ya sames pot as mine.

https://www.rx7club.com/showthread.p...44#post8959444

guess its not the sensor.

its the position of the jet.
AITs are largely effected by the pre-compressor jet cooling the air as it is super-heated by the compressor.

I always thought of it like this...

Pre comp injection increases the density of the air coming into the compressor and makes it that much harder to heat (it is heat resistant so to speak), as such the air exiting the compressor is not nearly as hot as it would be sans water injection.

This also totally discounts the evaporative cooling affects of the water, which more recently have been proven to show temp decreases.

My ideal system would spray water pre comp, a little methanol right after the compressor (for charge temp cooling prior to the IAT sensor) and a little more water into the lower intake manifold (one tiny jet for every runner).

You would have to run two pumps, one for methanol and one for water, but you would get max benefit of each chemical. Some time when the economy improves I will get back into it and start building some crazy systems.


Nick,

How is everything holding up? Are you driving the car much?

i drive her everyday! I just went down in turbine size. I was at a 1.24 and I'm now at a .96. The car reaches full boost SO FAST now. It's fun. But now I have to install my boost controller. The 9 lbs spring is almost useless... She wants to jump to 15 psi. Time for more tuning.

I can't wait for you to get back into the AI game Brian, your set up was pretty sick. I've never seen a system like that. the low level sensor, the injectant volume gauge... it was done right.

I always wondered how that 1.24 really performed. Alot of guys really advocate the large large turbines and housings, but I wondered what kind of spool you're really sacrificing.

Did you notice any rise in EGT's with the smaller housing? Or any other changes to note?

I've seen a very slight increase in EGTs... but I am kinda staying out of boost until I fix an exhaust leak and tune a little more.

The real issue for me is, my entire turbo system was designed for high boost... I have 2.5" runners off the exhaust manifold, 3.5" exhaust... so the 1.24 (or maybe a 1.15) would be ideal for mmmm 25psi.

I am only running 9psi.

Since I am slowly climbing the boost ladder, that large of a turbine was hurting performance at this point.
I wonder how it would've done, though, if I'd opened up the turbo like it was meant to be. Ya know?!

EDIT** BTW, I was hitting full boost with the 1.24 at like 45-4800 (9psi). Now it's too fast to tell hahaha

My t04e spooled to 15 or so psi with the 1.15a/r at about 3800rpm.

i really wanted to try the 1.15, but all Elliot had available at the time was .96.

I think I had higher compression rotors than you though too, and a much larger exhaust. Did you have the 13bre or rew rotors?

i have the S4 rotors, and 3.5" exhaust. Was yours 4"?

No mine was 3.5" ... I was remembering your old DP then. You must have changed when you went to the t04e.

The rotors definitely were helping my spool, if I was to build the engine again though, I would go with the S4 rotors for safety's sake. Probably would have saved my engine.

i thought you had a 4" for some reason. I did change with the T04e.
What were the specs on your exhaust manifold?

I have 2.5" runners and wonder how that effects spool time with lower boost.
I was surprised to see your engine go from over-boosting. I thought the AI would save it...

Not at 30 psi... AI can only do so much. The boost went so fast that there was really nothing that could be done. Full throttle at 8psi...WG line fails...pop! 30psi.

I verified the AI to be functioning properly. I guess we know that because without it, it would have popped at about 20ish psi.

man... 30psi. I would like to hit 30, but intentionally!
So that was a silicon line? what advice do you have for me, about to install an electronic boost controller?

very tragic about your motor, and i'm sorry. but that must've been a hell of a kick from 8 all the way up to 30psi!

Nice setup again stylE, you've changed my mind about the pre-compressor jet, i've got an M2 on order right now.

Has anyone ever seen the push-on type plastic AI lines fail?

Cosmos motor was a huge surprise everyone that's followed his FD. I honestly wasn't at all surprised to hear he went v8.

Glad that you decided to try out pre-comp injection. I was stoked to see it work so well.
I've heard of the push on lines, but never seen/experienced them. Are they the same ones people use for fuel lines too?

I have never seen them fail, I had used push-loc teflon line they are good to like 500psi, but the failsafe for this is some sort of flow sensor. When an AI line fails it will either flow too much or too little. If you set a parameter with a potentiometer that controls the AI, and it falls outside of range, you can cut your boost controller and fall back to wastegate pressure. That is the best method I have seen for those who are tuned to run on the ragged edge with AI and that is what I had on my car.


The silcone line didn't fail. The banjo fitting on top of the wastegate came loose. It was the second time that happened. I was lucky the first time...not so much the second. The funny part about it is if I had driven more in boost I would have noticed it not holding steady and went to troubleshoot the problem. As it was I was never in boost and so when I did go, the line not being attached was a big surprise.

At 6-7000rpm in 2nd gear, you go from 8 psi to 30 in like less than half a second. It was like instantaneous. My gauge went red, I let off, didn't matter... the peak hold on the gauge was just over 2 bar.

I would do an fittings into the wastegate, and I would use some sort of high temp locktite. I can't link to the thread here because it is over on another forum, but if you want to see the proper way to run wastegate lines PM me and I will link you in.

I now have a FMIC!!!! (with AI)
I have left the world of chemical intercooling only.

Here is what I can take away from AI only:
It works great for low boost, 10 psi and lower.
There is a great boost response with AI only.
Cruising (non-boost) temps are hard to control when the ambient air temp is 95F or more.
Boost is more unpredictable with AI only. It jumps up in psi hard, and is hard to control boost with the right foot.

It was fun to run AI only for a while, but it's a little stressful to wonder/worry about the set up. Now there is a little more of a fail-safe and my temps all around are down in the summer. Also I want to go up to 20 psi, so I welcome the FMIC.

More later with pics and temp differences.

https://www.rx7club.com/attachment.p...6&d=1251748373

https://www.rx7club.com/attachment.p...7&d=1251748373