Is it just the engine management system that's different?

Is there any major internal differences?


Which one is stronger??

Cheers H

I think the strength is identical. My gems has a Thor crank. A basic problem with v8s is height of the inlet arrangement. The gems intake arrangement is very high practically touching the bonnet. This restricts the length of the intake runner. BMW twisted the intake to increase the length thus increasing the torque potential( quite a modern solution). It also restricts the breathing decreasing the bhp. Hence Thor engines were never used in sports cars. A common tweak is to shorten the gems intake trumpets( in sports cars)
Overall I suggest gems and Thor are about equal as management systems. Gems was developed by Lucas and sagem both now bust! It was only used in the British cars using the rv8 serpentine engine and the aj16 jag straight six.
Some of the ancillaries are poor( injectors) but replace the original Lucas with Bosch and a similar performance can be gained. Albeit with greater torque from the Thor. The trigger for the Thor crank sensor is a better arrangement.
Gems being a slightly experimental arrangement has some variety in components early v late. Some parts are difficult to get now for gems.

Driving mymy aj xjs at 80 getting nearly 28mpg I'd suggest any issues aren't with the engine management or the gearbox simply with the design of the rover v8 at 4.6l. ( same engine management and gearbox albeit 2wd v4wd)
The aj16 has 4 valves per cylinder (24 valves)

Am I the only know-nothing who was expecting to buy tickets to a cross pond punch up behind the bike sheds?