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

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Old 07-11-2014, 02:15 PM   #1
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Default Lets talk IAT's and methanol injection.

I know my car does not have a miata engine but the principle is the same. I am wanting to know what people think is an acceptable IAT to see in boost. I run 100% methanol and use two nozzles spaced about 6" apart and they are rated at 10 gph each so a total of 20gph. Below is what I am dealing with at the moment.

I want to know what IAT's people see in say a 4th gear pull

What IAT's you see when you do a launch with 1-4 gears

IAT vs ambient.

What IAT do you want to idealy see.





I have a turbo 2jz currently running a Borg Warner S366 on 20psi.
My methanol is triggered by my AEM on a engine load map but comes on around 7 psi.

I have a homebrew methanol kit. Its a devils own pump 1 gal tank inline check valve with two 10 gph nozzles.

On a single 4th gear pull at 85 deg outside I will see an IAT around 120Deg

On a launch with 1-4 or 1-5 pull I have seen as high as 165 deg.

On a 2-half of 5 pull in 65 deg temps I only see about 105deg.



I am wondering what others see and what they find acceptable. I have read about 50 different threads all all sorts of forums and it seems to me the 150 deg mark is what everyone whats to stay under.
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Old 07-21-2014, 11:34 AM   #2
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So far 105 people have looked at this and no responses. Your telling me no one on this site has any input on IAT numbers on what they see what they would like to see or even just badgering and telling me to run an inter cooler I am disappointed. Still interested in any info anyone has.
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Old 07-21-2014, 11:37 AM   #3
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are you measuring the temps after the meth?
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Old 07-21-2014, 12:17 PM   #4
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Yes temps after the methanol.
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Old 07-21-2014, 01:23 PM   #5
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IAT's shouldn't be more than ~30-40* higher than ambient. Since it's rarely ever 120f outside 160 IAT's are a little alarming. If my car was hitting 160+ I would definitely change the way my air was being cooled.

We had a discussion a couple years ago about running straight meth but that was in low boost. I honestly wouldn't really consider it at higher power levels. I can not tell you to get an intercooler. I can also tell you to vroom vroom less to fix your iat.
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Old 07-21-2014, 02:16 PM   #6
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Run half water if you want to control IAT.
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Old 07-21-2014, 03:21 PM   #7
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The point of water injection is to introduce liquid droplets into the combustion chamber that change phase during combustion. This significantly reduces the risk of detonation even with high IATs. Originally, alcohol was mixed in because this stuff was used in aircraft and needed to resist freezing.

Water injection alone does almost nothing to reduce IATs. It is really difficult for the water to phase change naturally (evaporate) during the short period of time it is in the intake tract. And with pressurization, you may be at a point where it can't naturally vaporize due to psychrometric effects. Anybody ever drain water from an air compressor?

Alcohol will evaporate more quickly than water, but removes a lot less heat (about half) compared to water when it changes phase.

The hype about "chemical intercooling" is BS. To really cool your intake air, you need a heat exchanger.

All of the above science is further confirmed by a lot of personal experience on my silver car.

Last edited by hornetball; 07-21-2014 at 04:39 PM.
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Old 07-21-2014, 05:08 PM   #8
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I've been running a home brew water injection setup on my car in a couple different variations over the past two years.

The highest I've ever seen my temps on a 1-4 pull are about 126F @ 20psi EVO3 16G turbo. Ambient temps that day were probably 80F. And that was with my current pre-turbo setup. 100psi pump and I think a 5gph nozzle.

Edit. And that's with a shitty tube/fin eBay intercooler 28x6x3 or something.
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Old 07-21-2014, 05:16 PM   #9
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I read OP when it as first posted and didnt reply. My only thought was "Why even care about IAT?"

Use water injection to prevent knock. The water isnt very volatile but it will still evaporate in that lava-hot-air and reduce IATs a bit, but mostly it will be going into the chamber and preventing knock. That is what matters.

People get fixated on IAT. They use a meth mixes and see lower IATs compared to straight water due to the volatility of the meth. They think its better because the IATs are lower, but yet again, who gives a ****? Is it worth the corrosion and the funky fuel tables?

Water with a dash of alcohol (to kill algae) is the way to go IMO.
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Old 07-21-2014, 05:20 PM   #10
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I could be wrong, but I would guess that even the alcohol won't have enough time in the intake tract to evaporate, at least not enough to seriously cool the intake charge. Both the water and meth prevent detonation in the combustion chamber, the water by soaking up heat and the meth by raising the octane (like E85 does). If you've got 2 IATs I'd love to see a before/after injection comparison.

If your intake tract is 1 cubic foot, and your S366 flows 600cfm, any drop of water/meth will therefore spend a tenth of a second (likely less) in the intake tract. This is also why I laugh at people who want less intake piping between turbo and IM because THROTTLE RESPONSE.
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Old 07-21-2014, 07:09 PM   #11
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Quote:
Originally Posted by slmhofy View Post
Edit. And that's with a shitty tube/fin eBay intercooler 28x6x3 or something.
Which is why your IAT is that low. Although with pre-turbo injection and a lot of alcohol, you'll be seeing more cooling from the WI than most.

On hot days in TX when I really get on it, I've seen 200F in the data logs (WI only, no IC, 10-11 psi). The water protects the engine. But running IATs that high sucks for power. An IC will be going into the Silver car soon enough.
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Old 07-21-2014, 09:39 PM   #12
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yeah if you aint knockin who cares what your iat is. nobody cares about losing power.
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Old 07-22-2014, 10:11 AM   #13
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I dont see any knock witch I know is good and I am currently running 100% methanol and will be going to a water methanol mix. I know the methanol cools the intake charge a good bit. I have three IAT sensors in total on my car. On on the elbow exiting the turbo one about 4" from the throttle body and one about 2" from the throttle body. The one closest to the throttle body is for the computer the other two are for a gauge on my dash. I have seen temps as high as 235* coming out of the turbo and with temps that high I was seeing 165* at the throttle body pretty impressive cooling after the methanol. I dont see any knock but I know cooler iat's make more power. I will mix some water and see what it does. I think I will start with a 80/20 or 60/40 methanol/water mix and see what it does.


As far as short intercooler piping I have no intercooler more for lack of space and places to run piping more than anything else I could really care less about throttle response my turbo starts to light off around 3500rpm and comes in like a train anything below that I have an engine that makes 200hp na so it still moves the little miata right along. I will do some experimenting and get back to you all.
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Old 07-22-2014, 11:42 AM   #14
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I ran a water injection kit on my miata a long time ago, I had a intercooler but on 105 deg days I notice my ait were going very high over 180* I added the injection system with 60w/40a mix and it brought it down to 120* ait. Less knock and felt more power.
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Old 10-21-2014, 11:32 AM   #15
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Quote:
Originally Posted by Savington View Post
Run half water if you want to control IAT.
i agree my buddy does that
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