the gauge reads OXYGEN content, you could be running meth, e85, and a standalone injection system of e10, and you would still target your appropriate value .75 or so under boost.

If your gauge reads 10 AFR while spraying meth it means you are spraying too much meth. Either up the boost, or bring the pressure down or change nozzles.


lambda is lambda on ANY fuel and ANY mixture of fuels. So if you want to tune e85 on a display that reads out gasoline AFR's you should note that 1 lambda=14.7 so being at 1 lambda on e85 would read 14.7 on the gauge, because the sensor doesn't care what fuel you are running, it reads oxygen content.

 

Not necessarily. Max power for methanol on a wideband that reads on the gasoline scale: 0.62*14.68=9.1. Again it depends on the concentration of methanol... Target lambda will change depending on the kind(s) of fuel injected.

It is also worth mentioning that those are ideal values, as in you aren't adding any additional fuel for knock prevention. If you look at the max power rich for gasoline, it becomes obvious...12.5 AFR on gasoline in a 9.5:1 compression LQ4 at 20psi is going to break ****. More fuel and/or octane will be necessary to slow down the burn so you can keep making power without detonating.

 

Good info , thanks to all involved .

Another question though , what is the stoich of meth/ water mix , say 70/30 ?
I run straight meth , but it's very noticeable when it starts to spray , a meth/ water mix feels smooth and seamless . So if I ever wanted to spray a mix I'm not sure how much to richen it up ?? Converting to Lambda would account for this I'm assuming ?

 

You really shouldn't care about the stoich of the meth/water mix since you are only spraying at WOT.

The way I see it is water is not a combustable fuel so it won't have any effect on your target lambda at WOT. You will just be spraying less meth when running a 70/30 mix which you would need to account for in your calculations. So if you are spraying with a 15 nozzle, you really only want to account for (15*0.7) of fuel. Someone correct me if I am wrong here.

 

^^ That's right.

 

If I write a book on this stuff, would anyone buy it? just kidding. I'm illiterate.

 

Good discussion so far. Everybody says lambda, lambda , lamda. But the wideband reads lambda displays air fuel ratio so it is relative. I just need to conform and speak Lambda.

AEM failsafe boost and lambda gauge is en route.

 

Yes thanks for the answers and info . It's defintley helping me understand my PE and wideband logging , got a great lesson also from a good member here . This place rocks .

 

Bringing this back up for more discussion on methanol. Jake, where did you get that max power is achieved at 0.62 lambda for methanol. I've read a few places that cars that run methanol as their primary fuel show best results around 0.72 lambda. Can any confirm or deny that. I know there are some cars on tech that do some serious 1/8 mile racing with dual injector methanol set ups. I want to ask them but can't find their threads

 

I guess I should specify: that is max power rich. That's usually the value we refer to in conversation because there is almost never enough octane to be venturing above that lambda value without seeing detonation. Methanol is another beast though. I've also seen some low boost e85 setups get leaned out to the point that they go past max power rich, max power lean, and then start to lose horsepower all without detonating.

Air / Fuel Ratios for a Wideband Oxygen Sensor - Hot Rod Magazine