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Ducati 996SPS Tech

   Ducati 996SPS

Amongst the bikes we are looking after is the 996SPS used by John Barton in the IoM TT races in 1999, with a 118mph lap in the production race this bike is the fifth fastest ever to lap the Isle of Man TT course. The bike is stone stock, completely standard in both engine and suspension apart from the careful setting of the squish and cam timing we performed before it set out for the island last May.

It has now completed 1500 miles of really hard running, none of your occasional trips to the shops for this bike! We dynoed it 'as raced', before we got to take it apart. Dyno run 005 shows the power. The bike was then stripped for a freshen up, just as we would for a normal customer bike, that means strip down with the heads off, lap the valve seats to remove any carbon and take away any dents in the set faces. We have noticed that the inlet valve seats on the horizontal cylinder take the biggest battering. As we reassemble the head we measure all the present shim sizes and then measure the clearances. In this bike there were six valves where the 'Half rings' that retain the valve were broken. This happens on bikes that are revved a lot, the design of the closing shim (which pulls over the half ring when assembled) stops it being a big problem; nevertheless it is something you keep an eye on and ensure you change the broken rings every time you service the bike.

To keep this in perspective our 748SPS racer only broke half rings at very fast circuits, Silverstone and Thruxton for example.  The more user friendly circuits, where you might rev as hard but for shorter intervals were not a problem, it is unlikely to be a problem for bikes only used on the road. This bike with two TT races under its belt had every excuse to need a few replacing. The clearances were pretty good everywhere with only one valve looking a little unhappy. The street motors use a very heavy valve spring to keep the valves seated. The early street bikes, and all the real race machines have much lighter springs that greatly lower the resistance when turning over the engine, they also give the opening rockers a much easier time.  The quid pro quo is that the engine may stumble a bit on tickover if the gas pressure in the cylinders is a little low to complete the action of shutting the valves, there may also be an emissions angle.

The belts were understandably a little loose but that was to be expected.  The chain was a little stretched and was replaced. After our experiences with the 996Bip we also stripped, checked and reassembled the alternator and clutch.

SPS-dyno hp
The dyno charts really tell their own story, Dyno run 005 is the as delivered curve, Dynorun010 is the version following the reset of the clearances, a lap in of the valve seats and  a thorough going over.  The final curve is the output after we had adjusted the mixture on the FIM Eprom with clear improvements in Horsepower and torque with a couple of zones slightly leaned out.




   The SPBip

All this has got us thinking, the 996SPS is very similar to the 996Bip. Sure there are changes but it is important to divide the parts on the SPS put on the bike to make it the premium model in the range and parts that make a difference to power and reliability for real world use.  The carbon fibre is very good, it fits and works brilliantly, much better than a lot of the carbon fibre we have seen, but the standard plastic works just as well (Yes Fred, even the air inlet ducts….).  suspension wise there is the rear shock, Ohlins please. (and in the year2000 bikes also Ohlins front Forks; Probably £2000 to retro fit the whole lot…).  For the engine though there are two distinct groups of components that are different, those for engine strength and those for the power. The SPS' role as a homologation special for racing shows in the crankcase halves without a separate centre gasket, the P8 'big brain' computer and wiring loom and finally the exotic Pankl Titanium rods. Power comes from revised cams, 50mm bore exhaust and a half point of compression.

We have been buried in the PC and burning the midnight oil. There are a lot of the power producing parts of the 996SPS that an be duplicated at reasonable cost, all of it can obviously be duplicated if there is a more generous budget. We can fit the Cams, we can fit the exhaust system and, thanks to a gifted computer engineer at Eprom that duplicates the SPS fuel maps in a version that works in the 'Little Brain' 1.6 computer. Our Full Monty rebuild gives you the benefit of as much of the compression as can be raised from the standard piston and head arrangement. The SPS motor uses different cylinder heads with a higher resulting compression ratio, we can obviously refit these but that is a slightly higher cost and by the time you add it all up a Foggy rep starts to look a good deal. We believe the compression is worth about 3 hp at the top end, but the lower compression greatly takes the pressure 9sic10 off the conrods making the standard parts a perfectly acceptable solution.

Caution: It is important that anyone thinking of going this route is very honest with themselves as to their intended use, the stiffer crankcase arrangement and the Ti rods are there to let a 996cc engine live at a constant and abusive 11000 rpm plus; the sort of abuse that comes with changing at the redline for hours on end and banging down three gears at once going into corners. If you're mainly a road user or do a couple of track days a year there is no problem, the standard rods will be more than good enough.  The Eprom we have has a revlimiter at 10500rpm, this is there to keep things in one piece, in the end it's your choice.

Dyno SPSBipThere are several variations possible; we can replace the cams and build in the highest compression we can get to with the standard head and pistons. At the very least this will allow the engine to hold onto its power for much longer, and add several bhp, combined with the gearing changes we recommend there will be a substantial boost at the top end, there are probably another couple of HP with a big bore exhaust, this would have other effects as the greater back pressure from the smaller pipe would give a little more power low down, but is a bit stifling at the top. See 'Supermono Tech; Donington and onwards' for the basic principles. You can see the sort of effect that will be achieved in our final dyno chart; this is a direct comparison with Marks 996Bip (Dynorun032 ) and the before (Dynorun005) and after (Dynorun017) refresher curves of the 996SPS.

By the time we have got the fueling right I am sure such a motor; cams, exhaust, Full Monty and Eprom will have as good a level of power as a standard 996SPS. Of course if you really want to go for it we can fit the heads and rods from the SPS as well, we would probably have to have a bit of a chat about the costs of that………

                                                      Neil Spalding

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