Water Injection with boost and IRTBs
 

I plan on building an FI system with a T25, IC, WI and IRTBs (from a GSX-R750). I have laser cut manifolds that I CAD designed for the intake and will be welding the exhaust and intake together myself. The intake manifold will have injector mounts where it does on the OEM one and the IRTBs have injector mounts also. Originally I was going to use a two stage injector system but as I need to do the wiring for fully sequential injection still I did not see the point.
Can anyone point me to a reliable source of WI information about nozzle placement? The only stuff I've found is for business selling kits and they suggest putting it where they say as they have race proven blah blah blah. Neutral/impartial sources seem to be no where on the net. I do not mind buying a book from such a source as that would be genuinely worth it.
What I would like to know is if I manage to put a WI nozzle in where the OEM IRTB injector goes will that provide good homogenisation with the mixture? The IRTB diameter is 42mm (at the plate), has around 100mm to the engine block and 80mm to the fuel injectors.

What you have described is an ideal location.

your picture will work just fine

Is the red indicating a coupler? if so I would just wonder about the meth possibly eating or hardening your coupler possibly, unless your just using water. Ive never run WI so Im not sure of this but just figured I would toss it out there.

there would be minimal contact so he would be fine.

Well if I get the sizing right the IRTB end 52mm OD will fit into the stubs on the manifold part so wont touch anyway. Don't worry it will all be internally smooth :)
Cheers guys looks like my build is gonna be proper fun. Gotta source some nozzles now then.

you know, you can use fuel injectors to spray methanol/water. its a win-win. my buddy is doing it on his evo and he basically made second fuel rail for water/methanol that goes before oem fuel rail.

um what about the rust issues urban did he source stainless injetors?

Fuel injector cannot be used for WI unless they are regularly replaced as they need to not rust. I know someone who has been doing it but runs a scrapyard so just yoinks injectors for free every for weeks when they jam open or closed.
I'm guessing he must be using a very high meth:water mix otherwise the rust problem would be bad.

One thing to consider, WI significantly cools the charge (which is why we do it, right?). If your engine management is using inlet air temps for some of its functions, it will be seeing a higher IAT than actual if you inject downstream of the IAT sensor. In other words, you'll be safe (spark retarded, etc.) but not as optimized as you could be. Most ECU algorithms (i.e., MS) are designed to monitor IAT prior to the throttle plate as a partially closed throttle plate also lowers temperatures due to a pressure reduction.

p = rho x R x T

IAT is not a calculation on my ECU it is premapped adjustment.
The WI will be driven from my ECU as well so it can be mapped appropriately using the PWM valve discussed in another thread.

My ECU has the brains of a MoTeC so nothing is calculated, everything is mapped. I have less outputs than the big boys though so I'm not sure if I can run sequential injection for both the fuel and water injection. I'll have to contact Dave about it.

yeah i have no ait correction on my MS setup as well i basically measure ambient anyway as mine isnt even in the intake stream. Like RJ said that is why we have maps.

Sequintial WI is way over kill dude. Unless you are planning more than 300 whp i wouldnt even recomend progressive to tell you the truth. Simple works best when WI is concerned.

IRTB's

I've heard of ITBs which is common aberivation, but not till I got my miata and was looking at various intake stuff did I see IRTBs being used, whats the R stand for?

most people say racing lol but obviusly its not. It stims from the only makers of itb kits calling them Racing most likely becouse they are not carb o.e and all the cali fanboys and smog reps hate em. :pitlab:

Thanks, I figured it was that and was likely caused by just some company using that name and it caught on in the miata community.

I thought it was "Individual Runner Throttle Bodies".

IRTB stands for Individual Runner Throttle Bodies.
ITB is the incorrect abbreviation to use for a total intake system as it is missing the one CRUCIAL letter. Individual Throttle Bodies is a complete misnomer, its like having instructions in another language you know what they should be for but can't be sure because you have no information.
Anyone using the term racing with their IRTB kits should be steered well clear of.

Why use WI in single stage when my ECU will output it without a problem? I can do it precisely using PWM valve for each cylinder whether thats batch injection or sequential. Single stage or double stage may be the best option for kits on the cheap (and have been proven to be better than progressive) but I can get the parts for way less than a devils own kit or something and it will be WAY superior than any kit any aftermarket supplier unless I go to a race engineer.

its just more hassle than its worth setting it up. But if you are set on doing it for he hell of it go for it. WI is easy you need
1 pump
some lines
a few wires
a resevior tank
a activation switch ie boost toggle whatever
and a nozzle that is it
Lines are cheap
wires are cheap
nozzle is like 20 bucks
and the switch is 15 dollars or so off ebay or if your ecu can output a 12v signal you dont need one
the tank can be anything that is relatively fuel stable i used a 1 gall gas can to suplement my setup. Like anything else the kits are made to cater to newbs. and the price reflects it. bottom line 150 bucks and i could WI most any setup.

Its not really more hassle when everything is off the car and in my shed for building :)
Plus I should be using a pump, a reservoir, 4x checkvalve, 4x PWM solenoids and 4x 50cc/min nozzles plus the lines and wires for connections. It should cost $250 (US eBay mostly) in all and I will have a WI system accurate to a few drops per combustion cycle as well as having that same variance across 3 boost maps for different driving. If it that ain't worth a few scratched knuckles what is :D

My only other concern is failsafe like ZX so I'm thinking maybe a 1gph separate methanol injection triggered by lack of flow but thats for when I get track heavy after all this fun and frolics.

cool i look forward to the results man