Does Perrin catback exhaust LOSE torque?
 

Hi ALL,

First post here. I bought my BRZ, limited GBS 6MT abotu four months ago. I've been in forums for a while and walked from the car back in May (because I had a car at that point and they shafted me on the lease). I walked and then in January my primary car died and luckily the same model that I had originally ordered happened to be down the street.


Anyway, I recently installed a perrin catback exhaust yesterday, professionally by a shop that has installed them before. It sounds great and I love it.

But, I feel like I LOST torque in the lower RPM's. It is pretty noticeable. I also feel like it has definitely smoothed out the power band and closed the power dip a little bit. But I enjoyed full torque around the 2k RPM, and now I feel like it is not close to that.


What gives? Does it need to season a little and break in? I have the AEM intake coming in tomorrow too, which the dyno graph shows it also loses low end torque. What's going on here?

the exhaust likely didn't change things enough one way or the other for you to notice. it may just be an expectations thing. the car being louder tends to make our brain expect a commensurate increase in power, which when it isn't there, makes it seem as though the car is making less power than before. just a theory...

in any case, if you can discern the difference of +/- a couple hp/tq, you should be in italy karting, with a bright f1 career ahead of you lol. it's simply not a significant enough difference for us mere mortals to reliably quantify.

Mine certainly doesn't feel like it has lost any torque anywhere. I have been running the catback for several months. It's just a pipe and in the end it's not going to make much difference either way on an otherwise stock setup.

Maybe something is wrong then, because I definitely feel a decrease in torque immediately. There was a torque surge in the low rpm, then a noticeable dip of tq in 4k range, then another surge.

Now, I feel no torque surge in the lower RPM's and instead it is very smooth and linear all the way throughout. This is not necessarily a bad thing per say, but I can definitely notice it.


Check out this AEM intake dyno. Look between 2100 and 3100, the blue line is stock. It's almost at 120 torque. The red line, aem intake is almost near 115 or lower. http://ft86speedfactory.com/images/411408DS-2.jpg


Anyway, I hope you guys are right and that it's just in my head but I love this exhaust and don't want to put the stock one back on bc I lost a couple tq's in the low end. I am afraid that tomorrow when my intake comes in, my low end will be even worse :(

I have seen that happen with all kind of cars and truck: lost of torque after bigger exhaust installed. If possible, try install only the axle back.

Yeah exactly. I was thinking since the back pressure dropped in lower rpm that is why it lost torque. Maybe the piping is too large.

If you lost enough torque to feel a "drastic difference", you're talking about a drop of like 10lb/ft+, not 1-2. There's simply no way the exhaust caused you to lose that much torque.

It's either perception from the extra noise, or the ECU needing some more drive cycles to adapt to the new parts. Give it a few more drives to see if it improves. If you REALLY feel like you've lost a noticeable amount of power then have it dynoed back to back with the stock vs perrin exhaust and see what the dyno says, it won't lie to you.

Here's Perrin's published dyno chart:

http://www.perrinperformance.com/ass...back_large.jpg

You bring up a good point about the ecu needing to adjust. Since I only got it installed yesterday, it will take a few days to settle in I guess.

I wouldn't say it's DRASTIC. I would say it is a tad under 'very noticeable'.

It could be a bunch of things. Maybe I am expecting it to increase bc of the noise. Maybe because it smoothed out the power band to be more linear, then it feels this way.

Hey wbsrazzle, I remember you from the "other" brz forum when I used to go there. Welcome to this one! Anyways, I really don't have anything helpful to add. I didn't notice any loss when I installed my perrin exhaust. I'm hopefully going to get it on the dyno sometime this year and see what my mods have done.

The cure is to get a tune. Once you open up these cars (breathing wise), a custom tune will yield better performance. Oncee you add the intake and complete the entire exhaust system, look into getting EcuTek and having a custom tune done...or buy the OTS tunes that have been created (FA20Club). As far as a recommended tuner to go to, I would go see EFI Logics in CT. They are EcuTek certified and have tuned tons of Subaru's. It's a bit of a hike for you, but the results are well worth it.

I think you are mistaking smoothness for lack of torque.

peaky often feels stronger but smooth often IS stronger.

If anything my car feels like it has more pull than before. My perrin catback is non res and sounds great too.

Haha, thanks man. It took me a while to come to this one, but I am glad I joined!

I also think that may be happening. Since the power band is smooth, it doesn't feel as torquey. Also it may be that the sound is leading me to believe there will be a much more noticeable power increase.

I love the sound and the feel though, it's absolutely perfect amount of loudness and tone.