Kames Summer Sprint Weekend - 24th & 25th July 2021 - Recap
For this year we've decided to enter the Cross Border Speed Championship (XBC) and Lowland Speed Championship, racing our sprint prepared 107 in the 1400cc Road class.
The championships consist of both Hillclimb and Sprint formats with a varied calendar taking place at some great venues across Southern Scotland and Northern England.
It was a bit touch and go at the start of the year with several rounds being dropped, but once things got going we readied the car and set our sights on Kames for its debut.
It was an absolute scorcher of a weekend in the tropics of East Ayrshire; the track looked great bathed in blue skies and sunlight.
We actually arrived at the hotel about 4am on Saturday after working well up to 11pm the Friday evening putting decals on the car and getting the last few bits together - 2 months preparation with a full front end and partial engine rebuild, it still comes down to the wire, 6 hours behind schedule; but we made it, squeezed in a few hours rest and got to the venue about half way into the first practice runs later that morning.
The track layout at Kames follows an outer circuit which is run 3 laps clockwise one day and 2.75 laps anticlockwise the next. There's quite a bit of elevation at the top of the track, dropping down through the sweeping S pictured above, with a tight 180 degree corner at the back end, a reasonable straight with a kink, leading into a more open 170 degree turn that rises back up to the highest point.
Being a purpose-built sprint venue, it's narrower than a typical circuit but there are still a few opportunities for different lines - at least in the C1 - and the confined proportions make the track a thoroughly enjoyable technical challange with good balance between straight line speed and driver skill.
Heading up the class was the Gordon Motor's Peugeot 205 with its 109bhp 1360cc engine and short ratio gearbox; a pretty formidable joint entry built by Jody & Campbell Gordon who each registered their own times behind the wheel.
The other joint entry was the Mini Cooper of track locals Fraser and Brian McCurdie, with a bored-out 1380cc carbureted A-series engine; this was a very entertaining car to watch and looked like an absolute handful, not least when it nearly lost a wheel during the first practice session that morning!
Graham Shee had managed to sneak a turbocharged Fiesta ecoboost into the A1 class but he was a nice guy to talk to and with a similar power-to-weight ratio of 120hp & 1200kg, we're not going to say too much about it.
I'd hoped to run a new spec 1.5" exhaust system on our car, along with an AEM piggyback fuel controller to correct the air/fuel ratio in open loop, but these things always take a bit more time than a tight schedule will allow to get right and I made the decision to run a modified standard exhaust at the event instead; with custom single-pipe Sportex silencer and the second lambda removed for less restriction in the tiny 32mm ID centre pipe.
In the week leading up to the event I'd made an addition to our prototype induction system which corrects for the side approach angle and improves flow through the throttle body - The engine seems to be running well with a total 7% increase on the closed loop fuel trim at part-throttle, however this undoubtedly is running a bit leaner than I'd like in open loop at WOT without the AEM installed. The car feels reasonably quick though; all in all I'd be happy if we were tipping a real 70bhp or so at this point, with a bit more torque than the figure would suggest.
I took an out-of-position practice run to get a feel for the track and then it was straight into the morning's timed session.
Photo credit: Kevin Brown
We clocked a 103.89 and 103.78 respectively across the first two runs; exactly the consistency I'd like. At the time I was still getting a feel for the car and track, I hadn't put a thought to the timing sheet or our comparative pace but as it would turn out these times put us right up the order into second place and a good job too because the laptimes seemed to drop off a cliff after lunch..
I was left scratching my head a bit in the afternoon session but I think by then the fatigue had set in from the sleepless night and scorching heat; which was also taking its toll on the car as a quick check with the back of the hand revealed burning hot rubber soaking up rays on one side and cool shaded tread on the other. Tyre pressures were anyone's guess.
The morning's effort had stuck; we rounded off the day with an appearance at the awards presentation and the satisfaction of bagging some silverwear on our debut amongst a respectable field of competition.
Saturday's Fastest Run:
Sunday rolled around and I was a lot more rested this time, keen to remain consistent through the day and manage the heat a little better. The Mini and Fiesta entries had both gone home, leaving me to contend with the Gordon's 205 as the only 3 class entires on the Sunday; I wanted to focus on just learning the car, developing my approach to the sessions and avoid that drop in pace we experienced the previous afternoon.
The track in anticlockwise direction was more of a power layout and our comparative times seem to confirmed this. I can conclude that we're able to get on the power a lot earlier out of slow corners than the bigger & more powerful cars, accelerating up to about 50mph or so we're arguably just as quick as anything else in the road classes but once you cross that point they begin to pull away with varying degrees of rapidity -
In the clockwise direction we ran on Saturday, coming out of that tight hairpin onto the McMillian's straight, the Gordon's 205 & I are both accelerating from a slow speed and are probably quite evenly matched a good distance along it; only as we climb through 3rd gear is the 205 beginning to make considerable ground on us.
Conversely, running the track in the anticlockwise direction we enter the straight from the much more open 170 degree paddock bend; I'm already doing 50 out of the apex and reaching for 3rd gear as soon as I line up McRae's Kink, this means the 205 has the entire run down to the hairpin to put the legs on us and pull out a good chunk of time.
It would be a bit short sighted of me to say they're only faster in a straight line though, reviewing the trackside footage I can see that Jody in the 205 is able to carry a lot more speed through the middle of the corners than I am in the 107. I think clearly the other area we need to improve on is the slow speed cornering - I have a decent front end on the car and it's very quick to turn but the balance is still predominantly understeer and through the tight radius at the hairpin I was just waiting and waiting for the car to come around, which it never really did.
It was a similar situation throughout the lap:
On the tighter second corner of the 'S' sequence at the top of the track where the chequered flag was located, the approach was a bit different in this direction with a sharper entry into more sweeping apex. Despite my attempts to flick the car in I kept running right up to the grass at the exit, just unable to get the rotation in the middle of the corner.
Paddock bend I was having to brake very late, hard to the inside on entry to square off the corner and reduce the time spent turning the car, then fading to the outside on exit as I tried to pick up the speed onto the straight. It definitely wasn't ideal but at least allowed me to claw back a bit of time on the entry without hurting the exit more than I'd lose in the middle anyway..
One good takeaway from Sunday was the consistency - Staying out of the sun and keeping the tyre pressures in check between runs seemed to have done the trick.
The brakes really began to work in the afternoon too - I fit a new set of Mintex M1144 pads prior to the event and whilst they were sufficiently bedded to the solid Brembo discs with about 250 road miles, I hadn't had the opportunity to properly heat cycle the compound. I'd realised a lot of my missing time on saturday afternoon was a) due to exhaustion but b) I wasn't stopping anywhere near as hard as I should have been as a result of my impaired judgement; trundling up to the corners like a set of traffic lights. After a conscious effort to really find the limit of the brakes on Sunday, they absolutely came alive that final afternoon - suprising me by stopping well short of the mark in Timed 2 and then managing to capitalise on that to find nearly a full second on the brakes in Timed 3 and finish the day on a 96.59sec.
I think if I'd pulled it all together for one more run that afternoon a 95-something was possible but alas it was time to pack up and head home.
So we were on a bit of a tight schedule coming into the event - there were a few things I wanted to do with the car which I just never really had the chance to sort out; the exhaust and the Fuel controller mainly. The way the car is running at the moment obviously needs these points addressing; it's almost quicker on part throttle and definitely a lot of gain at the bottom end without making much at the top. I'd say this is characteristic of both the limitation of the standard exhaust diameter as well as the leaner running condition when the ECU reverts to its base-map open loop fuel table under load. The closed loop trims are consistently hitting +10% on part throttle which suggests to me that at WOT the engine is getting at least about the same excess volume of air more than the standard open loop fuel table is ideally mapped for. Correcting these two things should allow the engine to produce a good amount more power with the improvements I've already done to the intake plus it will run cooler, reducing the risk of knock and the ecu retarding the ignition timing to compensate.
The other immediate problem was the understeer slowing us down mid-corner. There are a few ways to balance a car depending on the scenario but the simplest solution available to us is the toe setting. I run the fronts pretty much parallel at 0deg, erring on the side of toe-ing out. This is within the standard specification and allows a quick front end without putting too much strain on the tyres - I do a lot of mileage and they're pretty expensive consumable items at the end of the day. I like the setting here and the front end response on corner entry is good - so in this case it's the rears that I need to work on.
By toeing out the rear wheels slightly you encourage the car to rotate through the corner at the expense of some stability. I actually took the car to have the toe setting measured at the back yesterday so I can work where we are right now and where we need to be - it's currently reading 0.2deg toe out on the rear left and zero toe on the rear right - this basically means the car is going to rotate better in a clockwise direction and was very likely contributing to the fact we were a little further off the pace on Sunday's anticlockwise layout. The car simply wouldn't turn as well to the left with the loaded outside wheel tracking in a straight line.
I adjust this by the use of shims between the hub and rear axle - it's a bit tricky because the 4 bolts don't form a perfect square so there's a lot of practical math involved in matching sizes to achieve a particular setting but I'm probably going to aim for 0.3 to 0.4deg out on each side, with a fraction less camber than I'm running currently, and see how that shapes up.
With these 3 points addressed, I think I'll be in a more competitive shape when we get to Forrestburn in 4 week's time. It should be a good one.