Author Topic: Exhaust (Read 7465 times)

Frank · « **on:** June 04, 2006, 10:29:17 pm »

hey, i have a 18hp b&s and i was wondering would it hurt the engin if i run it with the stock pipes but without the muffeler(I cant spell) anything will help :?:

thanks,
Thor

dragman · « **Reply #1 on:** June 04, 2006, 10:40:23 pm »

if u run straght pipes u wont have the back presser it will be loud i dont see how it will hurt .I have straght pipes on both of mine

dynamark · « **Reply #2 on:** June 04, 2006, 10:57:47 pm »

i would run some kind of pipe .if the pipe is to short it Will burn a valve . if your building a racer or not .sooner or later it Will burn a valve the cold air will suck back in the head and warp it if it's a racer it's worth the effert to add a good pipe /cant win if ya can't be competitive

hope it helps

dynamark

Frank · « **Reply #3 on:** June 04, 2006, 11:07:34 pm »

How short is short the pipes rightnow are about 1ftlong

TrikeKid · « **Reply #4 on:** June 05, 2006, 12:16:07 pm »

The header on my mower is about a foot and a half with all the bends(exits in front of engine, I didn't build it) and it was run hard before I got it with no trouble.

SilentNoise · « **Reply #5 on:** June 05, 2006, 02:30:40 pm »

Best way to figure out how long of a pipe would be perfect for your motor is by doing "the spray paint method".

Paint a good length of exhaust pipe with regular old spray paint - not the high-heat stuff and preferrably white (or another light color usually works best). Bolt it on to the motor, fire it up, and let the motor run for about 5 minutes or so (heck, go for a rip around the meighborhood if you can). You should be able to see a point where the paint stops being affected by the heat of the exhaust. Chop the pipe off at that point and you'll have the perfect length that you're looking for.

MTDrider1160 · « **Reply #6 on:** September 04, 2006, 10:07:08 am »

i took the stock muffler and took it apart, removed the baffles then drilled more holes where the exhaust comes out then welded it all back together.

Chris · « **Reply #7 on:** September 05, 2006, 10:52:25 pm »

Quote from: "dragman"

if u run straght pipes u wont have the back presser it will be loud i dont see how it will hurt .I have straght pipes on both of mine

I hate seeing things like this...

Backpressure = bad
Exhaust scavenging = good

In a prefect world you could have 100% efficient exhaust scavenging with 0% backpressure. Backpressure hurts performance; it's something that you do not want. Exhaust scavenging does affect performance. With too large of a pipe the exhaust cannot scavenge properly and you'll loose bottom end power. With too small of an exhaust you can generate excessive backpressure and loose power also. The trick is finding the proper balance between backpressure/exhaust scavenging to create the maximum exhaust velocity and power

mowdak1 · « **Reply #8 on:** September 05, 2006, 11:35:34 pm »

Yeah George explains that around here someplace... 12" - 16" of 1" pipe, step up to 1 1/4" for a foot or so, then to 1 1/2", and tip it with a few inches of 2" chrome tip to make it crack... or at least I think that's what he said! :wink:

Red Horse Racing · « **Reply #9 on:** September 06, 2006, 07:10:08 am »

Where did Dragman say back pressure was bad?
Where did he say it was good?

All he said was it would reduce it.

Dale

Chris · « **Reply #10 on:** September 06, 2006, 12:49:07 pm »

Quote from: "Red Horse Racing"

Where did Dragman say back pressure was bad?
Where did he say it was good?

All he said was it would reduce it.

Dale

In the way he worded his post it was implied; I just wanted to clarify :wink:

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Author Topic: Exhaust (Read 7465 times)