CategoryLife

Locost: Airfield Testing

I get super nervous when it comes to things like this, logistics and towing always freaks me out. Getting the car to and from an airfield… on time… on a trailer… with all my tools and spares… there is plenty that can go wrong. Fortunately barely anything went wrong!

Setup

Prior to IVA I need a reasonable fuel map in the car so it can be driven around, undertake the emissions tested, test the speedo etc. I have changed so much in and around the engine that I needed to start from scratch this time around. Following lessons I had learnt running DIY fuel injection in my daily Sierra, I knew the benefits of using throttle position as the ECU load input, this is known as alpha-n tuning and is what I will be running in the Locost from now onwards as opposed to the blended tps/map setup I had been using before.

In short, I needed somewhere to drive and map the car. It had to be private land and with plenty of space to be able to drive at wide open throttle for long periods of time. After a visit to my local airfield, and a phone call with the very generous land owner, I was ready to go.

I made a big push to get the car into a ready state for the day, finishing with a pre-IVA job list of about six items. If all went well, I would be in a comfortable place to put in my paper work afterwards. Spoiler: my job list is now much bigger!

Journey

I barely slept the Sunday night before Mondays testing and after making sure everything was loaded correctly I arrived 15 minutes early at 9:45am.

Fortunately, my nerves amounted to nothing. The drive was a cool 1 hour 15 minutes with no hassles and very little traffic. Within half an hour of getting there my brothers Alex and Neil arrived to help me out, having driven for hours to get to the airfield. I love it when a plan comes together.

Initial Running

The first job of the day was to build confidence in the engine, shake down all of the many new components on the car and get some of the cruising fuel table positions filled in. Alex took to the drivers seat while I plugged in the laptop and watched the ECU do its thing and auto-tune the low speed elements of the table.

I did scoot the car around a little bit before everyone arrived and I could already tell it was driving better than it ever has, at least from a handling perspective. Over the winter I was very specific about the alignment I applied and made sure it was dead straight. The limited slip differential has also completely changed the feel of the car.

More RPM

After an hour or so of driving, and lots of stopping and checking for leaks, we started to build up the engine speed and mapping the wide open throttle (WOT) parts of the fuel table.

First 3000rpm, then 4000rpm, then 5000rpm and soon 6000rpm. The engine sounded loose and happy, free revving to whatever we threw at it. The auto-tune feature of Tuner Studio was pulling fuel out every thousand RPM we went up, suggesting my initial guess was too rich, exactly as I had planned.

Things weren’t entirely without incident and a number of issues became apparent at this point:

  • The front wing stays, on the rough surface of the World War 2 airfield, were far too soft. The wings themselves were bouncing around all over the place.
  • The clutch was progressively falling down the pedal. You could put this down to temperature but I was pretty sure the slave cylinder was leaking into its rubber boot. We removed the pedal stop to allow us to keep going.
  • The fuel filler tray gasket wasn’t doing its job and fuel was weeping out of the top of the tank. Eventually this went away as we burnt through fuel but would need to be fixed as soon as possible.
  • The fuel injectors were leaking at the manifold side, just a little, and the seals clearly weren’t sealing correctly.
  • Worst of all, the engine was burning oil badly on over-run. Sometimes clouds of it, sometimes not.

We decided to take note of the issues but simply crack on. Its not often you get access to an airfield for the day and we wanted to get the most out of it.

Calibrating the Speedo

I had a three point job list that I had to get done at the airfield:

  • Map the engine enough to get the car driving reasonably
  • Confirm the brake balance locked the front wheels before the rears
  • Calibrate the speedo

The first two were not a problem at all, but the third required a bit of thought. The speedo appeared to not be working at all, at least with the calibration I had put in at the beginning of the day. Based on my early maths, with a 4.3 ratio differential, and four bolts on the prop-shaft flange to read from, the gauge should have been seeing approximately 15000 pulses in a mile and that’s a what I set it to.

Given that this number was clearly wrong I adjusted the pulses per mile to 1000 and took the car out for a short drive, while referencing the GPS speed on my phone.

32 mph on the GPS, was 20mph on the gauge, at 1000 pulses per mile

My initial guess was super far off! How did I mess that up? Anyway, it was reading low, so by reducing the number of pulses per mile we could increase the speed seen on the gauge.

Doing a little bit of quick-maths suggested the actual calibration should have been 625 pulses per mile. Given that for the IVA the gauge has to read between the actual speed and 5% over we opted for 600 pulses per mile.

I did however want to back calculate my maths, which I will do here:

1 mile is 1609.34 meters
625 pulses per mile is 1609.34/625 = 2.574 meters per pulse

a 185/60 r13 ns2r tyre has a diameter of 552mm
this gives an circumference of 552*3.142/1000 = 1.734 meters

therefore 2.574 / 1.734 = 1.4844 full wheel turns per pulse

with a 4.3 differential ratio that is
4.3*1.4844 = 6.38292 propshaft turns per pulse...

that makes no sense

So yeah, the maths doesn’t add up and I don’t trust the gauge manufacturers instructions… but it works!

In fact, lets do some maths in the other direction…

4 pulses per propshaft rotation
4.3 propshaft turns per axle rotation
4*4.3 = 17.2 pulses per axle rotation

1.734m circumference gives 17.2/1.734 = 9.919 pulses/m

1 mile is 1609.34 meters
1609.34 * 9.919 = 15963.04346 pulses per mile

Now this kind of looks like the number we came up with in the end… can you see it?

15963.04346 * 4 / 100 = 638.5217384 ~= 638 somethings

Now the gauge manufacturers documentation describes this number as the “frequency”, so the factor of four kind of makes sense, maybe, and the factor of 100 could just be for the sake of storage or to give resolution for certain gearboxes.

Either way, done.

Driving on my own

Even though the engine was blowing a fair bit of smoke on up shifts we decided to get some miles on the piston rings and shake the car down further. Issues aside, it felt fantastic. Getting from a stand still to 70mph happens pretty damn quickly and the steering feel was better than it ever had been.

At the far end of the air strip was a number of coned gates setup for truck driving tests and I couldn’t help but have a little play in-between them. No complaints regarding the chassis.

Evolution of the Fuel Table

Below is the Volumetric Efficiency (VE) table we started the day with, the table we ended the day with and the difference table showing the changes made. The VE is simply a measure of how much fuel flow the ECU is demanding relative to the amount required to achieve stochiometric mixture at wide open throttle. Technically, if the engine is 100% efficient as an air pump, it would achieve 100% VE across the top of the table.

As you can see, the fuel table isn’t perfect, especially at high rpm and part throttle where it was barely touched. Its quite difficult to consistently drive this area of the table! I also did a substantial amount of manual adjustment based on what the wide open throttle numbers suggested. I could smooth it over more but I am going to leave it for now.

Notice that at low RPM the engine needs more fuel for lower throttle angles. This makes a lot of sense, as the throttle plates don’t act as much of a restriction at low flow rates, but as the flow increases at higher RPM’s they do a better job of restricting flow into the engine.

This map will do for the IVA, then I will take the little red car to the dyno.

Final Thoughts

I am really glad we got this day to shakedown the car. Its highlighted a few jobs that really need to be done before submitting my paperwork and its better to get them done now rather than later.

The engine is still a bit of a worry but my gut feeling is the valve guides have worn out. Prior to rebuilding the engine it had started doing the same thing and I had assumed it was the piston rings. The engine has fresh stem seals, so it points to the guides themselves. I have a spare cylinder head in great condition that I am going to drop in.

The chassis feels great and it was nice to have someone else drive it for a change. I’m looking forward to getting on the road later this year.

On Projects and Hobbies

I have been building and playing with my little car for almost thirteen years now. When I first started the project I envisioned having it on the road within three years (because I wasn’t going to be one of “those people”), driving it, racing it and moving on to better things. In hindsight: I was naive.

In fact, it became a running joke. I was talking to one of my friends on the phone the other day about the car and how progress was going (it turns out I actually barely talk to people about the car anymore). I stated it would more than likely be on the road in less than a year. He jested that I would be saying the exact same thing next year. In my early twenties I would have taken this very personally, as an attack on my capability or my word or some other nonsense; forgive me, I was naive. The reality is, he might be actually be right and more interestingly: I apparently don’t care.

Something I have come to realise is that the core value in a project like this is not in finishing it. Great, you get a ludicrously expensive mildly fast sports car; you could have bought a Miata and had the deposit for another house instead. You’re an idiot Josh.

The value in building a car is in overcoming the complexities, the new skills you learn and the time you get to spend with yourself (or with a friend or family member if you are doing a shared project).

On the outside looking in, if I had undertaken this project to get a sports car at the end, then yeah that’s absurd. That’s funny. That’s a joke. So I can definitely see why people can see it that way. Heck, I even see it that way!

But in reality, it’s all about “The Journey”. It’s a cliché. But it’s a cliché for a reason. It turns out its most likely a truism, as true for building cars as it is for life.

To build the car I have had to learn welding, fabrication, fibre glassing, painting, wiring, engine building, suspension design, upholstery, blah, blah, blah, the list goes on. It is unlikely I would have been exposed to these things had I not taken on the project. I have also had to learn my limits, my likes and dislikes. I know that I can hammer on at a project for going on thirteen years without giving up, that’s pretty cool right?

I have also learnt that I desperately need time alone. Those six to eight hours a week I spend squirrelling away surrounded by four walls and a car is incredibly cathartic. I listen to music, I listen to audio books, I listen to talks from modern philosophers and sometimes, more often than not, I listen to nothing at all. The sound of tools. The sound of my own thoughts. It’s a much needed break from the outside world.

Regarding the three year plan, I think it’s do-able depending on what you choose to build, your starting skill level and where you are in life. But I had none of these stars aligned. I chose a complicated custom build, with little to no experience (I had built a stock car that was all) and I was nineteen years old. I look back at that kid and I think: you had shtick you handsome fool.

Since I first cut metal I have:

  • Gained a degree in Mechanical Engineering (4 years of my life)
  • Changed jobs four times, excluding an industrial placement year
  • Changed location five times
  • Changed house eight times
  • Switched careers
  • Moved the Locost between four locations
  • Gained two cute dogs and held onto a mega fiancé (marriage pending COVID)

All of the above is not conducive to completing a project car and that is okay, because of all the above is life. Reality. Stuff that happens outside of the garage. Stuff that matters.

I think what I am trying to say is, when I sit back and look at what I have achieved in thirteen years I say “wow, I am proud!”, and that’s what hobbies are all about. Progress in a sea of uncertainty and change. A constant when everything is variable.

So go out, get a hobby, don’t set an end date, and just enjoy yourself.

ManDoCar: Episode #3, Painting Dinghy’s, Man Do Compressor, Nissan Leaf Smugness

It happened again. Alex and I got behind our microphones and discussed the state of our hobby projects and many other random pieces of Engineering.

Dinghy updates, paint types, the magic of radio 4, man do compressors, compressed air cars, the Nissan leaf, electric car ownership, tesla’s, drag simulation, smugly pre-heating your car, the Locost’s shiny bodywork and the label “sports car”

Follow us on Twitter @ManDoCarPod

ManDoCar: Episode #1

I couldn’t bring myself to write a full article on how the car is getting on, so I decided to do something a little different: a podcast! Enjoy. All the relevant pictures are below as well as dingy chat!

We discuss painting, IVA preparation, driving at Snetterton, engineering learning, SpaceX hydraulic systems, faulty brake callipers, peak performance, why limited slip differentials rock, the Hoonigan donk, exhaust wrap, and lastly, engineering in a pandemic.

Dingy Chat

Pantone 333c Colour Chip

The Locost

New steering rack mount. Major surgery!
The chassis finally in a state to clean and paint. Spring 2020
Chassis all cleaned up and steering rack back in
Steering joint over the 10 degrees required for IVA
A very clean and red engine block
ARP Main Studs. Lovely.
Plastigauging a main cap
One of the old big end bearings. Not nice at all. These were new not long ago.
Inside of the drp sump pan.
New seat padding by JK Composites.
Bottom end back in the car.
The entirely wrong brake calliper slides …
… this is what they should look like
A freshly rebuilt and cleaned diff. Kaaz Limited Slip inside!
Auxiliary belt idler. Makes the engine much quieter.
Front lights! Looking great
Oil on plug #1. Not fouling, but not great. Need to do a proper break-in before any concern.
Hello!

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