Meth Injection question

[roadtrip_69]

A couple questions for those in the know.

I have the Snow Performance 2.5 system installed about 5 inches from my throttle body. Running "boost juice" or 50/50 meth/water combo.
The system is linear so that it kicks on at a preset boost level and builds up to full spray at preset full boost.

The questions are:

What should I be aiming for on my Wide Band. When its set to gasoline. As a safe afr, without too aggressive of timing?

If I have fuel mapping set to say 11.1 to 1 afr and the spray kicks in, will it be more or less lean/rich than the 11.1? (which again I guess is hard to say since it starts off spraying slow and then full out towards max boost?)Or does a 50/50 spray even change the reading much on a Wideband?

What is a safe AFR for 93 octane w/50/50 spray? That is fairly safe but still aggressive enough to feel the little extra? ( And I know I've read that timing makes a bigger impact than the afr itself, but car is very finicky when I try to tune the timing, seems to respond better to Fuel/air tuning)

I am maxing out a 20G (Trying to just get the most out of it before I move up to something more fitting for the built bottom end), also have a FMIC Mishimoto that has a large core and surface area. Typically max boost is set between 22 to 25psi.

Sometimes I seem to get knock WHEN the meth injection kicks in. I had it set to 8psi when it starts and by 23 PSI its full out. Logs always show around 8 psi when I get knock. Seems to correlate.
I'm showing low to mid 11's on AFR at this time, with the meth engaged as well.

My theory is maybe its coming on too much too soon and quenching the fuel mixture, I bumped it up to 10 PSI where it starts coming on now. Just to see if it makes a difference thats noticable. I am running the #6 nozzle which is a bit larger than I actually need (according to their documentation its good for 400-600 hp)the kit didn't come with a 5 only the 4 and 6. Figured I'd air on the side of caution.

Thanks!

 

[danl]

The wideband does not care if the fuel is methanol or gasoline, it will read the same "AFR" which is really just a translation from lambda. The methanol will richen it up the wideband AFR. If you know your flow rate and % of methanol, you can do the math to determine how much richer it will be than your target AFR.

If you are getting knock transitioning into boost, reduce timing at the transition. If your engine is "finicky" everywhere then perhaps you need to verify your base timing or some other factor(s). If you are playing with methanol you need to learn how to read the ground strap on the plugs.

It is hard to determine a safe afr because that really comes down to fuel distribution in each cylinder. You could have two cylinders at 13:1 two at 10:1, averaging out to 11.5:1 on the wideband. Not knowing how evenly the methanol and air is distributed per cylinder makes this impossible to answer. See above about reading plugs as the cheap method. A more expensive method is a wideband sensor for each exhaust runner.

 

[1SICDSM_]

I'm running the AEM kit. With pump gas and meth I shoot for 11.2 ish. The meth will richen it a full point I've seen.

Is the 8 psi the start of the pull or when making the pull, when it gets to 8 it knocks?

 

[jdxnc]

I tune meth exactly as pure pump gas, 11.0-11.5 AFR. Personally I liked a 75/25 mix, this got me into the 9's with a single 14gph nozzle.

Also in my opinion, if you have Ecmlink, ditch any controller/pressure sensor the kit came with and simply control it via Ecmlink via load, use one of the outputs(FPS or EGR) to a 30A solenoid to turn the pump on and off full blast, no progressive crap. This will allow you to use AUX maps to get the fuel mix perfect when the meth comes on as it will know when the meth is spraying instantly. WAY easier to tune this way.

Dial in you tune at a lower boost on pure pump gas, then turn on the meth and you dial in the amount of global it pulls in the AUXmaps page and that's pretty much it. You might try adding a little more timing if you're feeling frisky .

 

[Ven]

I tune meth exactly as pure pump gas, 11.0-11.5 AFR. Personally I liked a 75/25 mix, this got me into the 9's with a single 14gph nozzle.

Also in my opinion, if you have Ecmlink, ditch any controller/pressure sensor the kit came with and simply control it via Ecmlink via load, use one of the outputs(FPS or EGR) to a 30A solenoid to turn the pump on and off full blast, no progressive crap. This will allow you to use AUX maps to get the fuel mix perfect when the meth comes on as it will know when the meth is spraying instantly. WAY easier to tune this way.

Dial in you tune at a lower boost on pure pump gas, then turn on the meth and you dial in the amount of global it pulls in the AUXmaps page and that's pretty much it. You might try adding a little more timing if you're feeling frisky .

I'm running an AEM multi input controller. This is an interesting way to go about it. I think I'm going switch my input wire to trigger off the egr solenoid and tune it exactly this way too. Just out of curiosity, when you were running water meth where was your water meth nozzle and IAT sensor located?

 

[jdxnc]

I'm running an AEM multi input controller. This is an interesting way to go about it. I think I'm going switch my input wire to trigger off the egr solenoid and tune it exactly this way too. Just out of curiosity, when you were running water meth where was your water meth nozzle and IAT sensor located?

It really simplifies the tuning process.

Meth nozzle was 6" before the TB and IAT about 12" before the nozzle, down in front of the transmission.