The Cosworth FBA
This must be one of the best kept secrets as far as Ford engines go! The only road car it was ever used in was the top of the range Granada Scorpio, always with an automatic gearbox , and the only visible sign was a small 24 Valve badge on the boot.
However the story of the engine is very interesting and explains why it is arguably the most desirable Ford engine.
The original Ford V6 was the 3 litre "Essex". This was a Heron head design which results in a flat cylinder head face and heavy pistons as they have the combustion chamber recessed into the crown. Not a recipe for a screamer, but the Essex design was a good torquey engine.
Cologne 2.8 litre V6
The Cologne engine was supposed to be better, and could have been as it had conventional heads but was strangled by an Inlet manifold that in effect siamesed the otherwise free flowing inlet ports, and the (restrictive) exhaust ports were siamesed anyway, so only 2 cylinders of the 6 had their own ports ( this is progress?). The well over square bore to stroke ratio should have meant good high end performance with perhaps lower torque at low revs, but the restricted breathing meant that you had neither top end power nor bottom end torque. The only way I found to get some grunt out of this engine was to fit a (Sprintex) supercharger! It meant that there was good low and mid range torque, but the exhaust ports bottled up at just over 5000 rpm so there was no point in revving it.
Cologne 2.9 litre V6
The later 2.9 litre version with 6 port heads should have been better ( is it me or was it bloody minded to change the cam drive from gear to chain so you couldnít easily put the 6 port heads on the 2.8!) but the heads were designed with lots of swirl so they didnít seem to flow that well, and the engine was not that much better than the 2.8.
As far as I was concerned, this left the other wise excellent value Sierra XR4x4 without a modern high performance engine. I believe that this was allowed to happen in order to stop the XR4x4 competing with the Cosworth Sierra (I hate turbo's, nasty things! see Why I donít like Turbo's)
I believe it started life as a racing head design by Brian Hart Engines for the then new "Cologne" V6. When Brian Hart was bought by Cosworth, they acquired the design, and used it as the basis of the engine they were asked to produce for the top of the range Ford Granada Scorpio. This was intended to be a high tech modern refined engine to help the Scorpio compete against BMW and Mercedes. This meant that the resulting FBA design was a road going version of a racing engine!
A full race version of the engine, the FBE was also produced and used in the ProSport 3000 Sports racing cars, where it produced over 300 HP.
The aluminium 4 valve heads fitted onto a modified Cologne block with lifter bores blocked etc. but fundamentally little changed. The front of the engine is changed so the long chain drive for the 4 camshafts can be accommodated. The heads are typical Cosworth 4 valve pent roof design with central spark plug.
In my car the heads have been little modified, a little bit of valve pocket work but they are basically good to start with. The intake manifold has been retained so far but its probably got to go at some point as the new camshaft has more overlap and lift, and at small throttle openings at low speed there is some flow reversion which makes it run roughly, that's my current theory anyway.
On the rolling road it gave 286 bhp at the flywheel and 290 lbs.ft. torque.
The next stage (see FBA Next stages) is to fit individual throttle bodies and intake runners to each cylinder, and a Motec engine management system which will enable me to get full sequential injection, idle and lambda control and better starting. The individual runners etc is a full race set-up so it should improve the top end although the main reason for doing it is to get rid of the cylinder induction interaction at low speed mentioned earlier.
ã Copyright D.Bell 2001