Exhaust + Backpressure Question - Toyota Yaris Forums

zen · 08-25-2015, 11:03 AM

Past the cat, I have a 2.5" straight pipe installed to a basic exhaust tip. I'm not running anything significant like boost or plan to any time soon. Would this type of exhaust bring back any type of backpressure or enough backpressure for a NA engine? I'm also hoping it would help with resonation. Yes, initially I wanted the straight pipe setup because it was very cheap to have done and got tired of seeing the 1" outlet but I also planned to find a muffler in the future, which is now.

http://www.ebay.com/itm/4-SLANT-TIP-...0ee945&vxp=mtr

CoryM · 08-25-2015, 10:14 PM

Backpressure is bad. It's always bad. It reduces power. What you are thinking of is Velocity (which is good). Smaller pipes cause the exhaust gases to move faster, creating more velocity, which helps pull the exhaust out of the combustion chamber. This helps with low end torque. 2.5" exhaust is way too big for a 1.5L NA car no matter the muffler. If you want to regain the low end torque you have lost, you need to reduce the tube size (assuming no other mods).
Cheers.

zen · 08-26-2015, 03:31 PM

Ah ok, in the near future I am planning to install a short ram intake as well as DC Headers..would that help regain what I lost other than reducing the tube size?

tmontague · 08-27-2015, 06:27 AM

I can't comment on the exhaust size but in regards to the DC header it will help quite a bit.

I didn't notice a big difference in top end but it definitely moved the power band back in the rpm's. When i'm driving conservatively and early shifting the engine gets up to speed quicker and with less lag. It seems to have more pull as well in various gears.

zen · 08-27-2015, 11:22 AM

Yeah definitely going to be picking one up soon.

CoryM · 08-27-2015, 11:58 AM

I've not used a DC header, and exhaust flow is not overly simple, but it *should* help. The longer primary tubes help increase velocity. The primaries are larger on the DC which may not help in that regards, but people comment on the increased low-end so it's probably good. Short ram intake will probable not do much either way to be honest. Unless the Yaris is one of the few vehicles where the OE intake is choked up, replacing them often does not help (and sometimes makes it worse). If you want torque, consider a "Tooter spacer" http://www.yarisworld.com/forums/showthread.php?t=49609 it does the same thing as longer primary header tubes.

Putting the OE exhaust, with an aftermarket muffler, on will help too. The pipe size is fine, but the mufflers perform poorly.

Cheers.

Rigaud · 08-27-2015, 12:28 PM

Quote:

Originally Posted by CoryM

I've not used a DC header, and exhaust flow is not overly simple, but it *should* help. The longer primary tubes help increase velocity. The primaries are larger on the DC which may not help in that regards, but people comment on the increased low-end so it's probably good. Short ram intake will probable not do much either way to be honest. Unless the Yaris is one of the few vehicles where the OE intake is choked up, replacing them often does not help (and sometimes makes it worse). If you want torque, consider a "Tooter spacer" http://www.yarisworld.com/forums/showthread.php?t=49609 it does the same thing as longer primary header tubes.

Putting the OE exhaust, with an aftermarket muffler, on will help too. The pipe size is fine, but the mufflers perform poorly.

Cheers.

What's your setup, changes?

CoryM · 08-27-2015, 10:19 PM

Quote:

Originally Posted by Rigaud

What's your setup, changes?

Powerwise, I am stock. I've only done suspension mods as the Yaris is my boring daily-driver and winter autoX car. I am likely going to do an unusual engine swap when it's time for more power (and LSD!). If I were to build a daily driver 1.5L, I would run whichever header has the longest primary tube (so long as the primary size doesn't get too large), tooter spacer, quiet aftermarket muffler, light-weight pulleys, and tune. I am not sure how restrictive the OE cat is, so may want to research that as well. I would also run a light-weight flywheel, but that isn't for everyone. I already run light-weight rims as well (and NT01 tires

). This is all done in order to get better torque, and throttle response which to me is what makes driving fun.

Cheers.

PS: when I want to go fast, I drive this one

08-25-2015, 11:03 AM	#1
zen Drives: 2014 Yaris HB Join Date: Jul 2014 Location: N. Chas, SC Posts: 36	Exhaust + Backpressure Question Past the cat, I have a 2.5" straight pipe installed to a basic exhaust tip. I'm not running anything significant like boost or plan to any time soon. Would this type of exhaust bring back any type of backpressure or enough backpressure for a NA engine? I'm also hoping it would help with resonation. Yes, initially I wanted the straight pipe setup because it was very cheap to have done and got tired of seeing the 1" outlet but I also planned to find a muffler in the future, which is now. http://www.ebay.com/itm/4-SLANT-TIP-...0ee945&vxp=mtr

08-27-2015, 06:27 AM	#4
tmontague View User's Garage Drives: '08 2zr swapped Vios M/T Join Date: Oct 2012 Location: Caledonia Ont. Posts: 2,938	I can't comment on the exhaust size but in regards to the DC header it will help quite a bit. I didn't notice a big difference in top end but it definitely moved the power band back in the rpm's. When i'm driving conservatively and early shifting the engine gets up to speed quicker and with less lag. It seems to have more pull as well in various gears. __________________ No one ever wants to give a Yaris the point by...

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08-25-2015, 10:14 PM	#2
CoryM Drives: 2009 5-door, 5-speed Join Date: Sep 2011 Location: White Rock BC Posts: 687	Backpressure is bad. It's always bad. It reduces power. What you are thinking of is Velocity (which is good). Smaller pipes cause the exhaust gases to move faster, creating more velocity, which helps pull the exhaust out of the combustion chamber. This helps with low end torque. 2.5" exhaust is way too big for a 1.5L NA car no matter the muffler. If you want to regain the low end torque you have lost, you need to reduce the tube size (assuming no other mods). Cheers.

08-26-2015, 03:31 PM	#3
zen Drives: 2014 Yaris HB Join Date: Jul 2014 Location: N. Chas, SC Posts: 36	Ah ok, in the near future I am planning to install a short ram intake as well as DC Headers..would that help regain what I lost other than reducing the tube size?

08-27-2015, 11:22 AM	#5
zen Drives: 2014 Yaris HB Join Date: Jul 2014 Location: N. Chas, SC Posts: 36	Yeah definitely going to be picking one up soon.

08-27-2015, 11:58 AM	#6
CoryM Drives: 2009 5-door, 5-speed Join Date: Sep 2011 Location: White Rock BC Posts: 687	I've not used a DC header, and exhaust flow is not overly simple, but it should help. The longer primary tubes help increase velocity. The primaries are larger on the DC which may not help in that regards, but people comment on the increased low-end so it's probably good. Short ram intake will probable not do much either way to be honest. Unless the Yaris is one of the few vehicles where the OE intake is choked up, replacing them often does not help (and sometimes makes it worse). If you want torque, consider a "Tooter spacer" http://www.yarisworld.com/forums/showthread.php?t=49609 it does the same thing as longer primary header tubes. Putting the OE exhaust, with an aftermarket muffler, on will help too. The pipe size is fine, but the mufflers perform poorly. Cheers.