donmagicjuan
15+ Year Contributor
- 824
- 34
- Jan 21, 2006
-
Bremerton,
Washington
I think you're probably right about the best setup from a tuning perspective being 100% methanol. If I remember right it's the extra energy released from the burning of the methanol along with adequate cooling that gives it the slight advantage. Water, while having a greater latent heat of vaporization, does not release energy in the combustion chamber. However, I also like the cleaning effect that water brings to the table. That's probably why I'll always inject at least a small amount of water in my mixture. It sounds like your nozzle choice will serve you well. Let me know how it works out for you.
As it turns out, things start to get kind of complicated when you talk about AFRs as seen on a wideband when dealing with methanol injection. As you may know, O2 sensors work on the concept of "lambda." A stoichiometric mixture corresponds to a lambda of 1, and the calibration of the controller assumes a stoich value of 14.7 for gasoline. The problem you encounter with methanol in the mixture is that the two fuels have different stoichiometric ratios, which throws off the reading on the wideband from the actual AFR. There was an interesting thread about this a while ago that you might find interesting. Check it out if you like, there's some really good info in there: http://www.dsmtuners.com/forums/showthread.php?t=237238
I ended up leaning my mixture out to about 11.5:1 as indicated on my wideband. I experienced no knock during a 4th gear dyno pull at that ratio, which tells me it's still pretty safe. I didn't really want to push things and go further, but I probably could have. I think your question is a legitimate concern about the later spool times in lower gears, but I'll give you a couple reasons why I wouldn't worry about it. First, in lower gears, there is less load on the engine, which means there will always be a lower propensity for knock. When tuning close to knock thresholds, I often noticed that I would knock in higher gears but not in lower ones. Secondly, you'd be surprised how lean you can go when you're actually spooling up the turbo. I've learned from some very well respected members on here that you can not only get away with AFRs circa 13:1 as high as 10 psi, but you can greatly enhance your spoolup times by doing this as well. The best way to make sure that you're safe, however, is to just capture some logs in the areas of interest to confirm that you're free of knock.
Hope that helps.
As it turns out, things start to get kind of complicated when you talk about AFRs as seen on a wideband when dealing with methanol injection. As you may know, O2 sensors work on the concept of "lambda." A stoichiometric mixture corresponds to a lambda of 1, and the calibration of the controller assumes a stoich value of 14.7 for gasoline. The problem you encounter with methanol in the mixture is that the two fuels have different stoichiometric ratios, which throws off the reading on the wideband from the actual AFR. There was an interesting thread about this a while ago that you might find interesting. Check it out if you like, there's some really good info in there: http://www.dsmtuners.com/forums/showthread.php?t=237238
I ended up leaning my mixture out to about 11.5:1 as indicated on my wideband. I experienced no knock during a 4th gear dyno pull at that ratio, which tells me it's still pretty safe. I didn't really want to push things and go further, but I probably could have. I think your question is a legitimate concern about the later spool times in lower gears, but I'll give you a couple reasons why I wouldn't worry about it. First, in lower gears, there is less load on the engine, which means there will always be a lower propensity for knock. When tuning close to knock thresholds, I often noticed that I would knock in higher gears but not in lower ones. Secondly, you'd be surprised how lean you can go when you're actually spooling up the turbo. I've learned from some very well respected members on here that you can not only get away with AFRs circa 13:1 as high as 10 psi, but you can greatly enhance your spoolup times by doing this as well. The best way to make sure that you're safe, however, is to just capture some logs in the areas of interest to confirm that you're free of knock.
Hope that helps.
