VG,

I can't find my notes that I built that post from (and I do have a nasty sinus infection so brain power is questionable today), but I did switch somewhere in the middle from a 75lb/hr hypothetical setup to my own. I think I messed up the 139 figure swamping from the other example and then divided it yet again... (where's the smiley for brain fart)

Be that as it may, methanol with register leaner than gas when tuned correctly. Typically, you aim for 30 to 50% of your fuel by volume with 100% meth.

BC and Trick are correct as well, the 1:1 doesn't increase flow across the injectors, just gives enough pressure in the line to overcome the boost on the other side of the injector, so we still use the 58psi rating (96 @ 43.5 = 110.9 @ 58).

110.9 * 8 = 887.2 total fuel volume
887.2 / 6 = 147.86 gph

I also appear to have estimated the gph of the nozzles and did so using the wrong psi from the pump... But even if that number was correct, I can't see wtf I dropped one nozzle's worth of flow out of the equation... All that O2 is part of why meth's stoich is 6.5:1... For the sake of argument here, let's assume the 15gph is accurate.

The ratio percent meth is 30/147.86 = 20.2, leaving 79.7 gas by volume. (bare in mind that the gph est of the nozzles assumed 150psi from the pump, but I believe it is a 250 psi pump at max voltage -- really flowing about 16gph per nozzle but whatever)

so plugging all that in, we get
.202* .93 * 6.4 + .797* 1.07 * 14.7 = 13.74

Okay, so now we have the mix stoich = 13.74

so that gives a correction value of 13.74/14.7 = .935 so 11.5/.935 = 12.3 on the gauge (and if my 16gph figure is correct, then a target of 11.5 should be reading 12.41).

I'm a little troubled by VG's example, though. His number of 8.93% meth should NOT be making stoich higher than gas alone which makes me wonder if it isn't as straight forward as this mole weight calc shows it to be, although this is discounted as an indication that you are not spraying enough meth to affect the stoich...

Here's another way to look at it (MightyMouse -- somewhat similar HP range to me) : https://ls1tech.com/forums/showthrea...4&page=1&pp=20 and this may make more sense

**I also originally stated that you lock in your VE, turn on the meth and remove fuel. An alternate would be to add timing or boost to lean the AFR back out**

 

This is making my brain hurt, I am out

 

What starts with a p and ends with a whine?

 

JOHN?

 

Ahh, that makes much more sense now. The reason I'm being so critical here is that I've been having serious tuning issues. I've always thought you should tune richer with meth since it's stoich is 6.4:1. I've tuned it from 9:1 on the guage to 11.5:1 and it's still sluggish and bogs sometimes. I think I need to lean it out further and see. Or up the boost.