Meth vs. Water Discussion

NYSpeed Automotive
1

Yes, I saw InnTune’s ad in theory-forum, but have further thoughts which were not answered there. His thread was more of a FAQ / how-to.

To reference:

Now, for what I’ve been debating for a few weeks with some gearheads.

From a performance perspective: Straight meth FTW - Meth adds fuel, which means it brings power to the table.
From a daily driver perspective: Straight water FTW - Water cools CC temps, and is ALOT easier on the injection equipment. Water cools the charge better, but doesn’t add octane of its own.

Material vs. Material…

Water is more effective then meth (by mass) at cooling the cyl. charge
Water vaporizes @ 212* F
Vaporizes 70* higher then meth, so will only help you once you get into the CC most likely.
Water is inert & will not burn. If it doesn’t burn, simply remains a gas… well now that steam is taking up valuable space - and not doing anything.
The volume of steam is now taking up space in the cylinder charge and actually making the charge LESS dense, and more humid - slowing flame speed. This means you have to run more timing, which negates some of the point of using water to battle knock. Of course, it’ll allow you to make more power then without it.
Oh, and water doesn’t eat rubber & aluminum.

Our friend Meth brings a bunch of octane to the table.
Meth vaporizes @ 149* F
Meth vaporizes @ lower temps then water, so it could actually start cooling the charge in the intake tract (150* IATs are not unheard of).
Now, Meht brings octane. Octane increase flamefront speed… now we can pack in a more dense charge then before & make more power.
Meth evaps earlier on then water, however, it will not take out as much compressive heat for the same reasons - meth doesn’t cool as well as water (50% per mass).
And of course the meth is bad on the pumping system with the eating of rubber & aluminum.

Heres where I start waivering, tell me if I’m correct.

The reason that we are injecting anything in the first place is that we’re talking about pure combustion chamber cooling (which is the same reason you run richer then stoich anyways). Bringing down internal temps, allows BMEP to be increased while keeping engine bits from melting & cancelling preignition effects.

So, technically speaking: If we’re injecting extra gasoline (running rich), meth (extra octane & some evap cooling), or water (great evap cooling)… it doesn’t matter - as long as you tune the setup to take advantage of the new found efficiency (BMEP), and work around the side effects of the fluid itself. Okay? Good.

Meth & water both bring cooling to the table, and both are effective knock suppresants (water because of cooling, meth because of octane). Water provides greater charge cooling with lesser amounts (per mass) then meth does. Water does almost 2x what meth does in this aspect. So, how much meth would it take to get upto the same efficiency of water injection?

Water > Meth, amirite?

2

from the facts you’ve posted you appear to be correct. good read though. Remember though that because of the octane/cooling of meth, as opposed to cooling only with water, i would think that the potential is better than simply water.

3

just use race gas

4

water/meth is alot more cost friendly for a DD then running around with race gas. With turbos you can limit the boost pressure on the street so as to not detonate. On a supercharger if your pullied for more then 93 octane can satisfy WOT its nice to have the water/meth there to keep things under control.

5

with the uprising cost of meth i wouldnt say so

6

even if I were to consider that, WHY?

Washer fluid is cheap.

Water is free.

Both of which may be a more effective means.

7

youll still make more power with race gas but water meth is almost the next best thing.

8

right, you’ll make more power on race gas because the ignition cycle becomes more efficient meaning that you can stuff more dense of a charge into the CC… Thats not what I’m asking, sorry. :slight_smile:

Besides, I quite easily put ~2500 miles a season on the car. Why waste the race gas when water, meth, and washer fluid are free… I’m not going to buy two drums of 100 octane, and I wont run C16 leaded.

The question is which of the two is better / more efficient.

9

u can get 100 at the pump (its what i run)

but i always thought a 50/50 mix of water/meth was the best route to take

10

Meth injection is always a big discussion on the buick forums since a lot of guys have been running it for a long time. My car even has a “Power Injection” light because GM was thinking of using water injection but instead decided to use an intercooler. Here is one of the discussions from the forums:

[LEFT]Carl Ijames posted the following long ago.[/LEFT]
[LEFT][FONT=Arial]Alcohols do have much
higher heats of vaporization than hydrocarbons which means they will cool
the intake charge better. For comparison, hydrocarbons are about 70-80,
methanol is 262, ethanol is 204, isopropanol is 159, water is 560, and
nitrous oxide about 40, so methanol absorbs about 3.5 times more heat than
gasoline as it vaporizes.[/FONT][/LEFT]
[LEFT][FONT=Arial]Now, from the above, it would seem that water is the clear choice for an injection fluid. Again, it is not that simple as vapor pressure comes into it. Vapor pressure is tied closely to the boiling point of a liquid. Alcohol vaporizes (boils) at a lower temperature than does water and this affects the performance of the injection fluid.[/FONT][/LEFT]
[LEFT]John Estill did the following calculations about the time that Carl made the above comments and was not challenged on the math.[/LEFT]
[FONT=Arial] Water injection: 0.40 lb/min of water will vaporize, cooling the air down from 150 F to 109 F.
Methanol:
100%: 1.08 lb/min of methanol will vaporize, cooling the air from 150 F to 96 F.
50%: 0.55 lb/min of methanol/water will vaporize, cooling the air from 150 F to 107 F
Ethanol:
100%: 1.26 lb/min of ethanol will vaporize, cooling the air from 150 F to 100 F.
50%: 0.57 lb/min of ethanol/water will vaporize, cooling the air from 150 F to 108 F
Isopropyl:
70%: 0.76 lb/min of alcohol will vaporize, cooling the air from 150 F to 107 F.
91%: 1.14 lb/min of alcohol will vaporize, cooling the air from 150 F to 104 F.
100: 1.50 lb/min of alcohol will vaporize, cooling the air from 150 F to 102 F.

---------------------------------------
From the above, I gather that methanol actually works better than water when it comes to cooling due to its lower vaporization pressure even tho water when it boils releases more heat. I may be wrong as I am not a chemist.

[/FONT][LEFT]John may not be a chemist, whereas Carl is, but, John is very competent technically and I believe the above explains why methanol is a superior injection fluid as it seems to back up what we see in practice. Notice that about 2.5 times more methanol is consumed in the process but it reduces the resulting temperature more than water, or combinations of water and the three kinds of alcohol.[/LEFT]

I also run straight Meth on my car as do a lot of guys on the forums.

11

Depends on the setup. Most guys say they run best with a blend, anywhere from 30/70 meth/water to 60/40 meth water… The best thing ive seen, to best utilize race gas on the street, is the system they call “octane on demand” where they have basically 2 fuel systems, one for race gas and one for pump gas, and when your tooling around town youll run off the pump gas, and only when you go to wot or get into boost will you switch from the pump gas to the race gas. Complex but pretty well thought out, race gas isnt cheap these days

12

That sounds like really great setup. Infact you could be running 87 and have it switch to 93 or 100 when you hit like 3-5 psi. Overtime, could be cost effective.

13

100 oct at the end of the season was 5.30/gal

14

Out of curiousity, what were you getting MPG?? (And I understand you used race gas for a reason other then just racing- i.e. tuning)

15

correct, i seen about 17-18 city, 23 highway

16

93 octane ftw, screw 100, way too much money for a “street” car

17

In almost any car we use a 1:1 mix of distilled water/99.99% pure meth.
Water for extra cooling in the cylinders.
Meth for extra cooling primarily in the intake tract.

The extra octane meth has isn’t as much of an issue since the amount of meth being injected compared to gas is very small in most cases i.e. 5% or less of total fuel volume being injected.

I see about the same drop in EGTs on 50/50 mix vs. straight water at the same flow rate, but the straight water is more taxing on the ignition system and makes the mix harder to burn. Also as you mentioned, meth is a fuel so burning it helps do actual work.

The above info 87GN posted only focuses on intake temp, but the end focus of injection is to affect cylinder temps and EGTs is the next best way to measure that. Sure meth will lower intake temps more because it’s more likely to vaporize in the intake tract, but then when you get in the cylinder the water goes to work…hence the benefit of 50/50 mix.

“And of course the meth is bad on the pumping system with the eating of rubber & aluminum.” I think at this point everyone knows your average gas pump isn’t meant to pump meth so this shouldn’t be an issue. Any meth kit we’d use is meant to pump meth at up to 100% concentration. Properly implemented, a meth kit should only spray for moments at a time with the whole mix burning/evaporating so none is left to do any harm to aluminum. We recently had a customer engine apart for upgrades who has been spraying more meth than any of our other customers and his all aluminum engine came out looking brand new on the insides.

If you don’t use enough nozzle pressure to properly atomize the mix, don’t place the nozzle or size it properly, or don’t tune for it properly, THEN you can run into pooling and corrosion of aluminum.

This sounds like a great idea, but I’ve been through it. It’s a lot of work and expense, plus adds a lot of weight. It’s really not worth it. By the time you add the cell, pumps, lines, fittings, secondary rails, secondary injectors, secondary FPR and return line, controls, etc. it will take a VERY long time to recoup your expenses and you have a much more complicated system which is far from light.

18

we’ll have to see how much race gas fluctuates, because im sure 93 by spring time is going to be $4+/gal

19

I run 93 octane in my GN, but with alchy injection I’ve run as high as 26lbs boost with no detonation. I go through about a gallon of denatured alchol per month. $11.00 @ Value Home Center. I tried running a meth / H2O mix (85/15) but got knock @ 24lbs.
Now, 100 octane with alchy, I can run 28lbs no problem.