olddragger

iTrader: (3)

I am FI with the Pettit kit.
results was from dyno with runs without and runs with it on. It is a progressive spray tied to maf voltage. The hp lost was after 6K rpms.
Ambient temps do not matter in regard to the w/m affecting the tune as my iat is before the nozzle. I am not tuned for w/m and do not want to be. We have too many valves in the intake etc etc to really fine tune for w/m injection. That would be messing with dynamite imho.
never inject water or water meth before your iat on a maf tuned engine.
I did not log EGT. My lead max timing is very conservative at 14.5 and i am running a little rich at 10.9 on an innovate a/f gauge. This is during the accelerator pump stage part of the map then it leans up to a 11.2--11.4 range. I am tuned for as much realibility as we knew how. The timing split is at the oem 5.
Intake temps were less than 100 maybe a tad over at times.
Pump 93 unleaded with ethanol crap octane gas.

I dont want to hyjack this thread with all this, but my point is that water injection or even w/m injection will allow you to run 87 octane gas if you want to. It will help with keeping deposits down (this is proven--even BMW is considering using it on its DI engines), and it does have the ability to increase gas milage. Just look at the desiel trucks and what they are doing about their mpg with it. Lean burn should be possible also with it set up correctly.
I dont think I would run it all the time though due to lubrication issues.
interesting thread

Nadrealista

IAT beeing measured before the meth nozzle is probably why this is not working as well as it could.

ECU is setting fuel and timing for XXXF IAT while actual IAT is probably good 30-50F cooler..if you could substitute IAT signal to ECU from secondary temperature sensor located post meth nozzle you would be in business.

Highway8

iTrader: (11)

That is only true if IT are well above ambient. If your intercooler is doing its jib, IT won't be too high and your only chance to make more power is from running a more agressive tune.

But this thread us about NA water injection and the only real benefit is from lowering EGT's and extending engine life on track cars.

Nadrealista

IAT will always be higher that ambient even on NA car. With water/meth injection you can get well below ambient temps.

For example on a hot summer day ambient is 95F, NA engine would probably see 110-120F..water meth comes on and knocks IAT down to 60F..so in the hot summer day your car is running like it is cool spring/fall day, definitely making more power than you would with IAT of 110F. it essentially makes back the power you would loose due to the high heat and heat soak.

I also own twin turbo Audi S4 with W/M injection and here what it IAT looks like when the meth is running. IAT dip well below ambient(which was around 22C that day) even on FI car:

olddragger

iTrader: (3)

not true in our cars man --because the iat sensor is measuring the air BEFORE the water vapor cools it. The pcm never sees the cooling benefit of the spray. I dont know of anyone injecting before the oem iat sensor with the RX8. Since ithe iat is part of the unit that also houses the maf--if they did the vapor would really mess with the maf readings and that would not be good.

Nadrealista

I understand that part as I stated in my post earlier.

My question is it possible to separate MAF and IAT signal - they must be sent via separate wires from MAF to ECU? Put secondary IAT sensor into intake manifold past the location of the W/M nozzle and send that IAT reading to ecu instead?

Highway8

iTrader: (11)

IAT on a na car is at or within ambient during wot as long as your pulling in fresh air.

Brettus

iTrader: (2)

Had mine separated for 3 yrs .

https://www.rx8club.com/series-i-do-yourself-forum-73/diy-iat-sensor-turbo-164751/

Nadrealista

are there any IAT logs of repeated WOT runs on our car?

neit_jnf

if you tune for it, with AP or whatever, and adjust the fuel and timing to be more aggressive then the water injection will show more benefits. stock, you'll probably lose power but it'll help lower combustion temp and it also keeps the engine nearly carbon free.

you don't need a complicated system, you could get a simple vacuum or gas pedal wot switch activated constant system with about 200-300cc nozzle.

RIWWP

iTrader: (2)

These points are why I'd really like to figure out a W/M setup for my 8. Not aiming for tune or power gains, just simply "a clean engine".

A question though:
Does anyone know of a system that is easy to hook up and remove? So for example, you bring the stuff out to your 8 on a saturday morning and hook it up, blast around and have some fun for a bit, get back home and remove it.

I expect that you don't need to have it actually injecting more frequently than "periodically" to obtain the benefits, and having an easily removable system would allow people with warranty concerns to "keep their car stock".

I was discussing this topic a week or so ago with someone else who started out adamantly opposed to the idea of w/m at all, for any reason. So I "scrapped" that idea and started back with "periodic seafoaming". And explained the reasons why it doesn't really work, and what you could do about it, and every alteration or suggestion he made brought us closer to a metered and controlled w/m injection setup.

I mean, you can pull in seafoam, water, whatever and let it sit. But we are pretty sure that does nothing. You can have the engine running and use vacuum to pull it in and burn it instantly. But that probably isn't much better since the vacuum is pulling it in large liquid quantities, not atomized. And then there is the issue that the intake valving is all before the service ports, not after, so there couldn't possibly be a benefit there. So moving the source to pre-valving would at least give a chance for any benefit there. And even if you do that, you can't put enough load on the engine to get all the valving to operate while also in a situation where you are feeding whatever liquid into the engine via a tube (unless you have a personal dyno). So pre-valve injection, controlled by something other than you so it can inject while you are putting the engine under load, and something that is atomizing the liquid. Basically a w/m setup.

But everything I've seen of them it's a fairly involved installation / removal, not something remotely temporary.

Brettus

iTrader: (2)

I did some experimenting with straight water injection (pre turbo) on my car recently . I wasn't sure if i was going to retain the system or not so i just direct wired it to the battery through a pressure switch and then to the pump . I held the pump in place with duct tape .
Would take less than 10 mins to install and even less to remove .

Go for the smallest nozzle you can get - mine is about 150cc s .

Brettus

iTrader: (2)

https://www.rx8club.com/showthread.p...36#post1580936

olddragger

iTrader: (3)

running the water injection every now and then would be ok--this engine can take a LOT of water while driving without any ill affect ( except you may need to do a uoa. I mistakenly left my setting on megaflow banzai flow and used 1 1/2 gallons in less than 15 miles of in town driving!
Engine never skipped a beat--it was not injecting at idle.
I did change my oil--just in case lol.
Sparkplugs will also look better.

Nadrealista

if I am reading your chart correctly IAT will rise with consecutive runs as I expected..OEM IAT sensor location is not well suited to show this due to its location. we have rather long intake manifold and I am sure it transfers quite a bit of the heat to air going trough, not to mention that we have coolant running trough our throttle body. Which reminds me that I need to do the by-pass mod.

olddragger

iTrader: (3)

I used to think that too, but there are times when the intake manifold doesnt really warm the incoming air. The air is moving too fast to absorb it and there is a protective boundry layer present within the runner.
Monitor your iat and then give the engine more throttle. The iats will drop fast. You dont have to give it much throttle for this to occur. At idle the iat sensor will heat soak.
Trick question--is the intake charge traveling faster at wot than at idle? Think about it