Cerbera Red RoseThere were lots of reasons why we wouldn’t want to take this job on. First off the engine in the Cerbera AJP V8 has a 75 degree bank angle with a flat plane crankshaft. This means that the firing interval is uneven and some special software would have to be written to cope with it. Then the engine has wasted spark ignition so we had to produce a special ECU with the right number of ignition drivers. There was no information available on the wiring of the original ECU and last, but not least, Julian Lane from Joospeed told us that this particular Cerbera was one of the most sorted in the country - having been back to Blackpool under complaint regarding a lack of performance.

Just to add to the drama these engines make obscene amounts of power and we were going to have to map it on the rolling road and try to find the grip whilst not melting the engine. We began by metering out the wiring loom and putting a recording oscilloscope on the signals to see what was going on. Next we bought in half a dozen ECU plugs so that we could make up an adapter. We wanted to be able to switch ECUs very quickly for comparison purposes and also so that the owner (Julian Rowntree) could swap back at any time if he had any problems.

There’s always a lot of talk about rolling roads reading differently but we have calibrated ours and check it regularly. The Red Rose Cerbera turned out to be the most powerful aspirated engine we have run to date with 388bhp at 7000rpm. Driving the car on the rollers a couple of things were obvious; light throttle calibration was causing a lot of crackles and pops and it was very difficult to drive slowly! Half way through the power run we had a big dip in the torque and we believed that the mixture was going far too rich in this area – evidenced by black smoke from the exhaust, never mind the lambda reading. The ECUs were swapped over and we started on the new calibration.

It was obvious straight away that we needed to do something about the light throttle driving. Load site one (1) on our 16 load site system normally sees about 6 bhp on something like a Caterham R500. On the Cerbera we were seeing over 30 bhp at the wheels! We closed up the load sites to give us more control in the light throttle area. I spent a lot of time working on light throttle running. This is an area of calibration that is hard to compare in terms of before and after since you need to drive the car on the road to “feel” the difference. I managed to lose all the crackles and pops and make the engine run pretty much jerk-free on light load.

I always concentrate on light throttle running around the legal speed limit with any car that we map. I lean out the fueling as much as is sensible in order to help the fuel consumption. Apart from the fuel cost this also helps to extend the range between fill-ups. The power is the bit that interests most people though. I am happy to report that the exercise was well worth the effort. Although peak power remained pretty much as before between 6000 rpm and 7000 rpm we had gains everywhere else. It would appear that the calibration was spot-on for maximum power so we couldn’t improve in the one area which always makes the headlines. Check out the graph and you can see the gains for yourself.

Cerbera Power CurveJulian Rowntree took me out in the car for a final check. I had the lap top with the data logger active so we could identify any problem areas. He was very happy with the results. We had the engine running down to 1800rpm in top gear and it would still pull away cleanly with no snatch or jerk. Julian described the car as “very civilized” but that doesn’t mean we have completely tamed the beast. Performance is still in the traction-breaking wheel-spinning totally insane bracket. We still have some work to do in that we want to give the new M3DS8 management system the ability to switch maps. We plan to wire in the 95/98 octane select button so that you can switch complete maps rather than just retard the ignition. That way you can have a track map complete with crackles and flames from the exhaust or a “civilized” map for everyday town driving – all at the press of a button. The owner also now wants to have a new exhaust system made up to try and get even more power. Then the car will be back for re-mapping.  Since the Red Rose 4.5 worked out quite nicely we now plan to take on the real challenge. I have been told that the original 4.2 AJP engine is a total animal so we plan to take a crack at taming that one next.

Cost of the conversion comes out at around £1000 plus VAT. This includes the ECU, plug-in loom adaptor, software and communications lead (giving you full access to the system) and the rolling road set up at Emerald is included. If you have a competent rolling road that you prefer to use then the kit is £750 plus VAT and carriage charges. We will supply a base map pre-installed but the whole point of the system is that you can then have it and fine tune the map to suit your engine.