Sprinting a Mygale M12 Ecoboost

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andylaurence
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Re: Sprinting a Mygale M12 Ecoboost

Post by andylaurence » Fri Jul 24, 2015 3:03 pm

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.

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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

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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.

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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.

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andylaurence
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Re: Sprinting a Mygale M12 Ecoboost

Post by andylaurence » Wed Aug 12, 2015 10:19 pm

I've started scanning the car and have a start to the left-front. Download it here.

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Re: Sprinting a Mygale M12 Ecoboost

Post by flynfrog » Thu Aug 13, 2015 10:24 pm

What method are you using Andy? Kinect?

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Re: Sprinting a Mygale M12 Ecoboost

Post by andylaurence » Fri Aug 14, 2015 7:12 am

Yep, Kinect and KScan3D.

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Re: Sprinting a Mygale M12 Ecoboost

Post by andylaurence » Sun Aug 16, 2015 7:58 pm

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.

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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.

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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.

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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...

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Here's the video...

andylaurence
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Re: Sprinting a Mygale M12 Ecoboost

Post by andylaurence » Fri Sep 04, 2015 4:42 pm

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:
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Timed Run 1:
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Timed Run 2:
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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.

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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.

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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.

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

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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.

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

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andylaurence
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Re: Sprinting a Mygale M12 Ecoboost

Post by andylaurence » Tue Oct 13, 2015 5:42 pm

We rocked up at 08:00 ready for our last event of the season at Curborough Sprint Track. After discovering my helmet goes out of date at the end of the year, we prepared for first practice. I hopped in and we fired the engine, but there was nothing. The extinguisher pin had shorted the battery to ground. We borrowed another battery from Clive Wooster, but it appeared that was dead. We thought that was it, but I checked the battery to be sure it was dead. It wasn't. At that point, I realised what I'd done. I'd forgotten to press the ignition switch. We re-fitted the battery and went for first practice a little late!

Since the last event, we'd topped up the oil, but with the car sitting in a temporary workshop, we've been unable to run the engine to get it to the right level. It was over-filled as we discovered when the catch tank filled on my first practice. We headed back to empty the tank. We both brought our times down through practice, emptying the catch tank after every run.

In the timed runs, we were separated by just 0.21 seconds, which is the closest we've ever been, less than 0.7%. It got closer still in the second run with just 0.04 separating us, just 0.1% different. On that basis, I won the class and was advanced to the class winners' runoff. The positions in the runoff would be decided by who improves the most over their class-winning time. I gave it a good punt and lopped 1.25 seconds off to finish on 30.72, winning the runoff in the process. All-in-all, a good result for the Egoboost!

The results show some interesting information. Whilst our times are incredibly close from the start line to the finish line, we were split by around 3 tenths after 64 feet. That's clearly an area where I can improve my performance and I lost over half a second to the fastest cars of the day in just the first 64 feet.

The other thing to note is the trap speeds over the finish line. We were one of the better cars, with 108mph being our best. This was faster than all the road cars, all but one sports libre racer and beaten by only three of the 1100cc class single seaters. On that basis, we're losing in the corners, not on the straights, so the lack of downforce is key here. Also, noting the lack of power and the heavy weight of the car, this suggests that we're running much less drag than the other cars, which also points to less downforce. Winter plan must therefore be to both reduce weight and increase downforce.

andylaurence
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Re: Sprinting a Mygale M12 Ecoboost

Post by andylaurence » Tue Oct 13, 2015 5:45 pm

Here's the onboard video from my driving partner. My onboard video will be uploaded soon and I'll do a data debug.

machin
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Re: Sprinting a Mygale M12 Ecoboost

Post by machin » Tue Oct 13, 2015 9:39 pm

Are there obvious things you can do to reduce the weight, or is it going to be a case of "a little bit here, a little bit there"?
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Re: Sprinting a Mygale M12 Ecoboost

Post by Pierce89 » Wed Oct 14, 2015 1:23 am

As far as weight loss in a racecar, the first thing I always ask is, "are you using a lithium battery, yet?". If not, that always easily a few kilos.
“To be able to actually make something is awfully nice”
Bruce McLaren on building his first McLaren racecars, 1970

“I've got to be careful what I say, but possibly to probably Juan would have had a bigger go”
Sir Frank Williams after the 2003 Canadian GP, where Ralf hesitated to pass brother M. Schumacher

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Re: Sprinting a Mygale M12 Ecoboost

Post by machin » Wed Oct 14, 2015 12:37 pm

First I always ask: "What can I remove entirely in order to do the type of competition I intend on doing"? This is normally the cheapest and quickest way to weight loss IMO....

...Much easier when you're starting out with a production-derived car of course!
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Tim.Wright
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Re: Sprinting a Mygale M12 Ecoboost

Post by Tim.Wright » Wed Oct 14, 2015 1:14 pm

In amateur classes, the easiest few kilos to throw away are generally from the driver ;-)
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Re: Sprinting a Mygale M12 Ecoboost

Post by flynfrog » Wed Oct 14, 2015 3:17 pm

Tim.Wright wrote:In amateur classes, the easiest few kilos to throw away are generally from the driver ;-)
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Re: Sprinting a Mygale M12 Ecoboost

Post by andylaurence » Thu Oct 15, 2015 6:48 pm

There's a fair amount of potential weight loss. I'm hoping for 30kg over the winter, which is over 6% and more than the driver could lose. I ran a lithium battery in the last car, but whilst out was 5 kg lighter, it's a real pain. The voltage mismatch between lithium and the lead starter pack means the starter pack will discharge the onboard pack. It only takes one helpful person to plug the starter pack in for you and your day is over and the lithium pack is dead.

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Re: Sprinting a Mygale M12 Ecoboost

Post by andylaurence » Thu Nov 26, 2015 10:41 pm

At Curborough, it became clear that two different styles of driving are leading to very different start times. I was losing a few tenths in the first 64 feet to Andrew every single run. So how did this happen? Let’s take a look at our final two starts to compare. Here’s Andrew’s start in the final timed run. The top graph shows RPM, the next shows the relationship of front to rear wheelspeed, the highlighted graph is throttle position and the bottom graph is front wheel speed.

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Andrew launches at 3100rpm and 31% throttle. Revs continued to climb on a steady throttle and at 17mph, he’s flat out and the car gains traction (the dip in RPM and the front/rear wheel speed traces) at 35.9mph. He reaches the 64 foot marker at 43mph. Conversely, here’s my trace from the runoff.

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I launched at 5200rpm with 18% throttle. I modulated the throttle until 33mph when I hit full throttle and finally gained traction. Moments later, I hit the 64 foot marker at 43.1mph but a tenth behind, despite this being my best start of the day by a couple of tenths. Andrew’s smooth style and most likely his clutch control have led to a succession of good starts. Clearly, lower revs are viable and beneficial with the heavy production-based engine.