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Methanol/Water Injection Place to talk about meth/water injection.

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Old 07-13-2011, 12:59 AM   #21
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Yup I got it last go around but that clears even more up. I don't want to run %100 meth on my street car 50/50 is a pretty good compromise nor do I want 2 systems! Hehe. Thanks for the information man I appreciate it. Any particular books you have been reading or forums? I would love to be more versed. I am actually very intersted in removing my ic. I am less conservative I think then you I run 15psi on my stock 1.6 and I am going to give 20psi a shot.

Also can you speak on the merit of phase change pre tb. Seems like most ecu's run a 3d map based on air temp sensor at the tb. Thoughts?
Well, I have a good handle on the science because I have a BSAE, an MSAE and am a registered PE in Mechanical Engineering (thermo is considered part of mechanical engineering). Plus, my BSAE is from Annapolis. I'm sure you can imagine that thermodynamic cycles involving water were somewhat emphasized there.

However, the science is just a starting point. Actual observations on the car count for a whole lot, it's just that sometimes you need the science background for proper interpretation. I will tell you that I was very surprised by the results of my WI installation. I fully expected to have much more phase change in the intake tract than I do. Your temperature results confirm mine . . . for the most part water doesn't change phase until the combustion stroke starts.

There are some good NACA reports on water injection on the internet. Also, search for Harry Ricardo. He is considered the father of water injection. RB Racing also has good info on their website. See http://www.rbracing-rsr.com/waterinjection.html.

BTW, if I were going for 20psi (or, in Fae's case, "ALL OF IT"), I would consider an intercooler mandatory. The higher your boost, the better the intercooler works because your charge temperature is higher (greater "delta T"). That's one disadvantage of pre-turbo injection, you reduce the effectiveness of the intercooler.

Thermodynamically, if you get cooling through liquid phase change prior to the throttle body, it is equivalent to the effect of an intercooler. It lowers temps. That's actually not 100% true because the phase change also creates more gas, which helps keep pressure up. So, it's a bit better than the intercooler from that standpoint.

One thing to keep in mind about intake temperature sensors is that they do not have immediate response. In addition, you have to be careful with their mounting so they are seeing the intake temperature rather than engine bay temperature. There are plenty of horror stories out there about heat-soaked intake temperature sensors.
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Old 07-13-2011, 01:17 AM   #22
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One thing to keep in mind about intake temperature sensors is that they do not have immediate response.
???? Why not? Flow restriction be damned my ATS sensor bulb sits in the airstream and my logs show pretty snappy response. About 1*F-ish for each psi. BTW I have a small intercooler.
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Old 07-13-2011, 01:18 AM   #23
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Results: I have NOT been able to get close to approaching MBT under 6000 RPM over 6psi. I've tried spraying a shitton of water at lower boost levels and RPM levels but I am I see occasional big knock. Interestingly, most of the time, the big knock occurs when I WOT in third gear when I'm at or above boost threshold. My WI system has a flow gauge and I can see flow occurring instantly, but I still get some knock. On big long 4th/5th/6th gear pulls, there is no knock.

Any ideas about this?

I will be switching over to 100% meth soon and have two WI tubing splitters in the mail. The plan is to add two more nozzles to the system, one at IC outlet before the ATS, and one in the air filter for pre-compressor injection.
The 4th/5th/6th gear pulls tell me that you WI is doing the job. I think you are beating it to the punch when you slam WOT in 3rd. Note that once detonation starts, you have to back way off to stop the detonation before getting on it again. I think what you need is a WI system that reads your mind.

I also think you'll be more likely to have detonation at 100%meth than with a 50/50 mix (assuming that the meth is still performing a WI function and not being used as your main fuel). At least that's what most of the references say and thermodynamically that would make sense.

Most of the NACA references talk about liquid to air ratios, where the liquid is the fuel + WI chemical. Don't forget that you can also go richer if you've reached the limit for WI.

16-25psig? What happened to "ALL OF IT"?
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Old 07-13-2011, 01:27 AM   #24
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???? Why not? Flow restriction be damned my ATS sensor bulb sits in the airstream and my logs show pretty snappy response. About 1*F-ish for each psi. BTW I have a small intercooler.
Well, most temp sensors have ~1-2 seconds of lag (depends on design). So, if you're relying on the temp sensor to trigger some sort of save the engine algorithm, that could be a long time.

That lag would be a measure of how long it takes to reflect a new steady-state condition. Unfortunately, you can't really judge that as you go through an acceleration. Lag and responsiveness are different. The sensor can be responding as you expect, but still be several seconds behind reality. The best place to judge in the logs is to look at the point where you settle into a steady-state cruise.
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Old 07-13-2011, 01:50 AM   #25
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The 4th/5th/6th gear pulls tell me that you WI is doing the job. I think you are beating it to the punch when you slam WOT in 3rd. Note that once detonation starts, you have to back way off to stop the detonation before getting on it again. I think what you need is a WI system that reads your mind.

I also think you'll be more likely to have detonation at 100%meth than with a 50/50 mix (assuming that the meth is still performing a WI function and not being used as your main fuel). At least that's what most of the references say and thermodynamically that would make sense.

Most of the NACA references talk about liquid to air ratios, where the liquid is the fuel + WI chemical. Don't forget that you can also go richer if you've reached the limit for WI.

16-25psig? What happened to "ALL OF IT"?

Thanks for your feedback, it's very helpful.

Hmm I do have a 3D map with boost/rpm/duty to control WI flow. And a 3D map to trim fuel. I could set it up to flow a lot more in low boost rows and run richer on the fuel. Right now it rams from 14:[email protected] to 12:[email protected] so maybe as you said, it detonates after the throttle snaps open because of the on the transition. I think you might be right that the WI provides overall cooling of the combustion chamber itself and brings the temperature down slowly.

I think I'll adjust my fueling trim map to run 12.5:[email protected] on upwards (which means I'd actually be adding fuel on top of my base fuel map until I reach 9psi). I'll spray enough mixture on top of that 12.5:1 fuel ratio to reach an 11.5:1 ratio. After that's stable, I'll try adding more timing again and see how the knock logs look. Maybe the benefit of additional timing and spool will overcome the power loss from running rich at low psi.

I'm not running more than 25psi because I blow the welds on the intake I mean I blow out the dipstick because I need more crankcase ventilation. That's ALL OF IT for now...

Regarding methanol, I'd like to spray 20% meth to fuel. That will be a lot of meth and I will need a bigger tank. :( Mixture will actually be 95% meth, 5% water, and 1% extra for meth happy smell additive.
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Old 07-14-2011, 01:45 AM   #26
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Checking in.

So I retuned my WI fuel trim map today for 11.5:1ish AFR from 4psi to 12psi and left my WI timing trim map the same. It actually ******* worked and I did not have knock. I was expecting it to feel doggy and slow but it actually spools quickly. Timing FTW.
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Old 07-29-2011, 03:33 AM   #27
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its so nice to here people talk about this in a good way.
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