Talk Morgan Forums Morgan Sports Cars Maintenance & Servicing Changing Classes and Engine along with it!!!!

Being 1972 and 1984 cars they don’t need a cat.

Thanks Andrew, at this stage my collapsed cat theory is just that, a theory!

I doubt the custom long equal length primaries four into two into one manifold that Matt at Fusion Fabrications built me is the restriction, it looks very optimised to me.



However, as per my last post there's strong supporting evidence to suggest the cat is causing a flow restriction, and THB l don't really trust so-called sports cats



Of course it could possibly be the silencer that's blocked, or perhaps even a bit of both



I must say I feel rather sanguine about it all, because every modification we've made has behaved exactly as expected at low and mid rpm:

* The big-valve head improved torque
* The Phase 3 cams broadened the curve
* Idle quality remained excellent,
* The engine revs cleanly to 8,250 rpm,
* MAP stays at 100 kPa,

Fueling and ignition are also under excellent control, so the only thing that hasn't actually behaved as expected is the last 1,500–2,000 rpm of the power curve. That makes me think I'm not dealing with an engine that's fundamentally mismatched, quite the opposite in fact. I'm dealing with a single bottleneck that is only exposed when exhaust mass flow becomes very high.

Whether that's the catalyst, another part of the exhaust, or cam timing is still to be proven. My guess is is we'll cut the cat out and Monty will immediately make 200hp plus, and with some cam timing changes on the dyno to prove what the engine wants, we'll get to 213hp or there abouts. Anyway, the only way to find out is to test it, so soon Monty will go back on a different dyno that James uses regularly, and where we will run a pressure test engine side of the cat.

If we do find a restriction the sports cat will be removed, TBH I doubt it's doing much emissions cleanup work anyway. In the meantime, and with all this great weather, I'm focusing on extracting as much pleasure out of the car as I can. l love the way Monty drives and he is definitely way faster than Stage 2 Monty, so while it seems likely there's another 30hp or so to come, I'm in no particular rush to release it.



NB: This may be of interest?

https://www.talkmorgan.com/ubbthreads.php/topics/819716/re-cracking-job#Post819716

Some of the images have been lost but you'll get the idea

To close this question. I was sent the details:

105 Db static test
92 Db drive by