Water/Alky AFR

[silvercoupe97]

This seems like the correct forum, if not, mods/admin please feel free to move it into the correct one.

Anyhow, my question is about water/alky injection AFR tuning. I've read 12.5 AFR and some a little more rich. I've seen a lambda reading of 1 which is way too lean for me since 12.5 AFR = .854.
Any help on this will be appreciated.

Thanks in advance,
John

[JoeThaMan]

Well, alcohol is intended to run at a different a/f ratio than with gasoline. The stoich a/f ratio for Methanol is 6.5:1 (equivelant to 14.7:1 for gasoline). Since methanol has a significantly higher octane rating and better cooling properties, Running a safe a/f with gasoline (11.5:1 or richer on turbocharged vehicles) and using alcohol as a supplemental fuel would be more than adequate to maximize performance and reduce chances of detonation to occur.

[silvercoupe97]

First, I'd like to thank you for the response Joe
So, you're saying that 11.1 - 11.5 AFR is a safe bet to run water/alky injection?
Then, what's all the jibber jabber with 12.5 AFR? Is this number just a leaner tune with the injection just like 11.1 AFR is a leaner tune for pump gas?

Please don't take this as a doubt to your response, I'm just trying to understand it's tune a little more.

[JoeThaMan]

Well, you're going to make more power the closer to 12.5:1 you can get. Peak power is made at 12.5:1 a/f ratio. Unfortunately, on a forced induction application that is running a little lean to be a safe a/f ratio. With Alcohol you could probably run a little leaner than 11.5:1 or with a leaded high octane race fuel, but I recommend 11.5:1 to be on the safe side.

[silvercoupe97]

I gotcha. I'll tune for 11.5, then I'll start tuning for knock and see where that takes me on my wideband. Even with crappy 92 I had no knock from 10.7 and it felt very nice, with good 92 it was even better...smoother. I was working my way to 11.1, but then reinstalled my stock MAF and it went straight to running rich as one would imagine it would. So, I'm thinking to retune as close to 11.1 before activating the injection just so that it makes it easier tune for when the injection kicks in.
I appreciate your answers Joe and I'll post back with what I tune to for future referrence

If anyone else has something to tell, feel free to chime in. More info is better than no info...as long as it's not misinformation that is

[silvercoupe97]

Well, that was weird, I posted a response and it's gone, lol. Oh well, good thing for the back button.

I gotcha. I'll tune for 11.5, then I'll start tuning for knock and see where that takes me on my wideband. Even with crappy 92 I had no knock from 10.7 and it felt very nice, with good 92 it was even better...smoother. I was working my way to 11.1, but then reinstalled my stock MAF and it went straight to running rich as one would imagine it would. So, I'm thinking to retune as close to 11.1 before activating the injection just so that it makes it easier tune for when the injection kicks in.
I appreciate your answers Joe and I'll post back with what I tune to for future referrence

If anyone else has something to tell, feel free to chime in. More info is better than no info...as long as it's not misinformation that is