Water/meth injection: a theoretical and practical discussion

[mr2magic]

I didn't mean to infer that you have a bad tune! Sorry if it came across that way.

I just like keeping things as simple as possible

[JD]

No absolutely, all input appreciated. I'm going to plumb the nozzles in perpendicular to the runners as it seems simpler, but using your logic do you reckon I'd be better pointing them upwards against the flow? I think they will, to some extent, disrupt the intake flow anyway so I did wonder what might be best. I have bosses to weld in of angled is better.

edit: i wonder if there's some way I could emulate the max intake flow, at max boost pressure, in a visible environment that would allow me to see the spray pattern at different angles - like if I had a transparent tube to act as abranch of the intake manifold, and then blew some air down it at 1.2bar, matching the intake flow rate of the corresponding engine rpm, and put some kind of dye in the water, so I could watch what was happening to it. Not very scientific but I know that spray pattern for fuel injectors is tested in a similar manner, so I suppose it's possible. Is there already something like this somewhere?

[2mad]

Still very interested in this JD .. I think as long as there's a little bit of time for the automatized w/m to mix with the incoming charge your good to go .. obviously some flow data regarding jet angle/positioning would be great (why have the manufactures not done this ).. looking forward to pics and real world experience of this setup ... I think real gains will come from a remap but knock suppression (basically running race fuel on boost) should give a boost to performance depending on you present map. worked great with my mines ecu ... and an afc tune unleashed more power for me .. so you should get a real benefit from having a mappable ecu.


Again watching with interest .. direct port vs single pre-throttle body injection .. interesting stuff



Kev.

[Danbob]

FYI, before drilling my manifold I emailed all the major Water injection system manufacturers to ask their opinion on the inlet runner vs pre throttle body placement debate.

So far only Snow Performance have replied. This is what they said:

My Email:

Hello,

I have one of your Water injection kits and am trying to find the optimum placement of the Nozzles.

Background
Application is a Toyota 3S-GTE engine (Gen 3) - 4 cylinder turbocharged. Sprint car with side mount IC (AIT sensor located after TB)
Mid-engine car so intercooling is poor, engine currently out of car so not much additional work to add nozzles to runners. Current WI system is not progressive. Standalone ECU.

Options
One argument is I should use a single jet positioned at the throttle body or between IC and TB, allowing the water to cool the charge and the IAT sensor to see this.

The other argument is that the water does not have time to cool the charge in this situation and the IAT sensor only shows a cooler temp because it becomes wet and therefore the sensor accuracy is no longer valid. They argue that I should use four individual jets in each of the manifold runners as the manifold was not designed to be a “wet manifold” and placing in the runners ensures each cylinder receives the correct amount of water.

Please could you give me your recommendation for the nozzle placement?

Is it scientifically proven that the WI does actually cool the charge air and therefore I should place the nozzle further upstream to allow it to cool the air? Or is it more important to ensure each cylinder receives equal amounts of water by placing in the runners?

It’s very difficult to find solid fact and data on this topic
Thanks very much

Dan

Snow Performance Response:

Dear Dan,

thanks for your inquiry.

According to a statement from the technical division:


I would recommend to inject right after the inter-cooler if he is looking for cooling. In a moderate Bar-application the water will evaporate before the IAT sensor.
So this shouldn´t cause any problems.


We usually only recommend a direct port set up if it is a high HP+boost application that is using the methanol as a fuel source and needs exact quantity's to really dial
in the fuel/timing tables.

Hope that answered your question. Let me know if I can help with anything else.

Kind Regards from Hamburg/Germany

Magdalena Skawianczyk
Sales

I'll post up responses from the other manufacturers, AEM, Aquamist, Devilsown etc. etc. if they reply

[JD]

Nice work, Danbob. That's very interesting. If it turns out that I've really overdone it in terms of my setup at least I'll have something to keep for a future build

[tubby_tony]

I use the Devils Own kit and asked the same question of them way back in 2008 (may have been earlier). I placed mine just after the inter cooler as advised.

[jimGTS]

i know everyone likes pictures, heres my setup.

if anyone hangs on the US forums, they will know of TexasAce, hes done alot of work with water/meth injection on the mr2 and his other cars.
on the mr2, he suggests just after the intercooler if using a single nozzle, so does TFS who i got my kit from.

[synXero]

How often does it run out?

[jimGTS]

hard to say as i top it up all the time. id guess 1-2 gas tanks to the full WI tank.

it is a weekend car, so does get boosted alot of those miles (its not a daily).

[2mad]

Depends on how far you drive, how long you stay on boost and how big the tank is.. could last a month , a week or a day if you track it ... its one of those how longs a piece of string questions .

[kev8611]

Since I am considering getting one of these I had a read through this and there is some interesting points.

Need to watch how I say it as the vultures will no doubt pick flies here but a good point was made regarding where the injector should be placed, I would think if its not placed before the IAT then the ecu will still detect high inlet temps and back off the timing resulting in loss of power? But isnt the whole point in water meth to reduce charge air temps? so what good will it be injecting it direct into a cylinder when the ecu has already pulled the timing? I am not saying this is incorrect, just making sure I have the correct advice before I go buy a kit and start instaalling it in the wrong place.

Also, Are carb manifolds an exception to the rule that inlet manifolds are not designed to take liquids?

Thanks

[Ryan S]

I think the general opinion is that you ideally need 4 injectors mate, 1 on each runner so each cylinder is getting the same amount of water, I personally don't think that's right at all, On the induction stroke the air is forced in, now unless one runner is smaller than the others how could there possibly be an uneven distribution of water? I say this at the risk of total meltdown by some members of course

edit: on the other hand it could hurt to have 4

[kev8611]

Yeah i was thinking that but by doing it that way the charge temps will still be high so the ecu will still pull timing resulting in..... just the same?

[Ryan S]

Yeah i was thinking that but by doing it that way the charge temps will still be high so the ecu will still pull timing resulting in..... just the same?

I don't think the charge temp would be high as there'd be water in with it, I do however think you'd get a totally wrong AIT reading either way, Chargecool it man

[kev8611]

Surely the only way the IAT will give an untrue reading is if its faulty? I mean if the charge temp is 30 degrees then its 30 degrees regardless of what substance is in it. Ueah ok mass etc needs taken into account but just for talking sake.

However if your charge temp is 50 degrees and the ecu pulls timing.... then you inject water, that doesnt seem right.

I would go a charge cooler but I think that still relies on good airflow and will still heatsoak to some degree

What a minefield lol

[Ryan S]

yeah, but your sensor would surely be soaked in water all the time?

I just don't trust it haha

[kev8611]

It will be injecting a mist i would have thought and due to the pressures that occur inside the manifold it wouldnt have much chance to build up on the sensors.

[Ryan S]

Ooooooooh, ok man, haha, I fear I've read too much about this, so much that the whole theory of it has put me off for life!!

[kev8611]

Yeah the way i see it, if single port (indirect) never done good. It wouldnt be on the market

I think I will have to think a bit more. Will be interesting to hear others views as there is good and bad from everything these days lol.

In the meantime, im gonna rig up a temp sensor so watch this space...... inlet temps through the roof haha

[Ryan S]

Interested to find out what your temps are