How to attack Meth dependent SD
Thread Starter
Racer
Joined: Jun 2011
Posts: 303
Likes: 13
From: Marietta GA
How to attack Meth dependent SD
Doug of ECS told me and I've read multiple posts stating that if you tune completely meth dependent and the meth ever fails for whatever reason then you go so lean it shouldn't damage the motor, or would be less likely to. 14/1 being safer than 13/1 for example. Any of you guys who tune your SC setups Meth dependent and are more knowledgeable than myself, how do you go about attacking the vve table? Maybe my meth is coming in too fast but it goes rich quickly. After playing around with the vve table it seems difficult to get it to match that curve, especially after calculating coefficients. In other words how can I pull 10-15% fuel at 120-125 kpa without completely skewing the rest of the table? Any insight or advice would be appreciated. I'd love to see a screenshot of someones vve table that has this worked out. I should mention I have a manual 2013 grandsport w/ ECS kit and meth. I am just running low boost right now(6lbs). I want to get the fueling correct before I start adding boost.
Last edited by 1966427; Jun 27, 2018 at 10:14 PM.
Instructor
Joined: May 2018
Posts: 134
Likes: 57
From: Alberta, Canada
You're better ff on the HPT forum for this type of thing, very few here do their own tuning from what I've seen.
Some good info:
https://forum.hptuners.com/showthrea...ht=meth+tuning
Some good info:
https://forum.hptuners.com/showthrea...ht=meth+tuning
Race Director
Joined: May 2004
Posts: 16,667
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From: Raleigh, NC
St. Jude Donor '15
On my own car I've just got a big *** dip in the VE table where meth kicks in, so I did it that way. Works fine, is consistent, etc. but took some time to get just right. I also try to prime the meth system before using it, seems to be slow to spray the first time I use it after the car has been sitting
HOWEVER, that's on a manual transmission car. For an auto I'd lean more towards the PE table method as dropping the VE table like that reduces "airflow" as far as the ECM is concerned which effects the torque calculations the transmission needs
HOWEVER, that's on a manual transmission car. For an auto I'd lean more towards the PE table method as dropping the VE table like that reduces "airflow" as far as the ECM is concerned which effects the torque calculations the transmission needs
Thread Starter
Racer
Joined: Jun 2011
Posts: 303
Likes: 13
From: Marietta GA
Ok, thanks schpenxel. It's a 6-speed. I've had the same experience needing to prime the meth. I backed down the initial setting on the alky controller and that has helped ease it in. Should be able to slowly work the table now that it's less of a violent drop. Just interested in how others are tackling this situation. Are you of the same mindset that if you tune for 11.5 or so w/ the meth that if the system ever fails it goes so lean that it will just backfire and be less likely to damage anything? I think I've read you setup some additional fail-safes on your car.
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Race Director
Joined: May 2004
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From: Raleigh, NC
St. Jude Donor '15
Yeah, something like that. Depends how much meth you're spraying really as to how lean it will go. I do agree with the making it go really lean without meth vs. just a little bit
My personal opinion for a long time has been that if without meth you're at say 0.85 lambda and with meth you're at 0.78 lambda, you've got a bad situation.. if you lose meth you're going to be at a point fueling wise where you should be making MORE power at a time when you really want the opposite.
I'm on E85 + meth these days so meth not spraying doesn't freak me out "quite" as much, though it's obviously still not ideal..
My personal opinion for a long time has been that if without meth you're at say 0.85 lambda and with meth you're at 0.78 lambda, you've got a bad situation.. if you lose meth you're going to be at a point fueling wise where you should be making MORE power at a time when you really want the opposite.
I'm on E85 + meth these days so meth not spraying doesn't freak me out "quite" as much, though it's obviously still not ideal..
Last edited by schpenxel; Jun 27, 2018 at 10:39 PM.
Thread Starter
Racer
Joined: Jun 2011
Posts: 303
Likes: 13
From: Marietta GA
10-4. That's the part that scares me about that strategy is I am probably not spraying enough meth for it to go "super lean" if it does fail. What, if any in your opinion are the negative side effects of tuning it a little lean, maybe a touch over .78 lambda and just spraying the meth on top without any other adjustments? From my understanding at that point you will have lower iat's and more octane but wont have much if any power gain. Is there any danger running it @ .70 lambda or so w/ the meth?