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September 2002
CCC September 2002
Simon McBeath catches up with the progress of the motorcycle motivated PCD Saxon hillclimber - probably the lightest racing car on the planet
We profiled the lightweight carbon composite PCD 'Saxon' (1100cc racing car class) hillclimber in the July 2001 Tech Focus and at that time this superb race car had yet to turn a wheel. So, just over a year on, how has the car performed on track, and what development issues have been encountered? We persuaded owner Rob Barksfield and designer/constructor - and former Lotus F1 chief designer turned freelance - Martin Ogilvie to demonstrate the world's lightest racer (probably...) at the Chobham test track.

When I interviewed Rob and Martin for that original Tech Focus feature, one of the refreshing things about their attitude was their willingness to take risks with the car's concept and design. That was, to a large extent, what enabled them to get the PCD down to a starting weight on just 208kg - fuelled , oiled, watered and ready to go. But equally, they both went in with eyes wide open, knowing that risks don't always pay off, and portions of humble pie might need to be dished out later. As Martin put it, with some things "you just don't know until you try." They also expected there would be paddock detractors, and sure enough, that turned out to be the case too, with a predictable degree of rumour and misinformation being bandied about on and soon after the PCD's debut.

But what really matters in the wonderful world of motorsport is performance on the track, and how the car stood up against its opposition and to the rigours of competition. A few problems had been encountered in the run up to the first events. Early testing had shown the amount of oil that had to be carried in the wet sump was critical because of the slightly more inclined installation angle of the engine in the PCD. It also became evident that the crank was thrashing around in the oil, so a slightly deeper sump pan was made with modified baffling to enable sufficient oil to be carried without the crank wasting energy by splashing around in it. There was also an issue with the differential mounting. The original 6mm bolts proved too fragile and sheared, so the bolt size was upped to 8mm. And one of the diff bearing carriers was also modified to stiffen and strengthen the diff support. Which just went to show the level of loads encountered, even with a very light car.

But its debut at Gurston Down in June 2001 gave a good indication of overall potential, as well as the areas that were going to need development. With a best-in-class power to weight ratio Rob and Martin were always confident in the car's ability to accelerate, but to be fair to them they were always less certain what the car would be like to get off the startline. Sure enough, the sheer lightness of the car, coupled to the readiness of the Ray Debben-tuned Suzuki to light up the rear wheels made it difficult for Rob to achieve consistent, good starts. That the car also originally had a very short throttle pedal movement didn't help with the driver's control of wheelspin either and the evidence was plain to see. Most major hillclimbs provide not only elapsed run times. trap speeds and halfway split times but also first 64ft times too, and the latter figure gives a very good indication of the quality of start you achieve. Rob was losing between two and three tenths to the opposition in the first 64ft, a lifetime at the sharp end of such a competitive class.

But once the car left the line its performance was very good, and trap speeds were generally right up there with, if not better, than the best opposition. Bearing in mind that the car's spring, damper and geometry set-ups were all complete guesswork at this stage, two second places at that Gurston double-header debut meeting represented a very respectable beginning. Rob was only beaten by the top man nationally in the 1100cc racing car class in 2001, Mark Budgett aboard his well-developed Force Suzuki. In fact in the Sunday event Rob was only three hundredths of a second behind Budgett, which was all very heartening.

The next stop was Shelsley Walsh, and the startline problem was as bad here as anywhere, exacerbated by the Shelsley startline having gotten very slippery over the years (it was resurfaced on the 2001/2002 winter for that reason). Rob was 0.3 to 0.4 seconds down on start times here, but was able to claw most of that back by the finish. His elapsed time on his first competitive run was straight into the 28-second bracket, just 0.15 secs away from the old record, and his trap speeds were five to 8mph better than the opposition. Forced to miss the second timed runs in order to dash to catch a flight for a business trip, Rob nevertheless hung on to second place on the strength of his only timed run. If only the car could get off the line better...

CCC September 2002
And that became the major quest in the car's development really, for the problem was also evident in accelerating out of slow corners. Rob and Martin played with the rear cambers, tracking, damping and springing, and also with the diff, running it anywhere between open and locked.

Going stiffer on the rear suspension proved to be the wrong way to go, and subsequently they have been going softer with possibly a bit more to go in that direction. On the diff front things were less conclusive, and another type of diff is set to be tried once Rob gets up and running this season - work commitments and other projects on the car have significantly delayed the start of Rob's 2002 campaign "We had a reasonably structured test plan, but we're chasing a set up with nowhere really useful to test, as you can't easily simulate a hillclimb at a test track," Rob said.

But at least that first season, in 2001 brought the first class win at Gurston in July, and in eight events Rob achieved first, seconds or third place finishes every time out, only failing to start one event when a grumbling diff hearing forced withdrawal. Rob, in fact, extols the positives: "Just about everything has worked, so the fundamental design is very good. The engine has been totally reliable, temperatures have been right, the small (rechargeable NiCad) batteries have worked, the tiny (1.3-litre) fuel tank, the small driveshafts, the small suspension fixings, the remote starter, the small diff - everything has worked.

CCC September 2002 "The brake capacity and feel is good. We did have to change the clutch master cylinder size to reduce the throw on the clutch. But the steering and driveability are very good, and there are no handling vices, although because it's so light it can break away pretty easily, it is sensitive to over-aggressive driving. But it is very good to drive and has been pretty trouble-free. The only issue is traction off the start and from slow corners, but you can take quite a few liberties with it. Incorrect damping did cause problems over the bumps at Wiscombe Park (in Devon), but in fast corners the car is absolutely planted so the aerodynamics are certainly working well, and still enabling good top speeds. And one of the very positive things has been the plaudits from the paddock. The car has got a bit of a 'wow factor'. We got used to it working on it for 14 or 15 months before its debut, but it did attract a lot of interest and curiosity. Some of it was of the 'it will all fall to bits' variety but in general there have been lots of positive comments from people at all levels in the paddock. And I think it's fair to say that it has raised other peoples' games too.
"It crashed pretty well too!" joked Rob in reference to a costly off into Wiscombe's unforgiving tree-lined boundaries. But the suspension sheared off and the nose deformed and broke off as they were designed to do. The chassis took the impact well and only two small cosmetic repairs were required - all reassuring stuff. The detachable, frangible front wing supports also proved their worth in an earlier off, saving the nose and wing. So, where to from here? "We feel we haven't concentrated on springing and damping as we probably should have". Continued Rob. "But it's difficult to find the resources and time to solve problems. Even last year with two events per month it was very challenging to do changes and make progress." Unstated in this remark is that Rob spends much time away from home on business, and also that by its very nature hillclimbing offers little seat time in which to evaluate changes. Furthermore, as one circuit racing preparation expert commented to me recently on his first trip to hillclimb, there's no scope for warming up, not even the luxury of an out-lap before you go for a time. On the hill you have nail it from cold and hope you anticipate the grip levels correctly. In those circumstances it's inevitable that sorting a new car takes many months.

Another aspect to be evaluated is that of tyres. It was always matter uncertainty that putting 208kg car on tyres designed (structurally) for a Formula 3 car weighting two and a half times much was the right thing to do. But there isn't a great deal of choice available in truth, although Rob has some narrower Hoosiers to test against the F3 size Avons. The other major change to the car is that Martin had another front monoshock mechanism made up over the winter to accommodate a bigger anti-roll spring wire diameter, which will offer increased roll resistance, This could have the dual benefits of shifting some dynamic weight transfer from the back to the front, and reduce roll angles, both of which may help with rear end grip when exiting corners.

And the most obvious visual change to the car since we last photographed it is the appearance of a stylish, hopefully downforce-inducing, underbody. Martin designed it and had it made - in carbon of course - and says it's a case of "trying it to see whether it's excess baggage or not." As I said earlier, it's this willingness to take risks and experiment with an open mind that makes this project so interesting, and there are certain to be yet more radical developments to this amazing car. And you have to admit that, so far at least, humble pie ain't on the menu.

The biggest development leap that has been made to the PCD Saxon is in the engine, and our 'old' chum Steve Broughton at SB Developments has become deeply involved in this. As regular CCC readers will know, Steve is a whiz not just with Vauxhall engines, but also with engine management systems generally. And as he was keen to demonstrate that management systems could be successfully retrofitted to bike engines that originally breathed through carbs, it was entirely logical that a partnership developed with Rob. It seems there has been a perception in the world of bike engine tuning that the management systems would not produce the goods. SB: " I think people sometimes reckon you only need maximum power at maximum rpm and they're not looking at what's happening up to that point. And apparently even some of the bike manufacturers have said that carbs are better. But for driveability you need to look at management systems." Martin Ogilvie chipped in "Even Formula 1 is going for driveability now." And Rob Barksfield picked up the theme: "There's too much misinformation about and that has soured things a bit. Maybe other people [who have tried management] used inadequate hardware. And in truth the development curve is pretty steep. But Steve knew how to make it work."

So how did SBD go about converting Rob's already potent Debben Suzuki to a full EMS, and why did he succeed at the task where others. apparently, have not? Interestingly, things were kept as simple as possible. For starters, standard Suzuki Hayabusa throttle bodies and injectors were used rather then getting anything custom-made. The spacing of the inlets were a bit different, but the throttle bodies connect via rubber pipes so that was no problem. Because of the different engine installation angle between the GSXR and the Hayabusa, the throttle bodies were inverted so that the injectors fired downward at the back of the inlet valves - this worked out just right, apparently. And Steve already knew that the standard Hayabusa injectors should flow enough fuel for approximately 200bhp, and you might recall from our previous feature Rob's engine was stated at 190bhp at the crank on carburettors.

The MBE 967E ECU was selected. SB: "This provides 'grouped' injection rather than sequential, or in other words it fires all four injectors every 360-degrees, rather than firing them individually every 720-degrees. This is better for response and driveability because it means there is always fuel in the intake ready to be drawn in. Sequential is theoretically better for peak power (and economy) but drivers usually find grouped injection to be more responsive. The only downside, especially with a high revving engine, is that you can run out of time to open and close the injectors. The bike injectors are 14-ohm resistance, which take about a millisecond to open, and the same to close. Lower resistance injectors are faster but the software 'drivers' are not readily available. They're also not as suitable because they're bigger, which is not necessarily good for idle. "However, with the Hayabusa injectors we are running close to the limit, using up to 85 or 90 per cent of their capacity. This means the injectors can get hot, and also doesn't leave too much 'space' capacity for the extra fuel demands of lower ambient air temperature or higher barometric pressure. So we may switch to Peco injectors that can flow more fuel."

So were there any tricky problems? "We thought there would, for example dealing with rapid throttle changes and rapid rpm increases. But we really didn't find any issues. Not that it was easy. but it was less complicated than we expected. Essentially we did the first dyno runs with Dave Iles and Dave Midgley at Griffin Motorsport in Swindon on carbs to see what the power was. The engine was already on an MBE ignition system, but we still weren't sure how the injection would work. So then we switched to the injection system and we found that where the carbs wouldn't allow the engine to pull on full throttle until about 5000rpm, with the injection it would pull on full throttle from as low as 2200rpm." Rob confirmed the assessment following testing at Avon Park and at Chobham: "That's the biggest transformation, there is torque available immediately and it is so much more driveable. This must be the way to go." Which is particularly interesting when you learn that Ray Debben had also done some more mechanical engine tuning work on Rob's engine prior to this management project. Rob describes it now as "more of a drag race set up, with a radical top end. It's very sensitive to valve spring pressure and valve seat seal, and is much less a 'fit and forget' set up. The compression is up considerably too" The cam profiles are also somewhat more radical, and the throttle body size is now bigger.

So it was no great surprise that the engine now produces about 10bhp more than it used to, meaning the car is approaching its target of 1000bhp/tonne. But as Rob remarked "that's why the mapping has been so satisfying because the engine responded so well. The carbs were very good at wide open throttle, but we don't do that very often. We need the engine to be optimised at part throttle for driveability, and we have got 1500 to 1800 more useable bottom end rpm on full throttle and the part throttle response is phenomenal." That, in conjunction with peak power that has to be around 200bhp sounds like a formidable combination. The decision to go to a full EMS was, Rob says, partly down to the expected better mid-range response, but also because it would enable the exploitation of launch and traction control. This should help to make starts more consistent and effective and improve exits from slow corners

Also, as you may have noticed from the pics, the PCD has been fitted with a steering wheel-mounted, paddle operated gearshift. Powered by compressed air, and controlled by a pretty sophisticated box of electronics and software, this mechanism is going to take a while to develop, but Rob reckons it shows the promise of being a very good, reliable system. Once developed and sorted, you too could buy one, so watch this space....

Rob Barksfield SBD Webpage
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