Would like to do dual exhaust conversion

KMA · Sep 20, 2007

Like many of the PT owners here, I have a lot of heat build up and would I'd like to convert my 422 to dual exhaust. I thought the simplest way to do this would be to locate a Robin engine exhaust port adapter to change it to NPT threading. From there, I could use standard piping and other parts to route the exhaust out of the engine compartment. I also thought it might be easier to then select a set of threaded mufflers.

Does anyone know where to locate an adapter like this? If not, is there somewhere that sells exhaust pipe that would fit this engine? (not sure of the diameter, etc...) I've been searching all over with not much luck.

Thanks for the help!

SnowRidge · Sep 20, 2007

Try Jacks Small Engines. They sell on the web, and they have that sort of thing for Kohler. They might have them for Robin.

MuncyBob · Sep 20, 2007

Kevin...I was also considering doing this, but being the gentleman that I am I'll wait for you to do it first with pics of course!

Rivco · Sep 20, 2007

KMA said:
Like many of the PT owners here, I have a lot of heat build up and would I'd like to convert my 422 to dual exhaust. I thought the simplest way to do this would be to locate a Robin engine exhaust port adapter to change it to NPT threading. From there, I could use standard piping and other parts to route the exhaust out of the engine compartment. I also thought it might be easier to then select a set of threaded mufflers.

Does anyone know where to locate an adapter like this? If not, is there somewhere that sells exhaust pipe that would fit this engine? (not sure of the diameter, etc...) I've been searching all over with not much luck.

Thanks for the help!

KMA, You could do what I did on my 180. The 422/22HP & 180/18HP engines are the same size and specifications with the exception of the carb & governor settings. Feel free to download the pictures ( these pictures are of my well tested prototype set up )to give yourself a few ideas.

. I'll leave the pictures uploaded until tomorrow.
Then they go back into my vault...only to resurface by special request

Barryh · Sep 20, 2007

Rivco said:
KMA, You could do what I did on my 180. The 422/22HP & 180/18HP are the same size with the exception of the carb & governor settings. Feel free to download the pictures ,to give you some ideas.. I'll leave the pictures uploaded until tomorrow.
Then they go back into my vault.

This is on my list also... Wish someone would make and sell a kit .... Hint Hint

Rivco · Sep 20, 2007

Barryh said:
This is on my list also... Wish someone would make and sell a kit .... Hint Hint

Not to go against TBN's rules and regulations,.... but what would you guys be willing to pay for a well tested dual exhaust bolt on kit???, or Carry all bed, maybe a mini hoe with 12" or 16" buckets,or how about 42" adjustable pallet forks,or maybe even a Hydraulic boom lift etc. etc. Send me a PM if interested.

KMA · Sep 20, 2007

Rivco said:
KMA, You could do what I did on my 180. The 422/22HP & 180/18HP engines are the same size and specifications with the exception of the carb & governor settings. Feel free to download the pictures ( these pictures are of my well tested prototype set up )to give yourself a few ideas.. I'll leave the pictures uploaded until tomorrow.
Then they go back into my vault...only to resurface by special request

Rivco,

The pics look great! If you don't mind me asking, what did you use to mate the piping to the engine?

Thanks!

Rivco · Sep 20, 2007

KMA said:
Rivco,

The pics look great! If you don't mind me asking, what did you use to mate the piping to the engine?

Thanks!

The robin engines don't have a female threaded exhaust port like the Briggs & Straton and a few other engines so I had to duplicate the OEM exhaust flange. I fabricated them from 1/4" A36 steel plate ( mild steel ).

KMA · Sep 20, 2007

Rivco said:
The robin engines don't have a female threaded exhaust port like the Briggs & Straton and a few other engines so I had to duplicate the OEM exhaust flange. I fabricated them from 1/4" A36 steel plate ( mild steel ).

Thanks again! Maybe instead of making a whole dual exhaust kit, you could whip up several pairs of the exhaust flange-to-NPT threaded adapters to sell to anyone interested in trying dual mufflers.

Gravy · Sep 20, 2007

My attempt at adapting the Robin factory complete side-mount exhaust kit http://www.tractorbynet.com/forums/power-trac/100127-robin-exhaust.html didn't improve the noise level or power as much as I hoped, but I think the factory exhaust manifold might work well with a better muffler. When I finish destroying the current muffler, I'll try something different.

My limited knowledge of exhaust system design suggests that a properly designed single exhaust gives a wider usable power band than a dual system. I suspect that duals with a crossover and large volume mufflers would be best. I hope somebody figures it all out so we can all steal the design!

Gravy

Marks481 · May 5, 2009

holy old thread revival, batman.

That out of the way...

I finally had all the pieces and parts that I needed to do my muffler mod. I cut a couple of flanges out of 3/16" 304 stainless, based on using 3/4" schedule 10 tubing for the manifold. I intended to enlarge this to 1" (with a 3/4->1" reducer) after the elbow welded to the flange.

I pulled off the PT muffler, and was surprised to find the exhaust ports on the engine were 1.09" ID (which is the same as the ID of the 1" schedule 10 tubing). It seems wrong to put an exhaust manifold on this of a smaller ID (like PT did, no big surprise).

I guess I will bore out my flanges and use the 1" schedule 10 elbows instead. This will be tough based on the amount of room on teh flange, but I think that I can orient the flanges vertically; the robin engine has places to put studs (although they aren't tapped) for vertical flange placement.

SnowRidge · May 5, 2009

Tim_in_CT said:
I pulled off the PT muffler, and was surprised to find the exhaust ports on the engine were 1.09" ID (which is the same as the ID of the 1" schedule 10 tubing). It seems wrong to put an exhaust manifold on this of a smaller ID (like PT did, no big surprise).

I think I mentioned PT's using a "step down" exhaust manifold on their welded up muffler when I pulled mine and replaced it with a stock Kohler muffler. I'm certain it is one of the contributors to the PT running hot syndrome.

Marks481 · May 6, 2009

I kind of remember the soot rings on a picture of your muffler header (that look like mine does, since the PT built tubes are a smaller diameter and are not located concentric with the exhaust ports) and your post-mortum of the PT muffler. ahh, here is the post:

http://www.tractorbynet.com/forums/power-trac/37706-exhausting-pt-425-a.html#post421849

The hole that they cut in the square cross-member header doesn't line up with the stub tube (there is about a 1/4" lip), giving a further blockage. Definitely not the ported and polished job that most tractor racers would expect....

SnowRidge · May 6, 2009

Tim_in_CT said:
Definitely not the ported and polished job that most tractor racers would expect....

LOL. Exactly.

MossRoad · May 6, 2009

Tim_in_CT said:
Definitely not the ported and polished job that most tractor racers would expect....

Now you went and made me spit my beverage all over my monitor!

KMA · May 6, 2009

Boy, if anyone can come up with plans, a kit, or custom built dual exhausts for the Robin powered PT 4XX I would be pretty excited. Anything to make my tractor run a bit cooler would be welcomed. I just don't have the tools, skills or time right now to do something like this myself. Also, if someone could just weld up some flange adapter thingies to mate to the engine and are threaded on the other side for piping, that would be pretty neat too.

SnowRidge · May 6, 2009

KMA said:
Boy, if anyone can come up with plans, a kit, or custom built dual exhausts for the Robin powered PT 4XX I would be pretty excited. Anything to make my tractor run a bit cooler would be welcomed. I just don't have the tools, skills or time right now to do something like this myself. Also, if someone could just weld up some flange adapter thingies to mate to the engine and are threaded on the other side for piping, that would be pretty neat too.

Check with Robin. Kohler makes flanges and such for their line. Robin may also have something similar