AEM water methanol injection system

AEM Performance Electronics Water Methanol Injection System Evaluation

By Mike Kojima

Long ago in the days well before MotoIQ in the early 80’s, as a teenager, I started tinkering with water injection.  Being somewhat of a mad scientist, I had equipped the first engine I had ever built, a small block Ford with domed high compression pistons which had a compression ratio of about 12:1, something that was impossible to run well with the 92 octane gas and mechanically controlled fuel and spark available at the time.  I always had to concoct toxic and carcinogenic mixtures of gasoline, methanol, toluene and acetone to keep my car from detonating to death.  Fortunately my friend’s dad was a technician at TRW and he was always bringing home 5 gallon drums of these chemicals that had expired use by dates for us to clean parts in and put in our gas tanks.  Somehow I think I might end up paying for all of that soon but that’s another story.

Somewhere I had read that the P51 Mustang fighter used water alcohol injection to give it more power under dog fighting conditions so I rigged up a water injection system using an old windshield washer pump and experimented with various mixtures of stuff from my friend’s ad hoc chemical supply house in the reservoir.  I found that my crude system sorta worked, it suppressed detonation but had drivability issues and it was sort of lame to try to throw a switch to turn on your system while driving fast.

Edelbrock var jection
Edelbrock's Vara Jection was the first electronically controlled water injection system that tried to match water volume to engine load. They came out in the late 70's early 80's when gas started to get crappy as a crutch to help those old high compression muscle cars survive on unleaded gas.  Spearco had a crude hobbs switch boost activated system back then as well.  Neither of these systems worked that well, probably because they had lame pee stream nozzles and used 15 psi windshield washer pumps.  They were still better than my push button homemade system.   Although I found this picture on the internet, I swear this sure looks like the unit on my car from the ground, my lame high schooler wiring and the light blue overspray all around.  I wonder if one of my old photos somehow found its way on the net?

This sort of got solved when Edelbrock came out with a water injection controller the next year (I think I was still a teenager).  It had RPM and vacuum sensors built into some sort of box that controlled the injection rate with crude spray nozzles.  This system worked much better and I used this until I rebuilt my engine with a lower 10:1 compression ratio after tiring with messing around with this stuff.  I noticed that if I used water, I would seem to lose power and methanol would work but I would have to dump a lot in and the tank would empty out super quickly. 

I tried my system on my buddies L20B Datsun engine after I convinced him to run 13:1 using the water injection to keep it from detonating apart.  However the 4 throats of the Mikuni carbs each needed their own nozzle and the pump we used didn’t have enough volume for all 4 nozzles. Due to the low volume pump, the system didn’t work right and we ended up melting the ring lands.  He was pissed at me because he blew the engine before I could get the system running right and I told him he was an idiot for keeping his foot in it when the engine was detonating like gangbusters.  After that I lost interest in trying to tune high compression naturally aspirated engines with water injection.

Aquamist water injection system
Aquamist's system actually does work.  They were the first to use high pressure pumps and atomizer nozzles. I like the simplicity of their base systems but I don't like the linear water delivery curve and the lack of failsafes.  Aquamist's high end systems now have all of this figured out but they are somewhat complicated.  Still good stuff and the first water systems that in my opinion actually worked.

Fast forward to the early 90’s, Gas had fallen to 91 octane and turbos were starting to become all the rage and detonation was always a problem.  I found out about a water injection system from the UK called Aquamist that was popularized in the WRC cars of that time.  My friend Peter Medina (who now owns Synapse Engineering) obtained a couple of units for himself and he and I began to tinker.  The Aquamist system had a high pressure pump and an atomized nozzle.  This system worked really well.  I really liked it until I blew up an EVO when the system's Hobbs switch failed and filled up the engine with water.  The nozzles also tended to clog easily. The lack of failsafes and the fact that the system didn’t have any sort of water volume adjustability other than jet sizes  made tuning rather difficult, made me once again put water injection on the shelf.  To be fair, Aquamist has since come up with vastly improved systems with mappable water controllers and metering valves but we haven’t evaluated them yet.

Aquamist water injection
Here is an Aquamist system installed in one of my 90's turbo SR20DE powered cars.  This sucker made just over 400 whp on pump gas with water injection and 529 whp period.


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Tuesday, May 04, 2010 10:24 AM
Great article! I have been looking at the different kits and have been trying to figure out the differences, and what to look for. This article helps a lot. I can't wait to see how the tuning goes.

AEMs sells another kit that recirculates that has a five gallon tank. Is that for a hyper-miler car, always pumping or something that is still on and off just with larger displacement like trucks?
Mike Kojima
Mike Kojimalink
Tuesday, May 04, 2010 12:13 PM
I htink the bigger kit is for trucks or race cars that need a lot of water for a long time like a Rally car.
Wednesday, May 05, 2010 5:15 AM
Argh the message system ate my comment, so here goes a second attempt.

I have always been interested in setting up a water-methanol injection system just didnt want to grenade a motor, didnt have the money to afford that happening. But this AEM system seems to have a lot of fail safe tech built in which is sweet. Now on to my question and main reason for posting, would tuning the car to run on E85 allow you to further increase the boost? seems like you would further increase the detonation threshold. Do you have any plans of doing a project that is tuned to run E85?
Wednesday, May 05, 2010 5:03 PM
I still think WAI is an aspirin for other serious problems that must be adressed in a car. To much a high comp ratio/boost level for a to low octane number.... Way to much advance in timing, blah blah blah.

This system IS light years ahead of those first ones; true, but im still not completly convinced; as Mike said, 1 little failure(noozle blocked, empty tank, pump fails, TOO much variables) and good bye expensive engine...

On the other hand, its use as a temperature controller for track use, is quite interesting...
Naji Dahi
Naji Dahilink
Friday, May 07, 2010 2:58 PM
There are ways to protect the engine in case the WI system fails. I tuned an Evo VIII with an Aquamist WI system and the owner of the car set it up to default to the 91 octane map that is in the ECU. I tuned two maps for the car; a 91 octane map and a 91 octane+meth/water injection map. Should the WI system fail, the ECU will switch to the safe 91 octane map. He tried it and it worked. I do not know the details on installing the switching harness that made it happen, however.

The car made about 390 whp on a 50/50 meth/water mix on 91 octane gas. We set the boost to about 27 psi and held it to about 24 psi by redline. He was running all the bolt-ons and a turbo similar to that of an Evo 9. The car hits flat 12.0 in the 1/4 mile. With more tweaking, I am sure we can get it into the 11s.
Thursday, September 16, 2010 8:42 AM
WMI is a very touchy subject. If done right, and tuned right its fairly safe. It does require some maintenance and also careful eye from the owner. Most people want the power, but not the watchful eye on the system. Then things go bad. REAL BAD. WMI as tempting as it is, with all its benefits, when used on a OEM turbo set up I still find people showing knock in the lower gears. Most tuners don't check for this since most cars are tuned in 3rd gear (5 spd) 4th (6 spd). So your car is knocking and you don't know it. I know this first hand. If it wasn't for my own data logs, I would have never found it. Later, I had my tuner re check it on the dyno. KNOCK in the lower gears. We moved the checkvalve, did all kinds of stuff. Nothing helped. So, for me, I pulled the kit out and sold it. wasn't worth the hassle. Now a days with E85 becoming more available, its truley a safer alternitive. Safer meaning it takes less of the "watchful eye" out of the owner. I know Mike has used Meth for sometime, Mike knows his stuff. Im just being the devils advocate here.
David Reynolds
David Reynoldslink
Tuesday, January 23, 2018 10:28 AM
My system continues to make a relatively quiet buzzing sound after the engine is turned off.
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