Exhaust Questions

[semaj4712]

Let me start off by saying this is my first post on DTT, so if I am posting in the wrong section I apologize ahead of time...

I have searched around and cannot seem to find a solid source on my questions so I figured I would post in here and see what you guys think.

First question I have a 75 Honda CB500T, and was planning on running a 2 into 1 exhaust with no muffler heat wrapped, question I have is, what is the power loss in terms of 2 into 1 and the no muffler versus say, 2 into 1 with muffler, or 2 straight pipes no muffler, and stock...I have heard many different things, mainly that 2 into 1 is a huge power loss, but that doesnt seem right considering I know a lot of people run the 4 into 1 exhaust on CB500F and up

I also was wondering until then how much power loss would I experience if I ran stock pipes but removed the mufflers? Would there be a significant amount of power loss, I want to do this as I am stripping the bike of weight including the mounts for the exhaust in the rear and the taillight assembly which will be replaced with a placeholder and brake light right where the exhaust muffler currently goes on the left side...

Anyways thanks in advance for the help

 

[VonYinzer]

Honestly, I don't think anyone has run actual numbers on power loss in those parameters. Running straight pipes will lose power. It will require rejetting of the carbs. It will create a poor running engine. At least poorer than stock in most situations. You need to run baffles of some kind to keep backpressure in the system. Also, the stock pipes without the mufflers are really too short. And no muffler or baffle is LOUD. Not in a cool way. In a cops called, every ride longer than 30min ends with a headache way.

As far as a 2-1 set up. If done correctly, it should INCREASE power. But, it needs to be built correctly. There are some articles/threads here on DTT tbat explain the science way better than I could.

Good luck and post some pics of the project.

 

[AlphaDogChoppers]

I don't know who the fuck told you that 2-into-1 exhaust would cause you to lose power, but they are full of shit.

A collector exhaust, whether 2-into-1 or 4-into-1 will always give you the best performance if it is properly designed. It's important that the collector not be too large in diameter. The whole idea behind it is that the pressure wave traveling down the pipes add to the scavenging energy that pulls the last bit of exhaust gasses out of the combustion chamber. Using a collector exhaust allows the cylinders to help scavenge one another.

Now, as far as no muffler vs muffler goes...
Sometimes, when the pressure wave traveling down the pipe gets to the end of the pipe to the open air, a reverse pressure wave goes back up the pipe. This is called reversion. It has more of a tendency to happen at lower RPM, so two separate headers with no muffler will tend to cause you a bit of loss of torque at the lower end of your power band. That's why a little backpressure from a muffler will sometimes make an engine feel torquier. No mufflers will tend to give you a little more on the top end, however.

 

[teazer]

I respectfully disagree with ADC. Dude that's crap

2 into 1 works well in a motor with evenly spaced exhaust pulses but interferes with flow on a 180 degree twin like a 500T. Most aftermarket systems are not designed for performance because there is not enough margin to justify days on a dyno getting the best out of it.

ADC and others are correct that removing the muffler is not a smart move. It increases noise and decreases performance at most if not all engine speeds.

 

[semaj4712]

Thanks for the help guys, a lot of interesting information, I figured the stock pipes without the muffler would be a bad idea, but it seems even on here there is some question regarding the 2to 1 exhaust as well, since I have no intention to race the bike and am simply looking for fun if the power loss is negligible I will probably go this route...I have a guy thats going to custom weld it for me so I will sit down with him and come up with the best solution for my situation

I will probably start a build thread as I get going a little bit more