33 replies to this topic

[Vipernoir]

Heretic as it may be to even suggest it, but I think the RC40s fit better too.

[Dusky]

I have a peco ready to installed atm...
Optimal would be blanking of 1 of the 2 exits( centre exhaust,double endpipe out.of the muffler)

[asmith366]

I've got a twin 3" dtm centre exit, with large bore link and y piece with a lcb have had no issues with loss of bhp, i took it to the rolling road to check & all he did was put different needles in and set up the mixture properly. plus it sounds pretty sweet! 

[Mr Joshua]

Straight through pipe with the back box for an XR3i (preferably picco power master if you can still get them) you will have to get a70° mandrel bend so that it all lines up. Beats an RC40 for performance in all areas. Six months of road testing every variation of exhaust configuration I could get my hands on or fabricate and on a1275 nothing came close to the performance the engine delivered when fitted with the setup I described.

That's the only performance freebie on my car I'm giving away.

[Dusky]

I've got a twin 3" dtm centre exit, with large bore link and y piece with a lcb have had no issues with loss of bhp, i took it to the rolling road to check & all he did was put different needles in and set up the mixture properly. plus it sounds pretty sweet! 

If it just the end piece I can imagine that the pressure is still high enough.. Does it look a bit like this ? (my peco exhaust )

 

 

Straight through pipe with the back box for an XR3i (preferably picco power master if you can still get them) you will have to get a70° mandrel bend so that it all lines up. Beats an RC40 for performance in all areas. Six months of road testing every variation of exhaust configuration I could get my hands on or fabricate and on a1275 nothing came close to the performance the engine delivered when fitted with the setup I described.

That's the only performance freebie on my car I'm giving away.

Enlighten us

[Mr Joshua]

I use to design the exhausts for new trucks way back when had access to fabrication equipment so all the info you need is in the post above.

[Kaj]

I'll also second the use of a Maniflow system. Noisy but built to last with skidded box. Had mine fitted for 10 yrs and still going strong. I have the Stage II manifold as well. Fits perfectly.

 

Oh and their made in the UK!!!

[KernowCooper]

I have a stg 2 Maniflow LCB with the single side exit back box fitted and its a excellent system and the correct size to produce maximum power, if you have a twin exit large bore system then you are loosing power compared to the Maniflow or the RC40 setup, its been proven by several tuners, Calver for one who did a giant exhaust test several years ago.

[Gr4h4m]

The yellow book has some flow figures, and we are all using the wrong exhaust, we need some super turbos!

Anyway the rc40 is quoted by Mr V as good upto about 120-125 bhp at the fly. It was also designed for the a series to help cut down the noise created by the a series exhaust pulse.

The peco didn't look good the the cros section cut pics in the book.

[Mr Joshua]

But are you looking at the pecorino for the mini? The one I use was designed for a 1600

[Dusky]

But are you looking at the pecorino for the mini? The one I use was designed for a 1600

me? Yes

[Cooperman]

If you want twin exit pipes on a 1275, the diameter of the pipes should be about 1.25" each. The reason, as has been explained on here umpteen times, is because the most efficient way for the exhaust gas to exit is at the same speed as it moves down the pipe. If the cross sectional area changes near the end the gas velocity decreases and the gas pressure increases at the point where the cross section increases.

The twin parallel pipe exhausts are, quite simply, 'power-sapping noise boosters' and are not performance up-grades in any way.

[Dusky]

Ooh, I always thought pressure decreased...

Wont be fitting a parrel ^^

[freshairmini]

If you want twin exit pipes on a 1275, the diameter of the pipes should be about 1.25" each. The reason, as has been explained on here umpteen times, is because the most efficient way for the exhaust gas to exit is at the same speed as it moves down the pipe. If the cross sectional area changes near the end the gas velocity decreases and the gas pressure increases at the point where the cross section increases.

The twin parallel pipe exhausts are, quite simply, 'power-sapping noise boosters' and are not performance up-grades in any way.

 

Ha, thats funny tho because when my mini was on the road and I fitted a stage one kit, with one of these  'power-sapping noise boosters' (for context it was a maniflow twin tail pipe DTM style zaust, linky ) and still got a 15 to 20% increase in power when set up on Slarks rolling road... soo bit puzzling eh lol

 

I have printouts if anyone wants proof.

 

I can appreciate that ridiculous twin 3" pipes would prlly not do any good, but maniflow's offering seem to net me some more horses before AND after a rolling road sesh.

[Mr Joshua]

To add. I tested all the systems I assembled on a mini hill climb between the A505 bypass and cadington (before it got ruined)for those of you that know it.

With a full RC40 kit fitted I could hold third quite comfortably, it would still pull but I would lose speed if I selected 4th while still on the steep section of the gradient and have to shift back to third.

With the system I run now with the 4 1/4" oval exit not only can I shift into 4th but it allows me to continue to accelerate.

Same hill same engine. Proof of the pie as they say.

At the time I spoke to an engine test bed engineer, told him how I had gone about my research for want of a better word and he said your approach in engineering terms was not pretty but you seem to have fluke'd it. Your combination of bends, pipe and back box have worked out well against the odds, I'm surprised at how well it seems to have worked.