Rear Exhaust vs Side Exhaust

[MBEARDEN]

My Birkin has the rear exhaust and the exhaust backdraft is strong...from what I read the side exhaust is much better...what about the sound level...it's noisy enough now...it wouldn't take much to cut the exhaust pipe in front of the back tire.

[wemtd]

I find my birkin (wind wings, no doors) has more noise at speed from wind buffeting than the exhaust.

[MHKflyer52]

My Birkin has the rear exhaust and the exhaust backdraft is strong...from what I read the side exhaust is much better...what about the sound level...it's noisy enough now...it wouldn't take much to cut the exhaust pipe in front of the back tire.

 

If you cut your exhaust pipe in front of the rear tire and put a turn down on the end of the pipe you can reduce some of the exhaust note by turning it so the end of the turn down is facing the ground and wear ear foam ear plugs helps a lot I find. Only drawback is the exhaust dose kick up a lot of dust.

[rzempel]

A few guys have left the exhaust at the rear but added a section moving the exit to the side. Apparently it solves all the noise vs. backdraft issues. There's a picture here, to illustrate what I mean: http://usa7s.com/vb/showthread.php?t=4878

[pi7ot]

I recently converted to side exit, but replaced the muffler(Ultra-Flow ss). Mine is definitely louder with a lower tone. I miss the rasp. I'll keep the noise comment out of the opinion as it is down to what muffler you buy.

The Good:

1, clothes no longer reek of exhaust/fuel Emissions.

2, Less weight.

3, Looks better...maybe.

4, Sweeps the floor, good leaf blower.

 

The bad:

1, The turn out/down may inhibit egress.

2, You may need to fab up the heat shield if you change Muffler brand or dimension.

m

Edited November 8, 2011 by pi7ot

[MBEARDEN]

My primary consideration is the fumes...I drove 10 miles to work yesterday and reeked of fumes all day. Extending the exhaust pipe to the edge of the left rear wheel and getting it to he air flow looks like an simple answer. If it doesn't help the side exhaust will be next...I would think that angling the pipe down would reduce the sound.

Edited November 8, 2011 by MBEARDEN
changes

[slomove]

I wear earplugs anyway. With good quality ones (30dB or better) the exhaust noise does not really matter anymore.

[rzempel]

I would think that angling the pipe down would reduce the sound.

 

Angling it down might also increase the perceived sound as it reflects more from the hard road surface. Dunno for sure, but maybe. :shrug:

[pi7ot]

I always thought that a downward pointing exhaust wouldmake less noise.( bounce the sound waves off the ground and so they would be reflected upward and dispersed in a semi spread bore pattern).

The guy who welded my Birkin Exhaust commented that in drag racing circles, a downward aim of the outlet makes things louder.

So now, I'm

 

m

[MBEARDEN]

I have decided to have a local muffler shop make an extension turning the exhaust behind the left rear tire and getting the exhaust into the airflow....but looking at the current system, it barely reaches to the back of the bodywork...I wonder if a downturn pipe, maybe a few inches longer would get the exhaust into the airflow? Or maybe the spare tire is contributing to the airflow problem?

[MHKflyer52]

I always thought that a downward pointing exhaust wouldmake less noise.( bounce the sound waves off the ground and so they would be reflected upward and dispersed in a semi spread bore pattern).

The guy who welded my Birkin Exhaust commented that in drag racing circles, a downward aim of the outlet makes things louder.

So now, I'm

 

m

 

I can tell you this on my car the tip is at a 45 degree angle to the ground deflecting away from the car body and when it was off it was much louder both inside and outside of the car but that is only what I have experienced. I guess it also depends where your standing in relationship to the exhaust.

I still wear foam ear plugs for the wind buffet and the noise.....:rofl: :driving: