26 replies to this topic

[m1key]

hi, im doing a track day mini and im after a centre, twin exit dtm style exhaust that sounds like a rally car. does anyone know were i can get one from. if not it can be any style exhaust just rally sounding. thanks

[Cooperman]

The DTM is a power-sapping exhaust for various reasons.
A rally car exhaust is quite quiet as the noise limits are strictly enforced at scrutineering.
The best rally system I've used is a twin-box RC40 with skid plates welded to the fronts of the boxes for when it hits bumps and the entire system from the Y-piece end to the final pipe all welded together to make a one piece exhaust pipe system. That way it's less likely to break off. I also fit extra mountings as well.
The exhaust needs to be 1.75" internal diameter all the way from the end of the Y-piece to the final exit to maintain exhaust gas velocity at a constant figure and get maximum efficiency. The DTM slows the exhaust gases just before final exit due to the increase in cross-sectional area of the pipe(s) and thus increases exhaust back pressure and loses a few bhp.

[mini93]

if your just after a twin exit type centre thing for track use which sounds awesome, look at what the miglias run. Made by Maniflow but certainly not cheap

[m1key]

are these any good? which one is best.

http://www.minisport...fo_RCMROAD.html

http://www.minisport...T48DTM2.75.html

or could i get one of these http://www.minisport.com/mini-spare-parts/info_PHBPPS1FP.html and weld an extra bit of pipe to make it a bit longer

[m1key]

any one?

[crazycoleman118]

there too big, and the last link you sent is the centre pipe.. you will need a back box for it, otherwise it will deafen everybody, and sound like a tractor... none of them are the best, if you want a centre exit get one thats 1.75" in diameter its right for the engine assuming its standard

[Puddings]

just remember if you are doing track days you will have to pass the noise regulations normally 98db bear this in mind when making your choice

[MiniLandy]

any one?

Mate, you haven't paid attention to what you've been told.

Rally cars sound the way they do, because they use the exhausts that give them the most power.

The exhaust that will give you the most power, is probably the single box maniflow jobby, with an lcb. Single box RC40 is also a good option, again with an lcb.

Big, twin tailpipe back boxes will cost you power, and sound fake.

Good luck!

[mini93]

main thing you have to ask is...what rally car do u want it to sound like theres alot!

[Sprocket]

Depends on which track you want to do a rack day at, and when. The noise regulations differer from track to drack and even day to day at the same track. The best bet is to get the quietest exhaust system you can that is not restrictive, if you want to do track days Go with a loud exhaust and you will be going home early.

[valve bounce]

as said a twin box rc40 or a similair maniflow system,
sorry to hyjack but i was wondering what size system you would advise for a heavily tuned 1000 at the mo is a small bore 70's janspeed lcb into a 38mm pipe with a striaght threw center exit box any good?

[Cooperman]

A modified 998 usually seems to run best and to give most power when fitted with a 1.625" internal diameter pipe. That should be fine for up to around 6500 rpm, but if your power peak is above this (you said it is heavily modified) a 1.75" int. dia might just be a bit better for up to 7000+ rpm, assuming the manifold outlet is that size.
The 38mm pipe is a little on the small side for top end power, although it will be fine for low and mid-range revs. The 38mm is, presumably, the internal diameter. If it's the outside dia then it's too small.
For the 998 it is often said that the 3-into-1 exhaust manifold is slightly better, although there can't be much difference really.
With exhaust systems, a pipe that is too big is as bad as one that's too small as it's the exhaust gas velocity which is important. One thing that really saps power are those large twin-pipe final exits as the gas suddenly slows as it enters them and the back pressure thus increases auses a power loss and an increase in fuel consumption. The final exit pipe needs to be the same diameter as the main part of the exhaust pipe for best performance.

[bmcecosse]

Fit an exhaust suitable for a 1275 - because you WILL upgrade to a 1275 sooner than later.........

[lindy119]

Sorry to hijack also, but I recently made a compulse buy for one of these:



and it just looks very loud!! Haven't even fitted it yet!! But i was wondering if fitting an extra silencer is possible to reduce noise? But would that significantly damage the already stunted performance of my little mini?

Edited by lindy119, 22 August 2010 - 02:36 PM.

[Cooperman]

Sorry to hijack also, but I recently made a compulse buy for one of these:



and it just looks very loud!! Haven't even fitted it yet!! But i was wondering if fitting an extra silencer is possible to reduce noise? But would that significantly damage the already stunted performance of my little mini?

You will lose a few bhp with that final exit for the reasons given above. To optimise power the final exit pipe MUST be the same cross-sectional area as the main exhaust pipe in order to keep the flow of exhaust gas molecules as constant as possible and at the right velocity.
Exhaust noise has little to do with what is best in exhaust design and efficiency.