Discussion
The best quality is the Maniflow and that also gives the best flow so long as it's the 1.75" inside diameter pipe. The RC 40 is also good and it seems a bit quieter than the maniflow, but the build quality is not quite as good. I run an RC40 centre-exit back box on my 1310 cc rally car as it's quieter than the Maniflow and I don't want to fail the noise test at the start. However, I've had to weld skid plates onto the RC40, whereas they are standard on the Maniflow.
I don't know who JCB are (earthmoving and heavy site equipment?).
You need a 1.75" exhaust pipe all the way from the end of the exhaust manifold to the end of the exhaust pipe on all 1275 and larger Minis. The only exception is a racing engine when you want to use a sustained 7500+ rpm which means at least a 50% increase in exhaust gas volume over a normal engine at, say, 5000 rpm. With a pipe that is too large, the exhaust gas velocity becomes too low and the inertia of the gas molecules is reduced and prevents the scourging effect which the gas velocity should provide to better empty the pipe. Don't be tempted to have a big diameter final outlet pipe as this also spoils the exit velocity of the gas.
You need a 1.75" exhaust pipe all the way from the end of the exhaust manifold to the end of the exhaust pipe on all 1275 and larger Minis. The only exception is a racing engine when you want to use a sustained 7500+ rpm which means at least a 50% increase in exhaust gas volume over a normal engine at, say, 5000 rpm. With a pipe that is too large, the exhaust gas velocity becomes too low and the inertia of the gas molecules is reduced and prevents the scourging effect which the gas velocity should provide to better empty the pipe. Don't be tempted to have a big diameter final outlet pipe as this also spoils the exit velocity of the gas.
JCB? Do you mean LCB? If so its an exhaust manifold. Unless your car is heavily modified, a 2" exhaust is far too big, as Cooperman says stick to around 1.75" as a maximum.
I'd go for Play Mini or Maniflow (not had experience with Fletcher but never heard any complaints), but check the rear mountings, as some centre exit exhaust fit the the upright section of the rear subframe, and your car won't have the required holes for the bobbin mounts. This can be an issue as being behind the rear valance make drill access tricky, although the Play Mini centre exit systems have a bracket that the exhaust sits on which fits to the bottom of the subframe, so are less likely to fall off as the mounts won't shear. I had this problem with my old Janspeed going through the centre of London a few years ago when travelling to Crystal Palace for the LtoB run and inconvenient doesn't come into it.
I had an RC40 cat back on my SPi for about a week, thought it sounded awful, and wasn't that quiet either. I've since fitted a Maniflow twin exhaust and that sounds much nicer, and the build quality is fantastic.
I'd go for Play Mini or Maniflow (not had experience with Fletcher but never heard any complaints), but check the rear mountings, as some centre exit exhaust fit the the upright section of the rear subframe, and your car won't have the required holes for the bobbin mounts. This can be an issue as being behind the rear valance make drill access tricky, although the Play Mini centre exit systems have a bracket that the exhaust sits on which fits to the bottom of the subframe, so are less likely to fall off as the mounts won't shear. I had this problem with my old Janspeed going through the centre of London a few years ago when travelling to Crystal Palace for the LtoB run and inconvenient doesn't come into it.
I had an RC40 cat back on my SPi for about a week, thought it sounded awful, and wasn't that quiet either. I've since fitted a Maniflow twin exhaust and that sounds much nicer, and the build quality is fantastic.
The Maniflow twin set-up at 1.75" ID with a 13" 'cherry-bomb' followed by the back box is my personal favourite, although after 2 rallies it was bordering on being too noisy (thats 98 decibels at 0.5 m from the end of the exhaust at 45 deg and at 5000 rpm).
At the rear i use the basic 'choc-blok' mounting on the front of the rear sub-frame, then 4 off 'cotton-reel' mountings at the back of the sub-frame, two in the vertical web and two in the lower flange. It can't fall off!
At the rear i use the basic 'choc-blok' mounting on the front of the rear sub-frame, then 4 off 'cotton-reel' mountings at the back of the sub-frame, two in the vertical web and two in the lower flange. It can't fall off!
No, a centre exit is so easy. You can drill off the two holes in the vertical web by laying underneath with a power drill. Make a simple cardboard template of the hole positions from the back, then transfer this to the front (i.e. inside) face and drill through 5/16" clearance diameter. The vertical holes are, of course, so easy, but wear goggles as you don't want to do as I once did and spend an hour at 01-00 hours in A & E at Stevenage Hospital whilst a young doctor dug a piece of metal swarf out of my right eye (Ouch!). I had an eye patch like Long John Silver for a couple of days.
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