gems ECU

[Mark Adams]

spend said:

Hi Mark just for clarity as I understand it you are basically saying:

Rip out the Flywheel & replace with one from P46 (fairly rare manual version) + the engineering to lighten it.

Grind out the blank / casting in the block (opposite side to starter) and source the holder + sensor and tack weld it into the block.

Remove timing cover, drill out blanking in casting for cam phase sensor + drill & tap the clamping bolt, source the cam sensor & gasket.

Fit JE cam gear & a GEMS style cam shaft (Unless he has made the gear suitable for 3.9 style cams)

Source & fit the later style cam retainer (its different shape & diameters with the cam difference) which I'm not sure OTOMH if the block mounting holes / locations are the same?

Will the GEMS work OK without knock sensors or will it require the earlier blocks to be adapted to fix the knock sensors.

Hi Dave

It would be a lot of work to fit this system on a non-GEMS block, which sounds like the task you have listed. The honest truth is that you would probably be better off using a good quality after-market system instead to reduce the work, and as always I would recommend something like an Omex 710 (although nobody ever seems interested my recommendations on this subject).

If you are starting with a serpentine engine that already has the knock sensor bosses and crank trigger mounting, it is a lot easier. However it still currently involves lifting the engine in order to fit the crank sensor trigger ring, so is probably best considered only if the engine is being lifted for a rebuild.

John Eales does some fantastic lightweight flywheels for GEMS, although I do have a lightened P38 4.0 Litre manual flywheel in my Sierra 4.8. These weigh around 30 Pounds before lightening, so you wouldn't want to drop it on your foot! It is also possible to fix the trigger ring from an automatic flex plate to the back of the existing flywheel in certain circumstances, but I haven't checked for clearance on the TVR motor.

Currently I am working on a 5.1 litre version of the GEMS engine with John Eales, which has a cross-over manifold with throttle bodies and twin air flow meters. We are going to try some different triggers on the crankshaft pulley to see if we can get GEMS to accept them. Quite often this requirement is understandably a bit of a show-stopper for people considering the upgrade.

Out of interest, this engine will pass the California Smog Test. It has full Euro-III compliance with catalysts, four Oxygen sensors, and fuel tank pressure monitoring. It is currently cracking out about 385BHP, which will be "adequate" for the 700Kg Morgan that it's going in to!

There is a variant of GEMS that doesn't use the knock sensors, but obviously this would require mapping on the rollers since it cancels the individual cylinder mapping capabilities of GEMS. There are other pains with this version of the software, so I wouldn't recommend it really. Theoretically it would be possible to weld mounting bosses on each side of the block for the knock sensors, but getting them in the correct place could be a nightmare. Overall the machining could cost more than just using another block.