Tuining for fixed rate Methanol injection?.

[keithmac]

Hello all, I`ve got a 9b/13g setup running 450cc injectors on a hotwired walbro with a Shurflo pumped methanol system injecting approx 1250cc of 75%Meth 25%water pre turbo and directly into the manifold runners.

The problem is I did a lot of road tuning in 2nd gear and got a very good repeatable AFR of 11.5:1 with a good timing and no knock. I`ve since 1/4 miled the car and found in the datalog 3rd gear leans off to 12:1 (no knock still).

I was just wondering is this a common problem with using fixed rate methanol injection?. If I bring the tune down to 11.5:1 in 3rd gear second will be a tad on the rich side but I could deal with that, problem is I have no ability to tune for 4th gear pulls at 160mph on the road and I`m worried if I ever did need it I`ll be running 12:1 afr or worse in 4th which isn`t good.

Does the cars ECU add supplimentary fuel in second due to the speed of acceleration that complicates my tuning or do I have to re-think my methanol setup?.

My best time so far was 13.2@110mph in the wet, probably down to my poor driving, looking to get a 12 out of the old girl this year hopefully (full weight).

[arghx]

If you want to go all out, FJO sells a duty cycled controlled Methanol system which lets you map methanol delivery vs. rpm & boost. It's pretty much a standalone for alky. FJO Racing Products - Water/Methanol Injection Parts