How Much Alky Is To Much?

[Slow91z]

Plus you don't have to fill you bottle at every other stop light.

That's the only downside I can see to more alky.

 

[Slow91z]

Just to further explain my thinking on this subject, alky has a higher octane than gas...So more alky is a safer tune less likely to detonate (or preignite not trying to split hairs here) not to mention the cooling properies.

Now I understand there are some chemical properties that can change things, but IMO none of us are replacing enough fuel to make that a big deal...I obviously don't know the magic number where this becomes pertinent but as our cars get faster most of us are actually going to use less alky because our fueling needs are going up.

I can actually see a 11 sec. car with a dual nozzle kit have more problems then a 9 sec. car spraying all the alky they can.

EDIT - I forgot to say that obviously my statements are based on running pump gas...and as a side note to the original poster you said you are thinking about trimming it back some at the track where you use C16, but trimming the alky back even more on pump gas...Sounds backward to me unless you run a way milder tune on the street (and to me the fun of alky is my tune is the same all the time, as a matter of fact I think it's safer than having a strip and a street tune because if you get the tune right and never screw with it there is less chance to accidentally forget to turn the boost down, or timing or whatever and BOOM next time you get on it on the street).

 

[Alky V6]

The big unknown here is the two different fuel properties being mixed together. We all understand the cooling affect that the alcohol has on combustion temps, but we don't really understand what is happening after the alcohol has done its job and has vaporized, dissociated waiting for the spark, mixed with another fuel.
Alcohol engines operate at particular intake, cylinder, combustion and exhaust temperature windows. Gasoline engines at another higher set of temperature windows.
With an alcohol engine, getting cylinder and combustion chamber temps too high without adjusting fuel mixture to help control it will spell disaster. If you are getting exhaust temps over 1300-1350 F on an alcohol engine under high load, you'd best be changing something in your tuneup.
Alcohol engines run exhaust temps from 1050 to 1250 safely. My engine, 1200 last time I checked.

What is the exhaust temp range of a pure gasoline engine?

What kind of exhaust temps are you guys seeing with the mixed fuels?

Higher exhaust temps will equate to higher cylinder temps.

The low limit, beginning of the range autoignition temp for methanol is 725 F.

If you have a ground electrode or some carbon buildup that is beginning to turn red hot on you, how hot is that?

 

[Slow91z]

I don't have the data to answer your questions, but so far I have tuned my car with a very simple philosophy.

More alky is good, trim gasoline to compensate keeping wideband around 11.0.

Keep timing reasonable (low 20's).

Turn up boost until it's fast enough or out of fuel...Funny how I seem to always run out of fuel before it's fast enough!!

In the years I have been running alky injection (damn those years are starting to add up too) I have yet to hurt anything (cross my fingers). I have done this too 2 cars 1st one was a daily driver that I ran 28 psi everyday and I can tell you it hit 28 psi for at least a 1/8th mile every time I drove it. 2nd is my "new" car and since it's quite a bit faster than the 1st one I have been taking it much slower on turning it up. Much more money in this one if I kill it.

 

[Boost231]

EDIT - I forgot to say that obviously my statements are based on running pump gas...and as a side note to the original poster you said you are thinking about trimming it back some at the track where you use C16, but trimming the alky back even more on pump gas...Sounds backward to me unless you run a way milder tune on the street (and to me the fun of alky is my tune is the same all the time, as a matter of fact I think it's safer than having a strip and a street tune because if you get the tune right and never screw with it there is less chance to accidentally forget to turn the boost down, or timing or whatever and BOOM next time you get on it on the street).

for me 2 tunes is not a problem and safer IMOP. i have a xfi and an ams500. so what i do is load the pump gas tune in the xfi and turn the boost controller down a few clicks. then at the track i pump out the pump gas and put c16 and turn the boost up and load the new program. its easy. i myself like to run low boost on 91 and alky. i like being on the safe side. i run around 16-18 psi on the streets. i know i don't need the alky for these levels but i choose to because i use it more for the cooling effect then anything. i also run lower leves since it always hot as hell in arizona .Then at the track i run 20+ psi boost but i run good gas. o and another reason for the low boost on pump and alky. i have way to much money into my motor to push my luck.

 

[Slow91z]

Oh I'll tell you right now I wish so bad a XFI was in my budget.

 

[Alky V6]

Now this is the strange thing. I would not dare run leaner than 10.8:1 at 27 psi boost. Actually, I feel safer at 10:5 - 10.7:1 with no power loss. And I run pure methanol.

 

[Slow91z]

Exactly you run pure meth...On a straight gasoline motor 10.8-11.0 is still way in the safe zone...So add some meth to the mix (still WAY less than 50-50 mix) and 10.8-11.0 is looking like a good range to stay in.

 

[Alky V6]

Exactly you run pure meth...On a straight gasoline motor 10.8-11.0 is still way in the safe zone...So add some meth to the mix (still WAY less than 50-50 mix) and 10.8-11.0 is looking like a good range to stay in.

Well, I'll let you guys figure out the limits of gasoline and methanol mixes. So far, every warning or observation pertaining to methanol, no matter how short or vague the statement may have been, that I have happened to come across has proven itself out. Just keep your eyes open for failure patterns.
I will be watching with interest.

By the way, my 10.5:1-10.7:1 WB O2 sensor readout target range actually translates to a pure methanol a/f ratio range of 4.63:1-4.71:1.

 

[Razor]

I dont have any data of any Buick ever having any pre-ignition with an alky system from any mfg.

I think I make a pretty aggressive kit.. even with the trial and error involved, never seen it yet.

I guess one thing is something can happen.. like an elephant falling out of a plane. Another is seeing it happen.

My own exposure has been power dropping off.

 

[Alky V6]

Good luck fellas.