Remapping at the Dick Mayo Sprint

At the Dick Mayo Sprint, we experimented with boost to see if we could get a bit more power.  The base map was the original 200bhp map and we tweaked boost up between each run.  Looking at the boost vs RPM over the whole run, you can see that the boost was a lot more consistent at the original boost target than later on, which suggests the turbo is unable to flow enough.  We know the car's fitted with a restrictor and also the intercooler is a limitation.

Base map in first practice

Timed Run 1

Timed Run 2

Looking at this more closely, let's take a peek at the data down the Farm Straight on each run.  In first practice, the actual boost follows the target quite well.

Farm Straight in First Practice

In second practice with a little boost added the correlation is still quite good but there are a few wobbles on the purple boost trace versus the light blue target trace.  This is more pronounced than the trace in first practice.

Farm Straight in Second Practice

Over lunch, we brought boost targets up further and clearly this was more than the turbo could supply to the engine as there is a significant difference between the target and actual boost levels.

Farm Straight in First Timed Run

Despite this, we pushed for more boost in the next run and the delta remained in the final timed run.

Farm Straight in Second Timed Run

Next task is to remove the restrictor or machine it out.  Whilst it could simply be removed, the intake pipe would then foul the radiator pipe.

Turbo inlet restrictor

Before that though, I needed to replace the broken bodywork receptacles.

Bodywork receptacle

2015 Dick Mayo Sprint: That Cone!

Whilst I went home with a trophy from Bristol Motor Club's Dick Mayo Sprint at Castle Combe Circuit, I didn't achieve the performance I really wanted.  The final run was a disaster with a missed shift at Quarry and then clipping the cone at Bobbies.  Despite that, the timesheets showed it was only 0.13 seconds slower, so it must have been a faster lap, but why?

I've used wheel speed to determine the start of the run and due to the low resolution of the front wheel speed sensors, there's about half a second of difference in the start times.  As a result and also because they're slightly misaligned, a pinch of salt is required here!  The green/yellow traces show the run with the cone, whilst the blue/purple is the datum run of 59.99.

The start was similar for both, but a missed shift into 2nd gear on the datum run cost 0.25 seconds before Quarry.

Start

I was earlier on the brakes into quarry on the second run, dropping 12mph before the braking point of the first timed run, but this is likely to be the offset between the two runs.  I was earlier on the brakes after the rise and harder too, but this is again likely to be offset slightly and a missed downshift left me in neutral.  I dabbed the brake before clutching to select third gear, dropping 9mph at the apex.  It cost 0.7 seconds mid-corner and this grew to 0.8 seconds down the Farm straight.

Quarry

Into The Esses and the offset again makes it tricky to see, but I was harder on the brakes on the second run and applied throttle between the apexes on the second run.  There were two stabs at the throttle on exit of the first timed run.  A huge lift into Old Paddock didn't help on the first run and the net result was 0.6 seconds won on the second timed run through this sequence.

The Esses

Coming into the final part of the lap, a higher entry speed and later braking led to a higher apex speed and 0.6 seconds gained.  Bobbies was taken in a similar manner in both runs, but the lifting of the throttle on the second run shows the moment of impact and the time lost as a result.  Without that indiscretion and the missed gear at Quarry, a 58 second run was on the cards.  Next year...

Tower

 

Here's the onboard video of that pesky cone...

Castle Combe Test Day: July 2015

This data shows the best laps from Andrew and Andy at the Castle Combe test in early July.  The data is arranged into four graphs.  The top graph shows speed and RPM; Andrew in blue/purple and Andy in green/yellow, respectively.  The next graph shows timeslip relative to Andy’s lap with a change upwards showing Andy faster and a downwards trend showing Andrew faster.  The third graph shows throttle and brake traces in blue/purple for Andrew and green/yellow for Andy.  The final graph shows steering angle in blue/green for Andrew/Andy.

At the start/finish line Andy is travelling at 108mph vs Andrew’s 103.3mph.  This adventage shows itself in Andy taking 0.25 seconds by Folly where Andrew appears to have matched the speed and continues to go faster.  Andrew initially gains by holding onto the gears longer and his line is clearly better up Avon Rise as he continues to accelerate quicker.  Andrew reaches 139.8mph before swapping throttle for brake, whilst Andy makes just 137.5mph 0.65 seconds later.

Fastest laps part 1

Both drivers brake in two parts; before and after Avon Rise.  Andrew takes a longer and harder stab before the rise, whilst Andy takes a similar length but harder stab after the rise.  Andy drops from 112.6mph to 68.3mph, whilst Andrew drops from 99.4mph to 67.8mph over the same period.  By this time, Andrew is 0.394 behind, compared to 0.188 before he braked.  Apex speeds are practically identical, but Andrew holds third gear, whilst Andy holds fourth.  This results in a slower throttle pickup for Andrew, but the wheel torque will effectively be the same.  Andrew is flat out by the time he selects fourth on the exit of Quarry.

Andrew is 1mph slower on the exit of Quarry, but is again caught up at the end of the straight by revving to 6500rpm instead of Andy’s 6000rpm.  Andrew brakes for The Esses 1.2 seconds before Andy, braking for longer but not as hard.  Andy approached in sixth, whilst Andrew arrived in fourth gear; fifth is probably right.  Andrew dropped one gear, whilst Andy dropped two.  Both drivers stabbed the throttle between apexes and Andrew’s longer stab gained 0.01 seconds.

On the exit, a spike in the RPM trace and a big dip in the steering angle coinciding with throttle application for Andrew shows power-on oversteer, whereas Andy’s earlier application of throttle is not affected due to the higher gear selected.  The oversteer moment cost 0.15 seconds, which was almost 0.4 seconds by the time the corner was completed.  Both drivers took a big lift into Old Paddock.  Andrew took two up-shifts in quick succession, whilst Andy short-shifted into fifth.  Both approaches were remarkably similar with exit speeds almost identical.

Onto the second graph, Andrew was off the throttle into Hammerdown.  Whilst this looks strange and like he might have been following another car, it’s not too surprising as Tower is a particularly daunting corner.  The time slip went from 1.679 to 2.293 seconds from when Andrew lifted off the throttle to when Andy did and this extended to 2.664 seconds by the apex as Andrew didn’t need to brake so hard 

Best laps part 2

Again, Andrew was in a lower gear (3rd vs 4th) and this resulted in throttle modulation through Tower with corresponding wavering of the steering wheel.  Andy arrived at Bobbies 1.7mph quicker as a result.  Whilst both drivers lifted off at the same point for Bobbies, Andrew braked later, gaining half a second from turn-in to the second apex.  At this point, Andy was at full throttle in third gear, whilst Andrew had both feet off the pedals in second and the first application of throttle shows a rise in RPM and opposite lock application.  As the throttle is applied, the RPM trace wavers, showing the rear wheels are spinning.  Both drivers upshift at the same point; Andrew into third and Andy into fourth.

Westway marks what would be the finish of the Dick Mayo Sprint on Saturday and the timeslip is 3 seconds.  This continues to climb all the way to Camp as a result of the differing exit speeds from Bobbies.  Again, Andrew is early off the throttle before Camp, losing 0.25 seconds in the process.  Andy is first on the brakes with twice the pedal effort and both arrive at the apex in fourth gear.  Andrew’s apex speed is higher, but exit speeds were almost identical  Andrew passed the finish line quicker thanks to holding onto the gears longer.

The longitudinal G trace doesn’t go much beyond 1.2G under braking for either driver, which considering the lateral G hits a solid 1.8G, suggests that either the car is not strong on the brakes or the drivers both need to press the brakes harder.  If it’s the car, then the camber or brake balance could be the cause.  The only suggestion of a partial lock-up is the front-left over Avon Rise on these laps, but other laps show that the front tyres are under-rotating at various corners, despite no greater retardation.  The image shows front left with front right wheel speeds, brake pedal pressure with throttle and longitudinal G.  On this basis, it seems that the car is the limiting factor, either through too much static camber or a forwards brake bias.

Braking performance

Looking at other parts of the car, the charge intake temperature doesn’t exceed 53 degrees and the boost pressure peaks at 2.4bar absolute.  Injector time peaks at 77.86%, which suggests that 25% more fuel could be injected.  Keeping the lambda target the same, this means there’s a fair bit more power to come.  Lambda target is 0.88-0.96, so a little rich and headroom still.  More boost required?  The boost target drops from ~2.3bar at 5000rpm to ~1.9bar at 6000rpm.

Boost vs RPM

2015 Motorsport at the Palace

Motorsport at the Palace is one of the best events of the year.  Set in the gardens that once occupied a race track, the venue is picturesque, whilst the atmosphere is laid back and friendly.  The Mygale was sadly over capacity for the event, which is limited to 1600cc (1142cc for forced induction).  Luckily, the organisers were happy to ask the MSA for leniency so I could run in the invitation class.  I was fastest for much of the weekend, but was pipped to the fastest time of the weekend by David Seaton, who managed to go 0.07 faster than my best of 34.02.  Here's how that 34.02 went...

The data is split into three graphs; engine speed (red)/wheel speed (green)/gear (blue), throttle position (blue)/steering position (green)/brake pedal pressure (purple) and lat(green)/long(blue) G.  Off the line, revs held pretty high and also pretty constant.  Longitudinal G was a paltry 0.7 or so thanks to the low grip surface of the pathway.  Half throttle became full throttle and a subsequent increase in engine speed is accompanied with a reduction in acceleration.  The rear wheels gained traction at about 47mph, moments after second gear was selected.

Motorsport at the Palace Data Start>Chicane

Heading into the corner, brake pedal pressure varies, suggesting I'm stabbing at the brakes after turn in.  Whether this is altering the attitude or direction of the car, I'm not sure!  Lateral G peaks at around 1.2G.  Immediately after releasing the brakes, I'm back on the throttle, which is too early, as can be seen by the rise in revs, the maintaining of the steering angle and the subsequent rapid removal of steering angle accompanied by a release of the throttle.  Second time lucky on the throttle, a small amount of wheelspin continues until third gear is selected.

The right hander that follows is fast and narrow.  It's pretty daunting, which is why I lifted slightly on the way in, taking the apex at about 60mph and about 1.5G.  The lift is matched by a slight wobble in the engine speed, suggesting the rear end was a little mobile on the way in.

Into Big Tree Hairpin, I took two stabs of the brakes, dropping into 2nd gear at the same time.  The car decelerated at about 1.1g, suggesting I was tentative on the brakes, although the change in surface in the braking zone muddies the water.  The steering trace shows a small jink left to use all the track before turning into the corner.

Mid-corner was around 1.4G and an early application of throttle (spotting a trend?) wasn't met by opposite lock, although some wheelspin occurred.  I went in too slowly.  The second application of throttle caused a little wheelspin and some opposite lock before I selected 3rd then 4th down the straight.

Motorsport at the Palace Data Chicane to Finish

Moving onto the second image at the marker, I'm already on the brakes, having reached 73mph on the straight.  Down two gears into 2nd and brake pedal pressure is again variable with deceleration at just 0.75G.  There is a rise here and poor surface, but I'm clearly not braking late enough.  Note that the G traces both have an average filter applied and this is why longitudinal G does not vary with brake pedal pressure.

The first apex is off-camber with a poor surface, leading to just 1G lateral.  Again a stab of the throttle leads to a little wheelspin, but in this case just fires me to the second apex, where the throttle is pinned, leading to lots of wheelspin and opposite lock until I grab 3rd gear.  I reach 68mph before braking into the fearsome North Tower Bend.  Again, there's scope to brake harder.  After the first apex, throttle is picked up and lateral G remains at 1.1-1.2G all the way to the finish on the slippery surface with speed varying to match corner radius.

Two stabs of the throttle are taken just before the finish, which result in a big slide, as shown by the steering trace.  Ironically, I pressed the brakes harder after the finish than I did on the way into North Tower Bend!

2015 Llandow Sprint

Over the winter, plans were made to switch cars.  A Mygale M12 Ecoboost was procured, the car having won 7 races in the British Formula Ford Championship.  The Mygale saw its first outing at the Bristol Llandow Sprint.  I'd not warmed the engine up before the event started, so this was a baptism of fire.  First practice was wet after a shower whilst I was waiting to go out on my new slicks and a lurid slide out of Glue Pot grabbed my attention.  Second practice was dry and here's what it looked like.  My fastest run was a PB for me and thanks to the Life ECU, I have some pretty good data to show how it progressed...

The data is presented in three graphs.  The top graph shows engine speed (RPM) in red, selected gear in blue and speed (mph) in green.  It should be noted that the speed trace is calibrated for a different size of tyre and reads a few percent below what it should.  The middle graph shows steering angle in green, throttle position in light blue and brake pedal pressure in purple.  The bottom graph simply shows lateral G in green and longitudinal G in blue.

This run is the fastest of the day.  The white vertical marker on all three graphs shows the start of the run.  After the launch, full throttle is never found and at about 0.18 miles, the steering trace drops, which indicates turning right into the first corner, whilst also selecting 2nd gear.  At about 35mph, this is quite early, but the car still has enough revs that lag isn't huge.  Given how gently the wheel was turned and that lateral G barely exceeds 1, this suggests that a later turn-in at higher speed was possible.  Full throttle was achieved after the apex and lifting the throttle whilst turning in was enough to scrub speed off for the corner.  The dip in the RPM graph at this point shows that the rear wheels under-rotated, which probably helped turn-in.  Lateral was ~1.5G, which seems about right for cold tyres.

Full throttle was again used on the run into the next right-hander.  Two bites of the wheel were taken into the right-hander, the first with a partial lift and the second with a brush of the brakes.  This is my reaction to the shape of the decreasing radius corner; you can see the radius being determined by my use of brake pedal pressure rather than steering angle.  Lateral G doesn't vary much during this.

The data is presented in three graphs.  The top graph shows engine speed (RPM) in red, selected gear in blue and speed (mph) in green.  The middle graph shows steering angle in green, throttle position in light blue and brake pedal pressure in purple.  The bottom graph simply shows lateral G in green and longitudinal G in blue.

This run is the fastest of the day.  The white vertical marker on all three graphs shows the start of the run.  After the launch, full throttle is never found and at about 0.18 miles, the steering trace drops, which indicates turning right into the first corner, whilst also selecting 2nd gear.  At about 35mph, this is quite early, but the car still has enough revs that lag isn't huge.  Given how gently the wheel was turned and that lateral G barely exceeds 1, this suggests that a later turn-in at higher speed was possible.  Full throttle was achieved after the apex and lifting the throttle whilst turning in was enough to scrub speed off for the corner.  The dip in the RPM graph at this point shows that the rear wheels under-rotated, which probably helped turn-in.  Lateral was ~1.5G, which seems about right for cold tyres.

Full throttle was again used on the run into the next right-hander.  Two bites of the wheel were taken into the right-hander, the first with a partial lift and the second with a brush of the brakes.  This is my reaction to the shape of the decreasing radius corner; you can see the radius being determined by my use of brake pedal pressure rather than steering angle.  Lateral G doesn't vary much during this.

Arriving at the fast right-hander onto the back straight, turn-in is on full throttle in fourth gear.  The vertical marker shows the point the throttle is released and also shows the left foot dragging on the brake pedal whilst the right foot picks up the throttle realisign this is too much of a lift.  The steering trace shows that some opposite lock was applied when the throttle was closed as a result of under-rotation of the rear wheels shown by the red RPM trace dipping.  The throttle is then increased from 15% to 65% and this results in a second steering correction, which must have neutralised any wheelspin.  Lateral acceleration reaches around 1.8G, which suggests moderate downforce at these speeds.

 

Arriving at the chicane at the end of the back straight, I'm in 6th gear and apply the brakes properly for the first time, retarding the car at around 1.5G.  Pedal pressure is not reached immediately, so I need to work on hitting the brakes more quickly.  It is immediately clear that I've braked too early and bleed off pedal pressure quickly.  I drop two gears, although clearly go to drop three but have not released the lever enough to engage the ratchet for the final downshift.

Picking the story up at the verticl marker, I bleed off the last of the pedal pressure and turn in whilst simultaneously applying throttle.  Answers on a postcard why!  The curious pedal movements continue as the wheel turns left for the second apex and both throttle and a little brake are applied.  Naturally, this affects lateral G and the rear tyres scrabble for grip.  Turning into the right hander, feet have once again resumed normal behaviour and neith pedal is in use.  Application of the throttle co-incides with a little corrective lock and a spurious peak lateral acceleration of 2.8G!  In real terms, it's about 1.7G, which is in line with the speed of 70mph and the increased tyre temperature (and grip) from the last corner.

Cornering at ~1.2G, I decided mid-corner that I'd applied the throttle too early and lifted completely.  The dip in the RPM trace again shows under-rotation of the rear wheels followed by the throttle being picked up and opposite lock being applied.  The corner radious clearly decreased as a result because lateral G went up significantly to around 1.7G and speed did not vary.  Full throttle was applied and steering lock taken off at the corner opened up.

 

The final corner onto the front straight is approached at around 90mph whilst still turning right.  As a result, brake pressure was lower than previously and retardation peaked at 1.2G whilst still cornering at 0.7G.  I'm not sure why I released the brake pedal during braking.  Perhaps because I realised I'd braked too early.

Turn-in occurred with the re-application of brake pedal pressure.  Whilst still feeding in lock, I was also applying some throttle, which suggests I thought I was travelling too slowly and needed to pick up pace.  Lateral acceleration at under 1.5G amplifies this theory and the RPM trace shows a spot of wheelspin as the throttle is applied.  The throttle was once again picked up and soon flat out as the corner opens up onto the straight.

At the end of the front straight, I approached the bus stop for the first time in 6th gear, hitting the brakes quickly and consistently to slow the car at 1.5G.  I released the brakes during the downshifts from 6th to 4th and further still for the downshifts to 2nd.  Deceleration was not as rapid as a result, despite the engine braking.

I turned in sharply whilst releasing brake pressure and this clearly caused oversteer as the wheel is straightened.  Two pules of throttle split by a brush of the brake pedal match the further application of steering angle, suggesting an attempt to balance the car.  It's a similar story in the right-hander that follows before full throttle on the exit, which seems to be about on the limit for the tyres as the RPM trace wobbles a little.  Given the low revs in use here, this validates the use of 2nd gear through this section.

The left apex required a half second lift of the throttle and the application of throttle coincides with some lock coming off, suggesting that the car is sliding nicely at full throttle.

 

I arrived at the right-hander in second gear.  I fed in steering angle and brake pedal pressure at the same time to match the decreasing radius of the corner.  The dip in the RPM trace shows the rear wheels were under-rotating on turn-in.  Immediately after releasing the brakes, I was on the throttle whilst still winding on lock.  This was clearly too early as a partial lift was needed before full throttle was applied whilst still cornering at over 1.5G.

Arriving at the final corner before the back straight, I'd already shifted up two gears into fourth gear and shortly after turning in, a partial lift was deemed necessary.  Nearly full throttle was applied and the RPM trace shows that the rear wheels were not spinning, thus the rear end is not grip limited.  Is this a rearward aero balance or was I not on the limit?  Lateral G was down at 1.5G, which is low considering the temperature in the tyres on lap 2 and the high speed at this point.

A further lift of the throttle aligned with more steering angle unsettled the rear but this quickly stabilised and throttle was soon applied to exit the corner where lateral G rose to around 1.8G, peaking at well over 2G.  It looks like I need more confidence here.

 

I arrived at the end of the back straight in sixth gear and applied pedal pressure to retard the car at about 1.4G.  This is lower than the lateral acceleration being achieved, so I either need to brake harder or the camber angles on the car are severely compromising the braking performance.  Pedal pressure was bled off for the two downshifts and further still as the car was eased into the first apex.  The brakes were released for the second apex and I clipped the kerb, causing my foot to touch the throttle and a big spike in lateral G from the attitude of the car.  Full throttle was applied almost immediately and steering angle applied for the right-hander.

Mid-corner, I lifted off the throttle and lightly brushed the brakes (just resting my foot on the pedal), which led to under-rotation of the rear wheels shown on the RPM trace and caused some oversteer as shown by the steering trace.  Full throttle was again applied with a little wheelspin being the result, even when the steering was nearly straight.  Braking into the final corner happened at a similar time to turn-in and oversteer was the result with two pronounced steering corrections.  Application of the throttle then caused the rear to slide and a large correction was again required before full throttle was attained all the way to the finish line.

 

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