Alright, I did some datalogging with my newly set up AI system, and I thought I'd share the results so far.

This was previously in this thread: https://www.rx7club.com/2nd-generati...d-mod-1003503/

This is a 1st-2nd full throttle pull (~4 seconds WOT) with the hybrid and no AI.

AFM temp wasn't logged on this one, but initial IAT is 38.1ºC/101ºF. When I let off near the top of 2nd gear, IAT hits 56.3ºC/133ºF. So we have a 32º degree temperature rise in the span of 4 seconds.



This is a very similar 1st-2nd full throttle pull (~4-5 seconds WOT) with the hybrid and AI spraying. It's a 250cc nozzle, but I measured flow at 400 mL/min. It's supplied by a 200 PSI pump, so the nozzle may be rated at a lower pressure.

AFM temp is at 46.3ºC/115ºF and IAT is at 45.6ºC/114ºF initially. At roughly the same RPM/time point, IAT has DROPPED to 43.8ºC/111ºF, and then afterward goes up a little to 46.2ºC/115ºC.

So the end result is a basically zero temperature rise at the IAT sensor with AI versus a 32º increase without it. Ambient temps were at about 80ºF for both runs, so the AFM temp is clearly skewed a good amount due to the metal body heating up.

 

awesome logs. are you spraying pre turbo or post turbo?

 

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Yes, 100% water post-intercooler. This is 12 psi peak tapering off to about 10 psi on a T04b V-trim hybrid. The AI system switches on at 7 psi and is not progressive.

 

How much power are you making?

I'd be curious to see how the temperatures stabilize after a pull with 100% methanol compared to 100% water injection, as well as a 50/50 mix. Is that something you feel safe doing? If not I can always do it once I have my car set up :P I'd also like to see how the temps fluctuate under load, or a longer pull (3rd or 4th gear.)

Also can you explain why you put your nozzle in the intercooler instead of before? I was assume having it earlier in the intake stream would allow more time for it to pull heat.

 

10-12 psi on a V trim hybrid, stock ports, I'd guess around 285-300 whp.

There are only 2 places to inject water/alcohol. 1) Pre turbine 2) post IC

There is no point in injecting pre IC unless it is Pre turbine, because all you're doing is decreasing the (already marginal) cooling capacity of the IC core because it works off temp differential. At least injecting post IC you are cooling the intake charge beyond the max cooling capacity of the IC.

Some people are concerned about the potential damage water droplets could do to their comp wheel (although I would argue that if your droplets are that big your AI system is poorly engineered) or the corrossive effects of alcohol (above 50% Mixture). Nonetheless it has been proven effective. But that is another thread entirely.

Thanks for postings results RotaryRocket

 

It will hopefully get dyno'd sometime soon; I want to dyno tune it instead of doing 2nd-3rd gear pulls on highway on ramps. There really are very few options here in SD. But I do know I'm logging more airflow than Solareon did in his 324 whp dyno run: https://www.rx7club.com/rtek-forum-1...-2-1-a-884773/. His AFM tops out at 880 kg/hr at 5668 RPM, and I consistently see 903 or 925 kg/hr by about 6000-6500 RPM. Now I don't know how different one AFM is from the next, but the numbers would suggest I'm in the ~300 whp ball park too.

100% methanol is not suggested. I think just about any kit you buy will have warnings that the materials are not rated for use with pure methanol. 50/50 mix is what a lot of people use, since it still has most of the cooling capacity of 100% water, but methanol will combust & potentially allow for more power if tuned for it. Too much water can cause ignition break up, but the stock coils seem to be taking well to 400 mL/min.

Tuning is very different for 100% water vs. a 50/50 mix. To switch back and forth and take full advantage, you'd need a couple different maps to load. Besides, a methanol mix would have a lower boiling point, which would mean more of it would vaporize before reaching the IAT sensor. I'd expect the IAT measurements to be the same or better even though the actual cooling capacity of is less than that of 100% water (equal volumes). Those spraying 50/50 mixes will increase the nozzle size. There's a lot of info on this on the coolingmist forums.

Pre-intercooler injection would reduce the amount of heat the intercooler could reject (as sharingan mentioned), and most of the action happens in the combustion chamber anyway. EGTs would be the best way to monitor the effectiveness.

 

any pics on nozzle placements

 

Thank you for the information, I have taken a peek at coolingmists forums, but it's just so much to read and I dont have the time to sit down and read it all. It's nice to come here and get the info here and now instead of reading 50 pages worth of material with lots of controversy in between.

 

The water solenoid is in the foreground, and the nozzle is in the black 90* holder on the endtank. I said it was 6" from the outlet before, but it's more like 3".

 

Was maxing out my 20B AFM at just over 300whp as well. I have some logs of it flattening out around 7,000rpm. Very smart move on the WI, especially using the TMIC. Turn the boost up a little bit if you have the injector for it. Are you using the S4 or S5 tmic?

 

I'm very interested in this question.

Also, there was a thread that had pictures of a number of TMIC's asking which was S4 & S5. Shame on me for not subscribing. Anyone that can provide a line, it would be much apprecited.

 

This one?
https://www.rx7club.com/2nd-generati...olers-1001642/

 

S4 USDM. The S5 versions have a little larger transition from the inlet to the core. Mine has the AWS and ASV hook ups on the end, but I cut them off in an attempt to mount the nozzle there. The nozzle holder hit the top of the TMIC, so I had to relocate closer to the IAT sensor.

I do intend to up the boost to about 1 bar, but I wasn't going to go any further until I had the AI set up. Without it, IATs have spiked as high as 180º F, which is also why I have the mixture at 11.0 AFR or lower temporarily.

I'll post up some longer logs with highway pulls when I get a chance to do them. I'll also be measuring pressure drop across the TMIC by moving my boost gauge hook up to the compressor outlet.

 

That would be it! Thanks, and subscribed now.

 

welcome to the AI world, been running mine since i forget when. nice having peace of mind with IATs holding steady even under heavy loads. especially a good idea with the stock heat sponge of an intercooler.

 

RotaryRocket88,

What AI kit are you using? I am still undecided as to what kit I should purchase...I am trying to get it at or under $300 I have already exceeded my budget, but I NEED it if I dont want the engine to blow...

 

It's a basic Devil's Own kit with some modifications.

1) Solenoid instead of check valve
2) 40um sintered brass filter post-pump (McMasterCarr)
3) Cooling mist "clog switch" between the filter and the solenoid/nozzle


I have a couple fail-safes in the form of 2 LEDs that tell me when the system is powered and if the clog switch is no longer seeing pressures above ~100 PSI. Also, I may eventually end up with an EBC, which will be powered through the same relay as the AI system. That way if the system loses power, boost will drop down to WG spring pressure.

It's great peace of mind. Now I just need to dial the fuel back a bit and up the boost to extract some more power.
__________________

 

This is what I will be doing. Even though I am not running a huge turbo and large amounts of boost, I plan to slowly increase boost while playing with the tune. I want the AI there in case I pulled too much fuel. Granted a bad tuning mistake might not be saved from AI, but if I can chip away at it, I think I will be OK.

 

^ Bit by bit is the only safe way to go.

I did some more logging, and I thought I'd post it up. This is downshifting into 2nd gear, and then taking 3rd up to about 80 mph/6100 RPM. Ambient temp is 75F.

Temps are at 53C/128F as I get into boost initially, and they then drop to 45C/113F once I get into 3rd. By the end, they're still only at 48C/118F. It doesn't really seem to matter what I do; intake temps are rock solid at around 115-120F.

 

Nice piece of mind, especially w/ the smaller s4 IC. This thread is full of useful info, prepare to add another line to your sig

 

I would not suggest injecting before the turbo, one thing you do not want happening is the compressor wheel spinning at 40,000 rpm hitting little droplets it causes water erosion of the tips of the flutes. There are pictures and thread around showing brand new turbos with trashed compressor wheels from pre turbo injection. I am about to add injection at the intercooler inlet because I have read that the mist helps lower the coil temps and help with heat soak as well. As mixture goes, most people just use the blue cheapo depot windshield washer fluid.

https://www.rx7club.com/2nd-generati...amages-935311/

 

great thread / info. thanks

 

I need to bump this thread. I just bought a coolingmist water/aux injection kit, and I have NO IDEA where to mount the pump and tank. The pump is pretty big, and doesn't fit too well anywhere in my engine bay. I could put it behind one of the seats, but then it's all exposed. I'm really not sure where is a safe place to mount it. Any ideas?

 

Coupe? You could stick it in one of the storage bins behind the seats. Water lines could be routed along the transmission tunnel up to the firewall. My pump is next to the washer fluid tank, the filter and relay are tucked inside my airbox & the pressure switches are by the charcoal canister.