What kind of Mixture to run?

[GHawz13]

Does anyone run a mixture with the Denatured Alcohol? For instance a little water. I am using an SMC system. If so what percent water?

 

[robbil]

I have the same question, but from the other end of the spectrum. I'll be running an Aquamist 2c with my main consideration being water injection as opposed to alky, but I am wondering if I should run a methanol/water blend. Forgive me, but this is actually on a turbo Miata but I believe the physics will be no different.

I am new to this so let me test my understanding - tell me where I am off base:

• Water has unlimited octane, the common alcohols are in the 110 - 120 range.
• Water has twice the cooling capability of alcohol which in turn has twice the cooling capability of gasoline.
• Alcohols have about 1/2 the enegy content of gasoline.

The point of water/alky injection is to suppress preignition and detonation by raising the effective octane of the fuel and cooling the intake charge. It would appear that water is the ideal fluid with the major drawback that it is not combustible and at a high enough ratio will drown the motor. So in cases where extreme intercooling or octane increase is needed the injected fluid must contain a greater proportion of combustible fluid as we need to inject more to quell knock.

My questions are:

• At what proportion of water/gasoline will the water start to quench the combustion?
• Is there any advantage to injecting a proportion of alcohol before this point is reached?
• It seems that no matter the amount of injection necessary, water is still an ideal component of any injected fluid since it has unlimited octane and great charge cooling ability. Why would you inject just pure alcohol at all?

Thanks!

 

[Nocooler]

Water is a PITA to tune. I'd start with 100% denatured + lube, then slowly start adding water. Every car is different, and mine loves pure denatured - and while it runs good on 70/30, 50/50 - 100% alky is just easier for me.

 

[twidge]

What about running methanol in a kit? Doesn't that have a higher octane rating than just denatured?

 

[Turbo__Tim]

Originally posted by robbil
I have the same question, but from the other end of the spectrum. I'll be running an Aquamist 2c with my main consideration being water injection as opposed to alky, but I am wondering if I should run a methanol/water blend. Forgive me, but this is actually on a turbo Miata but I believe the physics will be no different.

I am new to this so let me test my understanding - tell me where I am off base:

• Water has unlimited octane, the common alcohols are in the 110 - 120 range.
• Water has twice the cooling capability of alcohol which in turn has twice the cooling capability of gasoline.
• Alcohols have about 1/2 the enegy content of gasoline.

The point of water/alky injection is to suppress preignition and detonation by raising the effective octane of the fuel and cooling the intake charge. It would appear that water is the ideal fluid with the major drawback that it is not combustible and at a high enough ratio will drown the motor. So in cases where extreme intercooling or octane increase is needed the injected fluid must contain a greater proportion of combustible fluid as we need to inject more to quell knock.

My questions are:

• 
  

Thanks!

First of all GHawz13, run 100% denatured at first. See if you can work it down to 70 percent alchy. Adding timing will assist you in burning more water content. (more heat) You won't get more than 70 percent out of the SMC kit IMO, until you take the timing to insane levels. Tune for 70 percent denatured, and 21 psi. This is a realistic goal at 22 degrees tiiming...

Using egt's, and knock sensors, of course...

• Water has unlimited octane, the common alcohols are in the 110 - 120 range.
• Water has twice the cooling capability of alcohol which in turn has twice the cooling capability of gasoline.
• Alcohols have about 1/2 the enegy content of gasoline.

All true!

My questions are:



At what proportion of water/gasoline will the water start to quench the combustion?

Is there any advantage to injecting a proportion of alcohol before this point is reached?

It seems that no matter the amount of injection necessary, water is still an ideal component of any injected fluid since it has unlimited octane and great charge cooling ability. Why would you inject just pure alcohol at all?

No answer to the first 2.

Alchy injection does 2 things.

(1) It cools the intake charge allowing more oxygen, thus more potential for power.

(2) The water in the mix carries the excess heat out of the cylinder, reducing high temperatures that cause knock.

Lots of guys inject pure alchy, and have good results. It has a cooling effect, but (like propane) the octane addition is minimal due to the injected mix comprising onlt 10 percent of the final charge. I suspect that like propane, it slows the flame front down, promoting a more complete burn that elliminates hot spots, and leaves fewer hot gasses behind to pollute, and pre detonate the next intake charge.

This is where propane and alchy share a common ground.

Pure water injection is possible if you have a 250 psi pump, and several small jets to atomize the mix. Without a fine mist such as this, the spark 'drowns', and power is lost. Atomization is key@!

Since our kits work at 60 to 90 psi it is best to run a 70 percent mix, so you get the precooling, and the cylinder temp decrease. It's a compromise due to the pump limitation. Going 2 stage works better since the cooling is accomplished a little at a time, so when the temperatures really begin to rise, the second stage comes on and delivers enough more alchy to quell temps, without flooding the spark.

Methanol will cool intakes better, and even has more potential energy, but I wouldn't go to the trouble of using it unless I was building a kit from scratch. The corrosion problems are there, and there is very little to gain. IMO others will say differently...

Just injecting water may work for you, and the Aquamist are great nozzles for the job. Easy to add and subtract nozzles, better mist, easier to tune. If you add alchy however, be prepared to change the lines once a year, as they become brittle over time. You don't want alcohol spraying around in a hot engine compartment - right?

Just a reminder to all to use the search function, and read for a few hours if you have an intense interest in this subject. You will find that your search will help to form more specefic questions. Not only that you won't just get my opinion either. (that is a good thing!)

 

[Steve Wood]

I am not sure why one should not use more than 30% water after the various experiences related over the years. On the other hand, I don't think there is much performance diffrence between 50% water which I would argue is optimum and the 30% that Tim likes so other than theory, measured performance is probably irrelevant.

The problem with mixing alky and water is that it takes a water soluble oil to provide lubrication. Easier to run straight alky, even if it does not work quite as well and give it a shot of Wd-40.

Lot's of argument over what is requred...it's obvious that almost anything works, low pressure, high pressure, tiny fogging jets, coarse NOS jets...you pays your money and takes your choices, it seems to me.


Here are some links that might give you some ideas

http://www.angelfire.com/super/buickgn/Alcohol.htm That is Bob Avellar's site. He has run many mixtures.

http://home.att.net/~stevemon/AlcoholInjMod.html that is Steve Monroe's site. He does not believe you need high pressure.

Steve Hill has a great site on alky, also but it seems to be locked at the moment.

that Miata sounds like fun to me.

 

[Two Lane]

REFERENCE ONLY (NO LONGER FOR SALE)

http://alcoholkits.tripod.com/

HTH

 

[robbil]

Originally posted by Steve Wood
that Miata sounds like fun to me.

It sure is! Lots of food for though here, thanks.

 

[blackbuick87]

Originally posted by twidge
What about running methanol in a kit? Doesn't that have a higher octane rating than just denatured?

Yeah, but you will be replacing your pump every month or so.

I have settled on 60/40 or so. Distilled water is easier on the pump and cheaper than alcohol

 

[Steve Wood]

No differnce in octane, but, methanol seems to work just slightly better....ruins a normal pump pretty quickly, tho.

 

[Red Regal T]

MINE'S STILL WORKING........60,000 MILES.......NO KLUTZ! WHY?