CSL intake vs Eventuri + Karbonius plenum (dynos)

[MBan]

Hi all,

As some of you may know, I had an Eventuri plus the OE-based Karbonius plenum, but I was keen for a bit more CSL-style sound. I had already tried the sound generator mod but it sounds a bit flat to me and I didn't like how Hodge-podge the engine bay was looking with all these bits and pieces.

I emailed Josh from Severn Tuning (aka pokeybritches ) and asked what the latest advice is regarding an alpha-n tune. His advice was that if you're doing it because your hardware requires it (i.e. supercharger or CSL intake), go for it. Suitably reassured, I ordered a race-style CSL intake from Karbonius and all the other bits and pieces required for the installation. For reference, here are the previous threads about my modifications:

Supersprint v1 stepped headers, s-pipe and Severn tune
https://www.zpost.com/forums/showthread.php?t=1816109

Full SS exhaust and Eventuri
https://www.zpost.com/forums/showthread.php?t=1868864

The install of the CSL intake went really smoothly thanks to guides provided by others on this and other forums. As others have experienced, you need to trim about 2cm off the snorkel on the 'race' version. I marked out the section that needed to be removed and took it to a friend who makes orthoses. He works with CF regularly and was able to get a super neat finish with a rounded cut-out.







My previous dynos were done at a workshop that specialises in modifying BMWs. I needed them to install the parts - I'm not skilled enough or setup to do a header install myself. Because I did the CSL intake installation myself, I went to a dyno closer to me. Before the CSL intake installation I re-baselined the car. This was done after removal of the SS x-pipe (too much drone and rasp for me) and with the Karbonius OE-style plenum, so not exactly the same as my last run but unlikely to be very different power/torque wise.

Josh from Severn had sent me an alpha-n tune. Once I'd installed the intake, I flashed on the alpha-n tune using the super-easy new software Severn provides and everything ran really smoothly from the start. I did some data logging, which I sent to josh to refine the tune. The next version of the tune is what I took to the dyno for the 'after' run.

I also rented out the dyno for a few hours and Josh did a few tune revisions to see if there were more gains to be had from Vanos and ignition timing changes. In the end, the tune I had was the best, so Josh obviously has his standard maps pretty sorted already. Apologies for double vertical lines on the chart - the baseline run had rpm on the horizontal axis, but the comparison had speed which is much less useful, so I added the RPM from the previous chart.

This dyno read substantially higher than the last one, but don't get caught up in the absolute numbers.



Peak HP gain is 5% which is more than I was expecting to be honest. While peak torque hasn't changed, it now holds this peak over a wider RPM range and I reckon I can feel this on the road.

Below is a table showing the gains at each stage of my modifications. Each stage is re-baselined, so I feel like it is a reasonable representation of total gains. The final number is a bit over 17%. If you assume my car was making full power when I started (I know, it's a big assumption), the gains are in the order of 40kW at the engine.


(edit: corrected some calculations in the table)

The sound is really amazing and a substantial step up over my previous setup of Eventuri plus Karbonius plenum. It also looks so much cleaner in the engine bay.

And the tune has been flawless. If anything, it's smoother below 2,000rpm and I haven't noticed any difference from the tune I had before, or from stock.

I am totally stoked and can't recommend Severn Tuning enough. There is genuinely no one else that I know of that provides this level and quality of service for us Z4ers.

[grannyknot]

Very slick, I like that you went with the satin finish with no stickers, understated.

[MBan]

Thanks - it’s about as subtle as a giant slab of CF can be! I think the race version also looks a lot more integrated than the normal CSL one, which kind of just hangs there.

[Vanne]

Nice.. Thanks for taking a base line and posting the numbers. enjoy the setup.