My car is running at 12-15psi depending on the gear. After a couple of hot laps, it seems limited to 8psi. Is this because of heat soak? They are BNR S3 twin turbos with a stock mount intercooler.

My water temps stayed under 78 degrees the entire time as well, usually between 73-75C.

 

Jesus, that much boost on BNR's on a stock IC? I think you need an IC!

The PowerFC, for example, will retard timing when intake air temps climb. I'm assuming you're running something like that. Your intake air temps are probably through the roof. Retarding timing will decrease power quite a bit. I'm not sure if something will dial boost back, but it's probably good that boost is dialing back.

If you're stuck with the stock IC (I see you're in Cali and I know a lot of Cali guys have to do what they can due to CARB and whatnot) you may want to improve ducting to it and look at adding water injection to help intake air temps.

Dale

 

Is it an OEM IC, or an aftermarket SMIC? That seems not clear from the description.

 

I have an SR Motorsports SMIC that has been widened. It's pretty similar to the greddy one, but still just marginally better than stock I think.

I just went around and measured my IATs, my gauge says around 63C driving around, and after parking for a while it went up to 80C!

The next step for me is a vmount, but I have another track day coming up. Would it be safe for the engine to run the car again with these IATs and just take it easy on boost? I am using an adaptronic select ECU.

 

Wow, that is pretty hot! I typically see intake air temps in the 40's with my front mount. You may be able to get the temps better with good ducting.

Also a fast acting intake air temp sensor can help.

Dale

 

any recommendations on a diff air temp sensor? and do you think it should be moved or is the stock location ok?

 

Not sure who all is carrying the fast air temp sensor kits currently, just Google around. Best is moving it but just using the stock location is 80% of the benefit IMHO.

Dale

 

 

Don't swap out the sensor without retuning or at least checking the tune.

 

One thing that can happen as things heat up is a collapsing inlet duct. Common fix is replaced compressor inlets with wire reinforced ducting from mcmaster.

You can do a cheapo air intake temp sensor kit yourself. Get a Triumph motorcycle intake temp sensor and a Bosch injector connector from an old Volvo at the junkyard. The sensor has a similar ohm/temp curve as the oem. Put it in the TB elbow or IC outlet. Or buy the kit.

I'm gonna guess you have inadequate ducting on your IC. In that case you could get those temps down without spending much money. Do you still have the intake/battery/AC dryer stealing air from the IC duct? That and the recessed inlet of the duct are the main weak points.

For comparison I've got stock twins running 11 psi and I don't see 60C unless I leave the hood closed at an autocross in between runs in grid. Typical around town temp is 40/45C. Modified the ducting on mine. Stock Mazda intercooler.

 

Here is how it looks under the hood...do you see any glaring issues or suggestions to changes?

 

Yes. Immediately plug that hole to the old battery tray and the hole that used to lead to the stock intake box. All the air that leaks out there should be going thru the face of your IC. Hard to tell, but it doesn't look like the entire face of the IC is covered by the duct.

 

Shall I create some sort of lining to go around the duct to seal it to the IC? Or is there some reason not to do so?

 

Sealing to the face of the IC is the least of your problems. Plug those holes.

 

Think of it like this. You want to force as much air over the intercooler as possible. So, you pressurize the inlet and make sure every ounce of air goes over those fins.

To pressurize the inlet you can extend the ducting into the bumper opening with some aluminum. The stock duct is incapable scavenging air from the bumper opening.

Here's a link to my thread with pictures of my ducting if you're looking for something to reference. I used aluminum sheet to block off the other openings and caulked the joints from inside the duct to seal.

https://www.rx7club.com/3rd-generati.../#&gid=1&pid=3

Lots of low hanging fruit on your setup. Good luck either way you choose to address it.

 

+1

Also, do you have the 99 spec rebar? That intake is meant to draw cool air from the opening behind the license plate. Without the 99spec rebar and air guide that intake is less effective.

 

I do have both of those pieces luckily! I am using a 93 undertray though

 

Any competent tuner will set the ecu to pull timing (and limit boost if the ecu is capable of it. The power fc cannot)) if certain parameters such as intake temps exceed a set threshold. 60C is hot. I personally won't even get on boost with those temps. You're asking for detonation. Any stock mount, regardless of size is going to have a difficult intake temps down. Because it sits directly on top of the radiator discharge, it heats up and never cools back down. Its a horrible design. If you add meth injection you can get away with it. Ideally you want to move to a vmount setup. It would also be a good idea to get a fast-acting intake temp sensor so you can see the temps in real time. The stock sensor takes forever to respond. This being said, it looks like something such as a solenoid is getting hot and acting up, defaulting you to wastegate spring pressure.

 

Thanks for your detailed reply. I am using an adaptronic select that was tuned recently. I have a track day coming up end of may and probably will not be able to install a vmount or my single turbo kit by then, and I just removed meth injection because it was causing tuning issues. I'll be doing what I can with ducting and pay closer attention to IAT's and not give it full throttle over 50C, would this be a safe plan?

 

Since you have the "meth" system I would try running straight water with a small nozzle, which shouldn't cause any tuning issues (maybe expose a weak ignition system) and will provide some relief to your engine/IATs when running hot.

If you don't want to do that at least you could rig the system to spray water on the outside front of your intercooler.

That stock mount lower IC intercooler inlet piping can get pretty pinched and get even more pinched when soft/hot because its a close fit to the engine front pulley- any better pics of the pipes/couplings used there?

Just plugging the battery box hole and cross-over duct to the stock intake on the IC inlet ducting will help your IAC a huge amount lapping the track. I made a plug of soft foam for the battery box hole and used tape for the airbox cross-over.

 

Also check the rubber primary turbo inlet hose. I've seen them collapse under load with high heat.

 

Keep the stock mount intercooler and add water. I am running 15 PSI on my stock twins with a Greddy SMIC and my intake air temps are low 30s max when running the smallest jet in the AEM WI kit (250cc/min). Perfect. Check out this video to see a shot of the engine bay and the track performance to get an idea.

 

^Very nice! Thanks for sharing. I especially appreciated the sound of the engine (or lack thereof) from inside the cockpit. Good stuff mate! And very sound advice re: SMIC location & modest WI combo!!

 

I also have SMIC and WI, injecting near where you installed your nozzle. But if you're still reading IATs from the sensor's stock location under the UIM, the readings are likely skewed by the water.

 

Perhaps but I have tested the SMIC with the water off and those temps climb above 50c, so I know it's working as advertised.