Tuning Meth with Boost
TECH Resident
Joined: Aug 2008
Posts: 910
Likes: 0
From: Dubai
same problem happened to a friend of mine, and I told him it would happen... A flow gauge wont help much either because if you're car has even a modest amount of power you wont be starring at the flow gauge. A shift light would be nice because those are frickin bright though.
It's impossible for me to tune my car on straight 91 octane with 14psi of boost. Before I do a pull I always prime the system and verify that AFR drops when I prime it. My LS3 seems to like 10.8-11.0.
I have an AEM failsafe wideband that flashes bright red when my AFR goes out of the programmed range. Saved my motor once already when my external Walbro 255 failed in the middle of a 4th gear pull. I was able to let off in time before it went boom.
TECH Resident
Joined: Aug 2008
Posts: 910
Likes: 0
From: Dubai
The problem with tuning a fuel mixture where both fuels have different AFR stoich values is the fact that AFR becomes sort of meaningless unless you know for sure the ratio of pump gas going into the motor vs meth and calculate accordingly. Stoich for meth is something like 6.5 AFR.
You can tune your car with meth and pump gas spraying simultaneously, youd initially have to decide how much meth you want to spray and adjust the controller, then tune the car's ECU until you hit the desired Lambda number.
You can tune your car with meth and pump gas spraying simultaneously, youd initially have to decide how much meth you want to spray and adjust the controller, then tune the car's ECU until you hit the desired Lambda number.
I don't know why everybody is so hung up on talking in Lambda vs AFR. The probe reads lambda and just converts it to gas AFR. So if I tune it to .75 lambda, that's just 11:1 AFR on my AEM wideband.
TECH Resident
Joined: Aug 2008
Posts: 910
Likes: 0
From: Dubai
LS1 Tech Stories
The Best V8 Stories One Small Block at Time
6 Common C5 Corvette Failures and What's Involved In Repairing Them
Pouria Savadkouei
Retro Modern Bandit Pontiac Trans AM Comes With Burt Reynolds' Autograph
Verdad Gallardo
Top 10 Greatest Cadillac V Series Performance Models Ever, Ranked
Pouria Savadkouei
Top 10 Most Powerful Chevy Trucks Ever Made!
Hennessey's New Supercharged Silverado ZR2 Has 700 HP
Verdad Gallardo
Coachbuilt N2A Anteros Is an LS2-Powered C6 Corvette In Italian Clothes
Verdad Gallardo
Awesome K5 Blazer Restomod Comes With C7 Corvette Power
Verdad Gallardo
10 Camaros You Should Never Buy
10 LS Engine Myths That Refuse to Die
Verdad Gallardo
Here is my strategy to tuning with meth water injection. Leave it turned off and log afr and IAT's. See what a normal IAT profile is and what your targeted pe afr is. For the sake of arguments, lets call it 11.5:1, and you see after a full run that your iat's go up to 145 degrees.
Now add in your meth/water injection and get your afr's back to the targeted 11.5:1 or slightly richer to 11.2:1 and look at your IAT's again, they should be dramatically lower.
Now, the added safety factor is in the PE adder vs IAT table.
Engine > Fuel > Power Enrichment.
Find the max temp of your run with the meth/water on, and above that value, add in enough of a pe adder (0.2-0.5) to pull your afr back down to 11.2-11.5 in case your meth/water cuts out. It's not fool proof, but it's an added layer of protection in case you have a failure. Granted, that's a sliding scale that will need to be changed from summer to winter, but lets be honest, at least here up in the north east, there's not too many people driving boosted cars in the winter.
Now add in your meth/water injection and get your afr's back to the targeted 11.5:1 or slightly richer to 11.2:1 and look at your IAT's again, they should be dramatically lower.
Now, the added safety factor is in the PE adder vs IAT table.
Engine > Fuel > Power Enrichment.
Find the max temp of your run with the meth/water on, and above that value, add in enough of a pe adder (0.2-0.5) to pull your afr back down to 11.2-11.5 in case your meth/water cuts out. It's not fool proof, but it's an added layer of protection in case you have a failure. Granted, that's a sliding scale that will need to be changed from summer to winter, but lets be honest, at least here up in the north east, there's not too many people driving boosted cars in the winter.
I've been thinking about this and have found that I could pull all the timing out if my second pump fails during a WOT run by way of the AFR vs Timing table. I worry more about WOT situations than part throttle/crushing conditions because you can't burn down your engine at those times. You have anymore suggestions?
Last edited by Monte4ever; Jan 25, 2014 at 09:14 AM.
Here is my strategy to tuning with meth water injection. Leave it turned off and log afr and IAT's. See what a normal IAT profile is and what your targeted pe afr is. For the sake of arguments, lets call it 11.5:1, and you see after a full run that your iat's go up to 145 degrees.
Now add in your meth/water injection and get your afr's back to the targeted 11.5:1 or slightly richer to 11.2:1 and look at your IAT's again, they should be dramatically lower.
Now, the added safety factor is in the PE adder vs IAT table.
Engine > Fuel > Power Enrichment.
Find the max temp of your run with the meth/water on, and above that value, add in enough of a pe adder (0.2-0.5) to pull your afr back down to 11.2-11.5 in case your meth/water cuts out. It's not fool proof, but it's an added layer of protection in case you have a failure. Granted, that's a sliding scale that will need to be changed from summer to winter, but lets be honest, at least here up in the north east, there's not too many people driving boosted cars in the winter.
Now add in your meth/water injection and get your afr's back to the targeted 11.5:1 or slightly richer to 11.2:1 and look at your IAT's again, they should be dramatically lower.
Now, the added safety factor is in the PE adder vs IAT table.
Engine > Fuel > Power Enrichment.
Find the max temp of your run with the meth/water on, and above that value, add in enough of a pe adder (0.2-0.5) to pull your afr back down to 11.2-11.5 in case your meth/water cuts out. It's not fool proof, but it's an added layer of protection in case you have a failure. Granted, that's a sliding scale that will need to be changed from summer to winter, but lets be honest, at least here up in the north east, there's not too many people driving boosted cars in the winter.
Thread Starter
11 Second Club
iTrader: (3)
Joined: Dec 2004
Posts: 107
Likes: 0
From: Coastal Mississippi
Thanks of all of the responses, this thread is covering a lot of great information. I have an appointment Tuesday to get the car on the dyno to start the new tune. I intent to approach the meth injection tune as The Alchemist has posted. I hope to end up with a meth enhanced tune not a meth dependent tune.
Yeah, I forget to mention the IAT spark advance tab. I only pull timing when the IAT's get higher, but that was because I had a crappy IAT sensor that was very slow to respond. Having meth spray on it, it wouldn't change temps at all. Now that I replaced it with a fast response sensor, I may add some timing when it goes really cold, but it'll depend on the difference between the IAT's with and without meth. If I see that without meth, it goes up 5-10 degrees above ambient, then I'll only add when the temp drops a fair bit below ambient.
Yeah, I forget to mention the IAT spark advance tab. I only pull timing when the IAT's get higher, but that was because I had a crappy IAT sensor that was very slow to respond. Having meth spray on it, it wouldn't change temps at all. Now that I replaced it with a fast response sensor, I may add some timing when it goes really cold, but it'll depend on the difference between the IAT's with and without meth. If I see that without meth, it goes up 5-10 degrees above ambient, then I'll only add when the temp drops a fair bit below ambient.