Straight pipes!

[Bwgad96]

Hi, I want to put straight pipes on my custom lawn mower. I want to be careful not to damage my engine, so is there like a minimum distance the pipes need to be or how could I make this work? thanks

 

[MIKE R]

I think as long as it is similar legnth to the muffler it should be fine. If working it or using it underload might cause early exhaust valve failure but not enough to make a visible change.

 

[Bwgad96]

Ok so as long as about 10-12 inches it wont hurt it? I can make them longer but just want to make sure before i do.

 

[tcartwri]

What rpm are you going to turn this thing?

 

[Bwgad96]

No more than the factory governer settings, whatever they may be.

 

[Tractor Seabee]

I bought a Sears 22 HP Kohler mower (w/0 50" deck) from a neighbor, as I had another older one starting to fail. The guy that had cut the muffler off and added a 3" vertical stack. Sounded like a Harley MC, and very loud (required ear muffs). My old one just siezed up in the transaxel so put that muffler on the Harley Mower and now I have one I can use w/o ear protection. I have a ne Husky mower so use it for a tower. He had it that way for several years and did not seem to have any adverse effect. Time will tell.

Ron

 

[Bwgad96]

Ok approxanently how long was the stack? I am just worried about back pressure.

 

[Tractor Seabee]

96,

It went up 4'. He just put a coffee can over to keep rain out. If you left on when starting it blew up about 4'; hit me in the head once.

Ron

 

[Bwgad96]

Ok thank you, i think im just going to weld up some longer pipes and just run it, worse case she blows but it is a 10 yr old engine so. thanks again

 

[tcartwri]

Using some assumptions about the engine, I get a value of 30" or 40" for a 1" pipe. With 40" being preferred.

 

[toppop52]

Back pressure won't be your problem, exhaust reversion could be if not long enough. You just want to avoid cold air being sucked into the hot combustion chamber between cycles. That will kill valves in a hurry. That said, anything over 6-8" should be fine as long as the diameter is kept relatively stock.