Talk Morgan Forums Morgan Sports Cars Classic Morgans (pre-CX) Roadster and 4/4 Sport

I don't think the MX5 engine is the way to go (for me, at least)...too peaky, not enough torque and not as fuel efficient, if my last MX5 was anything to go by.
The current set up with the 1.6 Sigma is almost there......just needs a bit of fine tuning.......now, where did I put that hammer ?

Perhaps the 2 litre Duratec? .......oh, it'll become a 75th Anniversary model then

I wonder what the implications are about matching up bell housings, gearboxes etc? The internals of the 4/4 Sport box seem to be the same as the Plus 4 and yet the gearboxes externally look quite different.

The 2 litre version of the MX 5 engine is the Japanese version of the Ford Duratec (or perhaps vice versa). The main difference is that the Mazda uses variable valve timing. If you look at the dyno chart on the Aero Racing web site you can see that the Plus 4 SS engine, which has larger throttle bodies and a sports exhaust system, is significantly better than the Standard Duratec. There is a dip in the torque curve at about 2000 rpm. I am certainly not an expert but I believe that may be due to the size of the throttle bodies. I would imagine that slightly smaller throttle bodies and a slightly lower state of tune would eliminate that. In any case it is not particularly peaky as you can see from the curves.

Plus 4 Supersports versus standard Plus 4 - Power curve charts (from Aero Racing)

Lets get back to your thread .

I would buy a new sump and use it to Invest in the Mulfab conversion and a sump guard as I chose to do after holing ours at 350 miles. As DaveW say's, you could always keep the original sump to switch back before selling if that concerns you.

Caterham offer the same motor with 150bhp - I believe down to larger throttle bodies. Shouldn't be beyond the wit of man. In any case, I shan't be doing anything until mine's out of warranty.

That's (kind of) along the lines of what I have been thinking too. I posted a question re: gearbox make/type/model a while ago, but did'nt get very far, unfortunately.

Surely it would be possible to have the existing box rebuilt with more evenly spaced ratios ? That would get rid of the huge jump between 4th and 5th and give the Sigma powerplant a fighting chance at the top end.
I know that would affect standing start acceleration times, but I think it's worth the sacrifice for a better 'on road' experience.

Thanks for the pics Frank, mulfab/mogsport are only 20 mins away, will give it some serious thought

Bin the charts, buy a Roadster!

Hi Easter,

Super Photograph of the Black 4/4 sport, I trust it goes as well as it looks.
I am currently purchasing it from Williams Morgan, my first Morgan after restoring a 1935 MG PA which I now have for sale.
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Welcome to the 4/4 Sport club!