March 2022

Refuelling

The theory was that the tank only had 3 litres in it, since the Koso Mini 3 LCD fuel display showed ~30% with the ignition on. So I filled the fuel jug with 5 litres of race fuel, and started pouring the fuel in to the tank. 1 litre, 2 litres, 3 litres, ah, the gauge is now starting to change. At 4 litres, it started to rise more rapidly and I continued filling the tank. At 5 litres, the fuel tank was brimmed, and eventually the gauge shows 98%. Not very satisfactory. VDO senders clearly aren't that good. My next tank will use a different sender.

Refilling the paintball bottle with compressed air was a lot simpler. After that I made a new bracket to hold the lipo battery down, and finally made a small change to the alternator strategy for when the alternator turns back on, and again, I'll be monitoring the performace over the weekend.

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Fuel sender

I tackled the VDO fuel sender again last night when the external digital LCD gauge showed 0% fuel remaining, and the day before showed 33%. The electrical connection on top of the sender, is insulated from the sender itself, and the spade terminal turns a small amount from side to side, if the attached crimp connecter is pushed.



I tried again to tighten the 7mm nut on the top of the terminal, whilst preventing the terminal from rotating, and I did manage to tighten it, just a small amount. Measuring the impedance across the sender terminals, it shows 58 Ohms, and plugging the wire back in to connect the gauge, it showed 33% again. I've added a small amount of cross check wax to the terminal to see if that is enough to stop it from rotating. At least the new gauge on the dashboard will give me a second opinion. I also moved the temperature sensor that was fitted to the outside of the fuel cell, to the side of the fuel pressure regulator. Thats the last body that the fuel passes through on its way to the fuel rail on the engine. It'll be interesting to see what temperature it reaches. Pete said his fuel inside his tank reached 40C on Saturday at Cadwell, on a mild spring day. I'll log the temperatures and see how they look after the weekend.

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Dashboard modification

Pete's altered the Plex dashboard display on his car, to include a fuel gauge that shows precisely how much fuel is in the tank. He's had a new tank made with a VDO sender, like mine, and at the moment the sender is working and the gauge is therefore accurate. My sender however has proved a little unreliable. It shows when the tank is full, and I can see the fuel in the filler neck, so I know when its full. But as the fuel level drops, the electronic display I've used, suddenly drops to a low level and flashes to indicate Low Fuel. At that point, I add more fuel, which is adding weight, and I dont want to carry any more fuel than I need to. I cant remove the sender unit, as its in the tank which sits beneath a chassis rail, so getting the sender out means taking the tank out, which means removing the floor.

I got thinking about the data that the ECU provides and I could recall seeing the ECU recording consumption. I had turned that channel off some time ago, I wasnt really worried about how much fuel it had used. But I thought that that would be really useful as a gauge on the dashboard.

There is a Clear Fuel Consumption command, in LifeMon and LifeCAL, and this command is used to indicate to the ECU that the fuel tank has been refilled during a pit stop, so the consumption counters are reset. From that point on, every milliletre of fuel is recorded, and the ECU doesnt forget that value, until the Clear Fuel Consumption command is run again.



If I could display that information, then I'd have an accurate measurement of the fuel used, which would give me a second opinion of the fuel level shown on the electronic gauge. But what channels do I need to pass to the Dash4Pro over CAN, to get it to display the consumption figure?

The only way to find out was to monitor the fuelConVol channels and run the engine. So I added the four channels available to the logging config, and displayed them in LifeMON, and ran the engine for a minute.

The results are as shown:



The two channels that return data that I'd like to use are fuelConsVol, fuelConsVolHR, and fuelConsVolRate. However in Datastreams, fuelConsVol isnt available as a channel that can be sent over CAN, whereas fuelConsVolHR is, so I selected that channel and then edited the DBC file using KVASER to set the channel name, and format.

Once the DBC file was imported in to the Race Technology CAN Manager, I opened the Dash4Pro screen layout editor, and modifed the Engine Health screen to show the value returned by fuelConsVolHR, and set the bar graph widget to show the same value, with a min of 0 and max of 10. The value shown can be seem climbing at a rate of around 0.001 litres per second. I've set it to show 1 leading zero, but it will show up to 99.999 litres.

So as long as I remember to clear the consumption in the ECU when I fill the tank next, the display will show the amount of fuel used, and some mental arithmatic will let me work out how much is left inside the tank. I am also logging the consumption at 1Hz, and the fuel rate at 25Hz using burst logging, so I can check the consumption during a run.



I could really scare myself and add a mpg gauge. The 102 octane race fuel costs around £6 per litre, so that might not be a good idea!

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Thefts at Cadwell

Several unlocked motorhomes were entered at Cadwell during the meeting on Saturday, resulting in the thefts of wallets and a purse. The threat of thefts never goes away, and the owners concerned stopped cards when they found out what had gone missing. Why leave a motorhome unlocked though?

The second batch of printed parts arrived yesterday. These are turning vanes/vortex generators, and I've plans on exactly where to attach them, which I'll do in time for the sprint at Anglesey next weekend.

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Mark Harrison testing his Shadow

I hadnt even spotted Marks name on the side of his Shadow, but I did get a photo of him testing at Donington. Mark won the British Sprint Championship many years ago, and has registered again for this year. I'm looking forward to meeting him and looking over his Reynard 94D F3000 which he'll be running. The Shadow looked and sounded brilliant.

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Masters Historic's

I spent the morning at Donington Park today, photographing and filming the stunning selection of historic race cars that were practicing for the coming Masters Historic Racing season. There was a huge amount of wealth on display. Unbelievable cars. The ground effect cars were particularly interesting to see, and I took lots of photos of the skirt materials and fixing methods.

My videos are now on youtube.

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Anglesey garages

The booking form for the garages at the Anglesey circuit, opened an hour earlier than advertised last night, so I siezed the opportunity and booked one. I'll be sharing with Simon Bainbridge this year, with the SBR Chrono, I'm in good company. There'll be lots of banter for sure :D

Finally, the records I broke at Pembrey and Kirkistown have been updated on the BSC website. It's only taken them 5 months to appear. And Steve Broughton and Matt Hillam both registered yesterday, so there are now 19 drivers in total. Which is still a long way down on last years championship. A sign of the times?

I've designed some new turning vanes for the car. In F360, I used the airfoil plugin, and twisted the profile, which took some head scratching. These are away being printed.

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WiFi

The TP-Link WiFi Travel Router that I fitted in 2019, expired last year. The heat and vibration got to it. TP-Link swapped it out, under warranty, and I've fitted the replacement back on the car. This time I've placed it inside the cockpit rather than at the top of the engine bay, and I'm hoping it should survive a few more years. I've hot glue gunned the USB connector so it shouldn't fall out. And I've fixed the switch that puts the device in to AP/RngExt/Client mode, so it cant be accidentally moved. When the ignition is switched on, the device takes around 20 seconds to boot up, and then WiFi is ready. Of course, with the engine running, the WiFi is permanently on.


Stuck safely inside the cockpit


TP-Link AC750 WiFi Travel Router

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0.1mm adjusting shims

I had to buy some new adjusting shims for the suspension rockers. The ones fitted have disintegrated and I had precious few spares, most of which were already squashed and distorted. Getting a quote from Mygale in France, came back with the usual uber expensive price. They wanted £2.39 each for them. Plus VAT. Plus £25 postage, it just wasn't worth it. So I did some googling and found a company called Stephens Gaskets, and sent them a drawing, and the price came back at £1.60 each, for 120 off 0.1mm stainless steel shims, with VAT and delivery. So I placed the order, and waited. They arrived yesterday, and they're a perfect fit.

The only problem with getting shims custom manufactured is the quantity required to get to a sensible price. In the end I had 120 made, which I'm sharing half with Pete, but it's still a great expense for what they are. Anyway, I fitted them last night, 2 on the near side rocker and 3 on the off side, and I'll replace the shims on the front rockers next. That'll leave me with around 45 to 50 spare shims, which I'll keep in a very safe place.


120 stainless steel shims, £192 worth!


Adjusting shim fitted to the front rocker washer


Needle bearings greased and ready for reassembly.

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Trailer upgrade

I've fitted the Rhino winch to the trailer, which now gives me a nylon rope which is easier to handle, and wireless remote control, which will make the process of loading and unloading much safer. The Superwinch that it replaced has done a great deal of work over the years, but the wire rope needed replacing as I was forever stabbing myself with the tiny bits of frayed wire that stick out. Simple enough to install, just four 8mm holes are needed. I need to work out how to install a battery inside the trailer. There isn't much room to play with, so I'm looking to fit a low profile battery in the storage space inside the trailer. The battery will be wired in to the 11 pin trailer connector, so it is charged when the van's engine is running.

Rubber insulating boots will be fitted prior to first use.

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Testing success

Testing at a very windy but dry day at Blyton, went very well. I'd not driven the car since putting it all back together, and everything worked perfectly. The gear change seems really sublime now, the hall effect sensor has made a big difference, with very smooth and slick up and downshifts. The rear wing supports were tested at 145mph, and there was no flex or oscillations, so I'm now happy that they'll take the load from the rear wing. The measurements from the rear 1300lb springs showed that they deflected 23mm at 146mph, which is a load of approx 5600N on the axle, and with the rear wing mounted 0.75m behind the axle, with a leverage of 1.26, thats approx 4400N generated by the wing.

The new rear suspension rockers were fine, they also coped with the loads. The 3D printed damper reservoir brackets look like they coped with the weight of the reservoirs. And the 3D printed vortex generators on the floor, didnt fall off, so I know that a few dabs of Sikaflex are all thats needed to secure them. The only issue was the two new wire ropes I'd made that support the floor ahead of the rear wheels, didnt seem to be short enough. With the rear wing down, and the diffuser floor connected to the wing end plates, the ropes weren't short enough to suppor the floor ahead of the wheels. So I'll have another go at making some shorter ones.

Basically, I'm ready for the first event at Anglesey in April.



This is a graph showing the signal voltage from the gear position sensor. Gold is the signal from the new Active Sensors Hall Effect sensor, and blue is the old mechanical sensor. It is much improved now. The data shows that the time to change up a gear has gone down from 0.09s to 0.07s, which definitely contributes to the smoother change.

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New sponsor

I've now got Fractory.com on board as sponsors for 2022, which I'm really pleased about. Just waiting for their stickers to arrive and I'll get them stuck on to the car.

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Rear rocker ratios

I've done some calculations, using the profile of the Mygale rear suspension rockers, to try and work out their motion ratio (MR). Although Mygale quote it as 1.87:1, the rockers have a rising rate ratio, which really makes the published MR pointless. I want to be able to fit softer rear springs, which means the MR needs to be adjusted accordingly. Its going to be a bit of an experiment to arrive at the right design. Using for formula on the Wavey Dynamics article on Rising Rate Suspension, with help from the article's author, I have created a spreadsheet that allows me to model the ratio. This now places me in a position where I should be able to determine the direction I need to go in to alter the rocker profiles to work with softer springs.

This is the approximate MR for the rear suspension.

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Printed vortex generators

I've got support this seaon from Delou's Motorsport Hardware, and I appreciate their help. They supply all forms of hardware and its worth checking them out for some great prices.

Motorsport Hardware

I've bonded six of the 3D printed vortex generators to the floor, ahead of the side pods, and I'll try some yellow wool on Friday to see if they have the desired effect. I've stuck them down using sikaflex, so they're easy enough to move if I find their position isn't optimal. And at least I know they cant just fall off.

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More aero calcs

Just to refresh my memory, I've gone back to basics. So the rear wing is 750mm behind the rear axle. The placement of the rear wing at that point affects the downforce on the rear axle, through leverage. With the wheelbase (d2) of 2713mm, and the rear wing sitting 750mm further behind the rear axle, this gives a measurement (d1) of 3463mm. Therefore d1/d2 = 1.276. So the rear wing sat at that location behind the rear axle, generates approx 27.6% more downforce than if it were sat directly above the rear axle. I'll factor this in to the calculations used to derive the measured force applied to the rear springs.



Obviously the front wing has a similar leverage acting on the front axle, and when I put the front wing back on I'll measure the distance and work out the leverage. I have been through all this before, but there's so much tech on the car that going back over things doesnt do any harm.

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Money refunded from Herts County Auto Club

Thankyou to Herts County Auto and Aero Club for the refund of my £160 Cadwell entry. See, that wasn't so hard. The Anglesey sprint in April filled up in 36 hours according to Longton DMC. And there are drivers on the reserve list. Yet Blyton is barely half full. Maybe people are having a change of heart given whats going on in Europe. Which sadly I cant see ending at all well for anyone.

So as a distraction from the insanity, I spent a couple of hours in the garage last night, and I have recalibrated the damper sensors. Instead of measuring the car's ride height, I shall be measuring the spring lengths, which will give me a more accurate picture of the downforce being generated.


Since the rear springs are 1300lb/in, for every 1mm the springs are compressed equates to 12.4kg on that wheel, or a combined 24.8kg force on the rear axle. So say for example the ECU measures 10mm of spring displacement, then thats 18.7mm chassis deflection, and 248kg of downforce, which is 2437N. Thats the theory anyway. If I go testing I'll see how the data looks.

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