# How close to the sensor can you put the jet on a golfV gti?



## GERHARD PETZER (Jan 21, 2004)

I want to move my jet lower down my intake pipe, on my GolfV Gti. There is a sensor that is basically in the middle of the pipe. I know that you can not put the jet before this sensor. So I am wanting to get as close to it from the top. I am hoping to get a better mix will the air coming in, and also avoid getting direct water on the throttle body. I am hoping to just get vapor by the time the water air mix gets to it.


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## Krieger (May 5, 2009)

you mean your MAP? its on the ride side of the throttle body pipe.

you can spray before afaik. its just reading pressure, not whats in the pipe.


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## GERHARD PETZER (Jan 21, 2004)

Map sensor, is that what it is? I have been told by a few guys not to get it wet as it will fail? I am hoping that the air flow past it will keep the water from the jet away from it. I have moved the jet about 5cm above the map sensor. As I said before, I am looking for a better mix with the hot air coming in. All I want is a cool dens mix of air going past the TB.


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## Krieger (May 5, 2009)

nah, if you pull it too far away from the TB, it wont get the valves and cylinders wet, and therefore wont up the octane as much.

you could always run two nozzles, one post IC, and one pre- TB, both small and get great octane increases AND plenty of cooling.

I plan on running 2 nozzles myself. one to spray just before the turn into my turbo, to keep the compressor from ever heating the air in the first place, and one just before the TB to up the octane like crazy.

either that or post IC, pre TB, havnt quite decided yet. the K03's shaft is really tiny and idk if it could handle any extra weight on the compressor side when the water hits the fins, even if its just like a 60 CC sprayer.


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## UCSBSHAWN (Oct 8, 2008)

dont put the nozzle before the turbo, it will eat away at the fins.


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## GERHARD PETZER (Jan 21, 2004)

Although I have two maps on my car, pump and race (GIAC chip) I am quite happy to run the pump map only with the water injection. My experiance is that w/m even at 60/40 mix is not enough to run the race map well. I have logged it and seen some high timing pulls across all 4 cylinders. I am looking to decrease the timing pulls I am having on my pump map, there by hopefully making more power. I am also worried about damaging another throttle body. So my aim is cooling and not octane. 
I have read that putting the jet before the turbo is not a good idea. I have read that the water mist is enough to "eat" away at the turbo compressor wheel. Also the IC can become water logged. If i was you I would leave it just before the TB.


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## Krieger (May 5, 2009)

UCSBSHAWN said:


> dont put the nozzle before the turbo, it will eat away at the fins.


pure water wont do that of its placed so that it wont spray directly on the fins.

I personally like the idea of a pre-turbo injection setup with water only because it significantly reduces the pumping effort from the turbo. Generally that means your wastegate will be open more at full load, which reduces backpressure, and your turbo may spool a bit faster. Some people seem to find that you can also use a larger turbine A/R without the normal sacrifice in spool up.

The reason for this unusual boost in turbo performance is that the water boils as it passes through the compressor, absorbing heat from the air. "Normal" compressor exit temperatures can be over 300*F which means the air is NOT very dense and must flow at either very high pressure or very high speed to reach a given mass-flow. By keeping the air denser all the way through the compressor, the turbo doesn't need to spin as quickly to accelerate the air.

If shooting a completely vaporized water (almost a fog) could do damage to the wheel, then why dont carbs get torn to pieces if the poorly atomized fuel shoots through them? Or what about on cars where there is a carb before the turbo? The turbo isnt hurt even though the fuel is def not atomized that well.

im thinking a very small nozzle, with >200 PSI of water shooting through it wont hurt a thing.

According to all the threads that ive read, and the tech articles, pre-turbo water injection has shown awesome results and changes the compressor map, essentially making a small turbo be able to flow like a larger one since the air is denser and the turbo doesnt have to work as hard to move less air.


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## GERHARD PETZER (Jan 21, 2004)

Krieger said:


> pure water wont do that of its placed so that it wont spray directly on the fins.
> 
> I personally like the idea of a pre-turbo injection setup with water only because it significantly reduces the pumping effort from the turbo. Generally that means your wastegate will be open more at full load, which reduces backpressure, and your turbo may spool a bit faster. Some people seem to find that you can also use a larger turbine A/R without the normal sacrifice in spool up.
> 
> ...


I would hate to see you hurt your turbo doing this! I think do a bit more resurch before going ahead with this. 
I have drilled my holes in my spare intake pipe, and placed my jet lower and moved my boost pickup point as well. I am waiting for the lock-tite to dry, and hopefully I can fit the whole lot this weekend.


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