Muffler removal, any power/fuel gains?

Not really, but you will put out more unnecessary emissions than the EPA might consider prudent!!!

 

I don't think anyone has run it on a dyno before and after a muffler delete. I highly doubt it would be worth much. It would likely sound like hell too. lol

 

Well if you don't mind contributing to lung cancer and other health defects known to be caused or exacerbated by SMOG then go for it. Just don't expect many of us to applaud you for your efforts because it's a very unpatriotic and irresponsible method of gaining power.

That being said, there is a HUGE difference between adding a down pipe directly off a turbo and just removing a muffler from a naturally aspirated non-performance vehicle. I spent 20yrs drag racing and modifying vehicles. In general not much HP/TQ is to be gained with simple muffler deletes. I've backed this up with both 1/4mile tests as well as dyno sessions.

 

You'll most likely just gain friends...especially late at night and early in the morning!!

 

What about the cat converters and sensors downline from the exhaust manifold? You don't care about removing them? Doing so would make any vehicle illegal to operate on public roads.

 

Wow, you went from a Ford Excursion to a Prius. Your wallet must really be happy when you go to buy gas:rockon: I don't have a clue about the muffler delete thing, but I would have to go with the "probably sound like hell" crowd.

Arkie

 

The muffler is the thing on the end of the exhaust system, back by the rear axle. On the engine end there are two catalytic converters and a heat exchanger that helps heat ICE coolant when the car is cold.

Removing the muffler won't do much except increase the noise (not cool on a Prius). I doubt if you would see any difference in MPG or power. Removing the other components would be be illegal, at least in the case of the two cat converters, and the car would not run correctly because there is an oxygen sensor behind the converters. It wouldn't take long for the check engine light to come and it would probably throw several codes.

The exhaust system should be left alone.

 

The fact you expressed your thoughts about the environment in caps says a lot about your ignorance regarding environment and human health and how that affects our economy and society as a whole.

 

Now that you have heard from the greenies (I also am not one, but believe in conservation), I can give you some real data from our experiments at Noise Cancellation Technologies on reducing muffler back pressure. We installed prototype Active Noise Cancelling mufflers in many vehicles (no hybrids though) which eliminated the muffler back pressure and on average it saved 2% on the highway MPG and 5% in city driving MPG.

I would expect that similar MPG results would be obtained in a Prius. Peak power from the ICE would improve by about 10% but that is only about a 7% change in total peak power since the electric power remains the same.

By the way, any improvement in MPG results in the same improvement in CO2 emissions and has little effect on other pollutants.

JeffD
The Doctors Denenberg and Family for reference publications

 

Translating Jeff's reply: Removing your muffler will likely reduce mileage and power, not improve it. The only thing that you will gain is noise.

Tom

 

Sorry. My post was rude. I won't edit it and pretend I didn't write it.

 

There are at least 4 stereotypical Prius Drivers

Drives a Prius to save the environment
Drives a Prius to reduce the debt
Drives a Prius to improve US security
Drives a Prius to save themselves money

A Venn Diagram of these groups would not necessarily have much overlap. Larry just has less overlap than usual.

 

Not quite, you will get more noise, but there will be a small increase in MPG and peak power. The links below go directly to three relevant publications that I wrote a few years back.

JeffD

Quieting The Environment: Noise Cancellation
http://doctord.dyndns.org/Pubs/CSXMUF.htm
http://doctord.dyndns.org/Pubs/Energy.htm

 

I know that would be true with a Otto cycle engine, the exhaust has not completely expanded when it leaves the cylinder, but the exhaust stroke has 30% more volume than the intake in a Atkinson cycle engine, doesn't that reduce the pressure in a Prius exhaust?

I suspect all he 'gains' is the weight of the straight pipe versus the weight of the legal gear.

 

Very interesting. I know that Honda uses active vibration and noise cancellation in their engines with cylinder deactivation. I bet we will see more of this if there is some fuel efficiency benefit.