Predator 670cc muffler options

[mibeaulieu]

Originally Posted by slonomo

Guys, here are pics of the Thermo King APU Tripac muffler, with part numbers. I'm telling you this muffler is super quiet. It's used for semi truck generators for running overnight in crowded truck stops while the truckers sleep. They have to meet sound requirements to be legal by DOT. I'm a Class A semi driver and I've used them, I've walked next to them while running, and I've slept with windows open in the truck while it's running. They are quiet. And the diesel engine that runs is bigger and way more loud than a little 440 clone or 670 Vtwin, guaranteed. I also am a mechanic and I've worked on these APU's, these mufflers are legit. Expensive, but legit.

You can look up and find the Stanley versions, Walker versions....not the same at all. We've used them on trucks and they are louder. The trucks would come back the next week and we'd be installing OE Thermo King mufflers at twice the cost. The drivers hated the $69 versions. The cheaper versions are made in China. The OE version is made in the US and is Stainless.

I haven't used one on a cart yet, but I will soon. The Stanley version I got from Tractor Supply is good enough for my cart. I have a decibel meter, maybe after work tonight I'll get some readings for you.

Here is the Thermo King website. Read about how much effort they put into making these quiet.

https://www.thermoking.com/na/en/roa...SAAEgKBkvD_BwE

Looks like it would be a good fit. Is there an adapter that you know of to get the 2 headers to the Thermo King inlet?

[slonomo]

Originally Posted by mibeaulieu

Looks like it would be a good fit. Is there an adapter that you know of to get the 2 headers to the Thermo King inlet?

You have to modify your header and weld up new exhaust pipe. I don't know of anyone who makes an exhaust kit for that engine yet. You can buy an exhaust pipe kit and cut and weld to make it fit your particular vehicle. Too many vehicles for bolt on exhausts I'm guessing.

Or

You can weld on a pipe to the end of the factory muffler, run that back to the rear, mount a second muffler back there. If you have two mufflers, it should be pretty darn quiet.

[raydhd]

Vegascarts sells headers for the Vtwin 22 HP predator with their install kits. Things being what they are call them and see what is available.

[BIKERMIKEYBLACK]

I first had a Stanley 22022 it was pretty loud now I have this stens it’s considerably quieter than the Stanley but not quite but ok for what we do I’m thinking of putting a baffle in it exit pipe like Slonomo did

[raydhd]

I actually used the Oliver tractor version of that muffler. Well built, fit nicely, and sounded good at idle and low throttle setting. Gave it WOT and it got LOUD. So much so it went right back into the garage and the muffler got taken off and ended up thrown in a pile with the original VC supplied RLV unit

[slonomo]

Ray, those $25 Walker/Stanley versions are tractor mufflers, designed for farm equipment lol. What did you expect? Farmers don't care how loud "ole johnny popper" is.... Those mufflers are straight through designs without any baffles. They do have the "punched tubes" but they are pretty much an open pipe. I doubt they even have any packing material.

There are many different ways to "muffle" sound. Basically the idea is that the sound waves get interrupted by small obstructions and then redirected. Some say the sound waves "bounce" but really to make sound disappear you need to absorb the sound. The other way is to use advanced sound engineering to find a way for the sound waves to "cancel" each other. That is, to bounce off each other repeatedly until they reduce themselves down in size.

The APU muffler I posted about is much different inside than the tractor muffler. I've used a few brands of those and the only one that works well is the expensive "Thermo King" brand. I've never cut them apart to see what's inside, but I'm betting they have more baffling, maybe a different shape baffling, and possibly some exhaust packing material. That would explain why they only last 4-5 years, maybe the packing material gradually blows out of them like the old 2 stroke exhaust?

Car mufflers usually use large baffles inside, little mini sheet metal walls shaped like the letter "V" or "U" to redirect sound. At lower rpm, some car mufflers have a little "trap door" inside that stays closed and traps a lot of the exhaust in smaller diameter piping and baffles. At WOT the trap door opens and lets the exhaust through a more open route. It's crazy, the little door has a hinge and spring and everything. Over time those little parts get rusted out and that makes the muffler louder.

[raydhd]

I think everyone here knows what your take on this is. I don't agree with you but that is my view. Whatever the others find we shall hear.

[tntawney]

Originally Posted by raydhd

Vegascarts sells headers for the Vtwin 22 HP predator with their install kits. Things being what they are call them and see what is available.

I have one of these. It is a direct easy fit. No hassle and it is fairly quiet. They are a bit price though.

[slonomo]

Originally Posted by raydhd

I think everyone here knows what your take on this is. I don't agree with you but that is my view. Whatever the others find we shall hear.

Are you sure? Would you like me to elaborate? Just trying to help the OP Ray. Appreciate you commenting.

[raydhd]

Have you really helped the OP ? Looks like Tntawney posted the real answer to the original OP's question. One of the carters here had a Zemco on his EZGO stocker, had a real nice sound.