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In the following text, we are only concerning ourselves with the two larger types of V6 engines, although tuning principles remain the same for all sizes of engine. Although slightly less in capacity than the Essex V6, these engines are lighter and more powerful (150bhp) but have less torque or grunt than the Essex. Basically, the 2.9 unit is a longer stroke version of the 2.8, but there are also other subtle differences between these two engines, which makes any interchange of parts very difficult. The 2.8 cylinder head has a 2 port siamese exhaust manifold design as against the more conventional (and better) 3 port design on the 2.9. Like the Essex engine, the 2.8 V6 had the same type of cam drive gear design and the same associated problems. The 2.9 has a much more reliable chain drive for the camshaft. The 2.8 engine can be tuned to a reasonable level (modified cam, staged heads, steel cam gear, etc.) but the poor cylinder head design is its ultimate restricting feature. The American version of this engine was fitted with 3 port heads but such items can be difficult to source in the UK. For those wishing to convert their 2.8s into 2.9s be warned, it is not easy and it is not cheap. Because of the different exhaust porting the camshaft phasing is different (they also rotate in opposite directions to each other). The 2.9 distributor, oil pump and drive shaft will also be required. The differences in the chain and gear drives means that, if you fit the 2.9 crank in the 2.8 engine, the front nose will require modifying. And because of the longer stroke crank, the pistons will protrude approximately 1.5mm above the deck face. The piston crowns can be machined down but this will affect their ultimate strength, especially if the compression ratio is to be raised.



With the 2.8, the con rods are the weak link. HD ARP con rod bolts are essential for over 6000 rpm. A con rod that has been stress relieved and shot peened can rev safely to 6500 rpm. An electronic rev limiter is a must have to prevent the consequences of over-revving. Carburettor engines can get good performance using either the 38DGAS or 40DFI5 and, for the more serious, conversions have been seen using a 4 barrel Holley carb. The inlet manifold on the MFi K-Jetronic injection engine is a serious restriction. The four ‘risers’ basically do not allow for sufficient airflow. Unfortunately there is not enough wall thickness to allow these to be opened out, so the only way to solve this is to build up the outsides with welding. With the risers sufficiently opened out, we have seen instant increases of approx. 15bhp.

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