streetzlegend

iTrader: (2)

Sup guys, I have used this combination in the past and it was pretty intense on how the car responded with the small shot i was putting in, back then i was in only in the 300whp plus a 35wet shot and the meth/water. Back then I was still in the learning stagse as far as tuning goes, the engine still lasted a couple years more, but now im in a whole new level with a built bigger(from VQ30 to built VQ35) motor, bigger turbo(HX35 Holset).

I wanna get you more experienced guys input on this, considering I am using the meth/water and running near stock timing (Maxima ECU) which is about 20-21degrees at peak rpm and no knock. When activating the nitrous (say just a 35hp wet shot), should I back off the timing a degree or two, or will the mixture of water/meth/nitrous produce extremely low temperatures that timing will still be safe that high?(specially since the water/meth slows down the rapid increase of pressure caused by nitrous during combustion) My ignition control has a feature that once the nitrous solenoid is activated it retards 2degree's instantly, just dont know if I should use it or not for such a small shot, I plan to run no more than a 50HP shot (NX to be exact).

btw, for those curious as to why not just up the boost, the reason being is that my turbo is basically at its peak efficiency so instead of increasing the boost and just generating more heat and less power, I rather keep the turbo producing an efficient output and add the nitrous.

I will greatly appreciate any help or advice on this.

I am running Emanage Ultimate + J&S Safeguard. (This is my EMS and im stuck with it, so pleaseno "you need a better EMS" comments" lol

thom000001

Well the standard for Nitrous no matter what (for safety) is too back off timing some. How much.....that you may need to "play" with.

Remember when boosted, nitrous will have an even larger effect since you are going to get an even larger temp drop for the intake charge.

tom

streetzlegend

iTrader: (2)

Thanx. Yea it might be one of those "gotta try it to see" type things, ill back off a few degree's and spray it, make sure im not getting any knock, then bring back the timing lil by lil.

MethTech

What it often comes down too is what you could get away with on C16. Injecting 50/50 water/methanol properly gives you about that level of octane when you start with 91 or 93 octane pump fuel.

My guess is that with the sensible compression ratio we are working with here and a relatively small shot (35), no timing pull at all will be needed.

This is not just because of the cooling effect, it's also a direct result of slowing down the flame front as stated before. Detonation is basically just a really rapid burning of the air/fuel mix in the chamber to the point of not having an orderly flame front. The water/meth slows down the flame front and prevents this along with cooling everything down so that it's less likely to happen in the first place.


Edit: I doubt you will need to pull timing even with a 50 shot. As you said, you will have to try it and see. I would start with a mild bit of retard, then work up from there.

ttg35fort

iTrader: (2)

I'm assuming that you have significant knowledge in this area based on your screen name. If this is true, do you have any data you can post?

ttg35fort

iTrader: (2)

Bump for data...

I have seen it claimed that a 50/50 methanol/water injection mix at 20% of the gas flow rate can provide a detonation retardent equivalent to 115+ Octane fuel. However, others in this forum who have experimented with meth injection have found that strait meth works better than a 50/50 mix.

This seems to correlate with the NACA Research Memorandum RA No. A7130. Specifically, in that report, water is shown to be very beneficial when the intake air temperature is high, but the effectiveness of water diminishes as the intake air temperature decreases. With our cars, we have pretty good intercoolers and our intake air temperatures tend to be fairly low:

https://my350z.com/forum/forced-indu...wondering.html

Hard data with various water/meth mixtures at our intake air temperatures would be realy, realy nice to have. Without data, we are basing our assumptions on the NACA report, experiences of others, and SWAGs (scientific wild @ss guestimates).

streetzlegend

iTrader: (2)

Thanks for the response guys. I to have seen those claims that when methanol injection is mixed with 93octane(what we have here) 100+ octane levels are reached. In my case, right now I am running a little bit of less water (say 25%/75%) since I upgraded the intercooler, bigger inlets, and two times bigger core than what i had before. I have a buddy of mine that swore by 100% meth, he was able to produce 395whp on a VQ30 at 9psi (turbo charged), that is ALOT of power considering less displacement and low boost, and the 100% meth.

As in my case, i like to stay with the water, at least a little bit. Just gives me a slight piece of mind since I dont have the largest intercooler you can get (who knows, i might not really need the water, but the car runs strong, so its staying).

Ill take the safe approach and lower the timing, maybe just 2 degree's and start with a 35shot.

ttg35fort

iTrader: (2)

That is very wise.

I think you said that you have a means for detecting knock. To give added margin of safety, it might be good to back the timing down even a little bit more and then slowly inch it up as you monitor for knock. No harm in that, other than a little bit of extra time tuning.

EDIT: I think Sharif has tuned at least one car (Mike's last build) both with C16 and meth injection. It would be realy cool if he were to chime in here and share his experiences...

streetzlegend

iTrader: (2)

Yea I dont mind the extra time tuning, I do it myself so its not like i have to be paying a tuner. The ignition device I have has a gauge which shows you if there is any timing being pulled due to knock, and how much timing was pulled. Thats how I have been able to get 21degree's in timing with no knock by tuning with that method. as soon as I see as much as 1 degree being pulled, I know the timing is too close to the limit. So I tune so the device dosnt show me any retard at all.

rcdash

iTrader: (18)

I have attached an article that covers some basics and supports the claim that injecting a 50/50 W/M mix increases octane rating by 25% over pump gas (93 * 1.25 = 116). I don't have real data to corroborate this claim (yet).

Straight methanol has an AKI of 119. At 20%, that would be .2 * 119 + .8 * 93 = ~98 octane. Of course, octane rating only speaks to detonation under pressure (relative to octane as a fuel) whereas methanol adds cooling to the mix and the increased latent heat of vaporization decreases the predisposition to knock also. Water even more so. If you're not knock limited, maximum performance will be had with a fuel (methanol) over water. If you are knock limited (for whatever reason, high compression, no IC, etc), increasing amounts of water will allow for more power.

ttg35fort

iTrader: (2)

^^^

Nice find Raj!

ttg35fort

iTrader: (2)

Here are the relevant charts from the NACA report I mentioned. It compares having no injection to injection with water, a 70/30 meth/water mixture, and a solution containing 30% amonia:






Looking at the top chart, at an intake temperature of 250 deg. F, water looks pretty good and actually outperforms a 70/30 meth/water ratio under lean conditions (a 0.65 FAR is an AFR of 15.4). Of course we never run that lean. At the AFR's that we run, a 70/30 meth/water ratio allowed about 25% higher intake air pressure in comparison to straight water before knock became an issue (the report uses the term "knock limited performance").

Now, look at the second chart, at an intake temperature of 150 deg. F. The effectiveness of water has dropped significantly. Here, a 70/30 meth/water ratio allowed for about 60% greater inlet air pressure as compared to straight water. This is because the reduction of intake air temperature is less critical as compared to 250 deg. F.

Keep in mind that our intake air temperatures are significantly lower, however. In the thread to which I posted the link, on a 70 deg. day Sharif measured Mike's intake air temperature to be 81 deg. F. If you extrapolate the data from the two charts, it appears that the gap in performance between the 70/30 meth/water mixture and straight water will grow even larger at the intake air temperatures we will normally see when using a good intercooler. Since our intercoolers are dropping our intake air temperatures so much already, the gains from using water to cool the intake charge are marginalized.

Since water is losing its effectiveness as the temperature drops, I speculate that the optimum percentage of water in the meth/water solution also will drop (i.e., significantly less than 30%). Again, this correlates with the little bit of testing that has actually been performed with our cars. As noted, such testing indicated that straight methanol outperformed a 50/50 meth/water ratio. Perhaps the optimum ratio is around 90/10, it's hard to tell.

It would be great if those of you who have actually compared straight meth to a 50/50 meth/water mix would chime in. Specifically, fill us in on the general differences in performance that you saw between the two.

EDIT: I will make one more SWAG here. I would venture to say that a 50/50 meth/water mix at fow rate of a 20% of the fuel flow rate probably is as good as C16 when an intercooler is NOT used, but this probably is not the case for our intercooled cars. Since an intercooler is doing much of the job at cooling the intake air charge, C16 in our intercooled cars is somewhat analygous to using C16 with water injection in a non-intercooled FI setup. So, although a 50/50 mix certainly will get us gains over pump gas, I don't think for us these gains will be as great as using C16. I could be wrong, though. Again, some of you tuners have already played with this, so your input would be greatly appreciated. Sharif? Hal? Sam? Roger?

Japtrix/HP Logic, when they were together, already did the comparison of straight meth to the 50/50 ratio, and Roger was the first person to tell me straight meth works better, but I don't know if they have done a direct comparison between a 50/50 mix and C16. I'll call him and ask.

Hydrazine

iTrader: (53)

Raj and TTg35fort,

Great findings! That's actually useful information.

rcdash

iTrader: (18)

Thanks Tony.

Terry, I believe your suppositions are correct. Water and methanol have different properties that play more of a helpful role depending on the circumstances. With that in mind, the other variables such as EGT, cylinder temps, compression ratio and fuel also make extrapolation of the NACA data to our platforms a bit more complicated. Even on our platform, a stock motor vs a high compression NA build vs. a low compression FI build may each benefit optimally from different W/M mixes.

I don't think any of the pro tuners (on the forums anyway) have free time for academic pursuits.

Hydrazine

iTrader: (53)

Academic pursuits is where the good stuff is. But yes, you are probably right about that.

ttg35fort

iTrader: (2)

I agree.

I meant information that they already have. I called Japtrix and spoke to John (Roger was tied up on a motor build). It also is John's understanding that straight meth works better than a 50/50 ratio for intercooled cars, but he was not involved in the actual testing when it was done. It was either Jack or Roger running the dyno for that one (Jack is now with HP Logic). John also indicated that he beleives that C16 outperforms meth injection on our cars. If I remember correctly, I think Sam also indicated to me that C16 works better than meth injection. It would be nice to have these statements come straight from those who actually did the tuning/testing, though.

Jack, if you are keeping up on the forum, did you do that testing? What were your results?

djamps

iTrader: (1)

Sorry if it's a dumb question. But what would the affect of 100% water be? Is it even possible?

ttg35fort

iTrader: (2)

100% water injection is possible, is well proven, and will certainly help. As the data shows, it is not as effective as a meth/water mix (nor straight meth), but it is better than no injection at all and is a relatively simple way to stave off detonation, thereby allowing you to crank up the boost a bit. Also, there would be no need to mess with buying methonal, although I would recommend using distilled water.

George at GTM runs straight water injection and reached over 700 whp on pump gas. If I remember correctly, he may have a 4.2L motor, but my memory is not infalible. I think he actually prefers straight water over both straight meth and a meth/water mix.

In my opinion, if you can reach your hp goals on water, then that is what I would recommend. It's pretty easy to get hold of distilled water in a pinch (every grocery store I have been to carries it), and it's cheap. If you are in a real bind and the stores are closed, you can use tap water, just don't do that all the time. You don't want deposits building up in the system.

EDIT: Even though Raj and I sometimes debate about the merits of straight meth vs. a 50/50 meth water ratio, this really is more of an academic discussion. If you can reach your hp goal with water, then use it. If you can't, then try a 50/50 meth/water mix. In my opinion, only if I could not comfortably reach my hp goals with a 50/50 meth/water mix would I move to straight meth. It is much cheaper to run meth that is diluted down with 50% water than to run straight meth.

When my motor for my new build finally arrives and we get it tuned, I am going to do a tune with water injection to see how far that will get me. If it gets me to 750 whp (not likely, but not out of the realm of possibilty), then I may stop with that. If it does not, I'll have one map for water injection and one map for a 50/50 meth/water mix if that gets me to 750 whp. If the 50/50 mix does not get me to 750 whp, then the second injection map will be based on straight meth injection. I'm confident that the 4.0L motor (which has ceramic coating on the pistons, valves, combustion chambers and ports) will get me to 750 whp with 93 octane and one of the injection solutions I have discussed.

streetzlegend

iTrader: (2)

The information and documentation posted above by both ttg35fort and rcdash are awesome and thank you guys for contributing to my thread, I always find this topic very interesting and there are lots of debates.

I really dont have any experience as far as testing different mixtures, but based on what I have researched and specially what has been posted above, this statement to me is the key as whether to run water or not:

" If you're not knock limited, maximum performance will be had with a fuel (methanol) over water. If you are knock limited (for whatever reason, high compression, no IC, etc), increasing amounts of water will allow for more power."

Which like terry posted, NACA obtained better results from more methanol and less water as intake temperatures went down. So it all comes down to whether that intake air temperatures are low or not. I live in Miami and on an average temperatures are in the 90's (feels like 100), which is why I believe in my particular case it would be more beneficial to leave a little bit of water in my mixture considering I dont have a name brand intercooler, just a regular ebay core; although it does the job I am positive my temperatures dont drop as low as known and proven brand intercooler. (I wonder if my turbo being rear mounted my temp's are infact low enough, but thats another topic for the STS guys)

ttg35fort

iTrader: (2)

^^^^

streetzlegend, if you have a hp goal, try water first. If it gets you there, great. If not, try a 50/50 mix. If that still does not get you there, then try straight meth.

If you don't have a hp goal, but just want the most hp you can get, my hunch is that straight meth will work better than a 50/50 mix. The optimum solution might be somewhere in between. I have heard of some people using a 75/25 meth/water ratio, so that would be interesting to try. If you are doing your own tuning, have a good knock detector, and want to spend some time, it would be really, really cool if you could try a variety of ratios and post your results in the forum. That would be really appreciated and would greatly help to shed further light on the subject.