Two more reasons why these cars blow up
 

I had two cars tuned yesterday and it made me think about this again. One was single turbo with a vmount and all the right cooling upgrades. The other was mostly stock with just an intake, dp catback, and power fc. Vmount car held a pretty steady 30-35 degree C intake temp even after wide open throttle runs and dyno pulls. Stockish car had intake temps in the 40s and they would immediately soar well into the 60s after just one pull. Vmount car was running 16-17 psi boost, stock car 10-11 psi. It was a partly cloudy day, medium humidity, temperature in the high 60s. Anyone that runs more than 11-12 psi boost on a stock intercooler is insane in my opinon. Its just asking to blow up.

-Intake temp sensor- This has been discussed before but I don't think people realize how much of a difference it makes. Mazda put the factory intake temp sensor in just about the worst location possible. It might as well be an egt sensor. Once the motor is heat soaked, the sensor takes forever to cool down. Instead of reading the temperature of the incoming air, the sensor will read whatever temperature the heat-soaked intake manifold is. Further, the stock sensor is relatively slow to respond. The car heat soaks and the computer thinks the ambient temperature is warm, so it pulls fuel. You hit the gas and boost, the actual temperature air goes into the motor, and boom. I have seen this happen many times to customers who say they were sitting in traffic and then hit the gas when it cleared. Yes you can set the pfc of other computers to pull timing past a certain temp, but then you lose power. The solution is to move the sensor. The best place in my opinion is on the cold side intercooler pipe before the intake elbow. The intake coupler between those two pipes acts as a thermal barrier and helps preven the pipe and sensor from heat soaking.

-stock intercooler- In my opinion, Mazda might as well have not even put one in. The car would have probably benefited from the additional space in the engine bay for airflow. Aside from being way undersized, it sits right on top of the radiator and almost immediately becomes heat soaked. Any stock mount that sits on top of the radiator isn't much better. I want to laugh when I see so called "intercooler upgrades" that don't even have a duct. The best solution is a vmount, as then the radiator discharge points down and away from the intercooler.

I feel that these two issues greatly contibute to these motors popping. It is hard to hear pinging in a rotary. Most of the time you don't even notice it. It is minor pinging over time that can kill these motors. It doesn't have to be one good knock. just my thoughts.

I'd be curious to know if there has actually been a failure that can be directly attributed to the AIT sensor in its stock location.

Interesting, I always wondered how much of a difference my v mount really made. I have a pettit ecu so i dont know my inlet temps. Oh and its ducted like crazy... i might have gone a little overboard. thanks for the tips i guess i will try to move the sensor. got to do some research.

oh yeah the stock IC is the worst. I have a cheap Ebay SMIC and I see temps in the mid 30's all day long.

Sure. I blew a motor that way many years ago. Had full bolt ones and an M2 large intercooler. Car ran flawlessly. One day I was in traffic and the car became heat soaked. If I recall correctly intake temps were about 64 degrees C. Traffic began to clear, a few miles later I punched it and boom. There is no way the air going through the intercooler was still 64 degrees.

Vmounts make a huge difference if done right. This particular car has a vmount, power steering, ac, etc and never runs hot. Coolant temps have yet to break 95 degrees C on the dyno or in traffic.

Woah thats impressive. I would defintiely like to have my IAT moved when I bring it in. Thanks for the info.

I didn't know that v-mount allowed the car to retain both AC and PS. If I had known I would have gotten that in the first place.

After-market SMIC's can be very efficient with proper ducting. It does not take a rocket scientist to modify the stock duct to accomadate an after-market SMIC. The duct's that the Greddy and similar units came with are use-less, as all it is a flimsy metal plate. We are going to do a write up in the next few months on how to modify a stock duct to accomadate an aftermarket SMIC.

What is your opinion on using a v-mount for a daily driven car? What I have read on this forum is that a v-mount is not practical for a DD. IMO, a v-mount is over-kill if you are still running the stock-twins, a SMIC with proper ducting can handle it just fine. In fact, I have seen several cars in Japan, that have ran for years with a medium size single turbo and a blitz/greddy/re-a smic.

I think more important then the intercooler is the ducting to it and the any additional ducting you can provide to the radiator.

I've made custom plates to sit on top of the radiator to blow the discharge from hitting the intercooler. It is still a compromise but better that stock. V mounts work great if done right. This car you can cruise with the ac on and it does not get hot. I had to re-route some of the ac lines but it wasn't that big of a deal. I don't feel its overkill. A front mount will usually have longer piping which is worse for twins.

That makes alot of sense.

I wish to relocate my AIT sometime in the near future, im just too lazy to do it.

And also IIRC, the stock harness to the AIT wont reach to any other location unless you extend it right??

I know thats my next mod if i ever have to pull off the UIM which i hope not to do anytime soon. Car runs good now so dont touch it if its not broke right? lol

Bring me the car I will do it in a couple hours. No you will most likely need to extend the wires. Its 2 wires. Easy.

I am glad this thread was made.I was wondering why guys say that smic are a good upgrade when it still sits on top of the radiator getting baked by all that heat. I made a thread where no one responded asking if it was a good idea for me to relocate my radiator so it can blow downward like if i had a v mount while still using the stock intercooler.

Rotary Experiment Seven.Let me ask you,I am thinking of getting water injection in the future, if i replace the AIT to before the intake would i need install the W/I nozzle before or after the AIT?

and is it a good idea to get water injection even if i am not pushing 400+HP?
I am more concern with cooling and having a healthy engine.

sorry for all the question.

The water injection should be before the iat. Even moving the iat sensor to the elbow helps as its not baking under the uim. Yes it is a good idea on any boosted car regardless of power level.

lol ill def give you my business in the future, i know you guys are really good at these cars.

But i am also pretty mechanically inclined myself, i just hate diagnosing problems lol

If the IC was fully heat soaked, I'd say it is possible. I never give my car full throttle until the temps drop back down to about 40 C or less, it usually only takes a few minutes on the highway (I'm running an M2 med stock mount). At low speed, it will take forever. Regardless, good thread, I'm sure moving the sensor helps.

what would be an i deal W/I for close to stock car and what size (nozzle/injector)?

When I installed my GReddy SMIC and built a duct I also added heat sheild insulation to the bottom to reduce radiator hesat transfer.

Is there a reason why guys with smic dont relocate the radiator so that it blows down? even if you build a sheald on the bottom of the smic wouldnt it restrict the radiator fans flow?

It's because we watch our AIT's that's why, and the difference is night and day over stock. One WOT run on the stock unit and you'll see AIT's in the 60's. Not nearly the case with larger aftermarket SMIC's. With my old PFS I saw temps in the 40's after WOT( starting in the 30's). Now with my large ebay SMIC I stay in the 30's (also starting in 30's). Granted I went single turbo and it really is apples to oranges by comparing the two setups but its still a SMIC.

This is good information, I'm glad this thread was created.

hmmm...well i am bringing the car in soon, might as well have that relocated, lol

Yes. Various reasons: packaging, routing rad hoses, fabbing brackets for the rad, modifications to the a/c condensor brackets, modifications to the a/c lines.

Why do you think Vmounts cost so much?

With a little effort, you can reach under the UIM and unplug the sensor. No need to remove the UIM. You'll have to get an aftermarket (faster) sensor, or buy a new stock IAT, but you just leave the old one in place. It's only the temp probe that sits in the air stream, so it's restriction is negligible. A little wire, some solder and your done.

I relocated mine some years ago, placing it just down-stream of the IC outlet. If there was a down-side on my car, it's that in the spring and fall when it's cool, the car runs rich significantly longer. That's still true now, but especially when I was still on the stock ECU.

Sometimes I think it is all relative. I have been talking to an owner in Japan, trying to buy some parts and he said he has been running this setup for 4 years now, NO PROBLEMS at all.
http://i4.photobucket.com/albums/y12...rx7/noduct.jpg

Looks like the radiator has been positioned slightly different, but I believe it is the stock radiator and no ducting to the smic.

^^ Looks like he's running a single turbo, which makes much less heat than stock twins, both in the engine bay and in the intake tract.