We have one on a 48cc. It's VERY quiet and no noticeable drop in performance. The drawbacks are that it gets VERY, VERY hot. Hot enough to give you sunburn on your leg. You must remember that a cat will burn any hydrocarbons in the exhaust...this means oil, fuel, etc. Less oil in the mix is better for the cat and it won't heat up as much.
I would like to see what is inside of the so call cat exhausts. From my experience on the oil industry running a cat on heavy/big industrial engines oil comming out in the exhaust spells the end of a $5000.00 cat comverter or an expensive engine over haul to get it back to meeting the emmissions. A engine with a leaking intake guide seal will cause a cat to plug or stop working so how can a cat on a 2 stroke work or work for very long? I think someone is blowing smoke.
Not really Norman! I understand where you are coming from. VW cats run between 400 and a grand. These are 30 bux. I looked inside and the catalyst has large pores. This doesn't scrub the exhaust as well as a cat with many, smaller pores. Most 2 strokes made today have cats on them...such as yard equipment. These require a leaner fuel/oil ratio. Our Echo blower takes 93 octane 50:1 premix and has a catalyst.
These bike engines for 08 have a sticker saying they need 40:1 mix.
Don't cats just run Hotter to Reburn anything that pases the norman Burn chamber? I mean like a chevy cat has platinum in a heneycomb that supeheats and reburns the exaust/
I just can't see how a 2 stroke one works.
When we got oil on our cats they would do a nueclar melt down. We had precat temp and postcat temp probs and they would shut down the engine if it went over 1200 on the post temp. seems like they had to get to 600 degess f to start working. I know the crankcase vent bypassed the cats so the vapors from the crankcase didn't go through the cat.
The emissions carp on these engine would drive you nuts when they didn't work right. They are tested every month so they have to work and that can be no fun at times.
I have had the exhaust stinger off on my 32cc because I couldnt believe the thing was running that hot.. it was cooking the rubber elbows designed for nitro engines that worked perfectly on my Zenoah.
What I found was a very wide bore mesh located in a second compartment in the exhaust box which takes the fumes from what seems to be a x-box-esque expansion chamber to another cat chamber and thence to the stinger.
I can attest to it working because when I tried to set up a tuned pipe on it (a total and utter disaster by the way) - the engine was chucking out pale blue smoke like the entire german high seas fleet was on the move.
The difference between the car and a chengine/tanaka type cat. is fairly simple. The former is finely meshed, designed to work with computerised and oxygen/mixture optimised fuel injection systems in engines that are toleranced so tightly that a gnats fart would get trapped... whereas a 2 stroke cat. would be coarser meshed in order that it can deal with a higher percentage of combustibles albeit at a lower efficiency per unit area.
Theoretically you could use a cat on a diesel engine if it were fitted downstream of some sort of particulate filter. Indeed the tier III/IV modern diesels use exhaust gas recycling and other technologies to provide better performance and cleaner emissions