Budget pre turbo WI

[theking]

In the past I have done 3 different WI systems, one was a budget system with the following components

1x fuel injector post intercooler - Flow tested to ~250cc @90PSI
1x Headlight washer pump of a Mazda - Pressure tested to 90PSI (6bar) with injector DC 100%
1x Relay triggered by megasquirt EMS that opened the injector @100% DC along with the pump
Misc hoses ++
Fluid: Windscreen washer fluid (isopropanol).


That system was on a ~400hp 6 cyl engine with a distributor, so I had some issues igniting the mixture when water was injected. I had to reduce the spark plug gaps, but once I did the water suppressed the knock issues I had (old engine design). However, fuel tuning was not an option as my AEM UEGO wideband went haywire for some reason. I suspect perhaps my injector ( and particulary its location where it sprayed 90degrees into the pipe, not with the flow) formed droplets instead of a mist.




This time Ill repeat the formula, but go pre turbo with the injector pointing towords the turbo, spraying from a distance of approx 6" pointing towards the turbo inlet. Compared to my old system, this should have 2 advantages.

#1 : Im now pointing the injector the same direction as the flow
#2 : Even though the injector gives a rather fine mist, shooting it into the compressor should make it even better.

This could screw up my turbo blades, however there are so many different opinions and results on this, Ill take my chances and see for myselfe. I am planing to buy a bigger turbo soon anyways.


The way I understand pre turbo WI, this will increase the efficiency of the compressor, and shift the compressor map to the right. My turbocharger is to small for its application, so this is exactly what I need. A bonus will be cooler air, and even though I have a LARGE FMIC, this can only be a good thing.

I do have a programable EMS, but I wont take my chances that this system works. So I will NOT tune for this. However, increased turbo efficiency, more flow from the turbo and cooler intake air should still create a fair amount of power.


To confirm, I will do power tests, either by EMS dyno (if I can make it work), or/and by pulling a gear from specific speeds, ie 60-100mph 4th gear.






Any inputs and suggestions will be greatly appreciated. The project start is approx October 30th (when I get back from work at sea).



My own worries:
Injector rusting: This was never an issue on the old project. 1 year of service, and the injector was still 100%.
Injector sticking: When running 100% DC, the injector could stick open, and there is really no good way for me to see it.
Poor atomization: Could f up my compressor blades.


Pics, flow testing ++ to come.

[theking]

Update:

Since Im not traveling until tomorrow, I could not wait to do a bench test of the system. The results were... poor.

I measured the injector cc/min, it was 200cc @ 2.5 bar. My total fuel injected at boost is approx 2000cc, so thats 10% at high RPM , a bit lower at lower RPM and full boost. So far so good.

However, the fuel injector has a terrible spray, and is probably not the best this application. I didnt bother uploading my own test video, I just found one online showing my point:

http://www.youtube.com/watch?v=fZ_N690mSfU


If this is pointed downstream towards the turbo, it will hit it with a giant "beam" of water... Weather or not that is a good thing is hard to tell, really. I mean, its probably not that much worse then a good old "suck through" carburator setup. Perhaps I should make the spray not hit directly on the compressor, and rater strike 90degrees down and hit the inlet hose...

Ill do some further testing and see what I can figure out.. Probably in 2-3 weeks... Ill study old style WI to see what they did back in the days..

[Richard L]

Fuel injector may not give the best atomisation for your application. Perhaps replace it with a oil heater spraying nozzle.

Better still, an air atomisation nozzle is even better.
Check this one: http://www.aquamist.co.uk/vbulletin/...ead.php?t=1590