1SIKSS 711rwhp/607ftlb
07-14-2011, 10:47 AM
#22
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Well you can't really do that on a whipple setup after the change whipple made. The IAT is in the back of the intake so yes, the air is cooled pre charge the IAT never sees that temp drop so it's gotta be worked into the tune, basically adding timing because of the "race gas" like effect instead of lower IAT
07-15-2011, 08:55 PM
#23
Let me try to simplify it. The air/fuel sensor in the dyno reads lambda, or just a basic coefficient of any given number (in most cases, 14.7:1 for gasoline). It will read parts fuel per part air, period. It doesn't care if those parts are gasoline, methanol, alcohol, brake parts cleaner, or kool-aid, because it's basically just an air particle reader/counter.
Now that being said, if you compare the stoich AFR of the two different fuels, you can obviously see that you need a lot more methanol to burn then you would fuel.
14.7:1 gasoline
~6.3:1 methanol
If you were comparing a partial meth burn to a gasoline-only burn, the two resulting AFR ratios wouldn't mean much of anything compared to each other, because at the same 'reported' AFR, the methanol burn is actually much leaner because the fuel has a much lower stoich coefficient. Again, this is a result of lambda value being set for gasoline stoich for both runs (this is just a read-out and not wholly important)
If you're pulling fuel and adding meth to replace it, 11:1 based on a 14.7:1 readout sounds pretty close, as it is much leaner in reality then 11:1 on gasoline due to the stoich coefficient of methanol, which would make more sense. You didn't specify and I assumed you were just adding meth and timing, instead of reworking the entire tune.
Now that being said, if you compare the stoich AFR of the two different fuels, you can obviously see that you need a lot more methanol to burn then you would fuel.
14.7:1 gasoline
~6.3:1 methanol
If you were comparing a partial meth burn to a gasoline-only burn, the two resulting AFR ratios wouldn't mean much of anything compared to each other, because at the same 'reported' AFR, the methanol burn is actually much leaner because the fuel has a much lower stoich coefficient. Again, this is a result of lambda value being set for gasoline stoich for both runs (this is just a read-out and not wholly important)
If you're pulling fuel and adding meth to replace it, 11:1 based on a 14.7:1 readout sounds pretty close, as it is much leaner in reality then 11:1 on gasoline due to the stoich coefficient of methanol, which would make more sense. You didn't specify and I assumed you were just adding meth and timing, instead of reworking the entire tune.
out of curiosity how many cars with meth injection have you tuned? on those cars you have tuned, how many of them have you pulled the plugs and read them after dyno pull to see how hot the plug is? just answer these questions then i will move on to my next question or explanation..
