Tuning questions with alky

[wiplash4-6]

First of all I hope you guys don't mind a tech question relating to Mustangs, you're definately way ahead of the curve on this stuff and the Mustang community simply refuses to embrace this stuff, even going so far as to say it's unreliable, not worth it, NEVER use more than a 50/50 mix, etc!

Last year I used a 70/30 mix on my D1SC blown/stock longblock 4.6 that ran 11.5 @ 121mph (13psi, 462rwhp457rwtq) on 104 octane in the tank. This year I built a motor and dumped the blower for a T76 Q-trim, and want to run a 100% mix of meth and use it to supply about 10-15% of the fuel enrichment so I can stick to pump gas. I'll be running 3 different tunes for 3 different boost levels, 15/20/25. The car should make about 550 rwhp on 15psi, 650 on 20psi and 700 + on 25psi, more once I get a custom turbo cams in there.

My questions are 1) is there some sort of octane calculation to figure out where I'l be at for a final octane number. I am not running a knock sensor (may install an MSD unit though) so I'd like to get an idea of where a good starting point would be for timing.

2) According to this article http://www.jagweb.com/aj6eng/superchargers.html the max power for meth is 4:1 !, so if my target on gasoline is 11.8:1, and 4:1 on meth with a 10% meth enrichment, I should see 11.0:1 on the wideband, and about 10.1:1 on a 15% mixture, correct?

I have read Razor's tuning thread and it says to tune for 11.7 to 11.8 on the alky but according to stoich's of both fuels it would seem that target A/F would be a little lean on either the meth side or gasoline side, and I'm assuming with the nozzles you guys are running you're close to 10% enrichment from meth.

Any input would be appreciated! Thanks guys.
Todd.

 

[Razor]

Depending on the volume injected will vary the A/F target. The more thats injected the lower the target AFR. If you plan on injecting a huge volume of methanol to support your goals.. you better be careful on your pump selection, and how your system is setup so that it can deliver the proper volume amount.

With what you have listed in your sig, you wont be able to achieve your goals.

 

[PhilM]

Meth n Eth are 140+ octane... that depends on the mix as well. Google it to find out what you're using then just run the #'s for your dillutions as/per nozzle size and ~ pump pressure.

You will calculate a target based on the above (amount entering the engine), as Razor had mentioned, because you know the stoich of the meth you're running.

On an aside, the wideband is a great tool for any tuning app, but a knock sensor seems to help quite a bit when tuning an alky car, ESPECIALLY, since you really don't have a good idea of the actual volume entering the engine with most setups... This would require a metered system ( ) that is calibrated to ensure a specific volume at a certain load condition.... Like a fuel injector. Problem is there aren't many long-term methanol compatible components that can handle it on the market (yet). Thus, ppl use fixed nozzles and an 'OK' guess on pump pressure that is somewhat related to pump speed, short term.

If you are trying to approach the stoich of meth alone... That is a TON of alky and since more the engine is relying on it now, errors become amplified --- so do broken parts. You need much more meth that a comparable HP setup for gasoline to approach that, so the general "add-on" alky kit will not get you there unless you have a custom made setup. You may want to look at the Weldon pumps, although, you cannot run H2O through them, they are mad $$$, and require their own maintenance.

Do it up! :tongue:

 

[Razor]

Phil,
I have to disagree. Unless were talking engines that will make 1500HP+

Dont have an issue with the current pumps either. Actually zero have failed since we changed how we did things Oct '04. I dont know, but Weldon pumps also can fail :wink: As long as its mechanical, there is a failure rate associated.

1000 RWHP is old news on pump gas now... running 40+ PSI boost is also old news on pump gas.. its been done already.

Anxious to see what you come up with :wink:

 

[wiplash4-6]

Depending on the volume injected will vary the A/F target. The more thats injected the lower the target AFR. If you plan on injecting a huge volume of methanol to support your goals.. you better be careful on your pump selection, and how your system is setup so that it can deliver the proper volume amount.

I wouldn't consider it a huge volume, I ran the numbers at work (don't have them in front of me right now), but off the top of my head if I'm making 700 crank horse and have a BSFC of .6 (for gasoline) and am looking to get 10% (or 15% can't remember which I calculated) of the fuel demand from the meth I should require approximately 22 gph (even with the meth calculated at 4:1). That can easily be achieved by two M10 or two M15 nozzles depending on pump pressure right?

As far as tuning if I tuned it to 12.8:1 on gas (which would be 90% of the fuel needed to achieve a safe 11.5:1 on gas) and wanted 10% of the enrichment to come from meth, then 10.75 would my target. Sounds easy enough but probably won't be in practice on the dyno or the road. The way I see it I'd benefit from 15% meth enrichment, but then if the meth fails I'd be seeing 13.5:1 on pump gas, at least at 12.8:1 there's a CHANCE the ring lands would live.

With what you have listed in your sig, you wont be able to achieve your goals.

By that I'm assuming the Snow pump? Can you sell just the pump, upgrade mine (it's supposed to be there better 220psi pump)? Let me know, obviously the pump is going to be the crucial link here.

 

[Razor]

I typically will pullout 15-18% fuel out of the tables and run the motor at 11.0 on a Buick. On LS1 they typically run them at 11.5. Some DSM's will target 12.0 on 25% replacement. Just depends.. the knock activity will determine that. At higher volume levels the meth system is part of your fuel tables. So it has to work...period. There is no dancing around it.

And also remember that there is pressure in the tube. So 100 PSI pump and 20 PSI boost = 80 effective PSI.

I wont get into modifying competitors products.. and you are correct with your last statement. I wont get into this on-line :wink:

You can contact Alternative Auto and ask what he targets the 4.6's at. www.alternativeauto.com . Since i'm not a Mustang tuner.. I wont advise on what I dont know.

HTH

 

[spork]

If you're using a wideband for tuning, I suggest looking at lamda, not a/f. Lamda is a constant no matter what fuel you are using, while a/f is just a calcuation made from lamda for the certain type of fuel you're using. Life with methanol and tuning will be much easier this way. No guessing on what your actual air/fuel ratio compared to what it was before the meth.