Talk Morgan Forums Thread Like Summary - Plus 4 CX - Initial Thoughts

Hello Mogsters,

I have exchanged my R100 for a manual 2022 Plus 4 CX from Williams. It is in Sport Green (which looks identical to their old Connaught Green) and it has tan upholstery, just like my last three Morgans. It had 2500 miles when I bought it a couple of months ago. The wheels were painted and the grill was black, so I asked Williams to change the wheels and grill to SS, just like my last three cars. They also added a luggage rack, Nitron dampers and a Le Mans filler cap. I know – I am in something of a rut here.

There have been a few surprises after it got it, though, despite a test drive and pretty exhaustive research, and I thought that I would list them here as well as a couple of questions… but fast forward if you allergic to technical stuff.

1. I did not appreciate how sophisticated the engine is. It was obvious that it was very efficient from the posted mpg figures, but… BMW has a training web site, and you can get access for £30/day. So I signed on and downloaded two manuals – one on the B48 (D, I think), and the second on the B46/48 TU. The first is very comprehensive and covers the theory of many of the subsystems, but is earlier than the closed deck design of our engines. The second manual specifies the B46TU as the 255 BHP version, with the B48 as the 302 BHP version, but other sources are less clear. Otherwise the engines are identical and have the new lighter crankshaft with bigger journals, VANOS (variable cam timing) on both cams, Valvletronic (variable lift) on the inlet cam, two complex ECU controlled cooling systems (the result of the closed deck design), ECU controlled oil pressure and a remarkable 350 bar (5075 psi) fuel injection pressure. It also has IROX coating on the upper conrod bearing shells, and to quote BMW “The polyamide-imide ensures, in combination with the hard particles, that the bearing shell surface is so hard that material abrasion is no longer possible.” Wow.

2. BMW calls the turbocharger “twin power”, which actually means that it has two turbines and compressors on a single shaft. Each turbine is connected to a pair of cylinders – 1 and 4, 2 and 3 - to provide even pulse intervals. The twin compressors are of the scroll design, in which the compressors do not rotate but move in an eccentric motion that compresses the air in a scroll – like a circular labyrinth. This means that the only rotating parts are the small turbines and the common shaft, which must be responsible for the really fast spool-up times. The electrical controlled waste gate dumps the compressed air into the exhaust, and I presume that this I what you can here woofing when you blip the throttle when you change down, or take you foot off after a burst of acceleration.

3. The Nitron shocks are part of the dynamic handling package, which on the later cars comes with a rear anti-roll bar. If you want this fitted to a 2022 the rear sub-frame has to be dropped to drill holes for the ARB mounting. You are probably aware that ARBs increase spring rate in roll, without affecting the two-wheel bump rate. They also affect the lateral-direction static stability of the car – a front ARB increases directional stability while a rear ARB reduces it. So the rear one would make the car more agile in the twisty sections, but I did not think that this was a worthwhile trade for the reduction in straight line stability considering the cost involved in fitting it, but chacon a son gout. I asked them to set the dampers to the recommended road setting of 11 clicks out from full hard. The recommendation for the track is 7 clicks out, but I have not experimented with the settings or the ride height. Yet. But I would be interested if anyone else has done so or tried different tire pressures.

4. The ride with the Nitrons is firm, well damped, and not at all high-frequency-rattley, which the trads can experience. The bump damping (tested over speed bumps) is about 0.6 zeta which is firm – as a rule of thumb the damping ratio can be calculated by subtracting the number of overshoots from 7/10. Pretty nice, though I think that SSL likes them a little softer (around 0.5 zeta, I think) for the trade. Perhaps the stiffer CX chassis can take a little more suspension damping.

5. I also ran some directional stability tests using wheel raps on a deserted road at 60 mph. The directional frequency response seems around 0.8 Hz, but it might be faster since the power steering affects the measurement. The damping ratio is about 0.5 zeta with the Avon tires, so both the frequency and damping are pretty much ideal, I think. It would be interesting to talk to the chassis designers, but I am not holding my breath. It would also be interesting to hear what Peter Ballard of SSL might contribute… I copied this to him, but he cannot post a comment under TM commercial rules. Nice to hear from him again, though. You are also probably aware that you can change the direction stability with tire pressure delta (front/rear – softer fronts mean more stability) and the roll contribution to turn in stability with front/rear damper stiffness settings.

6. I played around with S+ mode, and now use it all the time. The car feels a little sharper, which I like, and there does not seem to be a downside.

So in summary I think that it is a great car. Probably one of the best sports cars I have driven, and a lot more friendly for passengers than my Caterham CSR, which was from a different universe. The six speed box is very nice – almost as good as the CSR which sets the standard. The Bluetooth system is excellent and useful up to motorway speeds, although I plan to add a left/right and front/rear balance. I would like a permanent nav mounting, and have a plan as I do for more storage space. I bought a scissor jack from Germany, and after I dumped the extra spanners there was room in the bag for the lead hammer.

Leaving for Spain on the ferry and a drive down the West Coast in a week or two.

Regards,
David Poole

Hello David, I'd rather not deviate from the content of your excellent post re Morgan Plus Four ownership; however, did not want to ignore your question.

Historically, the commercial policy relates, primarily, to people who joined to hawk their wares and added little to the community and, in many cases, detracted from it. In latter years, it has been expanded to include people trying to drive traffic to sites that monetise content, be it directly or indirectly. As I am sure you can imagine, it needed to be a blanket coverall because otherwise, those who want to benefit from the community but detract from it are often the quickest to point to the lack of rules that stop them from doing what they are doing.

With all of that said, we take a pragmatic view on the above and my determining factor is always: does this aid the majority of the community and assist owners of Morgan vehicles. We have members who sell small parts that help other owners keep their cars on the road, we have artisans who mention and announce their products via TM and we have small businesses who offer advice and, at times and where appropriate, mention that they can help. As you can imagine, it is always a balance but TM generally operates in a genial and respectful manner and those who recognise they have a commercial product or service, which is relevant and could benefit the community, message me to discuss it. In doing so, more often than not, we agree something that benefits the community and allows the person to openly discuss what they have to offer.

As for a dedicated area, each time it has been mentioned to the forum, the general consensus, driven by the community is 'we would rather not.' With that said, people are also thoughtful and recognise that running TM, and keeping the lights on, isn't inexpensive; therefore, they appreciate that this may be an avenue that needs to be explored at some stage.

Hope that answers your question but feel free to PM directly if you have any others as I'd rather not detract from your interesting post on your CX ownership.