Water/meth injection: a theoretical and practical discussion

[JD]

I need to tap the cold pipe for the water injection but the aluminium pipe I have is only 2mm thick. I know plenty would say keep it ally but I'll need a thicker one to tap because 2mm just isn't anywhere near enough thread so I would consider SS. What are my options? I could tap the IC just before the outlet I suppose - would this be better?

[Nic]

Drill a hole and then weld a threaded aluminium boss to the outside of the pipe.

This sort of thing http://radtec.co.uk/products/435/Female ... ss-x10.htm

[JD]

Thanks Nic. That seems to be the way to go. I don't have a welder, though so anyone fancy helping me out?

[JD]

double post

[bobhatton]

I need to tap the cold pipe for the water injection but the aluminium pipe I have is only 2mm thick. I know plenty would say keep it ally but I'll need a thicker one to tap because 2mm just isn't anywhere near enough thread so I would consider SS. What are my options? I could tap the IC just before the outlet I suppose - would this be better?

The correct place for a water injection nozzle is as close to the inlet valve as possible and therefor one per manifold runner. The manifolds are what is known as dry, they are not designed for a liquid and therefore there will not be an even distribution to each cylinders, and the water will displace air and lower the power of the engine

Water does nothing in the manifold, all its work in done in the cylinders.

If the engine is not detonating when the water is turned on the engine will drop in power as the cylinder pressure is lower with the water.

[JD]

Thanks Bob, I will take it under advisement but may read more before I butcher my intake manifold! My understanding was that it should be placed after the I/C to maximise the efficiency of the IC but as far back as this will allow from the throttle plate as possible to maximise atomisation/distribution in the intake charge. I can see how individual nozzles in each branch would make sense.

It will be mapped for anyway.

[2mad]

My understanding was that it should be placed after the I/C to maximise the efficiency of the IC but as far back as this will allow from the throttle plate as possible to maximise atomisation/distribution in the intake charge. I can see how individual nozzles in each branch would make sense.

It will be mapped for anyway.

This ^^ I placed mine here..

Worked great, had very low iat temps

[Martin F]

My understanding was that it should be placed after the I/C to maximise the efficiency of the IC but as far back as this will allow from the throttle plate as possible to maximise atomisation/distribution in the intake charge. I can see how individual nozzles in each branch would make sense.

It will be mapped for anyway.

This ^^ I placed mine here.. Image Replaced With URL For Quote [url]http://i948.photobucket.com/albums/ad323/mr2turbobitz/Imoc/P21-06-12_2023-1.jpg[/URL]

Worked great, had very low iat temps

This is a good place to put it, if you put it in the inlet manifold the standard air temp does not pick up any of it's cooling effect and retards the ignition when it detects the higher temps side mount intercoolers inevitability put out at higher boost levels.

[JD]

good to know as that's where I've told the welder I want mine

[JD]

My understanding was that it should be placed after the I/C to maximise the efficiency of the IC but as far back as this will allow from the throttle plate as possible to maximise atomisation/distribution in the intake charge. I can see how individual nozzles in each branch would make sense.

It will be mapped for anyway.

This ^^ I placed mine here.. Image Replaced With URL For Quote [url]http://i948.photobucket.com/albums/ad323/mr2turbobitz/Imoc/P21-06-12_2023-1.jpg[/URL]

Worked great, had very low iat temps

This is a good place to put it, if you put it in the inlet manifold the standard air temp does not pick up any of it's cooling effect and retards the ignition when it detects the higher temps side mount intercoolers inevitability put out at higher boost levels.

another good point

[bobhatton]

My understanding was that it should be placed after the I/C to maximise the efficiency of the IC but as far back as this will allow from the throttle plate as possible to maximise atomisation/distribution in the intake charge. I can see how individual nozzles in each branch would make sense.

It will be mapped for anyway.

This ^^ I placed mine here.. Image Replaced With URL For Quote [url]http://i948.photobucket.com/albums/ad323/mr2turbobitz/Imoc/P21-06-12_2023-1.jpg[/URL]

Worked great, had very low iat temps

This is a good place to put it, if you put it in the inlet manifold the standard air temp does not pick up any of it's cooling effect and retards the ignition when it detects the higher temps side mount intercoolers inevitability put out at higher boost levels.

There is NO cooling of the inlet air with water injection

[2mad]

This ^^ I placed mine here.. Image Replaced With URL For Quote [url]http://i948.photobucket.com/albums/ad323/mr2turbobitz/Imoc/P21-06-12_2023-1.jpg[/URL]

Worked great, had very low iat temps

This is a good place to put it, if you put it in the inlet manifold the standard air temp does not pick up any of it's cooling effect and retards the ignition when it detects the higher temps side mount intercoolers inevitability put out at higher boost levels.

another good point

Absolutely Martin, That was the theory I was testing, lower iat's plus higher octane from the meth = less det and more advanced timing
Worked great for me and my mines ecu and the afc tune I did.
I really wanted to do back to back dyno tests just to put the final nail in the coffin just never got round to it but the difference between spraying meth and not was quite astounding .


Iat gauge test showing cooling (50+ without meth) on very busy roads, couple of 3rd and 4th pulls, +25c ambient temps... http://vid948.photobucket.com/albums/ad ... chedon.mp4


Remember the longer your on boost the colder temps get



Kev.

[JD]

This ^^ I placed mine here.. Image Replaced With URL For Quote [url]http://i948.photobucket.com/albums/ad323/mr2turbobitz/Imoc/P21-06-12_2023-1.jpg[/URL]

Worked great, had very low iat temps

This is a good place to put it, if you put it in the inlet manifold the standard air temp does not pick up any of it's cooling effect and retards the ignition when it detects the higher temps side mount intercoolers inevitability put out at higher boost levels.

There is NO cooling of the inlet air with water injection

Here we are specifically talking about water/meth, rather than just water, and it should work to cool the pistons at least? Cooler pistons are stronger pistons? The main benefit is knock-retardation, surely, allowing for more aggressive ignition timing, yes?

[2mad]

Here we are specifically talking about water/meth, rather than just water, and it should work to cool the pistons at least? Cooler pistons are stronger pistons? The main benefit is knock-retardation, surely, allowing for more aggressive ignition timing, yes?

As far as I'm concerned, "Yes" . You and martin f have covered most the pro's to running water/meth
I would, from experience never drive a turbo car in anger with out it

I wish now i had done a few test runs with just water so i could see if there was any difference in performance between just water and water/meth

[ashley]

There is NO cooling of the inlet air with water injection

Not arguing- just want to understand why we see lower IATs when injecting water then? Is the water "fooling" the sensor?

[ashley]

There is NO cooling of the inlet air with water injection

Not arguing- just want to understand why we see lower IATs when injecting water then? Is the water "fooling" the sensor?

To answer my own question: the IAT sensor is also reading the temperature of the water being injected, so the reading is no longer a pure inlet air temperature- it's an average of the air temperature (higher) and the water droplet temperature (lower).

My interpretation anyway...

So...is water injection actually producing an inter-cooling effect at all?? If my explanation is correct, then no it is not.

Starting to understand Bob's prior comments on this now (I think)

[Nic]

Good post on the subject of WI here by Chris Wilson

http://www.mkivsupra.net/vbb/showthread ... ost1220993

[ashley]

Yeah- you've posted that before, sure I read it before as well...but Bob's comments always get me thinking...

I'll go read it all again

[JD]

Good post on the subject of WI here by Chris Wilson

http://www.mkivsupra.net/vbb/showthread ... ost1220993

Very interesting, thanks.

[2mad]

There is NO cooling of the inlet air with water injection

Not arguing- just want to understand why we see lower IATs when injecting water then? Is the water "fooling" the sensor?

To answer my own question: the IAT sensor is also reading the temperature of the water being injected, so the reading is no longer a pure inlet air temperature- it's an average of the air temperature (higher) and the water droplet temperature (lower).

My interpretation anyway...

So...is water injection actually producing an inter-cooling effect at all?? If my explanation is correct, then no it is not.

Starting to understand Bob's prior comments on this now (I think)

I find this theory very interesting, is the IAT sensor is being cooled by the water and not the incoming charge of compressed air
I have been thinking on this and its a proper catch 22, How can I devise an experiment to read just air temp with out the sensor being cool by the sprayed water/meth (18c in the tank temp ish)

If it is the case the the IAT sensor is being cooled by the water/meth it would make for a much more efficient setup to fit a resistor instead of the temp sensor, clamped to 25c and fit 4x 0.3mm injectors, one in each of the 4 runners like bob suggested .

Personally I think water/meth cools the incoming charge but inlight of this new theory I cannot prove it


Kev.



Edit.. For the record the k type thermocouple sensor I used for the vid I posted ^ was about the size of a grain of sand sandwiched between two thin pieces of plastic .
I really couldn't say how much the sprayed water/meth affected it temp wise, at the time I didn't think it would be by much.