How to dyno a TMIC per Mazda: put a fan on that sucker!

[SeanMSIII]

MS3 has dynoed 242hp/282tq, but needs a fan on the TMIC!

As some may have noticed, I've been pushing the idea that the MS6/3 are dynoing lower than they should b/c people don't make an effort to get cooling air through the TMIC. Most of the time there's just a single big fan out front with the hood open. This is fine for N/A and FMIC engines, but it's just blowing air across the TMIC. Anyway this is an interesting follow up response to a question I posted on Automobilemag.com about their neglecting to send any air through the TMIC:

An update on the TMIC cooling thing...

Mazda contacted us said that they've managed to get repeatable 242 whp and 282lb-ft out of their cars by using a ($1000) 50-mph fan blowing on the front of their cars, and a powerful house fan bungee-tied to the top-mount. Ouch, that's a lot of power!

The product development engineer who gave me those numbers knows his stuff... enough so to admit that the GTI's intercooler also wasn't getting the air-flow that it would at high speeds.

Again, our goal wasn't to get peak numbers, just to look at how differently the cars made their power.

Of course, I'll be curious to see how much MS3 buyers can get their cars to put down when they resort to all the old tricks - icing the intake plumbing, spraying water on the intercooler, etc. But that certainly wasn't our goal here!

Jason

And my response:

Excellent stuff. Thanks for following up with Mazda. And while I appreciate what you're saying about advantages and all, it seems to me that you gave the GTi an advantage since the fan was at least blowing through its IC instead of over it. A $1000 50 mph fan is not crazy expensive or crazy powerful and how powerful could a house fan be? My point is that this is not trickery to get max peak numbers. It's just trying to approximate real-world airflow as much as possible. I'll definitely run my first dyno with a box fan bungeed on the TMIC.

Again, I appreciate your efforts to delve into the totally different ways the GTi, Si, MS3 engines make power. Whenever, I step on the gas in my MS3, I think I made the right choice, but can easily understand how others will find that the GTi or Si do a better job for them.

I'm sure that the Mazda figures represent the absolute maximum possible in ideal conditions. Everyone else will fall short of that, but it shows that we should be using this setup when we do our own dynos. We need to get the shops to use more than just a single fan up front since this will not accurately reflect real world conditions for a TMIC engine.

 

[SeanMSIII]

I can't believe you all don't find this interesting. If not Mazda's confirmation that they dyno with a fan on the TMIC, then certainly with them unofficially releasing whp/torque figures.

 

[GS455]

I find it interesting, and I appreciate your indepth knowledge. I just read and dont respond, but keep up the good work..

 

[tsunami]

wow good stuff man... and impressive numbers "unofficially" released to

 

[BKK Jack]

I think it is interesting that any car would be dyno-ed with the hood open and without a fan powerful enough to approximate the airflow for whatever speed the car might be tested. I mean, shouldn't your hood be closed, and if your speedo indicates 60mph, shouldn't you have a fan in the front of the car blowing air at approximately 60mph? If not, you won't be able to do wind-fishies!

On an MS3 with the hood closed, isn't the air flowing across the TMIC anyway? I don't remember seeing any scoops in the hood. Is there ducting on the underside feeding air directly to and through the TMIC?

 

[SeanMSIII]

I think it is interesting that any car would be dyno-ed with the hood open and without a fan powerful enough to approximate the airflow for whatever speed the car might be tested. I mean, shouldn't your hood be closed, and if your speedo indicates 60mph, shouldn't you have a fan in the front of the car blowing air at approximately 60mph? If not, you won't be able to do wind-fishies!

On an MS3 with the hood closed, isn't the air flowing across the TMIC anyway? I don't remember seeing any scoops in the hood. Is there ducting on the underside feeding air directly to and through the TMIC?

Well, yeah:

A TMIC w/o a scoop or a duct would be a god-awful design. The duct it pretty cool since it's pulling air from the high-pressure area at the front of the car. A scoop on the hood isn't gonna be nearly as good unless it's high enough to be a real bird-catcher like the STi's. The downside is that it doesn't vent the heat in traffic like a hood scoop so is perhaps more prone to getting hot if not exactly heatsoaked when you're in heavy traffic.

 

[GS455]

I looked at one last night. Engine bay is really stuffed. I think the heatsoak will be the biggest problem here in the desert. I will figure out a way to leak the hood from the back. Keep on thrashing it Sean.

 

[SeanMSIII]

I looked at one last night. Engine bay is really stuffed. I think the heatsoak will be the biggest problem here in the desert. I will figure out a way to leak the hood from the back. Keep on thrashing it Sean.

Yeah, kind of a nightmare if you actually have to work on the thing. If you take the plunge, be sure to let us all know what tricks you come up with. You can count on me to keep digging into stuff. Can't help it, really.

 

[BKK Jack]

Well, yeah:

That is interesting and thoughtful work by the engineers. I guess that is why they are engineers. However, that doesn't discredit my original statement regarding hood open dyno-ing.

 

[SeanMSIII]

That is interesting and thoughtful work by the engineers. I guess that is why they are engineers. However, that doesn't discredit my original statement regarding hood open dyno-ing.

No, I agree in principle, especially regarding the wind-fishies. I think the cooling air part is pretty unsophisticated for the most part. I haven't seen anybody using variable speed fans or doing much real world approximation. I guess only the manufacturers can afford to do that since probably have to have a wind tunnel. The local shops just try to keep the engine from overheating.

 

[BKK Jack]

No, I agree in principle, especially regarding the wind-fishies. I think the cooling air part is pretty unsophisticated for the most part. I haven't seen anybody using variable speed fans or doing much real world approximation. I guess only the manufacturers can afford to do that since probably have to have a wind tunnel. The local shops just try to keep the engine from overheating.

I agree, my thoughts are purely theoretical, because not only do I not have such a dyno facility, but I also don't have, nor will I be getting the MS3. Mine will be the NA model.

Blowing up your engine on a dyno would be bad, especially since you are probably just looking for bragging rights, or checking the impact of that last mod. So in practice, I would open the hood, turn on all the fans available and maybe pack some dry ice in there a la F1. As long as cooling efforts are consistent across the dyno runs, the results should be relatively valid.

Enjoy yours. 47 more days until I get mine.

 

[Captain KRM P5]

we faced similar issues in dynoing our own TMIC replacement;

http://mazda3online.web.aplus.net/product_info.php?cPath=22_160&products_id=653

 

[Davenow]

I cant possibly understand why anyone would need to be told to open the hood and put a fan on a TMIC. They have been doing subbies like that since forever. I really question the quality of any shop not doing so.


Or am I missing something here?

 

[SeanMSIII]

I cant possibly understand why anyone would need to be told to open the hood and put a fan on a TMIC. They have been doing subbies like that since forever. I really question the quality of any shop not doing so.


Or am I missing something here?

No, it is bizarre, but that is exactly how the shop that Automobile mag took it to do did it, and also how the vast majority of MS6 owners dynoes were done, also.