Mazda MX-5e Tesla Powered

[robcollingridge]

We are now a family with 3 MX-5s! :-)

Having restored Yoko (1990 Eunos Roadster 1.6) with my son Ethan, we have embarked on a much bigger project to collaboratively build an Open-Source Sports EV (OSSEV) from scratch.

As part of this project we are converting our newly acquired 1992 Eunos Roadster to electric power using the 220kw/295bhp/330Nm Tesla SDU. This MX-5e will be our test platform for developing and testing parts planned for the OSSEV
The plan is to transform this car into something that is faster, lighter and more involving to drive. It also means we will be developing a load of new components that should fit any NA MX-5 or Eunos.

Moderator edit: please don't link to your own website/social media pages

[robcollingridge]

visitinglondon said:

Lighter and more involving to drive?

Is this an early April Fool’s joke?

No joke. It will weight less than the original Eunos Roadster we have just collected. Slightly less range though :-)

Yes, more involving to drive too. Loads of driver focussed upgrades including ditching the power steering, improved suspension, better brakes, sports seating with 6-point harness, etc. And 295hp

[robcollingridge]

Toilet Duck said:

Was that pic taken at Woodbridge?

Yes. We had just bought this car and thought we would take it on track and see if it broke before we put time and effort into it. It got hammered all day on track and the only issue we had was a pin-prick hole in a coolant pipe :-) After several years and over £4000 it is an immaculate example of the 1990 Eunos Roadster

[robcollingridge]

Started stripping out the interior today. It is going to lose a lot of weight! We knew the soft top leaked but we only paid £1425 for the car. It was wet inside but just some surface rust which has now been treated. The soft top is going to be replaced with something more Lotus Elise like. Eventually, the whole wiring loom will be stripped out and replaced by something much lighter, that also supports CAN Bus. All the sound deadening has gone. Lighter seats are on the cards too.

The main focus is on preparing all the important bits for the conversion. The brake calipers are going off to be refurbished as new and every thing else is being replaced. New disks, pads, braided brake hoses, new brake pies and an electric Bosch iBooster will replace the current braking assistance system. The air conditioning system and power steering system is going too. This car will end up lighter than it was when we bought it :-)

[robcollingridge]

The interior behind the seats is now complete. We stripped the front off the car today and found very little rust :-)

[robcollingridge]

The Bearded Tit said:

Cool project. So, it'll be lighter than standard because of all the weight-stripping. Would be interesting to see how the weight compares if the EV swap was the only thing done. How much does one of those Tesla units weigh compared to an MX5's engine and gearbox, exhaust etc? How does it affect the weight balance?

The Tesla SDU is 88kg and it will sit where the diff is currently located. The batteries will be where the fuel tank currently is and will also run along the centre tunnel. We plan to move 12V battery and some other stuff into the bonnet area.

I'm in the process of building my own scales to measure the corner weights.

[robcollingridge]

snotrag said:

Interested to know why your getting rid of the Power Steering? The car was designed with steering geometry to work with power steering and uses the appropriate rack ratio.

The only MX-5s that come without Power steering were those poverty spec, naff run out models and it was done as a cost saving, not a 'performance improvement'. The Non assisted rack is awful.

The infamous 'depowered PAS rack' is similarly awful, generally used 'bEcoz RaceKar!" by people who think not having power steering is cool. Despited the fact the car drives better with it, on road and track.

We are going to see what it is like without. PArtly to save weight and also because we don't plan a vacuum pump to drive it. If it doesn't work out, we could add electric assistance.

Rob

[robcollingridge]

Smitters said:

Very interested in this. For some exceedingly odd reason I have a desire to EV swap a Morris 1000.

I guess it depends on what you intend to do with the car, but I'll be really interested in how you approach HVAC for comfort and screen clearing. If the power-steering makes a reappearance - because I assume you're going to need a decent amount of front grip to avoid terminal power understeer - Bad Obsession used an electric pump.

Edited by Smitters on Saturday 25th March 07:05

The plan is to install full electric HVAC and this will be a test of the system we plan to install in the OSSEV.

Rob

[robcollingridge]

We have finished stripping down the front end and treating any rust. The whole front end and the constituent parts of the bumper have been done. It's now time to put it all back together!



Whilst we are not using the 1.6 engine in this project, we are spending a lot of time to check it is all running well. It's only done 80,000 miles and would be an ideal donor for my son''s 1990 Eunos Roadster 1.6 which has done 135,000 miles.

[robcollingridge]

We are currently stripping out the dash, to replace it with a new black one. New black carpets and door cards going in too. Hoping to MOT the car very soon but we are also replacing the whole braking system first.

Moderator edit: please don't link to your own website

[robcollingridge]

And the dash is out. Hard work!



Pretty much all this is going. The car is being re-wired with a CAN bus and we are even contemplating a bespoke dash to save even more weight.

[robcollingridge]

ChocolateFrog said:

Sounds ambitious, must be a very small battery to get it lighter than the original car.

About 30kWh, giving a range of 120'ish miles.

Rob

[robcollingridge]

Our plan A is to do something radical and build a custom dash and this is what we will be exploring in the coming weeks. We can reuse the metal support frame.

[robcollingridge]

If this doesn't work, our plan B is to fit this new black dash.

[robcollingridge]

The 10" infotainment touch screens arrived today. These will be separate to the car's instrumentation and are basically stand-alone units that support Apple CArPlay and Android Auto. Really good quality and very responsive. Will be mounted centrally.

[robcollingridge]

shalmaneser said:

This seems a bit like scope creep? Isn't there enough to keep you busy?

Yes, it is really. It's not a huge thing but, I was interested to see what worked as it may make it easier to mount the 10" infotainment system and HUD.

Rob

[robcollingridge]

hairy v said:

Great project OP, what sort of range are you anticipating for normal driving?

About 120 miles. It's a compromise between weight and range basically. We want our MX-5e to be lighter than the Eunos we started with.

Rob

[robcollingridge]

NDNDNDND said:

Me too. I hated the hydraulic PAS on my mk1 - couldn't feel a thing. After a few frustrated track days I considered selling the car but couldn't work out what to replace it with. A chance drive in a Ma5da race car, back to back with a HPAS and unassisted car confirmed for me that the hydraulic rack is the worst option. The amount of feel and confidence offered by the unassisted racks was leagues over the HPAS. My car now runs a 'flyin miata'-style depowered rack. With the standard steering wheel and castor angle kept below 5° the steering weight is perfectly fine and you can actually feel how much grip you have at the front tyres.

If you're going for simplicity, why faff about with Bosch iBoost? There are off-the-shelf unservo'd brake kits available.

Edited by NDNDNDND on Thursday 6th April 22:25

Yes, we were planing to do the Flyin Miata modification to improve the feel. The car will be light enough not to need power steering and in my 450kg Fisher Fury R1, there was definitely no need for it.

The iBoost is because of the programmable regenerative braking. We want the iBoost to have a few different driving profiles and this will allow control of the character based on selected mode.

This MX-5e is a test platform for a scratch build.

Rob

[robcollingridge]

We had to remove the camshaft cover in the MX-5e as the gasket was leaking oil everywhere. Whilst the cover was off, we took the opportunity to clean it all up and paint it. It will now be installed in Yoko (my son's 1990 Eunos Roadster 1.6) and we will put Yoko's cover back in the MX-5e. We are looking after the engine because it will probably be transplanted into Yoko at some future date. This one has done about 80,000 miles and Yoko's has done 140,000+.

[robcollingridge]

Our plan A is to use the metal frame inside the Eunos dash as the basis of a new custom, modern dash. We have separated it from the plastic part and taken an angle grinder to it, to remove the unwanted brackets. It had lots of surface rust as Mazda don't treat this part of the car at all and it gets exposed to some damp inside the car. It is now cleaned up and painted, ready for our experiments :-)