best exhaust setup for improving mpg
02-13-2014, 05:44 PM
#47
For our engines? Yeah.
For some riced-out BS import? Anything over 30mm or so is probably stupid big. If you balance it to run 2,000-2,500 past redline, then MAYBE 35mm would be useful, I'd have to check.
But, I have actually SEEN Hondas up on the lift with 4" tube all the way back (!) no turbo, and they wonder why their performance is suffering (this was in automotive class. They hadn't gotten into theory yet...)
I figure this is the same mentality that compels them to mount a 5" Monster Tach - with functioning shift lamp! - when they've got a JATCO transaxle...
02-13-2014, 05:55 PM
#48
Herp Derp Jerp
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Year: 1999
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Engine: 4.0L OBD-II
Possible he made a typo. Late '90s Honda Civic stock exhausts are 1.75" to 2" depending on engine. 
5-90 generally knows what he's talking about.
5-90 generally knows what he's talking about.
02-13-2014, 06:27 PM
#49
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Year: 1997
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Ya..... He's one of the more knowledgable ones here, sounds di** ish but I'd be willing to put money on him knowing more than you. That last statement is just dumb of you to assume. It's more obvious that you don't know anything if you think that of him.
02-13-2014, 07:39 PM
#50
Here's a sweet link about exhaust:
exhaustsizefordummies.com
Last edited by mr white; 02-13-2014 at 08:03 PM.
02-13-2014, 08:03 PM
#51
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Year: 1997
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Sure buddy. Maybe he should stick to Jeeps instead of honduhs. Its obvious he doesn't know what Hondas need as far as exhaust size if he claims they only require a 30mm pipe. This "optimum 30mm size" would entail Honda is bad at engineering because they use a roughly 60mm (depending on the model) exhaust. Is honda terrible at engineering? He should email Honda and tell them he is superiour engineer and their exhausts on their cars should only be 30mm in diameter unless they Rev to 10500 rpm at which point then they should upgrade to 35mm.
02-13-2014, 09:44 PM
#55
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Year: 1998
Model: Cherokee
Engine: 4.0L HO
I gotta admit that you've got me curious about what that really is now...looks like some monstrous air handling unit or something of the type.
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Anthony Beaudoin (05-10-2022)
02-14-2014, 03:01 PM
#58
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Year: 1999
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Getting on topic I just realized that the jeep I bought is from California. If I change the down pipe to a normal down pipe will that do my jeep harm?
Just read this thread form the beginning and kinda confused. Do I stay with 2.25 all the way through, or 2.25 to the cat and have the cat, muffler and tailpipe 2.5?
Just read this thread form the beginning and kinda confused. Do I stay with 2.25 all the way through, or 2.25 to the cat and have the cat, muffler and tailpipe 2.5?