|
|
Post by Zed. on Jun 2, 2022 8:38:39 GMT
The Supertrap rear muffler has been around for a very long time, and consists of a rear bung with removable baffles. You fit only as many baffles as you think you need to make the noise tolerable. Not familiar with the M2 motorsport bungs, but it sounds like something that works in a similar way. ^^This  Not familiar with the M2 motorsport bungs, but it sounds like something that works in a similar way.  'bungs' as I see are smaller diameter pipes with mount-flanges of some description (common for ducatttttie obnoxiousness as the owners have little taste & wish to demonstrate it as well as their bank-ballance  ) worth a try though, can also add some backpressure and this sometimes improves drivability  Rich. |
|
|
|
Post by howardb66 on Jun 2, 2022 10:48:49 GMT
Have a look on SummitRacing zoona there’s loads of possibilities on there. |
|
|
|
Post by dickie on Jun 2, 2022 21:32:49 GMT
My M2 motorsport 2 1/2"system came with a plug up its back end which reduced the outlet size thus causing a restriction and increase in back pressure. so I drilled lots of holes in the baffle end to allow the gas out at high revs, In the end I just took it out as the ITBs still make more noise than the exhaust, which actually passed the MSUK noise test.
I would look at Supertrap for you application which should not cause too much back pressure.
|
|
|
|
Post by atlex on Jun 2, 2022 22:00:09 GMT
Wish we had Summit Racing here..
|
|
|
|
Post by zoona on Jun 2, 2022 22:16:38 GMT
Wish we had Summit Racing here.. It's very nice to have easy access to it... |
|
|
|
Post by warpspeed on Jun 2, 2022 23:04:11 GMT
One exhaust system company worth knowing about are Donaldson. They are the only company that give full specifications for their mufflers including back pressure at a stated Hp level, and a noise attenuation figures. Now these are really serious mufflers for trucks and large diesel engines, but they work equally well on cars. The thing about trucks is that if you have a 400Hp diesel engine, and you expect to be able to pull a fifty ton B double up a hill, you want to know how much back pressure a given sized muffler creates at 400Hp of exhaust flow. You need to be sure your truck is not going to lose power by fitting a particular muffler. If you have a genuine 400Hp turbo engine in your little car, exactly the same figures for noise and flow apply. And the figures are real and can be relied upon. donaldson-catalogue.com/exhaust/# Mufflers start at page 46 I have been thinking about ordering a Donaldson M065044. 1 inch Hg specified pressure drop (2psi) at 326 Hp. That works out to 1psi drop at 228Hp. So for our typical 230Hp to 330Hp turbo engine, roughly 1psi to 2psi drop. 15db to 20db of sound attenuation is quite good too. The unique side entry solves the problem of the very tight bend going into our rear transverse muffler, and it will fit easily, as it has no more height than the stock factory muffler. shop.donaldson.com/store/en-au/product/M065044/14107 click on specifications.
On paper, this looks to be fairly good compromise between noise and back pressure, and it should fit easily into the space available.
|
|
|
|
Post by zoona on Jun 4, 2022 16:06:41 GMT
THanks very much for all the input on this. I can't find a 3" bung/db killer (whateve they are called) that isn;t a piece of prarrie canoe off ebay. I think this may annoy some poeple... but I've ordered a bigger back box, and some more tubing, and I'm going to make that up and see how it sounds. I spoke to somebody at Summit and they helped me choose something that should be a bit quieter. Complicates packaging a bit... but we will see how it turns out. I did this before I read the above post. warpspeed - Just trying to understand the info in the post above... The one you mentioned:  Does this mean I can look for somethign that has a 320ish (or a bit lower for my car) value for 1" pressure drop? My problem is anythign that I can find with 3" is a much higher value, and larger dimentions. Woudl it hurt much to dorp down to 2.5" to go into a muffler? |
|
|
|
Post by warpspeed on Jun 5, 2022 0:38:28 GMT
When I finally get around to doing this myself, I plan to use a three inch dump pipe off the turbo, then three inch down beside the gearbox.
Over the last two to three feet where it goes under the L.H. driveshaft, gradually taper the pipe down from three inch to two and a half inches.
This can easily be done by splitting a three inch pipe and removing a long thin wedge of metal. Then closing it back up with hose clamps into a long smooth taper, then just welding along the seam.
A slight kick up in the two and a half inch pipe, then straight into the M065044 which will sit pretty much where the original muffler went.
Its a lot shorter than the original muffler, and located further over to the left hand side too, leaving room for a second short muffler if you find you need it.
If its still a bit noisy (I want mine pretty quiet) I will fit my trick poppet valve gizmo after the M065044.
You are right, the three inch version is huge, would cost a lot more, and would sit very low. It would also be more noisy and a lot heavier.
The M065044 has "some" slight back pressure drop, which is absolutely necessary to bring down the noise level.
Donaldson have distributors worldwide.
The link I provided earlier was for Donaldson in Australia, where I am.
|
|
|
|
Post by warpspeed on Jun 5, 2022 1:06:25 GMT
The exhaust coming out of the turbine is very turbulent, swirling and corkscrewing down the first bit of pipe, and there has to be a ninety degree bend right there too. So a three inch dump pipe is well worth having if there is sufficient room.
Once the exhaust gas is all heading in the same direction further down the pipe, there is no problem in narrowing the pipe down a bit, especially if its done gradually.
The physical size of the muffler is less important than the pressure drop the and noise reduction.
You cannot smooth out the exhaust pulsations without introducing some small amount of pressure drop, but obviously not too much pressure drop.
Its a bit of a juggling act, but about one to two psi at full power would be about right for performance.
If you want it less noisy, there is really no option other than adding more restriction to it unfortunately.
|
|
|
|
Post by zoona on Jun 5, 2022 3:10:58 GMT
Ok, will thanks very much for all the input.
I feel slightly better educated now...
I will see what my new muffler from summit does, and then maybe think again if it's not what I want...
|
|
|
|
Post by warpspeed on Jun 5, 2022 4:00:27 GMT
A bit of trial and error is the only way forward in this game.
Everyone has slightly different aims and expectations.
|
|
|
|
Post by zoona on Jun 6, 2022 2:18:56 GMT
A bit of trial and error is the only way forward in this game. Everyone has slightly different aims and expectations. That's the conclusion I've come to... I'll report back when I've got this new box up and running. |
|
)
le sigh