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Meth / water injection - revisited

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Old 10-27-2010, 10:08 PM
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Meth / water injection - revisited

Quoting MM from another thread . This is worthy of more discussion as many people here are taking it for granted that it is 'the answer' to our FI engine blowing blues .

Originally Posted by MazdaManiac View Post
Not really a bombshell. At least not from this perspective.

Having tuned/accessed/dynoed/datalogged/etc close to two dozen FI Renesis applications with W/M, I have found that in every single case, the power loss that comes as the price tag for the "insurance" that W/M allegedly provides is greater than just tuning the motor to a margin that would preclude its necessity.
W/M in concentrations where it does not cause excessive EGT increases (near 50%), adds so much fuel value that it completely negates up to .06 lambda in the fueling calculations. This is not acceptable to me.
If you adjust the tune (timing and fuel) to accommodate the W/M, you completely negate its value as "insurance".

Originally Posted by MazdaManiac View Post
With the Snow, AEM, CoolingMist and Devil's Own kits, I could never get the doses small enough.
Even with the finest jets and latest turn-on times, power always dropped and EGT climbed.
Because of the way air moves through the Renesis, even the smallest amounts of water quench combustion almost completely.

Once I got concentrations up to the point that combustion would continue, the fueling values would shift. At those concentration, the damage to the metal bits becomes a serious concern as methanol dissolves aluminum.

Last edited by Brettus; 10-27-2010 at 10:13 PM.
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Old 10-27-2010, 10:11 PM
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I'll go ahead and quote RP here for posterity:

Originally Posted by Richard Paul View Post
[Dave] Zeuschel used water/meth on the Merlin race engines at Reno. This was 50/50 mix. BUT these were very highly supercharged race engines and also had 120+ fuel. I can't recall exactly how much boost they ran and if I did I'd have to kill you if I told. 40-50 psi might be in the ballpark.

The tune on these engines was so far beyond what Rolls Royce designed that they sent a telex saying GOOD LUCK. According to Rolls calculations Dave was running 3500 + HP.

The H2O/Meth injection was used to control detonation and a complex anolog system of metering it was built custom. Realize that we are talking a lot of liquid to carry around on a plane for the entire race. Therefore it was regulated to use during critical times. as pointed out by the turbo user above it was only effective when used in a system that would otherwise not be viable. Ricardo has a section on water injection and I havn't read it in 20 years I think he basicly calls out that it makes more power then if it were detonating but iif you could not detonate you'd make more power without it.

Don't forget while methonol has a much higher resistance to detonation it has half the BTU's. When in the presence of water it will obsorb same and really being used as a coolant. Put the fire out and it is cooler. But why did you start the fire in the first place? To get the heat and thus expansion to move the rotor. Ha, you thought I was about to say piston.

It is not an explosion it is a controlled burn you want.

So not to ramble on here the answer to your question is no it is not going to help the NA engine except in some odd cases. I don't see those cases being with the rotary. Don't put out the fire, use it.
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Old 10-27-2010, 10:11 PM
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Here is the rest of the qoute from MM:

Originally Posted by MazdaManiac
At this point, I am recommending that people NOT use water/meth on the Renesis.
You gain far more power/reliability/safety from just getting the tune right.
W/M generally causes an FI Renesis to lose power and increase EGT.

With the Snow, AEM, CoolingMist and Devil's Own kits, I could never get the doses small enough.
Even with the finest jets and latest turn-on times, power always dropped and EGT climbed.
Because of the way air moves through the Renesis, even the smallest amounts of water quench combustion almost completely.

Once I got concentrations up to the point that combustion would continue, the fueling values would shift. At those concentration, the damage to the metal bits becomes a serious concern as methanol dissolves aluminum.
I'll also reiterate my question:
Very interesting stuff. So how much power loss on average do you see with using a 50/50 mix (on the same tune as running without)? In your opinion are there any situations where the charge cooling and octane boost would outweigh the potential damage to the engine from high EGTs and power loss like tracking or sustained high load driving in high temperatures?
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Old 10-27-2010, 10:28 PM
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Originally Posted by IronTanuki View Post
So how much power loss on average do you see with using a 50/50 mix (on the same tune as running without)?
On the last turbo car that I did a before/after comparison, the car went from 320 HP to 290 or so when the smallest jet was used with a turn-on point of 10 PSI or so.
IIRC, on one of the ~280 HP cali cars, the power only dropped about 7 to 10 with a 7 PSI turn-on and small jet.

My own car wont stop misfiring until the meth is essentially turned off. I removed it from the car today.

Originally Posted by IronTanuki View Post
In your opinion are there any situations where the charge cooling and octane boost would outweigh the potential damage to the engine from high EGTs and power loss like tracking or sustained high load driving in high temperatures?
Sustained load is exactly where the meth is at its worst. I think its only useful application would be to have it turn on when you are exceeding your tune in some way. Maybe over-boost or something.
BTW - meth is NOT an "octane boost" in the strictest sense. Though it has a higher octane, it has a significantly lower fuel value and higher mix ratio.
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Old 10-27-2010, 10:46 PM
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Very interesting.....
Good information, thanks everyone
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Old 10-27-2010, 10:56 PM
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This kinda leads on to another debate ...
MM - I have noticed your recent remarks about what AFRs you are running and tuning for . These targets seem to have gotten lower than what we used to regard as "safe" .

If one were to streach the envelope with a small turbo (cough) producing very hot air - would going to say 11.0 AFRs be a better bet than using water meth ?
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Old 10-27-2010, 11:20 PM
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Originally Posted by Brettus View Post
This kinda leads on to another debate ...
MM - I have noticed your recent remarks about what AFRs you are running and tuning for . These targets seem to have gotten lower than what we used to regard as "safe" .

If one were to streach the envelope with a small turbo (cough) producing very hot air - would going to say 11.0 AFRs be a better bet than using water meth ?
Yes.
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Old 10-28-2010, 07:57 AM
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Originally Posted by MazdaManiac View Post
meth is NOT an "octane boost" in the strictest sense. Though it has a higher octane, it has a significantly lower fuel value and higher mix ratio.
I think that measuring of octane rating of fuels, which have high latent heat of vaporization is meaningless, cooling effect will skew the measuring.

Have you tried straight water? Or higher ratios of water vs. methanol?
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Old 10-28-2010, 08:59 AM
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I believe Juan did some dyno runs with a variaty of jet sizes?
If I remember correctly he did have some demonstated power loss with the bigger sized jets.
But with a total of 150cc ( 2 jets, one pre blower and one post) he did not?
I do know if you spray during closed loop (boost or not) it mess's with your ltft's!
I am curious as to to why some are seeing increased egt's with w/m use?
I have not used an egt sensor, but when I track I do notice that the exhaust system seems to be not as hot. I relaize that is subjective only.

People will try to selectively edit their way to get you to use water injection by stating "One can basically double the power output of an engine using water/methanol" and "It was used effectively in Formula 1 before being banned for adding too much power". This is pure bunk. Water or water/alcohol/methanol does not make power...superchargers and turbochargers make power. The cooling effect of the water injection only allows you to run higher boost pressures and leaner mixtures without engine damage. The increased density or higher pressure ratio is what makes the power, not the water. The last time we checked water wasn't a very good fuel.

Aren't EGT's supposed to peak at around 13.2 afr?

Besides to the best of my knowledge water injection is not for reducing EGT's, it is not about increasing octane, it is primarily used for reducing the chances of detonation from engine hot spots. All the other "side affects" are just observations used for marketing?

Following with interest.
OD

Last edited by olddragger; 10-28-2010 at 09:22 AM.
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Old 10-28-2010, 11:21 AM
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Originally Posted by 999miki View Post
Have you tried straight water? Or higher ratios of water vs. methanol?
Yes. At anything less than 30% methanol, the power loss increases significantly (as does the misfire).

Originally Posted by olddragger View Post
I am curious as to to why some are seeing increased egt's with w/m use?
I have not used an egt sensor, but when I track I do notice that the exhaust system seems to be not as hot. I relaize that is subjective only.
Misfire.

Originally Posted by olddragger View Post
Aren't EGT's supposed to peak at around 13.2 afr?
No. EGTs will peak just after LBT, wherever that might be on a particular car.
However, they will go up and down depending on ignition timing and can spike significantly if the AFR is very rich.
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Old 10-28-2010, 11:39 AM
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What i am getting from this is that on the same car at the same PSI more power can be had by tuning to a safer AFR rather then by running a leaner AFR with meth.

However turning up the boost on the same car and running more boost with the meth injection will produce more power. (Untill the meth injection fails and the motor detonates and destructs itself.)

So using meth ONLY as a security measure, is not worth it. You would get more power and have a "safer" tune by jsut lowering the AFR's.

Using meth as a tool to run more boost is effective but one still runs the risk of the meth failing and the motor detonating.

Am i understanding this correct?
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Old 10-28-2010, 11:46 AM
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Wait wait wait

..so um...what kind of charge cooling did MM use to push his turbo beyond its effeciency range and make uba powa?

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Last edited by Mawnee; 10-28-2010 at 11:49 AM.
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Old 10-28-2010, 11:49 AM
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Originally Posted by Mawnee View Post
Wait wait wait

..so um...what kind of charge cooling did MM use to push his turbo beyond its effeciency range and make uba powa?
That would be considered using the meth as a tool instead of using it ONLY as insurace. He never disputed the fact that you could adjust the tune to use the meth to allow for more boost. He only stated that when using the meth for ONLY insurace that it would be more effective to just tune to a "safer" AFR.
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Old 10-28-2010, 11:57 AM
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Big power was through the use of fuel.
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Old 10-28-2010, 12:04 PM
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nitrous?
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Old 10-28-2010, 12:51 PM
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Originally Posted by Mawnee View Post
nitrous?
No.
116 octane, 12.2:1 AFR, 14° of timing, 17 PSI on the GT3082r.
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Old 10-28-2010, 01:03 PM
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Originally Posted by MazdaManiac View Post
No.
116 octane, 12.2:1 AFR, 14° of timing, 17 PSI on the GT3082r.
quoted for posterity

btw..that seemed way too easy. I expected an epic game of mouse and cat.

So was water/meth the only means of charge cooling you've used? I always had this suspicion you used something more exotic.

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Old 10-28-2010, 01:03 PM
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Whp = ?
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Old 10-28-2010, 01:18 PM
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Originally Posted by Phish806 View Post
Whp = ?
you mean you couldn't feel the earth move from where you were ?
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Old 10-28-2010, 01:20 PM
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Not at all... Must not have been as big as Mawnee is makin it out to be
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Old 10-28-2010, 01:22 PM
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Originally Posted by Phish806 View Post
Whp = ?
'Twas a bunch. Not really relevant since I can't profit from it and you can't learn from it for a multitude of physical reasons.

Originally Posted by Mawnee View Post
So was water/meth the only means of charge cooling you've used? I always had this suspicion you used something more exotic.
For those pulls, it was straight methanol in a very small quantity.
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Old 10-28-2010, 02:04 PM
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Originally Posted by Phish806 View Post
Whp = ?
a little birdie told me 430 ....
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Old 10-28-2010, 02:11 PM
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Originally Posted by MazdaManiac View Post

For those pulls, it was straight methanol in a very small quantity.
Cool, Thanks for sharing MM

Phish its an old subject, but I never really got the answer I was after in 'that' thread. It was semi on topic here so I thought I might have more success


MM is your assesment of water/meth renesis-centric or do you feel it applies to piston engines as well. What I mean is, is it a result of the renesis spark delivery inadequacies or the rotory compression method?
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Old 10-28-2010, 03:32 PM
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Originally Posted by Mawnee View Post
MM is your assesment of water/meth renesis-centric or do you feel it applies to piston engines as well. What I mean is, is it a result of the renesis spark delivery inadequacies or the rotory compression method?
Just read Richard's post. It pretty well explains my stance, though I do believe that the losses on the Renesis are greater than on a piston motor because of the charge inertia issue.
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Old 10-29-2010, 01:57 PM
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I will give up my w/m when you pry its button out of my cold dead fingers.

Juan, per dyno did not lose power with the total of 160 cc/hr nozzles?

Wouldnt adding more fuel also mean that carbon build up would be more likely?

Good discussion--- but i have always thought that w/m was to help insure my octane level was ok? When you are pumping your gas (lol) you really dont know what octane you are getting. Then you add ethenol..... now if you just run straight ethernol
How do the egt's rise, but the power goes down? That seems contradictory?
OD
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