compression ratiovs bigger exhuast

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i have a 98 mitsubishi mirage with a 1.5 L. some one in my class said that when you get a bigger exhsuast your car slows down because of the ratio is this true. And what would happen I get that 3" exshaust on my mirage. with only the cat no mufler

posted by  road_rage

Well, the size of the exhaust will not change the compression ratio. However I have heard if you get an exhaust that is too big you will not have enough back pressure to keep the motor happy (depending on your cam).

IMO, a 3" eshaust will be fine, and you will free up a few horses.

posted by  azkid110

3 inches on a N/A 1.5 liter?

Completely unnecessary. You won't lose any power, maybe a little torque down low but nothing up top. you also will prbably only gain like...half a horsepower.

Seriously it's a ****ing mirage.

And tell whoever it is that told you that adding a bigger exhaust will change the compression ratio to shove their head in an oven. The compression ratio is determined internally in the engine by the stroke of the cylinder and size of the combustion chamber.

****ing goddamn ricers.

posted by  Zalight

You needed to swear soooo much that you typed like 8 extra characters in total, just to over ride the censor? :banghead: :laughing:

Back on topic though. I agree with the general views here. Adding that sort of exhaust to your car will only make you look stupid, and it'll sound like you have an exhaust blow...

posted by  Cliffy

here's a problem for you and your classmates to work out:

using an expansion ratio of 1.39, what is your best case exhaust flow at advertised peak power rpm?

what diameter exhaust pipe would you need to maintain 55 m/s.

posted by  Wally

Um...no.
3" Exhaust is FAR to big for such as small motor. Supercharged and built Mustangs use 2.5" exhaust until they break the 10 second mark.

2-2 1/4" exhaust would be where your need to be at.

posted by  SlipKnoT

yes...yes I did.

posted by  Zalight

Ok...time for a "time out" lol :ohcrap: :laughing:

posted by  Cliffy

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