Pre-compressor injection test results

[endeffect0]

here is a question that might actuly be possible to answer. what is the actual flow rate of the nozzles used in the test at 250psi vs the 150psi that they were rated at.

all this talk about psi increase. I think we are missing something, if we are dealing with a turbo system that has a WG attempting to regulate it to a preset amount of boost. -Any witnessed increase of boost would have to be in excess of what the system was able to regulate. so unless you are running with no WG or with is completely shut, any psi increase would only really give us a guess at the increase in CFM or change in compressor map.

What i really want to see is some one measuring the CFM or lbs/min of air the engine is taking in vs a given rpm. if we had a good graph of that we would be able to accurately tell if we are extending the compressor map and or spooling the turbo sooner.

 

[forcefed86]

Found this today, pretty interesting.

Waterinjection :: View topic - Pre Turbo Injection - How Much and When to Inject

 

[dsm-onster]

That thread is precisely why I stated this:

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 .

There's an optimum amount to inject for your particular situation. Taking the post intercooler info off the data charts, you see that the mid range of nozzle flows do better. And starting the injection earlier does better.

See below. It's hard to decipher this graph. But look at the .5 nozzle results. That had output the lowest instantanious difference (spread in the two graphs) between the dark blue (intake temps) and magenta (compressor outlet temps).

The .9 jet looks lower over all but the intake temps (pre injection) are also lower. You're taking the heat out of the aircharge through the compressor tips, but putting it right onto the intercooler to heat up the charge again. Throttle plate temps are best with .6 and .7 nozzle. Apparently, there is enough post-intercooler piping and to atomize the water again.

The same transference at the intercooler applies with pre intercooler injection. If the water is already cold (injected post compressor), you push back heat soak. There's several testamonies in these forums alone. Click.

With the below chart you really see how pre turbo injection affects post intercooler temps too

 

[forcefed86]

That thread is precisely why I stated this:



There's an optimum amount to inject for your particular situation. Taking the post intercooler info off the data charts, you see that the mid range of nozzle flows do better. And starting the injection earlier does better.

See below. It's hard to decipher this graph. But look at the .5 nozzle results. That had output the lowest instantanious difference (spread in the two graphs) between the dark blue (intake temps) and magenta (compressor outlet temps).

The .9 jet looks lower over all but the intake temps (pre injection) are also lower. You're taking the heat out of the aircharge through the compressor tips, but putting it right onto the intercooler to heat up the charge again. Throttle plate temps are best with .6 and .7 nozzle. Apparently, there is enough post-intercooler piping and to atomize the water again.

The same transference at the intercooler applies with pre intercooler injection. If the water is already cold (injected post compressor), you push back heat soak. There's several testamonies in these forums alone.

With the below chart you really see how pre turbo injection affects post intercooler temps too

Agreed!

But….

Would it justify the extra weight/money of running two separate systems? Would it justify extra wear on the turbo? (if such a thing is a problem) I’ve also read that intake temps lower than 68*F actually cause a performance decrease. (Yes turbo cars as well). Depending on the IC and volume of air your pushing this is yet another thing to consider.

 

[autotalon]

I think the next step would be to crank the boost up to 30ish psi and see where the temps are by comparison. If temps can be maintained, then the extra boost is where you will gain more power.

 

[Car Cannibal]

Thanks for doing the test, this is an extra piece to the puzzle.

I'm not too surprised the Washer Fluid was best at that huge nozzle size but it had Glycol in it and that's a bit of a no no injection wise.

The crazy thing about the 7gph Washer data is it not only had the most psi but the lowest temp out, wow. It doesn't appear that you could get any more psi out of the compressor considering that data.

Curious though if there is such a thing as a sweet spot, a 2 and a 4gph could've killed those questions.

But none the less, very nice.

At least we have more proof to stop those who say this doesn't work right?

 

[Kevin Jewer]

Awesome work guys, this test is relevant to my interests...

all this talk about psi increase. I think we are missing something, if we are dealing with a turbo system that has a WG attempting to regulate it to a preset amount of boost. -Any witnessed increase of boost would have to be in excess of what the system was able to regulate. so unless you are running with no WG or with is completely shut, any psi increase would only really give us a guess at the increase in CFM or change in compressor map.

I was thinking the same thing, but if the effect of the wet compression is to reduce drive pressure, boost regulation will change on the same wastegate spring, so this could still be a sign that drive pressure went down.

IMO, the most telling bit of info would be drive pressure. IAT is important, but post turbo injection also does that. Wet compression has the added benefit of reducing turbine drive power requirement, which is the biggest gain IMO. In the case of compound turbos add the reduced drive pressure to much greater efficiency of the overall system and it becomes a no brainer. Then multiply it by two turbos and you understand the source of my boner.

What I plan to try on my setup is preturbo injection on the secondary at say 5 psi and up, and then bring in a second stage for preturbo injection at the primary also set to come on above something like 5 psi when it spools. Same pump, using solenoids to turn each nozzle on when the boost switches are made. I'll also try starting the injection on the secondary at WOT instead of boost to see how much it drops spool up rpm. Keeping IATs down on the transbrake will be beneficial as well, currently my crappy IC is practically heat soaked before I even leave the line. I'm dying to see the change (if any) in drive pressure, which I log. What I'm also curious to see is if preturbo injection on both turbos can keep temps low enough to run without the IC (perhaps on alky based fuel). It's possible doing some bench math. I have everything to convert the car to an alchohol based main fuel and just run a 5th/6th injector instead of a separate injection system, but I want to see how far I can push it on gas first.

Thanks for the tests, I need the motivation at this time of year.

 

[forcefed86]

Awesome work guys, this test is relevant to my interests...




I was thinking the same thing, but if the effect of the wet compression is to reduce drive pressure, boost regulation will change on the same wastegate spring, so this could still be a sign that drive pressure went down.

IMO, the most telling bit of info would be drive pressure. IAT is important, but post turbo injection also does that. Wet compression has the added benefit of reducing turbine drive power requirement, which is the biggest gain IMO. In the case of compound turbos add the reduced drive pressure to much greater efficiency of the overall system and it becomes a no brainer. Then multiply it by two turbos and you understand the source of my boner.

What I plan to try on my setup is preturbo injection on the secondary at say 5 psi and up, and then bring in a second stage for preturbo injection at the primary also set to come on above something like 5 psi when it spools. Same pump, using solenoids to turn each nozzle on when the boost switches are made. I'll also try starting the injection on the secondary at WOT instead of boost to see how much it drops spool up rpm. Keeping IATs down on the transbrake will be beneficial as well, currently my crappy IC is practically heat soaked before I even leave the line. I'm dying to see the change (if any) in drive pressure, which I log. What I'm also curious to see is if preturbo injection on both turbos can keep temps low enough to run without the IC (perhaps on alky based fuel). It's possible doing some bench math. I have everything to convert the car to an alchohol based main fuel and just run a 5th/6th injector instead of a separate injection system, but I want to see how far I can push it on gas first.

Thanks for the tests, I need the motivation at this time of year.

IMHO you'd be best off with the 2 pre turbo nozzles coming on as soon as possible at 100% with a 50/50 water methmix.(wot switch) My spool up speeds would increase each time i lowered my pre turn on point. Switch is as low as it goes now. (around 5psi.) I'm thinking a WOT switch and solenoid for the post nozzle (around 12psi) will be my next addition to the kit.

Then use a second system with 100% meth post starting progressively at say 10psi. Gains will be huge in your case. Even on e85, I wouldn't remove that IC. You'll need all the help you can get.

 

[Sp1kE]

That is absolutely great.
Thank you!

But as posted, that seemed to be alot of water "sloshing" around.
Any chance of trying a inbetween nozzle?
Say maybe a 3 and a 5?... if they even exist.

Once again, thanks!

 

[99gst_racer]

Glad to hear you're trying pre-compressor injection too, Kevin. I'm already looking forward to seeing your results with it.

At this point, I think I'm going to try running a nozzle pre-compressor on the primary turbo (16G) and then another, larger nozzle about 12" before my throtle body. And I'm going to try running straight meth. As much as I wanted to run windshield washer fluid, I really think there is quite a bit to be gained by injecting after the intercooler as well, and I'd rather be using methanol if I'm spraying post-IC.

We might try to get the engine back on the dyno for more testing in a month or so. If and when that happens, we'll test a few other nozzle sizes (probably a 3 and 5). We also want to test using large amounts of methanol and no intercooler. As well as using an EFI injector for pre-compressor injection.

 

[forcefed86]

Glad to hear you're trying pre-compressor injection too, Kevin. I'm already looking forward to seeing your results with it.

At this point, I think I'm going to try running a nozzle pre-compressor on the primary turbo (16G) and then another, larger nozzle about 12" before my throtle body. And I'm going to try running straight meth. As much as I wanted to run windshield washer fluid, I really think there is quite a bit to be gained by injecting after the intercooler as well, and I'd rather be using methanol if I'm spraying post-IC.

We might try to get the engine back on the dyno for more testing in a month or so. If and when that happens, we'll test a few other nozzle sizes (probably a 3 and 5). We also want to test using large amounts of methanol and no intercooler. As well as using an EFI injector for pre-compressor injection.

Your not running between stages? I'd think this is where you'd most benefit? Inlet temps will definatly be the highest at that point. Not like it's a lot of trouble to run one more nozzle!

 

[99gst_racer]

Your not running between stages? I’d think this is where you’d most benefit? Inlet temps will definatly be the highest at that point. Not like it's a lot of trouble to run one more nozzle!

Injecting into the inlet of the primary turbo will be between stages, as the primary turbo recieves the output of the secondary turbo.

I had considered injecting into both inlets, but I don't think I'll need to.

 

[forcefed86]

Injecting into the inlet of the primary turbo will be between stages, as the primary turbo recieves the output of the secondary turbo.

I had considered injecting into both inlets, but I don't think I'll need to.

Gotcha, not sure why my brain always thinks compound systems use the small unit to feed the big unit....

I'm in the same boat with the methanol. I just can't justify 2 seperate kits on a daily driver. 100%meth for me!

I bit the bullet and started the e85 fuel system on the other car. I think I'll just do pre injection w/ WOT switch, 50/50, and 4 .75 nozzles on it. Knock shouldn't be a problem. It is Intercooled as well. I'll make sure to post up the results.

 

[forcefed86]

I was checking this out again today....

If you all do do this again, make sure to put some sort of pressure gauge on the system. Flow data without pressure is kinda useless. Also did the HP numbers vary much from nozzle to nozzle?

 

[99gst_racer]

If you all do do this again, make sure to put some sort of pressure gauge on the system. Flow data without pressure is kinda useless.

Will do.

Also did the HP numbers vary much from nozzle to nozzle?

No, we weren't really set-up to see HP increases from this test that we did. The engine was already running on 33% methanol, so it wasn't the greatest test subject to gauge HP gains from pre-compressor injection.

I should have before and after dyno graphs from my compound set-up though. Hopefully not too much longer.