Exhaust diameter question

[ryanprins13]

Hey, i searched a bunch on the forum but the question seems to be only answered for people looking for more power or with larger motors. I found a bit on google but for other cars and im not sure how well it applies to festivas specifically. My question is what diameter exhaust is best for a stock festiva 1.3L with no plans to make more power? Mine is kinda bashed up and rotted out. I have 2 parts cars so i took the exhausts off both. The one is the standard 1.5in OD but no muffler and the flange is cut off back there. Couple pinholes throughout the pipe and the resonater would have to be replaced but the pipe is not squishable by hand. The other one is out of a carbed festiva so its got the cat with the heat pipe. The outside diameter is 2.1in. Resonater seems in ok shape and it has a flange for the muffler. I have a good muffler with a flange but no brackets, i have to weld them on. So anyway, the 2 inch exhaust is obviously (to me) less work and cheaper to make work- and thats the goal, im not lookin to spend money on it or else i would buy a whole new exhaust. However i do not want to loose any power. *My concern is does the 2.1inch slow the velocity of the exhaust down enough that you loose power on the n/a 1.3L? Or will there be no noticable power difference? The muffler is the stock 1.5in.*
Thanks


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[bhearts]

Hey, i searched a bunch on the forum but the question seems to be only answered for people looking for more power or with larger motors. I found a bit on google but for other cars and im not sure how well it applies to festivas specifically. My question is what diameter exhaust is best for a stock festiva 1.3L with no plans to make more power? Mine is kinda bashed up and rotted out. I have 2 parts cars so i took the exhausts off both. The one is the standard 1.5in OD but no muffler and the flange is cut off back there. Couple pinholes throughout the pipe and the resonater would have to be replaced but the pipe is not squishable by hand. The other one is out of a carbed festiva so its got the cat with the heat pipe. The outside diameter is 2.1in. Resonater seems in ok shape and it has a flange for the muffler. I have a good muffler with a flange but no brackets, i have to weld them on. So anyway, the 2 inch exhaust is obviously (to me) less work and cheaper to make work- and thats the goal, im not lookin to spend money on it or else i would buy a whole new exhaust. However i do not want to loose any power. *My concern is does the 2.1inch slow the velocity of the exhaust down enough that you loose power on the n/a 1.3L? Or will there be no noticable power difference? The muffler is the stock 1.5in.*
Thanks


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Depends where you want the torque peak. Bigger will give more top end, and smaller should help with cruise. Specially if you have a header. Primary exhaust diameter is a big deal for torque peaks. Well that mixed in with runner length

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[FestYboy]

Also be sure the 2.1" that you are measuring isn't a double wall exhaust (common).

[firebush357]

Here is a good read on how to calculate exhaust size needs. I'm assuming it is accurate. I'm not sure how many muffler shops carry 1.75" pipe but I think I may try to get installed from the Manifold back to a Borla muffler in a couple of months.

http://www.exhaustvideos.com/faq/how...pipe-diameter/

[ryanprins13]

Thanks for the help and the links. I know 2 inch is way overkill, just not sure if it will cause a loss in power. It is not double wall. I decided that i will just install it and see what it does. If its bad i will look for another 1.5 inch exhaust. Its the stock manifold and 'downpipe' to cat, stock cat and stock 1.5in muffler. So i dont know what going from 1.5 to 2 and back to 1.5 will do but i will find out. Just need to find some time to install it. Oh, and theres no issues putting a cat from a carbed car onto an efi car right?
Thanks again


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[FestYboy]

You can't swap cats, they are not compatible due to the PAIR system pipes. Also they are constructed differently.

[wrx603]

im in the same boat. mine fell off the other day....been running open down pipe for the past few days....hahaha