Back Pressure

[dirtfan21]

I know I know another exhaust question! Everyone has their own opinion on no muffler sound, it's too loud, it sounds good, it sounds like sh*t, and so on. My question, that through searching never seems to cover completely, is back pressure.

 

So here it is! If you run stock factory exhaust with the muffler cut out will this hurt the engine? Short term? Long term? THIS QUESTION IS REGARDING GMT 900 ENGINES

 

I am very aware of the possible loss of torque ect ect. Every topic I have read through the search doesnt fully explain this question in detail.

 

We can go back and forth on sound all day haha, but some like the no muffler sound and some don't, this topic isnt to discuss opinions on sound. I'm not gonna say which way I lean to or if this topic is even for me. But it is a topic that comes up quite often around here and on this board. So let's hear it guys. What's the story?

[jro909]

it shoulden't hurt anything, i don't think a muffler has alot to do with back pressure...when you start throwing bigger pipes and hacking cats is when the pressure starts to decline

[Big black truck]

No. Back pressure/reversion aids in drawing new fuel/air into the cylinders. You will not hurt your engine, but you can reduce the effectiveness of its performance. The reversion/wave in the exhaust pulses and pulls air/fuel into the cylinder for a more complete fill. The diameter and length of the exhaust pipe, together with valve timing , cam and intake are all variables in moving air through the engine.

[Nytemare]

No. Back pressure/reversion aids in drawing new fuel/air into the cylinders. You will not hurt your engine, but you can reduce the effectiveness of its performance. The reversion/wave in the exhaust pulses and pulls air/fuel into the cylinder for a more complete fill. The diameter and length of the exhaust pipe, together with valve timing , cam and intake are all variables in moving air through the engine.

+1000

 

In the grand scheme of things, I like the sound of the muffler-less GMT 900.

Now to go into a little more detail about the back pressure, If you have it tuned properly for the decrease in back pressure, ie; timing fuel trim spark etc, you will gain power. But, the the point that now you need to compensate for the loss in back pressure. The biggest loss in power you would see if having true duals without a H-pipe or X-pipe to connect the two sides and equalize the exhaust pulses.