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FSR AEM Meth Injection Install and Dyno Tune

Created on Monday, 01 April 2013 23:09

Import Tuner recently published an informative article on a Meth Injection install and tune we did on one of our client's Supras.


Subject:  1995 Supra TT 6sp

Modifications:  6765 Comp Billet Turbo, 264 camshafts, 4” exhaust, FIC 1100cc injectors, AEM Meth injection kit with largest nozzle

Management:  FSR installed and Tuned AEM Infinity

Here are the images from the magazine article.  You can also read the article below on this website which may be easier to see.

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This client decided to upgrade from AEM’s standard 1 gallon tank to their huge 5 gallon reservoir.  With the expert help of Nick Stanowski, the meth tank was seamlessly mounted in the hatch along with a sub and amp.  From there, we mounted the AEM high pressure meth pump with rubber insulators just under the meth reservoir.  This allows the reservoir to have a constant gravity feed to the meth pump.  Since this car sees the road course, it was important that meth would be delivered at all times to the pump!

From there, we carefully ran the meth line from the pump output up to the front of the vehicle.  At that point, it goes through a filter and meets up with the cold side intercooler piping.  We have our own meth bung machined; many shops use a 1/8npt half coupling but we’ve found it severely affects spray pattern!  We TIG weld our meth injection bung into the pipe about 16 inches from the throttle body.  We’ve tested five or six nozzle locations before settling on this location which gives us the best mix of cylinder to cylinder consistency as well as charge temperature cooling.

At this point, the system was ready to be wired up.  We usually mount the meth controller near the ECU.  It makes for clean and simple wiring between the ECU and the meth controller, and since we tune the car on the dyno, the client will not need to make any adjustments using the controller.  The wiring is pretty simple; power, ground, power to the pump (which you want to fuse), a low level indicator, LED, and the failsafe ground out.  We mounted the LED in a visible location near the shifter and connected the failsafe output to the Infinity ECU.

A car like this has a relatively small engine and relies on turbo boost to make horsepower.  The problem we run into is that a small boosted engine requires very high octane in order to maximize power safely.  Depending on the setup, a Supra that makes 1000 wheel horsepower on race gas is usually limited to close to half that on pump gas, just due to 91 octane limitations.  Race gas is very expensive, so installing AEM’s water/meth injection system is an easy way to increase octane rating which allows us to run more boost and a more aggressive tune without the expense or hassle of race gas.

We chose to run 50/50 water meth; water has better cooling capabilities and the meth is a super high octane fuel.  Combined, they cool the charge temperatures down and increase the overall effective octane of the fuel... only while under boost when you need it.  That allows us to make more power!  A 50/50 mixture of water meth is also non-flammable, since we don’t like to set our clients on fire, usually.

AEM’s meth kit comes with the tank, pump, lines, controller, nozzle with 3 different jets and built in check valve, along with various other bits for the install.  It is simple and cost effective.  The controller has a built in MAP sensor and you can tune the start duty and maximum duty by boost to determine where it starts to spray, and when it is all in.  Make sure to have this professionally set up; and you’ll see why if you read on.

Once we had the meth system up and running, we strapped the car onto the dyno.  Of course, we had the car already precisely dialed in without the meth.  We did a few pulls and the car made around 485whp at 14.5psi on just straight 91 octane.  You can see the log below where the green lambda matches the grey target lambda very closely (accell enrichment and o2 feedback are off for tuning)

Next, we used the infinity to manually activate the meth system without making any changes to the tune.  The result of spraying meth without having the car retuned?  455whp, a 30whp loss of power.  This is because the extra fueling caused the air fuel to drop about 10%, or run quite a bit richer.   You can see the log below where the green Lambda line is much richer than the target lambda.  For best power, we needed to make some adjustments.

Here’s the dyno chart of the pump gas tune vs the pump gas tune with meth, but not tuned for the meth injection.  The blue line with the pump gas tune and the red line is with the addition of meth but no tuning.


Thankfully, this car is running AEM’s fantastically flexible Infinity ECU.  We already had a 12 position switch installed in the car, so we started to configure the tune to reflect the meth injection.  By using AEM’s “mode switch”, we are able to have different positions on the switch activate different boost, timing, and fuel maps as well as trigger an output.  Since we tune so many cars, we have a pretty good idea of what kind of adjustments needed to be made.  We dropped in our revised fuel map, timing map, and boost maps which are activated by the in dash switch.  After a couple runs to fine tune the fuel delivery and boost, we were ready to see what the car would make with the meth system active and extra boost!

Running 25 psi, along with altered timing and fuel maps, you can see by the graph and log that our air fuel after the meth matches the air fuel before the meth.  That, along with the extra boost and timing, allows us to get a big bump in power safely!  Because the Infinity gives us a real time, super fast log of 6 different knock channels (one for each cylinder), we can see that the engine is completely happy with this extra power.  If we were trying to push it, we’d keep turning it up and watching how much power we gain per psi, along with how much timing we have to pull out to find the maximum safe power we can run on pump and meth.  Generally, however, we try to stay well below that threshold.


Failsafes are an important feature of the AEM meth injection system when paired with the Infinity EMS.  The AEM meth injection system can detect a number of faults including a wiring problem, power problem, ground problem, or a low fluid level.  When a problem is detected, the meth controller sends a signal to the Infinity.  We have the Infinity setup to revert to the low boost map and flash a light in case of any failsafe by the Meth controller.  That means if you run out of meth during a pull, it will automatically flash a light at you, revert to a pump gas only safe boost level, and automatically switch to pump gas safe timing and fuel delivery maps.  When the failsafe is cleared, it will automatically give you that extra horsepower and boost!  Further, the AEM Infinity has built in lean protection which is a reactive system that will add injector duty to maintain a safe air fuel if there is any meth delivery issue.  If the correct air fuel can’t be maintained, it will automatically initiate a rev limiter (programmable) and flash a light, all in the name of engine safety.

As you can see from the dyno graph above, the meth injection, when tuned properly, allows for a nice safe margin of power increase over just straight pump gas.  Since this car with it’s small turbo and mild engine makes around 800 on race gas and 485 on pump gas, the meth injection, at 620whp, delivers a nice in between that doesn’t require the expensive racing fuel.  Integration with a high quality engine controller is key to making this happen!