Jump to content

Welcome to Ultimate Subaru Message Board, my lurker friend!

Welcome to Ultimate Subaru Message Board, an unparalleled Subaru community full of the greatest Subaru gurus and modders on the planet! We offer technical information and discussion about all things Subaru, the best and most popular all wheel drive vehicles ever created.

We offer all this information for free to everyone, even lurkers like you! All we ask in return is that you sign up and give back some of what you get out - without our awesome registered users none of this would be possible! Plus, you get way more great stuff as a member! Lurk to lose, participate to WIN*!
  • Say hello and join the conversation
  • Subscribe to topics and forums to get automatic updates
  • Get your own profile and make new friends
  • Classifieds with all sorts of Subaru goodies
  • Photo hosting in our gallery
  • Meet other cool people with cool cars
Seriously, what are you waiting for? Make your life more fulfilling and join today! You and your Subaru won't regret it, we guarantee** it.

* The joy of participation and being generally awesome constitutes winning
** Not an actual guarantee, but seriously, you probably won't regret it!

Serving the Subaru Community since May 18th, 1998!

Guest Message by DevFuse

- - - - -

Exhaust Flow

  • Please log in to reply
2 replies to this topic

#1 Twitch de la Brat

Twitch de la Brat

    Village Psycho

  • Members
  • 1,684 posts
  • The Athol of Idaho

Posted 18 August 2014 - 10:26 PM

So, this is a rudimentary math sheet I did for flow rates out of a 1.8L engine.




This doesn't account for expansion or restriction. It is merely a maximum flow for an NA engine.

Turbo charging changes all of these calculations drastically with compression rates and thermal expansion.

But this allows you guys a formula to start with if you want to figure out the best exhaust size for your car.




PS: The stock exhaust on an EA car is about as awful as you can get.

The flow rate of a stock EA exhaust is still creating back pressure in top gear.




  • Members
  • Pip
  • 1 posts
  • Sturgis SD

Posted 05 May 2015 - 10:07 AM

So, I have a 1982 Subaru GL that I am currently doing a restore on. One of the things I want to change, and trust me there is a long list, is exhaust. My plan is to keep the cat in place but rebuild cat back removing the muffler. I was curious if this is a decent idea and if so, what diameter pipe would I experience the best gain with?

#3 zeb1234



  • Members
  • Pip
  • 9 posts
  • salt lake city,ut

Posted 25 February 2016 - 01:19 AM

i dont know the science but i eliminated middle cat.2inch y pipe to a standard exhaust generic. runs somuch better carb e82 from a 81-83 car 3 spd auto

0 user(s) are reading this topic

0 members, 0 guests, 0 anonymous users