Injecting prior to turbo comp' impellers

[SaabTuner]

Originally Posted by Richard L

Does anyone agree that having two identical jets, one before and one after the impeller should give a very good indication of how the two work.

Not necessarily. Only if the two jets are both flowing the same amount of water. The same size jet on the high pressure side of the turbo should flow a bit less water shouldn't it?

If the water amount injected is equal, it should give a good comparison of the difference in effect.

If the same jet-size is used, it will still be useful in determining proper jet-size before and after the impeller.

Adrian~

[Richard L]

Originally Posted by SaabTuner

Not necessarily. Only if the two jets are both flowing the same amount of water. The same size jet on the high pressure side of the turbo should flow a bit less water shouldn't it?

If the water amount injected is equal, it should give a good comparison of the difference in effect.

If the same jet-size is used, it will still be useful in determining proper jet-size before and after the impeller.

Adrian~

This is perfectly true, the pressure must be the same for both jets at the point of injection. The water pressure can easily be adjusted between 2-10bar on the 2c/2d. The post-turbo jet will run at a pressure higher, equal to the boost pressure.

[Richard L]

An example of Bert Waite using pre-compressor water injection to increase the power of his turbines engine.







He has also added this on his email to me:

I finished the Turbine project that I was working on. We went from 1,400 HP to 1,800 HP with the water injection system. The addition of the water to the saturation point not only increased the turbine compressor efficiency, but allowed us to add additional fuel due to temperature management. THANKS FOR ALL YOUR HELP!


He has been using water injection for many years and here are a few of his past and present projects:

In the Lotus application, I injected water before the turbo and after the intercooler. Injecting before the turbo or any supercharger/compressor , increases the efficiency of the compressor by increasing the density of the air. This one one of the main advantages in the turbine application.




I am working on a new project now that I am back on my feet. It is a boat like the turbine project. It is powered by two 6.6 liter small block Chevy engines with Whipple super chargers. It is intercooled and running about 1 bar of boost. The engines make 850 HP on a mix of 100 LL av gas and 110 octane racing fuel. The boat is a 8.5 meter cat and should run about 241 km/hr.
I would like to run the boat on straight 100 octane av gas with the addition of a water injection system. According to my calculations, each engine would need between 300 ml and 500 ml of water per minute or a total of up to 1,000 ml. Does that sound correct to you? At that rate, I am considering using the Shurflo 8030-813-239 pump which is capable of 9.5 bars at 3.3 l/m.

[Richard L]

So it is agreed that tow identical jet but alter the water line pressure for each jet so the back pressure will be the same for both jets.

Anyone else think there are other factors that we need to consider before slowMX5 starts his test?

[PuntoRex]

Installed mine this evening

I started yesterday, prepared the jet adaptor fitting:


The adaptor is fitted on a piece of 2mm alu. I hammered the alu board into shape & then drilled/tapped for the adaptor. Some silicon adhesive (gasket maker) was used to fix the assembly onto the hose. ( That was really a mess to work with ) ( And the hose was drilled previously of course ) Additional nylon ties secure the whole thing one step furthur. I hope the fitting can be trouble-free.

I did hesitate a lot about the jet location. For better access, it would be too close to my hot wire MAF. I was afraid, on such location, I'd experiece the hiccup as Hodrod did. Avoiding that, I'd have to place the jet just a few inches ahead of the compressor.

That's just what I did. On the picture above, the air flow is from left to right. The branch facing down in the middle is the outlet of recirc BOV ( which is 1" ID FYR ). The elbow on the right leads to compressor. You can see the jet is quite close to that.

The following picture shows it better:


It's about 6" to the end of the elbow, another 2" to the compressor blades.


I took 0.5mm jet on the pre-comp injection, 0.6 for pre-throttle. ( I ran 0.7 on pre-throttle only previously )

Since I have no check valves on hand right now, so I can just T the two jets directly. I know there would be some cross-flow & siphon, but I can't do anything about it. So... I arranged bigger jet on the pressured side, hopefully it could offset the cross flow somewhat. (I may be totally wrong & just fool myself)

Yet another thing that's not so optimum is that the pre-comp jet is quite far from HSV, about 3ft.

Anyway, it works!

Lukily I didn't experience the WOT bog down as Gelf. Yet not so lucky as Hodrod to get a rise in boost. Car just pulls harder on boost, especially in the midrange. The performance gain is easily sensible with a quiter turbo hiss.

This is really a very effective & worthy mod to me. Two thumbs up. Now I'm just waiting for Richard's mail of my check valves & other accessories to make the whole thing complete.

Thanks every contributor on this thread :wink:

[masterp2]

I have been following this thread with great interest. I am trying to develop a WI process for the duramax TDiesel with 30 lbs of boost. I have had initial reports that HP increases with it are not as dramatic as gas, especially the "tuned" trucks. I'm not sure why this would be, maybe someone could explain.

In any event, going to use it to reduce EGT's that are quite high, and to aid tow vehicles that overheat (seems the CAC is imparting too much heat to the rad). Considering 2 stages. Stage 1-towing-15 psi-2 nozzles-post turbo pre-CAC. Stage 2-performance-throttle switched at the floor-2 additional nozzles, 1 pre turbo-1 intake

Michael

[hotrod]

You can probably get some additional good feed back in the diesel forum as well as on this thread.

Just need some back ground info. I'm not familiar with the acronym CAC I assume your refering to an after cooler ?

Most of the conventional wisdom is that injecting between the turbo and the intercooler/after cooler is less effective than injecting after the last stage of intercooling/after cooling.

Are you using a pure water injection or a mixture of water and alcohol?

Water and methanol mixtures are supposed to produce some very impressive performance gains and lower EGT's. The bad news is the bump in power is addictive and too much methanol can push the engine to the point of blowing head gaskets due to high cylinder pressures, but the increase in torque is supposed to be very impressive.

The pre-turbo injection is most useful when your maxing out the airflow capacity of the turbo compressor at high rpm.

Right now my system is set up as pre-turbo only, and triggered with a pressure switch, but I plan on changing over to a system that is a bit more complex.

I'm going to add an rpm switch in line with the pressure switch so the pre-compressor injection only comes on after the engine gets to about 70% of max rpm. My experience recently also leads me to consider adding a temp sensor in the intake tract so that once the intake air temp drops below about 70 deg F. the pre-compressor injection is completely disabled.

Larry

[masterp2]

CAC, charge air cooler, IC. The stock Garrett turbo has 25 psi stock, 30 when chiped. A few people have played around with WI only getting 15-30 HP, 5% increases, from the 300-400 that are coming from the stocker, with 1200-1400EGT's.

That is using WW fluid, with meth.



Michael

[hotrod]

Thanks I figured it was and intercooler, but couldn't figure out the usage. Unfortunately each automotive enthusiast group develops their own common usage acronyms and some times the alphabet soup is hard to translate.

Second question, is your CAC an air to air system postioned infront of the radiator? If so then the heat transfer to the radiator would be due to the CAC pre-heating the air going through the radiator.

Two options come to mind, first under the heading of keeping it simple, you could also look at direct water spray on the outside of the CAC or on the radiator or both, rather than injection in the air stream between the turbo and the CAC.

The other way to take heat load off the cooling system is to add an oil cooler. The oil moves quite a bit of engine heat. On the WRX in stock configuration it uses an oil cooler that passes heat to the engine coolant. Folks have had good luck adding an air cooled oil cooler and passing that heat directly to the air rather than the radiator through the coolant.


When you refer to "gas" are you talking about propane injection?

The pre-compressor injection will only increase the max air flow by a few percent, so your 5% gain seems about right in that regard.

As I understand the effects on diesels you need to add some fuel to make full use of the air that you are already flowing so if you upped your fuel flow and then held the EGT temps in check with WI you should get more power than 5%

Larry

[slowMX5]

I must apologise for being slow to get my testing done - but a combination of a dead laptop (couldn't data log) and poor weather here in SW England has slowed me down. Doing 3rd gear WOT power runs on damp/wet roads isn't possible (it's dangerous and wheel spin will mess up the power/torque calcs) - so I am waiting on completely dry roads - or at least for my test stretch of road to be dry.

Hopefully this will happen by next weekend and I'll get the tests people have asked for done. I'll either post details of each test with torque and power figures or post complete comparison power/torque graphs overlaid on a website. PuntoRex's findings are encouraging.