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Pre-compressor injection test results

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99gst_racer

Moderator
11,976
1,542
Apr 5, 2003
Coloma, Michigan
So, Tyler (turbo23) and myself finally got around to testing pre-compressor injection this past weekend and it went well. This was basically just a test to compare AIT's using various fluids and nozzle sizes.

Set-up specifics: The engine on the dyno was a relatively stock 2.3L Ford engine out of a late 80's Thunderbird. The turbo was a Holset HX-35 running at 22-23 psi. The engine was producing roughly 450HP and 389 ft/lb torque. The nozzles were all mounted in the same location throughout the tests - about 4" away from the compressor nut. The pump used was the Devil's Own 250 psi pump.

Here are the results that we gathered:

No injection;
Before IC temp increase - 29 deg/sec
After IC temp increase - 4 deg/sec
Peak boost 22.09 PSI
------------------------------------------------------
1GPH 50/50 mix;
Before IC temp increase - 19.1 deg/sec
After IC temp increase - 3.0 deg/sec
Peak boost 22.88 PSI

1GPH H20;
Before ic temp increase - 24.2 deg/sec
After IC temp increase - 3.4 deg/sec
Peak boost 23.21 PSI

1GPH Washer Solvent;
Before IC temp increase - 24 deg/sec
After IC temp increase - 3 deg/sec
Peak boost 22.96 PSI

---------------------------------------------------
7GPH 50/50 mix;
Before IC temp increase - 16.9 deg/sec
After IC temp increase - 4.5 deg/sec
Peak boost 22.96 PSI

7GPH Water;
Before IC temp increase - 13 deg/sec
After IC temp increase - 4.7 deg/sec <---no IC fan - OOPS!
Peak boost 22.92 PSI

7GPH Methanol;
Before IC temp increase - 19.3 deg/sec
After IC temp increase - 3.5 deg/sec
Peak boost 23.0 PSI

7GPH Washer Solvent;
Before IC temp increase - 11 deg/sec
After IC temp increase - 3.8 deg/sec
Peak boost 23.3 PSI
-----------------------------------------------------------
10GPH Methanol;
Before IC temp increase - 14.3 deg/sec
After IC temp increase - 3.2 deg/sec
Peak boost 23.05 PSI

10GPH Washer Solvent
Before IC temp increase - 11.2 deg/sec
After IC temp increase - 3.4 deg/sec
Peak boost 22.71 PSI


So, surprisingly enough, our best results were using the 7GPH nozzle and injecting the windshield washer solvent. The "after IC" temp measurements are probably not too important as they only show that the intercooler was doing its job. We did remove the intercooler after the testing and found a small puddle of water right after the intercooler. It was pure water, but it was a very small amount (not enough to cause worry).

Big thanks to Tyler @ Street & Strip for donating his time, his shop, and his knowledge for this test. :)
 
We welded a small 1/8" NPT steel extension in the intake tube to act as a nozzle holder. This way we were injecting directly into the compressor rather than into a wall of the intake pipe.

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A view from down the throat of the intake tube:

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And here's a shot of the engine on the dyno:

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I realize Paul, that this is a very good amount of time and labor you spent there.
How the spraying is activated??? Boost or RPM or both??? Are you using boost solenoid? And the videos are really cool.......
 
I realize Paul, that this is a very good amount of time and labor you spent there.
How the spraying is activated??? Boost or RPM or both??? Are you using boost solenoid? And the videos are really cool.......
Injection was activated via Megasquirt at 6 PSI.

Great test. So how about HP increases?
The engine that we were using was already partially running on methanol, so we weren't seeing any major HP gains. The engine was running 4 injectors with pump gas, and 2 more injectors running methanol and mounted right before the throtte body.

But, it's safe to assume that a ~90*F air charge temp drop will be sufficient for power gains.

I should be able to get real world HP gains from running this same set-up on my 2G. I'm hoping to be on the dyno with it sometime on April.
 
WOW! Thanx for putting up the results! Pure water came in at a close second. Still better than alot more methanol.

What brand washer solvent? Do you have the MSDS or know what percent meth/water?

. . . Videos are great!! :thumb:
 
washer solvent was Camco "ice cutter" -30* stuff

label says;
methyl alchol 67-56-1
propylene glycol 57-55-6

not sure how to break that into %s though
 
Very cool test. THANKS FOR THE DATA. we all have been looking for these kind of test and you actually went out and did the foot work. thank you. :hellyeah:


few questions about the test if i may.
how was boost controlled on this system, are we assuming the increase in boost where shown is defeating some kind of MBC or was the turbo run 'wide open'. If it was controlled where (roughly) in the compressor map was it running. did these gains come in the fat part of the map or were you seeing increases well off of the efficiency band.

i assume there was no way of measuring lbs/min of air flow on this rig, in lew of that are you going to share with us the dyno plots of the pulls? or maybe just to simplify, the non injected and a few of the more interesting ones.


awesome work guys!:applause::applause::applause:
 
I guess the big question is how much different will injecting before the turbo be from injecting after the turbo. I guess you get better atomization since the blades will "cut" the liquid but how much are we talking here? And how much less safe is it to continually pump fluid through the compressor compared to it being right before the intake? I guess those are some questions i have with the setup. Really, pumping before the IC makes up for the inefficiencies of the IC in general, whereas the purpose of meth is to lower the air temps going into the combustion chamber. Am i making sense?

BTW, that first video is so cool. Ive watched it 10 times now.
 
engine was gated with a tial v44 and 2 blue springs, with no MBC. Not quite sure where it is on the compressor map. as with mort speed density systems, there was now way to meassure #/min. The dyno charts all look about the same, by about i mean give or a take a couple hp and torque.
 
I guess the big question is how much different will injecting before the turbo be from injecting after the turbo. I guess you get better atomization since the blades will "cut" the liquid but how much are we talking here? And how much less safe is it to continually pump fluid through the compressor compared to it being right before the intake? I guess those are some questions i have with the setup. Really, pumping before the IC makes up for the inefficiencies of the IC in general, whereas the purpose of meth is to lower the air temps going into the combustion chamber. Am i making sense?

BTW, that first video is so cool. Ive watched it 10 times now.

Google: "wet compression". It's a fascinating subject. The major benefit of "wet compression" or pre-compressor water injection has been show to be in it's ability to alter the effective efficiency of the compressor. IOW, alters the compressor map. More efficient the compressor, the less energy is needed to make turbine work into boost.
 
Thats pretty cool. But, does it effect it enough to change the dynamics of the turbo? For instance, causing imbalance of the exhaust and intake pressure (ie. true compressor surge).

The was pulled from a paper from Caldwell Engineering

"The application of wet compression system should address the risks associated with spraying water into a CT inlet. The primary components of such risk included: (i) water distribution, (ii) degradation of compressor inlet duct materials and fouling of the compressor, (iii) compressor casing distortion, (iv) combustion dynamic pressure, and (v) control system integration."
 
IMO water wouldn't be an option. It doesn't flash as fast, especially when temps don't even reach the 200* mark, and it has a higher surface tension so its harder for the compressor wheel to "cut" through it, and it didn't cool as well.

With methonal, distribution isn't near as much of a concern as it is with water, and it will flash quicker at lower temps. Also, I have personally built several methonal engines with aluminum heads, and intake set ups. These engines had been run for years, and we have never seen an issue where parts needed to be replaced due to corrosion, but we would run gas through the engine if it were going to sit for more than a month.
 
IMO water wouldn't be an option, it doesn't flash as fast, espcially when temps don't eve reach the 200* mark, it has a higher surface tension so its harder for the compressor wheel to "cut" through it, and it didn't cool as well.

with methonal, distribution isn't near as much of a concern as it is with water, and it will flash quicker at lower temps. Also, I have personally built several methonal engines with aluminum heads,and intake set ups. these engines had been run for years, and we have never seen an issue where parts needed to be replaced due to corrosion, but we would run gas through the engine if it were going to sit for more than a month.

Thats good to know. I might try meth preturbo injection then.
 
IMO water wouldn't be an option. It doesn't flash as fast, especially when temps don't even reach the 200* mark, and it has a higher surface tension so its harder for the compressor wheel to "cut" through it, and it didn't cool as well.

With methonal, distribution isn't near as much of a concern as it is with water, and it will flash quicker at lower temps. Also, I have personally built several methonal engines with aluminum heads, and intake set ups. These engines had been run for years, and we have never seen an issue where parts needed to be replaced due to corrosion, but we would run gas through the engine if it were going to sit for more than a month.

But you can't argue with the results!!! Pure water cools nearly as well as a low percentage of meth in a mix which did best. And the more meth you add the worse it gets. Pure water at 7gph did less than the low percentage meth in the water. So I wonder if running a 5gph nozzle and running pure water would be optimum volume flow for water with his setup :hmm:. But I suppose a little meth in the mix makes for a cooler charge before sudden flash to vapor.

Both water and meth suddenly turn to gas at the exducer, and water has a higher heat of vaporization and takes more heat out once it DOES vaporize. The point of wet compression is the fact that the liquids instanty flash to a gas at the compressor exducer tips. So it just comes down to which one takes out more heat instantly, and water does by far, per it's heat of vaporization.

Slim to none who inject the water properly have ever reported compressor wear. However I do see a compressor with surge porting likely having more issue with this.

VETTE, you use water injection preturbo to encourage spool up and/or to extent the map so that higher flows are more efficient. You are far from having surge problems in the first place, if you're hotside is laggy and/or your compressor is pushed to it's limit.
 
But you can't argue with the results!!! Pure water cools nearly as well as a low percentage of meth in a mix which did best. And the more meth you add the worse it gets. Pure water at 7gph did less than the low percentage meth in the water. So I wonder if running a 5gph nozzle and running pure water would be optimum volume flow for water with his setup :hmm:. But I suppose a little meth in the mix makes for a cooler charge before sudden flash to vapor.

Both water and meth suddenly turn to gas at the exducer, and water has a higher heat of vaporization and takes more heat out once it DOES vaporize. The point of wet compression is the fact that the liquids instanty flash to a gas at the compressor exducer tips. So it just comes down to which one takes out more heat instantly, and water does by far, per it's heat of vaporization.

Slim to none who inject the water properly have ever reported compressor wear. However I do see a compressor with surge porting likely having more issue with this.

VETTE, you use water injection preturbo to encourage spool up and/or to extent the map so that higher flows are more efficient. You are far from having surge problems in the first place, if you're hotside is laggy and/or your compressor is pushed to it's limit.

True. I would like to see how much extended the map becomes after using preinjection. This is cool stuff.
 
It won't bend the fins on the turbo at all? I thought it was a really close tolerance that water would even get in the way. Wow. Guess I was informed wrong.
 
It won't bend the fins on the turbo at all? I thought it was a really close tolerance that water would even get in the way. Wow. Guess I was informed wrong.
Any fluid that comes out of these nozzles is a fog after 4" - even straight water (albeit a heavier, less atomized fog). And I feel that a properly injected fog won't cause any damage.

I'll see if I can get a video or two of one of the nozzles in action without being mounted.
 
Awesome!:hellyeah:

While you still have a willing test subject, throw some more nozzles on for us? I know the 7gph netted the best results but if you just look at peak boost numbers a 1gph nozzle of h20 was only .1 lower than the 7gph nozzle. 1-7-10 are to large of jumps IMO. (I know thats what was sent to you and your awesome for sharing with us all!)

I know I saw a full LB increase of boost on my p-68 turbo with 2gph straight meth @ 250psi. Maybe if your setup was actually in a vehicle and the IC was working better you'd see the full 1lb increase as well?

Makes me wonder if a 2-4 gph nozzles might hit more of a sweet spot. Suppose were grasping as straws here with most of the tests being close together. Still... There has to be a recipe for max efficiency out of X cfm turbo.

From reading over on the aquamist sight the British lads seem to think 2gph(@ the rated 100psi) of water per 500cfm of turbo is the correct ratio. Thats why I went with 2/.75 nozzles (@250psi) on my e316g setup.
 
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