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fredmeister fredmeister is offline
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Join Date: Oct 2002
Location: Baltimore, MD, USA
Posts: 2,235
question on AFR and water meth injection

I installed water meth injection in my 79 930 and am in the process of tuning it now.
Question: Should I disconnect the system to tune the AFR without the meth injecting and then retune it with it hooked up?
Main question:
If the engine at high load (4th gear) and high boost (0.7bar) were running out of fueling but the meth injection was injecting at full flow, what should I expect to happen to the AF ratio? Meaning if the gas was lean but I were over fueling with water/meth fluid, would the AF ratio show rich or lean?
Right now I am running in the low 11's to even 10.9 to 1 AFR under high boost, high gear and am experiencing slight hesitation which tells me I am injecting too much water/meth and quenching the combustion. I just dont know if I am still getting too much gasoline and truelly rich or if the AF ratio would show 11 to 1 with a lean gas mix and too much water/meth. Its hard for me to believe that my stock WUR is able to get to a rich condition at these engine conditions when everything on the forum says it should be way lean.
hope I asked the question clearly.
1979 930 Turbo....3.4L, 7.5to1 comp, SC cams, B&B intercooler, Snow Perf water/meth injection, Rarlyl8 headers, Garret GTX turbo, 36mm ported intakes, Innovate Auxbox/LM-1, custom Manually Adjustable wastegate housing (0.8-1.1bar),--running 0.7bar max
---"When you're racing it's life! Anything else either before or after, is just waiting"
Old 07-22-2011, 10:25 AM
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