04

The Great ARK Design FR-S / BRZ Super Exhaust Shootout, Part 1

by Mike Kojima

The FR-S/BRZ twins are proving to be somewhat difficult cars to tune.  The FA20 engine is in a pretty high state of tune from the factory with a very high compression ratio and a lot of eletronic nannys.  It is hard to get the car to consitantly read power on a dyno to where you can accurately measure a gain of 5 horsepower or so.

At MotoIQ we have a formula for dynoing an FR-S/BRZ.  Fill car with 91 octane or the best fuel you can get in your area.  Drive the car for around 10 minutes to warm it up well.  Strap the car down on the dyno, monitor the engine with an OBDII scan tool, start it up and run it at low load in 4th with the dyno fans blasting until the coolant temp stabilizes.  Run the car several times until it is consistent, allowing the temperature to drop to the point where the radiator fans shut off before starting another pull.  This is also important so the oil temps don't get very high.  Whew, now you can do a baseline.  Repeat after every change.

So since we've learned how to dyno the FR-S/BRZ the hard way, it is now time for us to compare several exhaust systems from ARK Design.  ARK Design, proud sponsor of the Team America Time Attack team is a manufacturer of exhausts, intakes, clutches, wheels and electronics.  We have reviewed several of their parts before and have always been pleased with the results.

ARK Design makes 3 high quality exhausts for the FR-S/BRZ twins.  The three exhausts are tuned to please everyone from the picky daily driver to the hard core street/track guy.  ARK Design makes the Road Spec exhaust for those who want a mellow exhaust that is not too loud and with styling that matches the stock car well.  The Super Flow exhaust is for guys who want the highest flowing exhaust, like people running forced induction, having internally built engines or Nitrous.  Finally, there is the Racing Spec exhaust for those who want light weight, low backpressure and who are not too concerned about noise level.

Three exhausts, three different types of anticipated end use.  How do they stack up on the dyno?  Read on and we will find out.

 

The ARK Design Road Spec exhaust is super well made, Tig welded from 304 stainless.  In an age where many of the big brands are cheaping out by using 409 or lower grades of stainless and ugly robotic Mig welds where you can't see in the name of price competitiveness, it is nice to see an all 304 fully polished exhaust with old school craftsmanship.  The Road Spec exhaust uses a large volume reverse flow muffler can which usually does a better job of making things quiet.  It has a straight through perforated core resonator in the midpipe.  The muffler has dual outlets that fill the stock openings in the rear bumper nicely. 
A cool thing about the ARK design Road Spec is you can choose between long and short tips or even no tips to suit your aesthetic tastes.
Howard Watanabe first removed the stock exhaust.   The Road Spec exhaust sorta mimics the layout of the stock exhaust except the stock exhaust has a side instead of a center inlet to the main muffler.  Our test mule is a bone stock Subaru BRZ.
The stock exhaust is actually not bad and we have found that some aftermarket exhausts have zero gain over stock!  You can see smaller tubing diameter and crushed and tight radius bends of the stock part.
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Comments
VMax
VMaxlink
Monday, May 05, 2014 3:09 AM
Am I the only one wondering why the racing-spec exhaust is not exiting to the
left where it would have a better path when the muffler would be placed with
a little angle? Would require a new center-pipe though...

But overall very nice systems, as long as the factory ECU doesn`t dial the gains
out again!

Cheers!
jeffball610
jeffball610link
Monday, May 05, 2014 9:52 AM
I don't want to throw a wrench in here, but is it possible the results are so consistent because the ECU canceled out the gains? I know it would be a lot of trouble, but what if you switched back to the stock exhaust. I'm sure ARK's stuff works and they always make some of the most beautiful and well crafted products. Just trying to be scientific.
I'm also wondering what that stupid little box is right before the mid pipe.
VMax, I assume the race-spec part does that so they can use the same mid pipe for all 3 products. If the mid pipe didn't have that last bend, it would be easier to exit on the driver's side and save a few inches of exhaust.
jeffball610
jeffball610link
Monday, May 05, 2014 9:53 AM
You also teased us by reminding us of the Team America car. (I was reading up on it again last week) There hasn't been an update in over a year. Anything you can tell us about the car at this point?
Crousti
Croustilink
Monday, May 05, 2014 10:18 AM
@jeffball > i think the "stupid little box" may be a 1/4 wavelength resonator. These cancel a specific frequency based on its length. It usually is the "drone noise". I don't know if it is exactly that on this car, but it is on S2000 exhausts.

Check "Helmotz resonator" if you want to know more about that tech.
racingfan
racingfanlink
Monday, May 05, 2014 11:03 AM
Hey Mike. It looks like those are TRD suspension braces, is that right? Where did you guys get them?
VMax
VMaxlink
Monday, May 05, 2014 11:25 AM
@racingfan
If you look closely it says DC-Sports... so you might wanna check there! ;)

Cheers!

8695Beaters
8695Beaterslink
Monday, May 05, 2014 2:19 PM
I would guess that ARK was balancing thw weight of the car by putting the driver on the left and the exhaust on the right. But keeping the same mid pipe also makes sense to keep costs down.
Mike Kojima
Mike Kojimalink
Monday, May 05, 2014 2:47 PM
I don't think the ECU was canceling out stuff in between runs. We did have to do a lot of pulls to stabilize the readings between runs.
Burninator
Burninatorlink
Monday, May 05, 2014 4:42 PM
I think the race exhaust is on that side because after it clears the diff it can't just go straight or it'd hit the control arms. Bending to the right to clear the suspension then back to the left might put a kink in the pipe that's probly more of a restriction than just running straight to the other side of the car.
DrunkenMessiah
DrunkenMessiahlink
Monday, May 05, 2014 10:20 PM
"You also teased us by reminding us of the Team America car. Anything you can tell us about the car at this point?"

The Team America car is dead.

Eric is no longer involved in the project and the car is rotting in storage somewhere. It would take A LOT to make that car run like it was supposed to, let alone actually be competitive in the World Time Attack class it was intended to run in. I would not hold my breath for another, proper MotoIQ update on that project ever again. However, I would *love* to be wrong about that assertion :\
Mike Kojima
Mike Kojimalink
Monday, May 05, 2014 10:23 PM
How do you know anything about Eric and the status of the car?
spdracerut
spdracerutlink
Monday, May 05, 2014 11:01 PM
I think the way the rear sections are modular all using the same mid-pipe is genius because I had the exact same idea. For street use, put on the street exhaust. For track days, slap on the race part.

On the Superflow middle of the group design, that flow split is beautiful. I don't think I've seen one any better than that for flow.
Der Bruce
Der Brucelink
Tuesday, May 06, 2014 12:39 AM
Very well done comparo and just a reminder of the FA20 limitations NA. Time for Toyota and Subaru to split the sheets with the Z_6 chassis' motors. I'd love to see what the FR-S could do with Toyota's new turbo 4.....as well as what MotoIQ could do. I truly think these are great looking cars that just need a more adaptable engine.
VMax
VMaxlink
Tuesday, May 06, 2014 3:14 AM
@Burninator

True, its harder to clear the Diff/Control-Arm mount on the driver side without
having a tight bend there with the given center-pipe layout, but yeah I agree that its better to keep the costs down with the same center-section if it doesn`t
give you anything in terms of performance.

Cheers!
Der Bruce
Der Brucelink
Tuesday, May 06, 2014 10:56 AM
Well, I heard on a forum from a guy who says his friend has a somewhat reliable source and the source's cousin's friend said that the ARK BNR32 was taking longer so that an LS7 could go in the VQ's place. I mean, that's what I heard.....:-)
Burninator
Burninatorlink
Tuesday, May 06, 2014 5:17 PM
I don't know Eric, but from what I gather reading his articles, he'd burn the car to the ground before putting an LS7 in it. That may not be actually true, but I do know he loves turbocharged Japanese engines and has seemed a bit put off by the domestic V8s in FD.
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