15 replies to this topic

[sheldon1992]

Hi, 

 

My mini (1992 SPI Cooper) has had a sportex exhaust without the cat fitted. Apart from that, it's stock (apart from styling and a K&N air filter). Obviously before MoT I am going to have to replace it. I see the JCC do one that looks fantastic:

 

https://www.cooperca...in-upswept.html

 

I'm wondering if anyone has this or has put it on an SPI of similar age. Alternatively, is there something else you would suggest?

 

Thanks!

 

[cal844]

Far too expensive, you could have an identical system from sportex for much cheaper, and also fit a free flow manifold.

You will need
an appropriate cat
Sportex cat back system
SPI type LCB (or free flow to eliminate extra joints)
Fitting kit.

Edited by cal844, 18 October 2020 - 03:07 PM.

[cal844]

You need minispares.com part number

C-STN22

Rc40 cat back system and manifold. Cat is sold separately so best to call and do the transaction, or get them to give you part numbers and buy online.

[sheldon1992]

@cal844 - thank you. It is very expensive. I do wondered if anyone has it fitted and can talk to it. 

 

I'll look at the part you suggested.

 

I really don't want to lose too much of the sound, it's awesome! 

[cal844]

What is currently fitted? Reason for asking is that if there is a flange to join the cat to the rear section you can just replace the manifold and cat.

If you wish to retain the sportex exhaust have a look on eBay for a cat back system.

Kind regards

[cal844]

Here are links to the complete downpipe, cat and back system.

https://www.ebay.co....EUAAOSw-W5UtjS1

53.99 Free UK delivery


https://www.ebay.co....vAAAOSwNTVfUlVw

£240 delivered

Then a CAT on top of that.

[sheldon1992]

This is what is currently fitted:

 

https://www.minispor...st-removal.html

[cal844]

Even better, I shall edit my post with the correct rear section.

EDIT

You only need a CAT and rear link pipe.

Edited by cal844, 18 October 2020 - 04:06 PM.

[Cooperman]

The big problem with the existing system is the 3" diameter final tailpipe. You will be losing a few bhp with that.

The final output part of the pipe needs to be the same as the rest of the exhaust pipe in orde to maintain the exhaust gas velocity.

For a basically standard 1275 engine the pipe diameter needs to be 1.75" bore diameter. A modified engine can go to 1.875" bore diameter, which is what my very-modified Cooper uses.

Too many people don't realise that a sudden increase in pipe diameter causes the flow speed to slow and creates a higher back pressure which reduces the engine power.

A cat with an RC40 exhaust system is great.

[cal844]

The big problem with the existing system is the 3" diameter final tailpipe. You will be losing a few bhp with that.
The final output part of the pipe needs to be the same as the rest of the exhaust pipe in orde to maintain the exhaust gas velocity.
For a basically standard 1275 engine the pipe diameter needs to be 1.75" bore diameter. A modified engine can go to 1.875" bore diameter, which is what my very-modified Cooper uses.
Too many people don't realise that a sudden increase in pipe diameter causes the flow speed to slow and creates a higher back pressure which reduces the engine power.
A cat with an RC40 exhaust system is great.

I agree, the OP wanted to use the JCW system, hence I linked to that system.

I do agree that a single box RC40 with cat would be best

[Cooperman]

The RC40-011 is the best box for a 1275 engine in moderate state of tune, say up to around 110 bhp. 

You can link that into a cat, or add a centre box if it is too noisy. I have no cat on my 'S' because it is a 1964 car, but I have twin boxes to keep the noise at a sensible level. It is 1.875" diameter with a centre exit. 

The best way to mount such a system is to use the early car-type mountings with the metalastic block at the front of the rear sub-frame and a pair of 'cotton-reel' mounts right at the back.

If you want to spend a bit more, the Maniflow works well and is almost as quiet as the RC40 when used with a centre 'cherry bomb' box. With a Cat this may not be necessary.

[madaboutcherry]

i see that the contact details for the 'cooper car company' just happen to be the same as Minisport's. funny that.

[sheldon1992]

Thanks for all the advice. As much as I love the sound, I think I'll be putting on a RC40-011 with a cat. Sounds like I'll pass my MOT and get a few BHP back!

[Cooperman]

A classic car can sond 'nice' without being too noisy. I always think it funny when I see a relatively low-powered classic with a 'power-sapping-noise-boosting' exhaust system making a lot of noise and only capable of limited performance compared with small modern cars such as a Ford Fiesta.

If it's a genuine competition car, it may be different as they are optimised for competition against other old and relatively slow cars. 

My very-modified Cooper 'S' will do 0 - 60 in around 7.5 seconds, whereas my very quiet and smooth BMW 7-Series takes 6.8 seconds.

Minis are a 62-year-old design and we need to remember that. It's just a lovely, iconic classic car. It does not need to be noisy as well  .

[cal844]

The RC40 system is a brilliant system. I have the twin box one on my 1980 estate and it pops and bangs on a long over run but still sounds good under acceleration and is quiet enough for long drives.