My muffler recently completely rusted out on the side and now sounds like a little ricer fart car. I've noticed my gas mileage has gone from around 34 mpg to about 28 or less. I just ordered a new muffler, but just curious if this is the reason for the poor gas mileage. This is on a 91 crx si.

 

I don't think it would, I would only guess improve it because air is escaping faster

 

Running without a muffler will have no impact on fuel economy.No. If you want to get technical, it's the exact opposite.

 

How so?

 

yes how so

 

If you take the muffler off, the system becomes slightly more effecient. This means more air flows through, requiring more gasoline to burn. This is on a scale so small the average Joe can't measure it.

This is the reason why stationary engines are rated in units like horsepower per liter hour. Power output is directly proportional to air and fuel intake.

 

My car averaged around 36 miles to the gallon with the new muffler. It was only getting around 29 miles to the gallon with holes in the muffler. So yes, no muffler will hurt the gas mileage on a 91 crx si.

 

Yes No Muffler will kill your gas mileage. You would think, free flow so more hp and better mileage. WRONG! You lose tremendous Back Pressure which will make your car sluggish unless you have a turbo and if you had that, you would probably have an exhaust already.

 

that is by far THE single most uninformed comment I have ever read on HAN...congrats.

 

I think the message was that the exhaust is engineered to have a certain amount of backpressure. From the factory(esp on a CRX) the exhaust system is very restrictive. Obviously, a well-designed aftermarket exhaust system will help increase horsepower, but none at all will affect your engine's performance.