|
Post by 90GTVert on May 8, 2017 11:12:40 GMT -5
I think you can forget it being a real expansion chamber. That sucker is full of muffler parts and maybe a catalytic convertor if it's 2008+. The 2Ts don't even get real tuned pipes. There is benefit in tuning of 4T exhausts, but not with expansion chambers like this to my knowledge. 49ccscoot.proboards.com/thread/2195/2t-came-oem-tuned-pipe
|
|
|
Post by knobby on May 8, 2017 14:47:05 GMT -5
The up and down diameter on the pipe would screw up the exhaust flow if its not just a skin. Then picture the reversion wave.. worst case it comes back just as the exhaust valve is opening up trapping a bunch of useless spent hot gasses in the chamber! Best case it only screws up the exhaust flow.
I bet there is a perforated straight diameter tube right through there and the chamber is filled with fiberglass sound absorption material. This type design would make the most sense.
|
|
|
Post by knobby on May 8, 2017 14:48:59 GMT -5
Ah there you go.. I guess at least it looks cool. Probably very good at muting the noise too.
|
|
|
Post by pinkscoot on May 8, 2017 18:28:06 GMT -5
I think the only benefit, if any, that these mufflers MIGHT give, is a more free flowing exhaust. That benefit is quite nominal on a 4 stroke, but still there. If anything, you get this cool looking pipe that makes a mean sound. So only REAL benefit of buying one is to increase your penis size by 1/2". Not worth the money when better solutions are available at a lower price. Don't be fooled by the pretty contours and stated claims. 4 stroke and 2 stroke are different sciences all together. You need to think to yourself, what good is a pipe that sends a sound wave back up into the exhaust port gonna do when your output is controlled by a cam shaft and valves? Take a look at this video on how a chamber pipe benefits a 2 stroke (starting at the 2 min 15 second mark), and ask yourself if that same thing can happen with a 4 stroke, cam driven engine: How much more size do I get if I buy 4?
|
|
|
Post by eclark5483 on May 8, 2017 19:09:21 GMT -5
You'll get the Ron Jeremy special.
|
|
|
Post by 2stroked on May 8, 2017 19:18:05 GMT -5
At an average of .25 inch for each..... That's what I figured as well, that "chamber" is actually a silencer
|
|
|
Post by greggkinney on Jun 13, 2017 8:24:41 GMT -5
i have that pipe but off a tao tao gt5 it is NOT an expnsion chamber exhaust. it has a cat where it starts to swell then several chambers. no packing though it just goes through the chambers in a strange reverse like manner. even if you take that silencer off its just as mellow sounding
|
|
|
Post by jeff84 on Jun 13, 2017 10:02:33 GMT -5
from my understanding the only real way to get any scavenging effect on a 4 stroke is with overlap of the valves opening and is achieved with the cam profile.
|
|
|
Post by 90GTVert on Jun 13, 2017 12:02:05 GMT -5
from my understanding the only real way to get any scavenging effect on a 4 stroke is with overlap of the valves opening and is achieved with the cam profile. If the exhaust is tuned so the reflected pressure wave arrives back at the point of overlap, it can help. It will only work within a somewhat narrow RPM range and prob still not be a big gain, and I'd be a bit surprised if many or any 4T pipes even took this into account with their designs.
|
|
|
Post by jeff84 on Jun 13, 2017 15:14:18 GMT -5
well even overlap with an aggressive cam only helps at a certain rpm range. its actually very detrimental at low rpms. that's where that loppy idle everyone loves come from. its the sound of the engine about to stall
|
|
|
Post by greggkinney on Jun 14, 2017 8:02:57 GMT -5
ive had most of my luck attemting to tune 4t pipes by using anti reversion chambers.
|
|
|
Post by turbotype1 on Jun 14, 2017 13:07:55 GMT -5
Velocity is what makes 4 stroke headers work not reversion....
|
|
|
Post by greggkinney on Jul 12, 2017 22:05:28 GMT -5
Velocity is what makes 4 stroke headers work not reversion.... true.. i see lots of people trying large diameter pipe and getting a slow flow so to say. im a beliver velocity over volume, in and out
|
|
|
Post by houseoffubar on Jul 16, 2019 1:19:11 GMT -5
Dammit! Always a day late a dollar short😔 My wife has a Turino 150 (looks just like a vintage Vespa 2 smoker) I thought I would be clever and make a polished stainless “expansion chamber” with a small muffler for the right look, but make the chamber a chambered mechanical muffler, with a small two stroke style muffler after that. Oh well
|
|
|
Post by jackrides on Jul 16, 2019 12:39:31 GMT -5
Benji, the pipe you pictured is called a reverse cone megaphone. It will boost power in a 4T if the lengths and dia. are right. Reflected waves can push unburned mixture back into a 4T as well as a 2T, but very different numbers. No, I don't have the equations and without you may only have cop bait.
|
|