straight water vs Methanol or a Methanol mixture

[sstock]

Michael good info!
Maybe I'm trying to inject too much in my combo.
Iwas running a 2M turning on at 2psi thn a 7M on at 6psi of 70% Iso. Maybe it was slowing it down on the low end and I didnt need that much to get the cooling results. Like I said before, I could turn the timing up. I'm running the shurflo with the pressure switch disabled so pressures are in the 130psi range.
I think I'll give a 1 or 2 M nozzles a shot with ISO and see.
What turnon point are you using on the street?

Thanks
steve

 

[Michael Johnson]

I'm turning the spray on at 4-5 psi but keep in mind that I see full boost instantly from 2,000 rpm to redline. The set-on point is more useful with a centrifugal blower. With a 1M or 2M nozzle I doubt you'll get any noticable bogging. If you're running 2M and 7M nozzles I bet you're very rich. A 10% alcohol to water mixture will lower the AFR by 1 point. If you're CR is around 9.5:1 or less and you're running less than 15-16 psi of boost you might be better off running straight water with the 2M nozzle. If you're going to use alcohol then the engine should be tuned for it. Otherwise it's probably running extremely rich and the alky is robbing hp.

 

[monte_383]

Isn't there a "sensible heat" to go along with "latent heat" of evaporation? I seem to recall something about sensible heat when I had to calculate heat loss through a wall in my Structures class in college (or maybe it had to do with ventilation, I dunno). There's a possibility that both sides of the argument are actually correct, just talking about different types of heat. Water has a high latent heat value, but its possible that alcohol has a higher sensible heat value (which could explain why it evaporates quicker). Not a 100% on this, but I'm prolly close. I'm too lazy to actually look this up, but I figured someone that was more motivated could check it out and report back. HTH's -Chuck

 

[1badTTA]

This thread is dead

People are arguing about something without all the facts. The only way to be certain about anything on a car, is to test it on each car. It is obvious that not every single scientific fact about what is going on with alcohol/water injection on a boosted engine has been looked at and included in this thread. If they had, someone could easily figure out why some cars respond better to one than the other. Instead someone brings up the same point 20 times about water and its latent heat. What does it have to do with the combustion process anyways? If you are only trying to remove heat from the cylinder, improve your cooling system. If you are trying to make the most power, try different mixtures and don't worry why they work, just which works best.

 

[sstock]

If you are trying to make the most power, try different mixtures and don't worry why they work, just which works best.

WEll thats the fun of it.
I think this type of bench racing is productive and makes the sport better. Your right though, it isn't so much as to the theory or what one guy says or another but what you have personally tried and what has and has not worked in your particular situation.
The physics of these matters are very interseting but again you said there is more to the equation and that needs more exploration.

Later
Steve

 

[Michael Johnson]

Re: This thread is dead

Originally posted by 1badTTA
People are arguing about something without all the facts. The only way to be certain about anything on a car, is to test it on each car. It is obvious that not every single scientific fact about what is going on with alcohol/water injection on a boosted engine has been looked at and included in this thread. If they had, someone could easily figure out why some cars respond better to one than the other. Instead someone brings up the same point 20 times about water and its latent heat. What does it have to do with the combustion process anyways? If you are only trying to remove heat from the cylinder, improve your cooling system. If you are trying to make the most power, try different mixtures and don't worry why they work, just which works best.

Most grass roots R&D efforts are patched together from people sharing experiences and sparking new ideas to try like is happening in this thread. If someone wanted to pay a research company big $$$$ they would generate all the data you need to wring every last hp from water/alcohol injection. I think I've figured out what I need to make straight water work for my needs. If I get bored and get a shop with a dyno to work with me I will probably see what hp can be had from various W/A mixtures.

Water's latent heat is as central to the discussion here as alcohol's octane rating. Improving a cooling system has almost no impact on combustion temperatures. Changing a thermostat might but even that is minimal. Water will reduce combustion temperatures a great deal. In fact it can reduce them to the point of reducing hp output substantially. I don't see this as a water verses alcohol debate. It's a search for what can be done with each separately and together. Personally, I don't think there's one solution for every situation. It's discussions like these though that have helped me in the practical application of W/A injection. This in turn has helped me provide feedback to SMC in regard to use of their kit on Mustangs and how useful things like varying pump speed with air flow can be. These improvements ultimately help everyone regardless of what you spray or the car you drive. I'll take a little redundancy over not having the discussion at all.


monte_383,

I believe sensible heat is the heat absorbed by a substance without changing its state (i.e. solid to liquid or liquid to gas).

 

[LBS Blown Buick]

Ok, I did some testing on my Supercharged Z28 last night and this morning.

I had my combo tuned well with the DIY WB O2 @ 11.5 afr
using a 70/30 mix of water/meth. (No Knock retard)

I drained my tank and whent with 100% Methanol with cap full
of lube and no other changes.

I data loged 11 runs, the car is much stronger by SOTP, heck it jumps sideways now when the 2nd to third shift happens (AUTO).

Now W/ 100% meth My WB O2 shows my AFR down to 10.2 and I do get some Knock retard, when before with 70/30 mix of water/ meth I had a AFR of 11.5.

What AFR with Methanol injection should I shoot for 10.2 seems rich.
Maybe I'll try a 70/30 mix of Methanol/ water next.

 

[M3Turboca]

LBS Blown Buick thats some good info how much knock did you encounter with the 100% methanol.

Im curious with your next mix 70/30 if the 30% water will be enough to supress the knock.

If you have time please try a 50/50 mix as Im curious what your a/f ends up at and the performance changes.

I currently run a 50/50 methanol/water mix.

10.2:1 does seems too rich but your car made more power as you felt it I wonder if you would have made even more if you could have trim the fuel so that with 100 methanol you run 11.5-12.0:1

 

[1badTTA]

Originally posted by LBS Blown Buick
Ok, I did some testing on my Supercharged Z28 last night and this morning.

I had my combo tuned well with the DIY WB O2 @ 11.5 afr
using a 70/30 mix of water/meth. (No Knock retard)

I drained my tank and whent with 100% Methanol with cap full
of lube and no other changes.

I data loged 11 runs, the car is much stronger by SOTP, heck it jumps sideways now when the 2nd to third shift happens (AUTO).

Now W/ 100% meth My WB O2 shows my AFR down to 10.2 and I do get some Knock retard, when before with 70/30 mix of water/ meth I had a AFR of 11.5.

What AFR with Methanol injection should I shoot for 10.2 seems rich.
Maybe I'll try a 70/30 mix of Methanol/ water next.

There is no answer to that unless you figure out what ratio of gasoline to alcohol you are injection. Your 10.2 is actually lean since stoich for the methanol is 6.45

You need to inject more methanol untill you lose the knock, look at what the WB says, and you will have your answer.

 

[sstock]

Your 10.2 is actually lean since stoich for the methanol is 6.45


If he is running roughly 25% Methanol to gasoline his stoich is right on the money!

Good stuff, keep it coming!
Later
steve

 

[LBS Blown Buick]

M3Turboca,
I was seeing 5 to 7deg of Knock retard.

I just finished the Install of my PAC controller, (this thing is just awsome) I did some tuning runs with it for my Initial setup.

One thing I forgot in my earlier post is that after my runs my Intake Plenum was much cooler than it was with runing mostly water, so it seems that the Methanol actually cools more & quicker with the time it has in the intake track.

After I get this PAC setup and tuned I'll try differant mixes of
Meth and water.

It dose appear that water is a great Knock suppresser but you lose power too.

I belive and will soon know after testing that a mix of water & Methanol (mostly Methanol) will make the most power.

Also I updated my sig. to my current combo.