How does the exhaust system effect the performance and power?

[deepNdirt]

I was reading through some ads and come accross a CUT for sale, I noticed the exhaust pipe being nothing more than what looks to be a water pipe, I can only emagine what this must sound like, But more curious as how this effects the power and performance of the engine, It seems to me that such a small diameter pipe would be restrictive and could hold back power, it looks like 3 cyl. dumps into one pipe, the pipe not even as large as one of the cyl. exhaust ports, seeing this kinda reminds me of what my son has done to the exhaust of his Ram 1500. it of course has 2 exhaust into a crossover pipe then into a single exhaust system, Someone has given him some kind of after market muffler, he removed the original muffler which was about 3 ft long and 10" round and now has installed this oval 18" long x 14" wide muffler, that on the exit size has only a 2 1/4 flange, he then connect a short tail pipe to it a dumped it to the ground just in front of the axle, the muffler is welded into place and sound OKay if were on a hot-rod but sounds loud from inside the truck, Not to mention the smell of gas fumes, I advised him that he might expect some future engine problems. He's had it on now for about 2 months, what are ya'll thoughts on this subject? ( How does the exhaust effect the engines performance and power? )

 

[aczlan]

How many HP is that tractor? It looks like a 1" pipe which is about the same ID as the exhaust on our BX2660.

Aaron Z

 

[winston1]

I agree putting back pressure could affect engine performance but I would think what is on the engine in the picture would be ok. No baffles or anything in that and not much length. I sure don't know so just take this as my 2 cents and nothing more.

 

[deepNdirt]

I think the engine is a 22 Hp, it's a L200 Kubota , I realize that a 3 cyl engine will only hit a one cyl at a time so any one cyl is pushing exhaust out one cyl at a time, therefor the ports are probably about the same size as that pipe, But as the engine speeds up the exhaust compression builds and needs a larger space to escape through, right? I think is why some engine pre-detonate ( backfire )when cannot get all the burnt fuel/exhaust from the cylinders,

 

[Car Doc]

If it gets too much back pressure it will have blow by the exhaust valve guides is one bad thing. That would be an indication of that particular issue to a mechanic though if someone wasn't looking at the size of the exhaust otherwise. However looking at that pic I cant tell if that one is restricted or not but my guess is not badly. my .002

 

[Willl]

4 strokes for the most part don't scavenge like a 2 stroke.

4 strokes benefit as free flow/no restrictions.

Stuff in as much as you can, expel as much as you can.

 

[Willl]

But, you can go to far.

To short of an exhaust will let cold air back to the exhaust valve and mess stuff up.

 

[GWKID]

The message that I get from the picture is that the only consideration was, "What parts are available to get this thing going again?" It cannot be good but may not be terribly bad. Of greater concern is your son's truck. It sounds like he is asphyxiating the occupants.

 

[California]

Of greater concern is your son's truck. It sounds like he is asphyxiating the occupants.

Worst case: When I was a kid in the 1950's, a neighbor kid's family had a 'Americar' compact station wagon. (Maybe made by Willys?) The exhaust smell in the back seat was overwhelming due to exhaust leaks. A few years later the kid's dad went blind, then eventually died. In my opinion daily exposure to that exhaust poisoned him.


As for that tractor in the photo: I think it should run fine. It might be lacking the last 1.5 hp due to exhaust restriction but I doubt the operator could notice the difference. But I would take that as evidence there might be other cheapskate shortcuts - operating without a filter element in the fuel filter bowl for example. I quit looking at one potential purchase when I discovered this.

 

[Marauderer]

First, how is it running currently? This is a small low rpm industrial motor. Back pressure up to a point is a good thing. In 4 stroke motors having some back pressure will increase the low rpm torque. this is good. free flowing exhaust is great on really high rpm racing motors.

If it runs well, has good power, doesn't over heat I would say let it go and enjoy the journey.