meth - where to add timing safely?

[smokeshow]

I know this has beaten to death before, I've done a bit of beating myself... But I just can't get a good consensus on where to add timing for meth. Biggest recommendations I've heard so far are 1) add in the main spark table where g/cyl matches the boost level that activates the meth pump, 2) add in the IAT table so as temps drop with meth, timing increases with it, or 3) add in the AFR table.

I went with AlkyControl for the kit, so reliability is on the high end. But I certainly want to tune on the safe side so in the case there is a pump failure, the tune will pull timing and try to save the engine.

What tables should have added timing, or what combination of tables? I realize this is a very opinion-based topic, so be sure to share

[Snyper]

Is your meth nozzle before or after the IAT sensor? If its after then changing the IAT tables will make no difference cuz the sensor wont see the drop in temp if the meth isnt hitting it.

[smokeshow]

Haven't installed the kit yet, but it will be well before the IAT sensor.

[5_Liter_Eater]

I leave my main spark tables alone, set for no meth. Then I add spark in the IAT spark table under 80 degrees (I see low 60 degree IATs with my dual nozzle alky control kit w/ M10 and M15 nozzles). In the winter I will have to change this a little.

http://www.hptuners.com/forum/showthread.php?t=30629

What do you mean by the AFR table?

[smokeshow]

The IAT table would make sense to me, but some say it doesn't respond quickly enough to temperature changes if there was a pump mishap. On the contrary, there is no other way for the tune to respond to meth injection because no sensor detects it other than IAT.

This is the table I was talking about.

[Billf6531]

That table won't help you. It is based on programmed PE value, not on any AFR increase due to meth, since there is no variable sensor associated with this table.

[smokeshow]

Thats exactly what I thought. Someone recommended tuning with that table, and the thought of getting into PE and adding timing but at a boost level that hasn't activated meth yet just doesn't seem like a good idea lol.

So just to clear it up, the only sensor that is capable of detecting meth is the IAT sensor, right? So it would be wise to use that table on its own to add timing..

[5_Liter_Eater]

Correct. And to your point about it not reacting quick enough, in those logs I did see it took a little while (~20 seconds) for the IAT to start reading normally after I got out of the throttle. I would imagine that if the meth failed and I were still in the throttle it would not take near as long to react. If it took ~20 seconds to go from ~72 at the end of a 3rd gear pull back to 88 (ambient) just from getting out of it I would think if the pump were to fail and I were to still be pulling, maybe 5 seconds where the IAT's were still reading low enough to still be adding timing when no meth was actually spraying. So I supposed there is a risk if the pump were to fail in mid pull. The next time I got into it though it would not add timing and I'd be back to my safe tune.

I like the idea of adding timing in the lower IATs rather than keeping base timing high and taking more timing out for non-meth IATs.

[smokeshow]

Cool, I'll definitely use the IAT table then. If there is any sort of safety net with meth, that table is the best option.

So when you add timing, how do you gauge how much to add? For example, do you add until you see some KR and then back it off a bit, or is there another proven way to do it?

[5_Liter_Eater]

Typically you try to get back to stock timing, maybe a little more. The dyno is the only way to tell for sure what makes the most power.

[smokeshow]

The stock main spark table only has 1 more degree of timing than the new tune does. The IAT table is much less aggressive though. So I'm probably above stock timing as it is, before IAT goes up. Its commanding about 13°, and after IAT table pulls timing its about 10-11. That sound about right for a stock tune? Seems like it should have a bit more timing than that..

[5_Liter_Eater]

Well the timing being pulled by the high IATs is moot when you start spraying the meth. I forgot you PD guys run stockish timing, which still weirds me out.

[smokeshow]

Do you pull more timing without meth on a centrifugal blower? The stock timing seems low too, if its only at 13°. I guess the hot spot is around 18-19.

[5_Liter_Eater]

Stock for my LS2 is 19. I run 14 without meth and 18 with. Haven't put it on the dyno to see if more than 18 will make more power. I see TVS guys running 19 without meth and don't get any KR.

[smokeshow]

I've seen some pretty decent timing numbers with TVS blowers too. But I'm in a different situation with my truck. If I can gain back what the IATs take from me and maybe gain 4° on top of that, like your setup, I should be in the 18° range as well. I think that'll net some pretty nice gains.

[smokeshow]

Bill, you mentioned that you change where timing is added when winter comes. How often do you do that? I was considering that idea and it would probably work best...do you just move the cells to the left as the average daily temperature drops, and vice versa for increasing average temp? It seems that you'd have to change this almost monthly to account for temperature changes.

[IDRIVEAG8GT]

My two cents

From what I read is that with Methanol on most stock Compression Ratio LS engines with forced induction is that you can start at 16 degrees timing at 1200 RPM WOT, all the way up to 21 degrees to make maximum power, but the trick being that you have to make your timing table incredibly smooth. (I.E. Every different cell advance by .5 degrees timing.) The ECM has the capability to do this. If you make a timing table that erratically jumps, it trips the Knock Sensors. And thus you'll never be able to get away with having that much timing. I'll try to get more details upon what ambient air temp would be for this to run optimally and also what altitude.

[5_Liter_Eater]

Bill, you mentioned that you change where timing is added when winter comes. How often do you do that? I was considering that idea and it would probably work best...do you just move the cells to the left as the average daily temperature drops, and vice versa for increasing average temp? It seems that you'd have to change this almost monthly to account for temperature changes.

You have the shifting right. We don't really have "seasons" here. It's either hot, or not so hot. It's rarely under 70 degrees here so I will only have to change my tune for the few months out of the year that it is less than 70 out. As long as you're not adding timing at or above ambient you're good.

If you look back at the post I linked to it says "...for those of you that live where there are actual seasons, you may have to change this more often" or something to that effect.

[smokeshow]

Awesome info, guys. Will be installing the kit today or tomorrow, and then hopefully tuning as well. I will post up with more questions, I'm sure I'll think of something.

[backchannel]

Awesome info, guys. Will be installing the kit today or tomorrow, and then hopefully tuning as well. I will post up with more questions, I'm sure I'll think of something.

Post up if you have success. With my tvs, the iat's are a moving target and I don't know where you can use that table to deal with meth inj. - I assume your sensor is in the manifold. Logging iat's during a run showed increasing temps injecting or not. Injecting for me showed more boost but not much iat reduction - seemed to make the intercooler less effective. I don't bother with the injection now and my Z runs 140 @3300'. Good luck.
timing @ 1.36 2200[8] 3400[15] 4800[19] 6800[21] 10.5 cr 94 fuel no kr . I can use about 2+ because of my high altitude. I don't get the high #'s with PD blowers??