Hi - I have experience with the Miltek high flow catted downpipe ( 200 Cell ). I am wondering if there are any 400 Cell aftermarket cats out there ( I believe this is the cell count for the JCW ). I am thinking they might be a bit quieter then the 200 cell cats. Or if there is a reasonable price for the JCW cat - I'd be interested in that too.

Thanks !

 

Are you still on stock exhaust? You could always have a bigger resonator installed to the mid pipe....

 

No - I have tried a couple of different exhausts ( I will do a longer post on that later ). All have been mated to the Miltek 2.5 catted downflow pipe. Wanting to explore cats now - and think a 400 cell might soften the sound some ... Performance costs !

 

All aftermarket exhausts will be louder on their own, but add in a high flow down pipe, and they get even louder. A bigger resonator will certainly help, and keep the performance increase that comes from a bigger exhaust. I would try that route before going bigger cat in the down pipe. A resonator will be less expensive, too.

 

Thanks Nik - let me clear up a few things. I have tried a few exhausts ( Miltek catted and Akropovic are the last two ) as well as a few different resonators ( Vivid and Magna Flow ) on top of the catbacks. Bigger resonators do not necessarily reduce sound - there is science involved too ( reflection and wave canceling etc ... ). I have seen bigger resonators make things worse. Plus getting them to fit can be a challenge.

I now want to explore/test the 400 cell vs 200 cell cat. BTW - the 400 cell cat is more restrictive than the 200 - which is the route I am exploring ( opposite direction from what you implied with a bigger cat. Although some hi performance applications will fit a much larger diameter free flow cat to further remove restrictions ). I am not sure if there will be a material difference in performance in my set up between these two options. While most people claim there is - I have not seen the actuals to back it up. Losing under 10 hp is not an issue for me.

For others reading - I have seen some JCW cats for sale, might be rebuilt or aftermarket - but no specs are given on the cells, hence seeing what other people night know or what is available.

 

From what I can tell, there were two different downpipes on the N14 cars depending on Cooper S or JCW. On the N18 cars, the downpipes were the same regardless of being an S or JCW. So, there might have been some difference between CEL count on the N14 cars, but no such difference between the N18 engine cars.

I would just go grab a later model used OEM downpipe, and see how it works for you.

 

Yes - on same part numbers for n18 engine. But would want to know what the cell count is first. They could have gone either way

 

Here is an update on cats :

The N14 S Cat is 400 cell. The N14 JCW is essentially 300 cell ( 1/3 of this cat is 200 cell and 2/3 are 400 cell ). The N18 S/JCW cat is 400 cell.

Even though I have seen much stated about the need to go with a race cat ( 200 or 100 cell ) or even catless for performance, I have am still exploring the material impact of the race cat vs a stock cat. Note - the race cats tend to be 2.5 diameter. I am sure the OEM is under that ( perhaps 2.25 ) - so the race cats would be free-er flowing on both cells and diameter.

 

Interesting on the JCW N14 cat... Curious how you found this information?

 

Well my reasoning is that a good tuner would know what he or she is tuning with - kind of turbo, exhaust, cat etc ... So thought I would ask one - in this case Lou at Prototype I actually thought he might have cut one open, which he did once LOL.

Here is a photo of a the N14 JCW cat. You can see the different chambers from the geometry.

 

I think that's the first N14 JCW down pipe I've seen... Cool!

I knew Lou was a wealth of knowledge, and this is the cherry on the top for me. Glad he did my tune!

 

https://www.northamericanmotoring.co.../market/367553

 

yep looks like a two stage. Still have mine on my n14 jcw.

 

Thanks Nik - I found one with 75K miles. But I might need a second for my other Mini

 

Has Mini published anything about the "effective" cells and performance of this 2 stage cat. My guess is that is somewhere between 200 and 400 cells ( as these are the components, but don't believe it would be as simple as a linear interpolation - perhaps more multiplicative ... ). Also, you can see the cat expands in the direction of flow, which is always good for exhausts. So, I am sure some thought/science was put in this design - but since Mini discontinued it for some reason ( cost cutting would be my guess ), but would love to know what the performance of this is compared to a 400 cell 1 stage ( both effective cell count, pressure loss and sound difference ).

 

Just found this thread which gives some more info ( JCW N14 cat downpipe is 2.5 diameter, vs 2.25 for S ) ...

https://www.northamericanmotoring.co...per-works.html

I believe Mini claims ( paraphrasing ) this about the N14 JCW cat: The catalytic converter is an improved a two stage design ( improved over the single stage 400 cell cat, I would guess ). I have seen this stated a few times on different posts.

I am not an expert by any means on cat converters but I am guessing this cat could be:

1) A form of dual bed cat - where the first stage focuses on nitrogen elimination ( the 200 cell part ) while the second stage ( 400 cell part ) focuses on carbon monoxide and hydrocarbons.

or

2) Both stages focus on all ( nitrogen, carbon monoxide, and hydrocarbons ), just at different diameters and cell density ...

Both would be to provide acceptable cat conversion at less pressure drop, so you can run higher boost while minimizing the stress on the turbo gear.

 

We have the dyno numbers when we did stock runs on my car for intake development. We did not investigate the down pipe and compare at the time. My guess is when the developed it (N14 JCW) emission standard where different from the n18 JCW development and thus they were able to have a modified Cat to reach he power and also meet standards. Also the engines were assembled in Germany vs the stock N14 Cooper S.