say this is dependent on a few things. First off what turbo do you run and at what rpm's does it START (1 psi of boost) to build boost? If you have a faster spooling turbo like a 14b or something, you will want it to turn on a bit sooner. This is because most detonation occurs at the mid rpm range and a fast spooling turbo will produce more detonation than a slow spooling turbo at these mid rpm ranges.
But the sooner you have it turn on, the more you will use and the more often you will need to refill.
Also another thing is HOW MUCH you will be spraying at one time. If you just have a nozzel then you pretty much always spray the same amount. If your nozzel is big, then you will want to wait until higher boost until you start to spray, otherwise you might lose too much performance from your car in the lower rpm ranges.
Cool, I was waiting for a DSMer to install one. Let us know how it goes, because I am thinking of doing the same. What system are you going to use? Here are a few links, maybe you already know about them. I would put the injector by the TB elbow area like Ecoli said and set the spray to activate at about 12PSI (IMHO).
I dont have the link for my system but I will find it.
It uses a jet, not an injector. I have it running on the bench at the moment. I think I will mount the jet before the IC. I would assume that the alcohol would quickly turn to vapor in the hot air flow before the IC. Also, I would not need to worry about about the intake filling with alcohol if there was a pump malfunction since it wood pool in the bottom of the IC. Maybe the Alcohol would help keep the IC clean of oil? All of the injector settings are cockpit adjustable which is cool. It sell for around $300 bucks though and was originally designed for a Buick GN.
I will mount the jet before the IC. I would assume that the alcohol would quickly turn to vapor in the hot air flow before the IC.
True, you would get better vaporization in the hot outlet air, but you run into two potential problems with that setup. First, alcohol is flamable and in that hot outlet charge would be be POTENTIALY more likely to cause some sort of disaster. Second, the alcohol *might* condense in the intercooler. Though condensating alcohol wouldn't necessarily cause a problem it might not be a favorable thing either. On the other hand, the alcohol would only condense if there was a strong cooling effect in the intercooler, and perhaps if the intercooler got heatsoaked the alcohol would evaporate back into the intake stream when it is needed the most. Are you still running the stock intercooler?
If you try that method i would be very interested to see how it works out.
I have the tripodi deadhead kit. You should be able to search fopr his name in the archives to find his site. Anyways it is very affordable and nice, 100 psi pump that has been treated for alcohol injection and comes with a variety of nozzles.
I would stay away from the spearco kits as they tend to cause some more headaches because they need a pressurized tank due to the weak pump.
The high-end kit I would consider is the aquamist. Very nice kit that has been stock equipment on some european cars. Expensive but the nicest one out there.
I would think that injection befor the BOV is very dangerous - potential explosion of the turbo (it is hot in there even on the compressor side). I think the TB elbow would be an easy place to mount a nosle ... just my $.02
Regaurding the BOV, I think most of the nice systems have a boost controled selenoid that stops flow below the desired boost. so when the throttle plate is closed and there is vacuum in the manifold, the system *should* cut the alcohol.
Or you could always just dump to atmosphere
As for mounting it just before the throttle body, I would NEVER do that on my car because i would be afraid that there would not be enough time for proper atomization. Unequal distribution of alcohol or water between the cylinders could easily be the death of your motor.
The absolute best bet would be to run jets in each of the intake runners. You would need to use much smaller jets, and equalizing the pressure to them all would be vital to a proper setup. Perhaps there is even some type of fuel injector that will work with alcohol without damaging it.
I still plan on injecting right after the intercooler in my car.
Mount it in the TB elbow. Air velocities are highest before the butterfly than anywhere else in the intake system with exception of the valve collector. You want maximum velocity with a maximum of atomization at the same time, otherwise you will find that since the atomized water is heavier than air you will get some stratification due to the bends in the intake system such as the TB elbow, TB, and the mating of the plenum to the runners. You are really asking alot to have atomized water to remain that way for long periods of time vs. collecting on surfaces due to incidental contact and air shifts.
Yeah most setups for other cars I've seen have been right by the throtle body.
I'm probably going to get the aquamist setup and run a alchool/water mix. That system is also used by most groupN rally cars running up to three bars off boost !
__________________
Nick Drake
90 GSX
11.6 at 118, best trap 122 on a FP3052
3575 times soon
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