Power loss

Do you have to have your truck tuned after a new exhaust. Got a cat back and I feel like it's slower to get off the red light compared to before. Maybe i have read to many post that say you lose low end torque with cat back exhaust.

 

Disconnect your battery for the night. Force your ECU to "learn" your new driving habits. I'm pretty happy with my new catback. Looking to get the y-pipe this Spring.

 

Hopefully you didn't go with a >2.5" diameter setup. Some have experienced a loss of power by going with larger piping which has the unwanted effect of reducing the back pressure these engines need. If you stuck with stock size just with a less restrictive catback setup you probably do just need to disconnect your negative battery cable - don't even need to do it overnight. About 10-15 mins works based on my experience.

 

I got the mbrp which is a 3 in but a local muffler shop mechanic said that it should be fine since the needed back pressure it created by the cats.

 

Not sure if I'd ever listen to a muffler shop mechanic's advise over Toyota engineers'.

 

Good point

 

Have read some posts on the forum where folks have reverted from 3" setups back to stock b/c of similar problems. May not be applicable in your case, but most muffler shops may not be as aware of how the 2gr-FKS works in terms of atkinson and back pressure overall. Good luck though - maybe a reset is all you'll need!

 

I truly do not believe that back-pressure would be "good" for the Atkinson cycle of this engine. The whole point of the Atkinson cycle is to run the intake step of the cycle with a slightly open intake valve to decrease the amount of workload on the powerstroke of the piston.

The exhaust step of the cycle is unchanged:

Engines don't need back pressure in order to function properly. The less back pressure the better. However, by moving to a 3 inch pipe you may be changing exhaust gas velocity at lower RPM's. Your perceived lack of low end power is most likely due to pipes that are worse at moving exhaust gas pulses at low RPM and better at moving at high RPM.

https://blog.caranddriver.com/what-is-the-atkinson-combustion-cycle-and-what-are-its-benefits/

http://www.dsmtuners.com/threads/exhaust-the-straight-scoop-on-backpressure.168578/

 

good facts! thanks for sharing

 

You are experiencing an audible delusion..

Your truck has no power loss, you are simply hearing it work, where as you did not before..

3" is to big without the correct muffler/resonator...

Keep in mind,

Larger pipe, cooler exhaust = Less velocity..

Smaller pipe, hotter exhaust = More velocity..

 

I realize this thread's been dead for a couple months but.... RESURRECTION TIME! Nah, not really, I just had a question. I'm trying to find out what diameter of piping I need for an exhaust cutout in the midpipe just before the muffler. Can anyone tell me what diameter I need? I have looked everywhere and haven't found an answer. Thanks.

 

2 1/2 inner diameter

 

@Thatnoobguy to the rescue!!


Going from 2.5” to 3” should not have affected performance dramatically. Response to old thread

 

Thanks for the measurements!

 

No problem

 

I have an audible leak in my exhaust (not sure where yet), but ever since it has showed up I have an absolute loss in power. While travelling on the highway (or any speed above 60-70km/h), my ability to rapidly accelerate (in order to overtake or quickly achieve highway speeds) has been effectively nullified. My truck shifts into the lower gear and ends up all the way up to revs around 6k, and loudly wails as I try to accelerate beyond 100km/h. Do we think that replacing the cracked exhaust will rectify the issue? I understood that backpressure (or lack thereof) might create issues with power, but some threads here say they do not.

Thoughts?

 

Is the crack before or after the cats? Also you could just get it welded up instead of paying for a whole new exhaust at the stealer-ship

 

Yes, and you don’t want any of those exhaust fumes to end up inside your cab.