I've run water meth injection and liquid to air intercooling for a couple of years now and would like to share what I've learned and which of the two I think is most practical.
Water/meth injection worked wonders once I figured out the nature of varying ratios from 100% water to 100% methanol. Running 100% water will work fine but you must be careful with the injection rate. The boost level at onset is more critical because the risk of quenching the combustion mix is much greater and the reason for months I struggled with misfires as I switched back and forth between mix ratios making the misfire intermittent and therefore difficult to identify the cause.
After MSD coils which made matters worse, MSD wires which didn't improve anything and numerous different spark plugs, I finally narrowed the problem (which also changed its point of onset with considerable change in ambient temps, worsened with cold weather) down to the amount of water injected or, ratio of water in the mix. After running the motor with the injection system turned off the problem resolved completely (after the excessive timing pulled due to a bad knock sensor was restored).
I run pre and post turbo injection nozzles with the MAT sensor in between and several feet away from the pre turbo nozzle. The water/meth provides two benefits; cooler intake charge although it is not easily appreciated by the MAT readings and an octane bump. I currently run 15 psi with 11:1 compression and as high as 18 psi without knock retard on the meth alone and have gone as high as 21 psi although that was with the intercooler contributing.
The higher the methanol content the greater the cooling effect on the intake manifold but you trade off some of the combustion chamber cooling offered by the water which tends to offer more knock resistance than just a cooler intake charge. With 100% meth I have found the intake manifold cold to the touch following a boost load. I run about 66-70% methanol to water and will install a boost controller to start inching up to the higher boost limit.
The water to air intercooler did a great job of keeping air temps within 10 degrees of ambient during cruise and slowed the temp climb under boost and quickly returned it to baseline afterwards. It also offers intake charge cooling for as long as the car is moving where methanol injection does so only when triggered. On a hot day without the intercooler I have logged cruise inlet temps of 140+ degrees thanks to the hot turbo compressor. Every 10 deg drop in inlet temp offers about 1% increase in power so the water to air intercooler restored at least a 3% increase in available power during cruise conditions.
I've heard many shy away from alky injection calling it a band aid and taking a negative stance to having to keep an eye on the fluid level as well as concerns about system failure. I have a 1 quart tank that takes me more than a month to require filling. I have had a failure of the variable rate Snow controller which I purchased used. My engine was not harmed in the process because I pay attention to warning lights and missing activation signals.
The water to air intercooler is pretty much self sufficient and so far both systems have independently provided me with the same level of boost performance except the methanol system has more potential under sustained conditions because the longer it runs the colder the intake gets. The intercooler is just the opposite as the air charge gets hotter and hotter as its capacity to absorb heat diminishes. Another important disadvantage for the water to air intercooler is that it added about 70 lbs (and there's that pump always pulling 2.5 amps or more on the charging system). A good exchanger, intercooler, tank and supporting system parts add up in weight pretty quick as well as take up an awful lot of space.
If I had it to do all over again, I would install a well rounded water/meth system with a good variable rate controller and start the injection as low as 3-4 psi when a greater than 50% methanol quantity is injected. I have set my onset boost level about that low over the past two days and can feel the pickup increase that has resulted in second gear. The preturbo nozzle has not harmed my compressor wheel and it is keeping the intake charge temps under control as the temps appear to rise at a slower rate than with the water to air intercooler (2.5+ gal capacity) and so far I have not seen temps higher than 135 deg at 15 psi for the cycling I have boosted at. The intercooler however does pull the temp down to baseline within a few seconds where it hangs with methanol injection alone but that's not representative of the temp the intake manifold sees and in the end, there is no knock retard which is key here.
In my opinion as it relates to my experience, water/methanol injection is the way to go for these small cars with boost at a fraction of the weight of a water to air intercooler system and appearing to offer and have greater performance potential pound for pound.
I find this post to be very interesting. Some really good real-world data here. Forgive me if I missed it but can you tell about your motor/charger combo? Is this a turbocharged L67?
Turbo 3900, T67 series turbo. The supercharged motors are an exception to the rule. I have no experience with them and little knowledge on them except a big debate about water/meth injection not being as effective due to the blower arrangement.
thanks for the info i will be putting a Eaton m122 blower on my engine and plan on using water/meth injection on the engine i talked with snow a bit and they told me pre blower injection . I was glad to hear how much boost you ran with 11 to 1 compression and no knock . thanks again for the info i know you worked hard to sort this all out and worked on it a long time
Glad you all found it useful as I could find very little that proved significantly helpful when I was searching in order to get started with water/meth injection and basically had to discover for myself. From having trouble getting away from a Ford Ranger due to quinching to sending out such an intense blue flame from the exhaust at dusk one day from errant timing retard it reflected off the surroundings enough to alert me that it happened in my peripheral vision and no doubt put on a show for the cars behind me.
It is a difference you can feel in performance. Another phenomena that someone referred to as micro knock suppression which doesn't register, is that the 50/50 mix makes the motor pull smoother than it does on gasoline alone and you can feel it and see the difference in a dyno curve which goes from squiggly to near completely smooth without any enhancement.
I have used Water/Meth in the past with great result! I was surprised to learn the it was so frowned upon in the Eaton blower community not only with the 3800 crowd but Meth seems to have been a No-No since the days of the Ford Supercoupe. and most recently the 03-04 Cobras / GT500's However the Pros seem to outweigh the Cons with a turbo setup, Particularly spraying Pre-Turbo.
That thing must really move at 18 psi, Im curious what it would trap in the Q with a lazy launch.
Alkycontrol.com has a great kit
I run 100% Alcohol on my GN, and that's only denatured for now, at 22psi with a 6262 turbo, any more boost and the trans starts to slip. What a difference it made, the LC2 would knock at 16psi on 91 octane.
Originally posted by bigformula: a t67 on a 3900 should be 600 bhp and trapping 130 mph in the qtr mile at 18 lbs of boost. a dyno would be interesting to see.
I don't know how close it'll get to that if at all but I haven't made it back to the dyno yet. Here's a link to the first test that was limited to just over 4000 rpm due to the misfire problem. I don't recall having the injection system turned on at the time. Scroll down near the bottom just below the dyno graph.
Well this complicates things for me. Maybe I should get rid of my L67 and get a 3.9. I was going to turbo the 3.8 anyway. The 3.9 can actually handle some boost stock? How much boost do you think they can reliably handle without meth or water?
The turbo 3800 is a proven performer, but they are just now starting to get harder and harder to find. I figure over the next 4-8 years either the "High Value" (present 3x00 series engines) platform will become more popular or we are going to learn how to properly rebuild the 3800
as of right now support is limited for the 3900 swap so it would obviously require a little more Skill / Craftsmanship and less Google compared to a 3800 swap.
Would you go so far as to say that with your water/meth system an IC is unnecessary?
Yes, although it's hard getting use to it mentally. It's on the car but not in use now and I have read of several owners of factory boosted cars particularly GN owners ditching the stock intercooler and running methanol alone.