Water injection before intercooler? good? bad?
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From: Norn Iron
One other benefit people wouldnt realise.
At least injecting pre-compressor, actual flow/pressure will remain a known. And this also ensures a good spray pattern because of consistent high pressure
When injecting into the boost pipes, this will actually be a variable.
Richard did a test showing how much flow and pressure drop when trying to inject large quantities of fluid into a high pressure area, and it was quite dramatic
Once some of the pumps were trying to feed say 2 moderate size nozzles, pressure dropped off dramatically. Combine that with boost pressure acting against the pump and you might see actual spray pressure down to 60-100psi range when you think it's upwards of 160psi
At least injecting pre-compressor, actual flow/pressure will remain a known. And this also ensures a good spray pattern because of consistent high pressure
When injecting into the boost pipes, this will actually be a variable.
Richard did a test showing how much flow and pressure drop when trying to inject large quantities of fluid into a high pressure area, and it was quite dramatic
Once some of the pumps were trying to feed say 2 moderate size nozzles, pressure dropped off dramatically. Combine that with boost pressure acting against the pump and you might see actual spray pressure down to 60-100psi range when you think it's upwards of 160psi
One other benefit people wouldnt realise.
At least injecting pre-compressor, actual flow/pressure will remain a known. And this also ensures a good spray pattern because of consistent high pressure
When injecting into the boost pipes, this will actually be a variable.
Richard did a test showing how much flow and pressure drop when trying to inject large quantities of fluid into a high pressure area, and it was quite dramatic
Once some of the pumps were trying to feed say 2 moderate size nozzles, pressure dropped off dramatically. Combine that with boost pressure acting against the pump and you might see actual spray pressure down to 60-100psi range when you think it's upwards of 160psi
At least injecting pre-compressor, actual flow/pressure will remain a known. And this also ensures a good spray pattern because of consistent high pressure
When injecting into the boost pipes, this will actually be a variable.
Richard did a test showing how much flow and pressure drop when trying to inject large quantities of fluid into a high pressure area, and it was quite dramatic
Once some of the pumps were trying to feed say 2 moderate size nozzles, pressure dropped off dramatically. Combine that with boost pressure acting against the pump and you might see actual spray pressure down to 60-100psi range when you think it's upwards of 160psi
One other benefit people wouldnt realise.
At least injecting pre-compressor, actual flow/pressure will remain a known. And this also ensures a good spray pattern because of consistent high pressure
When injecting into the boost pipes, this will actually be a variable.
Richard did a test showing how much flow and pressure drop when trying to inject large quantities of fluid into a high pressure area, and it was quite dramatic
Once some of the pumps were trying to feed say 2 moderate size nozzles, pressure dropped off dramatically. Combine that with boost pressure acting against the pump and you might see actual spray pressure down to 60-100psi range when you think it's upwards of 160psi
At least injecting pre-compressor, actual flow/pressure will remain a known. And this also ensures a good spray pattern because of consistent high pressure
When injecting into the boost pipes, this will actually be a variable.
Richard did a test showing how much flow and pressure drop when trying to inject large quantities of fluid into a high pressure area, and it was quite dramatic
Once some of the pumps were trying to feed say 2 moderate size nozzles, pressure dropped off dramatically. Combine that with boost pressure acting against the pump and you might see actual spray pressure down to 60-100psi range when you think it's upwards of 160psi
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From: Norn Iron
No, it will only maintain 160psi to inject liquid when you are injecting to atmospheric pressure, ie pre-compressor, and when the pump has enough flow ability to keep up
If you inject into a boost pipe, you have boost pressure acting against the pump regardless, so less pressure actually gets used to inject water.
ie 160psi against 30psi boost only means 130psi to inject water, again while pump is able to maintain flow to support that pressure
As flow demand goes up, pump ability will still suffer and pressure will drop. It's no difference to a fuel system struggling to maintain pressure when the pump cannot keep up.
No, it will only maintain 160psi to inject liquid when you are injecting to atmospheric pressure, ie pre-compressor, and when the pump has enough flow ability to keep up
If you inject into a boost pipe, you have boost pressure acting against the pump regardless, so less pressure actually gets used to inject water.
ie 160psi against 30psi boost only means 130psi to inject water, again while pump is able to maintain flow to support that pressure
As flow demand goes up, pump ability will still suffer and pressure will drop. It's no difference to a fuel system struggling to maintain pressure when the pump cannot keep up.
If you inject into a boost pipe, you have boost pressure acting against the pump regardless, so less pressure actually gets used to inject water.
ie 160psi against 30psi boost only means 130psi to inject water, again while pump is able to maintain flow to support that pressure
As flow demand goes up, pump ability will still suffer and pressure will drop. It's no difference to a fuel system struggling to maintain pressure when the pump cannot keep up.
You repeated exactly what I said. Yes, I know that it's a pressure differential, so it's pressure at the nozzle, minus (or add) the pressure in the intake charge pipe. That's why the chart I posted is important. Instead of just guessing how much to inject, you have to actually use some math and do the calculation based on injector flow rate, what % of total flow rate you want to supplement with water/meoh, and boost pressure.
These pumps that Aquamist use are quite stout and able to maintain 160psi even at very high flow rates.
So instead of just guessing flow rates, and nozzle sizes, you use the calculator at this link.
http://howertonengineering.com/tech-...ating-jetting/
I have no concerns at all that the pump can keep up and maintain 160psi at the fast acting valve.
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From: Norn Iron
The test Richard did was on the larger pump ?
Even it struggled to maintain pressure once flow rates got high. The smaller 160psi pump will obviously perform worse.
If injecting water, flow rates will probably be low-moderate anyway so no worries. But with those injecting 100% meth, they will be demanding huge amounts of flow.
Almost all the pumps used are the Aquatec or Shurflo anyway, so really cant see there being huge differences in performance in that respect no matter who's kit people are using.
Even it struggled to maintain pressure once flow rates got high. The smaller 160psi pump will obviously perform worse.
If injecting water, flow rates will probably be low-moderate anyway so no worries. But with those injecting 100% meth, they will be demanding huge amounts of flow.
Almost all the pumps used are the Aquatec or Shurflo anyway, so really cant see there being huge differences in performance in that respect no matter who's kit people are using.
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From: Norn Iron
If you spray onto or near the sensor...there is bound to be some error due to spraying cool liquid directly onto the sensor. Some may evaporate, some will not.
If you can measure air temp as close to the intake valve as possible you'd get a more accurate picture, but then it would be almost impossible not to have some error from heat soak due to sensor location.
Ultimately it isnt super critical about accuracy though as long as the readings are consistent and reliable
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Verdad Gallardo This can easily be proven when comparing the power output of a non-intercooled alky injected setup VS an intercooled setup at the same boost levels. Even with a small pressure differential across the IC core, the intercooled setup will make more power. I’d look at EGT temps if you wanted to push a meth/water inj. system.
Last edited by Forcefed86; Nov 3, 2014 at 09:17 AM.
Thread Starter
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From: Lake Tapps, WA
Thats a ton of power at only 12lbs! Honestly with that compression ratio, intercooler, and E85... 12lbs is nothing. I wouldn't bother with aux. inj. Your charge temps should be plenty low.
If your dead set on it, I'd just run the 50/50 mix the dealers sell at 15Gph Pre TB and 2 GPH pre turbo. 300psi pump. Have it kick on at 10lbs or so...
If your dead set on it, I'd just run the 50/50 mix the dealers sell at 15Gph Pre TB and 2 GPH pre turbo. 300psi pump. Have it kick on at 10lbs or so...
Teching In
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No. Dip your hand in a bucket full of alcohol and wave it around. Your hand gets really cold, but you have little effect on the air surrounding your hand. This isn’t the best analogy, but a similar reaction happens when putting a sensor in front of the nozzle. The sensor itself gets saturated with alcohol and gives a false cool reading. You will also notice the closer you move the IAT sensor to your injection point the lower the IAT readings will be. If the IAT sensor readings were measuring actual charge temp, the reported temperatures wouldn’t vary a ton depending on sensor placement. I’m not saying there are no benefits to cooling the charge temps, just that the benefits are usually nowhere near what the IAT sensor is reporting.
This can easily be proven when comparing the power output of a non-intercooled alky injected setup VS an intercooled setup at the same boost levels. Even with a small pressure differential across the IC core, the intercooled setup will make more power. I’d look at EGT temps if you wanted to push a meth/water inj. system.
This can easily be proven when comparing the power output of a non-intercooled alky injected setup VS an intercooled setup at the same boost levels. Even with a small pressure differential across the IC core, the intercooled setup will make more power. I’d look at EGT temps if you wanted to push a meth/water inj. system.
I think that would only tell you the best mixture for dropping the temperature reported by the IAT sensor. That mixture would be water heavy and wouldn't be the same mixture most use for peak boost/performance. As said, the major benefit of the alky injection takes place in the cylinder. Dropping charge temps a small amount is a side benefit and not something you should judge the kits performance by. IMO most are better off with the sensor placed well before the injection point and tuning to the actual charge temps.
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From: Just outside Memphis
The two best places to inject meth for intake tract cooling are #1 just after the Intercooler and #2 just before the compressor. The worst place is just before the intercooler but after the compressor.
Most of the intercooler benefit comes from temperature differential so if you spray just before the intercooler, you get the benefit of the spray but make your intercooler less efficient since there is less of s temperature differential. If you got the intake charge even colder than ambient with the liquid injection before an a2a intercooler, the intercooler would actually heat the intake charge.
If you spray just before the compressor, you increase the compressor efficiency by ostensibly decreasing the tolerances through injecting a (mostly) non-compressible fluid.
If you spray just after the intercooler, you have more time for the meth to evaporate and cool the intake air and distribute into the air charge evenly.
Meth also gives you some octane cushion.
Most of the intercooler benefit comes from temperature differential so if you spray just before the intercooler, you get the benefit of the spray but make your intercooler less efficient since there is less of s temperature differential. If you got the intake charge even colder than ambient with the liquid injection before an a2a intercooler, the intercooler would actually heat the intake charge.
If you spray just before the compressor, you increase the compressor efficiency by ostensibly decreasing the tolerances through injecting a (mostly) non-compressible fluid.
If you spray just after the intercooler, you have more time for the meth to evaporate and cool the intake air and distribute into the air charge evenly.
Meth also gives you some octane cushion.
Thread Starter
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From: Lake Tapps, WA
The two best places to inject meth for intake tract cooling are #1 just after the Intercooler and #2 just before the compressor. The worst place is just before the intercooler but after the compressor.
Most of the intercooler benefit comes from temperature differential so if you spray just before the intercooler, you get the benefit of the spray but make your intercooler less efficient since there is less of s temperature differential. If you got the intake charge even colder than ambient with the liquid injection before an a2a intercooler, the intercooler would actually heat the intake charge.
If you spray just before the compressor, you increase the compressor efficiency by ostensibly decreasing the tolerances through injecting a (mostly) non-compressible fluid.
If you spray just after the intercooler, you have more time for the meth to evaporate and cool the intake air and distribute into the air charge evenly.
Meth also gives you some octane cushion.
Most of the intercooler benefit comes from temperature differential so if you spray just before the intercooler, you get the benefit of the spray but make your intercooler less efficient since there is less of s temperature differential. If you got the intake charge even colder than ambient with the liquid injection before an a2a intercooler, the intercooler would actually heat the intake charge.
If you spray just before the compressor, you increase the compressor efficiency by ostensibly decreasing the tolerances through injecting a (mostly) non-compressible fluid.
If you spray just after the intercooler, you have more time for the meth to evaporate and cool the intake air and distribute into the air charge evenly.
Meth also gives you some octane cushion.
9 Second Club
Joined: Nov 2003
Posts: 13,616
Likes: 185
From: Norn Iron
The two best places to inject meth for intake tract cooling are #1 just after the Intercooler and #2 just before the compressor. The worst place is just before the intercooler but after the compressor.
Most of the intercooler benefit comes from temperature differential so if you spray just before the intercooler, you get the benefit of the spray but make your intercooler less efficient since there is less of s temperature differential. If you got the intake charge even colder than ambient with the liquid injection before an a2a intercooler, the intercooler would actually heat the intake charge.
If you spray just before the compressor, you increase the compressor efficiency by ostensibly decreasing the tolerances through injecting a (mostly) non-compressible fluid.
If you spray just after the intercooler, you have more time for the meth to evaporate and cool the intake air and distribute into the air charge evenly.
Meth also gives you some octane cushion.
Most of the intercooler benefit comes from temperature differential so if you spray just before the intercooler, you get the benefit of the spray but make your intercooler less efficient since there is less of s temperature differential. If you got the intake charge even colder than ambient with the liquid injection before an a2a intercooler, the intercooler would actually heat the intake charge.
If you spray just before the compressor, you increase the compressor efficiency by ostensibly decreasing the tolerances through injecting a (mostly) non-compressible fluid.
If you spray just after the intercooler, you have more time for the meth to evaporate and cool the intake air and distribute into the air charge evenly.
Meth also gives you some octane cushion.
Teching In
Joined: Oct 2007
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Water injection does a great job of preventing hot spots in the cylinder which can be the cause of pre-ignition
I know this is an old thread, but I have a question, and there's a lot of good information here!
I have a supercharged (centri) jet ski with a 1.8L 4 cylinder pushing about 16-17lbs of boost. I have an aftermarket water to air intercooler as well and an unlimited supply of freshwater cooling the intercooler. Water temp right now is around 80F.
During a top speed run, I can see that my RPMs begin to drop. I sometimes lose 200-300rpm throughout a pull. I believe this is being caused by IATs rising during the run. In the jet ski world, this equates to 2-3mph. Also, since it's a centri blower, as RPMs fall, so does boost, just compounding the problem.
To try to help with this problem, I've thought about adding water injection. I have an infinite supply of water and I have 100+ psi available from the jet pump. If injecting a small amount of water into the engine would help with the heat fade I'm seeing, all I would need would be a water filter and a nozzle/solenoid setup. It would not add much weight or complexity to the ski.
Right now I'm making somewhere around 350hp. If I could keep this heat fade away by using water injection, it would certainly be a cheap way to gain some good/more consistent top end.
So my question, will injecting water alone provide enough of a cooling benefit to keep my IATs down and lead to less heat fade? The IAT sensor is in the intake manifold. Where would be the best place to spray?
Thanks,
Adam
I have a supercharged (centri) jet ski with a 1.8L 4 cylinder pushing about 16-17lbs of boost. I have an aftermarket water to air intercooler as well and an unlimited supply of freshwater cooling the intercooler. Water temp right now is around 80F.
During a top speed run, I can see that my RPMs begin to drop. I sometimes lose 200-300rpm throughout a pull. I believe this is being caused by IATs rising during the run. In the jet ski world, this equates to 2-3mph. Also, since it's a centri blower, as RPMs fall, so does boost, just compounding the problem.
To try to help with this problem, I've thought about adding water injection. I have an infinite supply of water and I have 100+ psi available from the jet pump. If injecting a small amount of water into the engine would help with the heat fade I'm seeing, all I would need would be a water filter and a nozzle/solenoid setup. It would not add much weight or complexity to the ski.
Right now I'm making somewhere around 350hp. If I could keep this heat fade away by using water injection, it would certainly be a cheap way to gain some good/more consistent top end.
So my question, will injecting water alone provide enough of a cooling benefit to keep my IATs down and lead to less heat fade? The IAT sensor is in the intake manifold. Where would be the best place to spray?
Thanks,
Adam
Last edited by HydroStream6; Aug 18, 2015 at 07:00 AM.