Talk Morgan Forums Morgan Sports Cars Morgan Plus Four, Supersport & Plus Six (CX & CXV Generation Vehicles) Morgan Park Plus Six Sports Exhaust

John, I was puzzled by that bypass looking box at the front and as you say can only assume the cats are closer to the power unit. It does look nice and loud I can't wait to hear one for real.

Is it the OPF or GPF (gasoline particle filter) if so its removal helps boost bhp to well over 400bhp.

Woo Hoo - thanks for that a very useful omission then
I'd never heard of one of those are they recent additions I wonder ?

The box at the front of the MMC sports exhaust, is a Heimholtz resonator, they needed to fit it to get rid of a nasty resonance at certain speeds

Simon @ SiFab.co.uk

Thanks for the clarification Simon

likely a typo, but one should read Helmholtz, not Heimholtz. Explanation of the resonator in https://en.wikipedia.org/wiki/Helmholtz_resonance

I doubt an overall benefit, frictional losses are increased due to more internal pipework surface area, try blowing down a long 15mm water pipe & compare to 28mm

The CAT is directly linked to the cast manifold



No wonder they had problems with a hot engine bay...

Crikey - if that's the Plus 6 manifold, no wonder the standard exhaust sounds so underwhelming.

There are only two manifold runners for six exhaust ports!

I guess this has been done to shorten the manifold and avoid any sharp turns or abrupt changes in the cross-sectional area - so that a close-coupled turbo will give a lag-free response and of course the catalyst runs very hot and therefore efficiently. But the downside is that the two branch manifold will have larger and out of phase exhaust pressure pulses. Larger pulses are good for spinning up a turbo, but the out of phase pulses are not as aurally pleasing as six smaller pressure pulses.

No wonder MMC needed the Helmholtz resonator to try to tune out the uglier harmonics. Not sure that throwing aftermarket solutions downstream of the Cat will do anything other than make the exhaust louder and no more tuneful.

Hello to all TM writer and reader,

as I can see our new exhaust development has arrived on Talk Morgan as well.
We don`t produce it by our own, we`ve got an expert for such performance conversions over here in Hamburg. They already produced the tubular exhaust manifolds and exhausts with flaps for the Aero and last Plus 8 models with
the BMW 4.8 engines. The normal power output of the BMW engines is around 325 - 330 BHP, after fitting our tubular exhausts manifolds with high performance race catalysts and a little ECU mapping we touch 400 BHP and the car performance is fully different. We could sell several of those system by a very high satisfaction of our customers. Cause even the side exit exhaust on the last Plus 8`s and Aero`s hasn´t been homologated, we now can offer an original factory exhaust with flaps to switch it less loud. Over here in Hamburg there is a Police group called "Auto Poser"especially for loud car exhausts, they confiscate loud cars and check the exhausts for road legality.
But back to the Plus Six exhaust.....
In comparison to the Factory sport exhaust which isn`t homologated, we will offer our system with German and hopefully European certificate. So our exhaust will be fully road legal and offers an fantastic sound. Rolling road test has been done in the meantime and the result has been very good. A different downpipe with the highest performance HJS stainless steel catalysts (Euro 6 temp) has been fitted for testing purposes as well.
Cause we are still developing the system, it is not the time now to offer all informations. We will do that when everything is ready.
The main problem is the acceptance of MMC for what we do over here...they are absolutely not happy about....

For to be fair I have to mention that MMC offers a new and different sport exhaust for the Plus Six now. Up to now we didn`t fit it, so I can`t say anything about the sound of this system. It looks different to the first factory sport exhaust,
but it isn`t homologated as well.

So far for now

Frank from Morgan Park Hamburg