Toyota Yaris Forums - Ultimate Yaris Enthusiast Site
 

 


 
Go Back   Toyota Yaris Forums - Ultimate Yaris Enthusiast Site > Technical Forums > Performance Modifications
  The Tire Rack

Reply
 
Thread Tools Display Modes
Old 02-21-2007, 11:06 PM   #1
Moose
Resident Redneck
 
Moose's Avatar
 
Drives: 07 Polar White Yaris Sedan 5M
Join Date: Jul 2006
Location: Cumming, GA
Posts: 265
Quote:
Originally Posted by Doc Zaius View Post
Alright... I started doing a bit of poking around and reading online as to the relationship between "backpressure" and torque, and why free-flowing headers and exhaust systems can decrease the amount of low/mid torque. People assume that since a more restrictive muffler/header/whatever has higher low-end torque, then it must be because of increased backpressure. Right? Wrong! Its b/c with a smaller diameter exhaust system, the exhaust gasses move faster. These faster moving gasses produce a slight vacuum behind them, which actually helps to pull the remaining exhaust out of the cylinder. This process is known as "scavenging". Otherwise, these gasses would be left in the cylinder, displacing new, fresh air/fuel, and thereby producing less power. As the engine speeds up (higher RPM), the scavenging effect is less pronounced, and the exhaust system's ability to flow gasses makes more of a difference, which is why the megan header works very well at very high rpm.

For some better information on this, please check out the following two very good quick-reads: Exhaust: The straight scoop on backpressure and Exhaust system backpressure.

Any thoughts/comments?
You beat me to it.
__________________
My other rides:
2003 Honda Civic LX Coupe 5M- S/C K24 w/ LSD coming soon!
1999 Honda Civic EX Coupe 5M w/ B18 powaa
1985 Toyota Celica GTS Coupe 5M- track whip
http://www.importlounge.com
Moose is offline   Reply With Quote
Reply

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
Megan Header Install [pics] Chris07LB Performance Modifications 132 09-29-2010 04:41 PM
WR Secret Weapon Intake Dyno Tested.. WRLEO Performance Modifications 70 05-17-2007 04:00 PM
GROUP BUY - Megan Racing 4-1 Header... riceboy Items for Sale by private party 489 01-10-2007 07:45 PM
VA/MD Owners - Megan Racing Header ProMotionTuning Performance Modifications 4 11-30-2006 03:54 PM
HEADER & INTAKE R&D. WRLEO Performance Modifications 80 11-23-2006 04:51 PM


All times are GMT -4. The time now is 08:58 PM.




YarisWorld
Powered by vBulletin® Version 3.8.11
Copyright ©2000 - 2025, vBulletin Solutions Inc.