New Perrin exhaust - lost torque

[Last Lemming Alive]

Originally Posted by extrashaky

I wouldn't believe it without actual dyno numbers. A change in sound can do a lot of weird things to how you perceive a car's performance. Sometimes it "feels" faster when it really isn't. Yours probably sounds like it should come off the line faster than your visual cues tell you.

I completely agree. I've owned my different types of cars and I've added exhausts to all of them, and sound plays a huge role in your perception of power. However where I was able throttle of the line with little effort before with the OEM exhaust it now falls on its face before it picks back up and gets going, that, to me is a sure indication of a power loss.

For the record I did find at least a couple other BRZ owners with this exhaust that have mentioned the same issues.

[krayzie]

Isn't 2.5" diameter kinda large for the stock tune? It's the same complaint when people just buy a cold air intake for their Hondas without anything else done to it, the powerband shifted to the top end.

[ze12o]

perhaps you have an exhaust leak? try to listen for any whistling sounds while driving.

i definitely felt power loss due to an exhaust leak.

[Xxyion]

Originally Posted by extrashaky

I wouldn't believe it without actual dyno numbers. A change in sound can do a lot of weird things to how you perceive a car's performance. Sometimes it "feels" faster when it really isn't. Yours probably sounds like it should come off the line faster than your visual cues tell you.

I can totally attest to this. I've gone through 3 different exhaust setups within the past year. Two of them were 3" exhausts and one was 2.5".

My second exhaust was the Megan Racing V2 CBE. It has the most airy woofy sound out of all my exhausts and it got to the point my car felt like it had zero power. And i was supercharged. I prefer a really tight tone on my cars and currently my Nameless supplies that. But now that i'm NA again i might go with a Perrin.

[wparsons]

I definitely didn't lose any low end torque with my Perrin 2.5" exhaust (resonated).

OP, did it happen immediately, or took some time? Any chance it's bad gas or anything else? Did you reset the ECU when you installed it? Anytime the ECU is reset (or flashed), the throttle response is brutal for a couple days and it feels like it has lost all low end power.

[humfrz]

Originally Posted by Last Lemming Alive

I just installed a Perrin 2.5" resonated cat back. I've been driving it around a week or so and I've noticed my low end torque is gone. It doesn't zip off the line anymore. It smooths out the power band nicely and sounds a bit better, but there is definitely a loss of low end torque.

I see I have two choices: 1) rinstall the OEM pipes. 2) add another upgrade to gain it back.

If I go number 2, which power mod will be the most economical to get the job done. I just want to keep the higher rpm gains and just give. Ack the low end torque I lost.

Hi ya, Last Lemming Alive ......

Have you had any other power mods done to your car .. ??

Did you do anything else, drivetrain wise, when you changed the exhaust .. ??

As mentioned up above, have you changed your source/type of gas ..??

(has anyone but you put gas in your car ...... like regular grade..??)

I feel there is something else working here, other than a change in the muffler.




humfrz

[N1rve]

I haven't felt anything different with my 3 Inch perrin exhaust. It's just gotten deeper and louder.

[Last Lemming Alive]

Originally Posted by wparsons

I definitely didn't lose any low end torque with my Perrin 2.5" exhaust (resonated).

OP, did it happen immediately, or took some time? Any chance it's bad gas or anything else? Did you reset the ECU when you installed it? Anytime the ECU is reset (or flashed), the throttle response is brutal for a couple days and it feels like it has lost all low end power.

Yes, unplugged and ran it for over a week. The installation was easy and I've doubled checked everything.

I reinstalled the OEM exhaust tonite, and even without unplugging it the torque was back. It feels like 7-10 ft lbs was gained.

[Last Lemming Alive]

Originally Posted by humfrz

Hi ya, Last Lemming Alive ......

Have you had any other power mods done to your car .. ??

Did you do anything else, drivetrain wise, when you changed the exhaust .. ??

As mentioned up above, have you changed your source/type of gas ..??

(has anyone but you put gas in your car ...... like regular grade..??)

I feel there is something else working here, other than a change in the muffler.

:

humfrz

This was my only mod. And the gaskin the tank was the same for the Perrin and the OEM. It wasn't a net loss, I did gain mid range and top end power, but I lost a bit of low end - say 7-10 ft lbs.

[humfrz]

Originally Posted by Last Lemming Alive

This was my only mod. And the gaskin the tank was the same for the Perrin and the OEM. It wasn't a net loss, I did gain mid range and top end power, but I lost a bit of low end - say 7-10 ft lbs.

hmmmm......let's see ...... it looks like the resonated mid pipes are about the same ...... or are they .. ??

If so, that just leaves the muffler being the sole difference.

According to the below graph, as best as I can read it, the Perrin system should allow the engine to develop more torque all along the power band (with the exception of that one little peak and a slight edge in the torque dip).

So, what's going on with you and your car .... ??




humfrz

[Last Lemming Alive]

Originally Posted by humfrz

hmmmm......let's see ...... it looks like the resonated mid pipes are about the same ...... or are they .. ??

If so, that just leaves the muffler being the sole difference.

According to the below graph, as best as I can read it, the Perrin system should allow the engine to develop more torque all along the power band (with the exception of that one little peak and a slight edge in the torque dip).

So, what's going on with you and your car .... ??




humfrz

I don't disagree. That graph is why I bought the system in the first place. I just reinstalled the OEM system, I'll drive for a week or so and compare.

[VTEC]

Originally Posted by Last Lemming Alive

In my experience on a NA engine when you typically gain on the top end you sacrafice on the low end and vice versa. This isn't iron clad of course there are exceptions. I thought this might be one when I looked at the dyno on perrins website. It showed no loss of torque at low rpm, but to me the loss is evident.

As far as how you loose low end power, if you just bolt on a more free flowing exhaust you will gain top end, but the reduction in back pressure will typically loose you low end torque. A tune would most like help with reducing the loss I imagine.

HP is meaningless for the most part. For a street car it's all about torque.

Like you said it's not that unusual to lose some low end torque in exchange for better top end power when installing a catback exhaust. But I didn't notice anything that drastic when I put in my N1 catback. Maybe your butt dyno is just really sensitive lol. Even more sensitive than Perrin's actual dyno lol

[DarkSunrise]

Originally Posted by Last Lemming Alive

This was my only mod. And the gaskin the tank was the same for the Perrin and the OEM. It wasn't a net loss, I did gain mid range and top end power, but I lost a bit of low end - say 7-10 ft lbs.

Could it be that you're not yet used to the increase in sound at part throttle?

In other words, it's now much louder under load without any corresponding increase in speed, tricking you into thinking the car has gotten slower.

The reason I say this is I've got the 2.5" Perrin and didn't notice any loss in low-end torque, but it is definitely much louder under load.

[oldgunfan]

Now-a-days if your not going to tune the car DON'T MOD IT. Back when I raced motocross if we changed something on the bike, pipe or whatever and you didn't need to rejet then you didn't gain anything, in fact you may have lost power.