18 replies to this topic

[dojo]

My blowing exhaust has fallen off. I'm going to take it in to get it fitted properly.

First question is can anyone identify this exhaust system and is it any good.

Second seems a good time to make sure I have a reasonable manifold on there, if I have this Y piece does that mean I would be running a LCB??

Thanks in advance

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[minidaves]

check your engine mounts and that looks 

[nicklouse]

if you have a Y piece you have to have an LCB if it is a good one who knows.

[Dusky]

Looks like a fletcher or the likes exhaust. Not good at all. Way too big for powah.

[dojo]

if you have a Y piece you have to have an LCB if it is a good one who knows.

thanks

Looks like a fletcher or the likes exhaust. Not good at all. Way too big for powah.

I suspected as much! I imagine powah been said in Tony Bellew-esk voice!


So it's a sporty looking mini, striped out etc, maybe I'll go for a side exit system. Its 1293 at the moment but I want to upgrade head, cam and rebore to 1330 over next year or so, will a 1.75 bore exhaust see me through for a fast road setup?

[cal844]

An RC40 1.75 diameter will be fine, I have a single box RC40 on my estate and it sounds good without blowing your ears 😁

[dojo]

An RC40 1.75 diameter will be fine, I have a single box RC40 on my estate and it sounds good without blowing your ears

Is there a bhp that 1.75 stops being good at?
What kind of % difference will I see by getting the correct size on there?

Thanks for the input guys.

[Cooperman]

A good exhaust is one where the diameter of the pipe is both correct and unchanged from the end of the manifold to the final exit.

For a 1275 to 1330 engine running at up to around 6700 rpm a 1.75" diameter pipe is optimum and this should be a single pipe right to the final exit.

The reason for this is that the exhaust gas molecules need to be at a good speed and pressure all the way. If the final cross sectional area is increased, the molecules slow and lose their inertia which needs to draw the upstream molecules along the pipe. Increasing the cross-sectional area of the exhaust pipe reduces the velocity of the molecules and locally increases the gas pressure, thus preventing the 'extractor' effect of the constant diameter single pipe.

Indeed, it is hard to envisage a poorer design of exhaust than the one you have. It will be costing you several bhp and torque and probably increasing the fuel consumption.

The best system is a Maniflow 1.75" exhaust system with a 'cherry bomb' after the end of the LCB and a standard box at the rear sub-frame. It can be a centre-exit or one which exits at the LHS end of the rear bumper, as the original Mini design. You can get away with a single silencer, but on a 1275 it would be a bit noisy at higher revs. Looks better as well.

[hhhh]

A good exhaust is one where the diameter of the pipe is both correct and unchanged from the end of the manifold to the final exit.

That renders the RCM not good then doesn't it?

[dojo]

A good exhaust is one where the diameter of the pipe is both correct and unchanged from the end of the manifold to the final exit.

For a 1275 to 1330 engine running at up to around 6700 rpm a 1.75" diameter pipe is optimum and this should be a single pipe right to the final exit.

The reason for this is that the exhaust gas molecules need to be at a good speed and pressure all the way. If the final cross sectional area is increased, the molecules slow and lose their inertia which needs to draw the upstream molecules along the pipe. Increasing the cross-sectional area of the exhaust pipe reduces the velocity of the molecules and locally increases the gas pressure, thus preventing the 'extractor' effect of the constant diameter single pipe.

Indeed, it is hard to envisage a poorer design of exhaust than the one you have. It will be costing you several bhp and torque and probably increasing the fuel consumption.

The best system is a Maniflow 1.75" exhaust system with a 'cherry bomb' after the end of the LCB and a standard box at the rear sub-frame. It can be a centre-exit or one which exits at the LHS end of the rear bumper, as the original Mini design. You can get away with a single silencer, but on a 1275 it would be a bit noisy at higher revs. Looks better as well.

 

Something like this ??
http://www.minispare...31.aspx|Back to

 

How much difference is there between side exit and rear exit??

 

Will I also have to change the Y piece and LCB if I get a smaller exhaust?

Edited by dojo, 19 March 2018 - 10:08 AM.

[Cooperman]

Yes, that is about the best available.
You should be OK with your Y piece, but do measure it to be sure.

There is no real advantage with a side or centre exit. The centre exit was originally designed for rally cars so that the rear silencer didn't get damaged so easily in the forests.

[dojo]

Sorry to revisit this... Just about to place order...

What difference will I get between a single and double box (1.75 Maniflow center exit exhaust)

Is it just a case that the single box is louder??

What does the cherry bomb relate to?

Im debating between these two

http://www.minispare...C-ARA332SB.aspx

http://www.minispare...31.aspx|Back to

Then using this kit to fit.

http://www.minispare...32.aspx|Back to


Thanks again

[dyshipfakta]

Twin box will be quieter. A cherry bomb is just a small silencer. Its personal preference really. Twin box is very civilised.

[Cooperman]

A single box seems to be ok on a 998 but a 1275 really needs the cherry bomb as well if it not to be too noisy.

[dojo]

So noise levels

Single box > Cherry bomb > Dual box

As its just a weekend toy does the single box matter? Or is it ridiculously antisocial (unbearably loud) in a 1293?
Its stripped out and racey so i dont mind adding to that vibe!!

Is the mounting kit ok??

Thanks for your help guys.