Practical 400kg sports car

[robcollingridge]

After 5 years of Fisher Fury R1 ownership (since I built it), I've started thinking about what I could replace it with and come to the conclusion that a bespoke build is the only way to go. My Fisher Fury R1 ( http://www.robcollingridge.com/FuryR1/ ) weighs 450Kg with half a tank of fuel and has about 160bhp. It's road legal but has no doors, windscreen, heater, reverse gear, etc.

I'm looking to get down to 400Kg and add some more practicality this time though and have started capturing my thoughts here: http://www.robcollingridge.com/400kg/

Does anything close to this exist already though? I'm not including 'open wheel' designs like the Caterham 7. It has to have full bodywork and 2 seats.

This is roughly what I'm planning:


Rob

[robcollingridge]

The same way that my Fisher Fury R1 weighs 450Kg but, I've learnt a lot since building it and can see loads of ways to save another 50Kg (at a cost though).



Rob

[robcollingridge]

OK, maybe I should define what I mean by practical. It will be more practical than my Fury in that it will have a windscreen (but no doors). Also planning a removable hardtop (not included in my 400Kg target). It will require a reverse gear this time to pass the new IVA test. Also plan to have a more spacious cockpit but, the overall size of this car will be tiny and like my Fury R1 it will be smaller than a Lotus Elan.

I'm planning carbon fibre shell seats which I consider comfortable and practical. There will be no doors, heater, or modern comforts. There will be no dash, just an instrument binacle over the steering wheel. Bodywork will be very thin and light. It will be bike-engined again. 13" wheels are assumed with Wilwood calipers and I will use 7mm thick discs as used in my Fisher Fury.

By practical, I guess I mean usable in all weathers. My Fury R1 is very much a dry weather car. Think Lotus Elise practical but much, much lighter.

[robcollingridge]

Crikey, loads of questions. Don't you guys watch the F1? ;-)

Like I said, my Fisher Fury R1 is my benchmark and starting point. It weighed 450.5Kg when it was corner weighted a few years back and various upgrades since have reduce this weight.



This project is about progressing to something lighter but still road-legal and with 2 seats and still with full bodywork. I think that I can make it slightly more practical by adding a windscreen (also removable) and a removable hard door with gull-wing roof panels to enable access. This latter part is not included in my 400Kg target. There will be no doors on this car as this will make the 400Kg target unreachable.

If I wanted and open-wheel, minimal bodywork design, then I would have have built a Syvla R1ot or Sylva/RAW Striker to start with. Beyond that, I considered a single seater design. This isn't what I want though.

Most of the questions posed can are answered in the detailed design sections on my project website:
http://www.robcollingridge.com/400kg/design/index....

My 450Kg Fisher Fury R1 cost about £12,500 to build five years ago and features no carbon fibre components at all. It also uses some quite heavy engineering, reusing parts from the Ford Sierra, Ford Escort Mk II and Lotus Elise. Whilst building it, I weighed everything that went on the car.

I know I can hit 400Kg with a similar car and moving to a mid-engined configuration will help in this. This new car will feature quite a lot of carbon fibre and the costs will more than double because of this. I'm also planning some innovative (innovation is my day job) solutions to aspects of the car.

1. All the instrumentation and switch gear will be bespoke and extremely light weight.
2. I did a custom wiring loom in my Fury. I can halve the weight of this in this car by clever use of electronics.
3. I'm planning to use clever design of 3D printed parts to reduce weight.

I've revisited every component I used in my Fisher Fury and in all cases, I can reduce the weight or eliminate parts altogether. Against this, I have to add the weight of the windscreen, wipers, screen demister and a reverse mechansim.

Rob

[robcollingridge]

I'm not. The 400Kg target weight does not include the hard top, just the windscreen. The access 'doors' are part of the hard top.

Rob

[robcollingridge]

I know bike-engined cars are not everyone's choice but, personally I love them and it is the only way you can get close to the weight I'm talking about. A 2003 R1 engine is 60.5Kg with all the bits to make it run (no exhaust manifold) and that includes the gearbox, clutch, etc. It is not ideal in town but, I love it in my Fury R1, which is mainly used on the road. The sound and 11,500rpm red line are a big part of it.

I loved my S1 Elise too but, it was a production car. No production car will get close to 400Kg because of safety regulations and manufacturers liability. This is a one-off and I don't have to worry about such things, just getting it through the IVA test.

I guessed safety would crop up at some point in this thread. Is a 400Kg car any less safe than my 450Kg Fisher Fury R1? I don't know the answer to that but, I'm perfectly happy with my Fury and I drive it like it is a motorbike with 4 wheels and understand the consequences of hitting another car. It is a lot safer than a motorbike, in that I can't fall off it.

It amuses me that people think 400Kg is so far from realistic, when I have a 450Kg car sitting in my garage that is quite close to what I'm trying to do. As I said before, my 400Kg target does not include the removable hard-top roof. It this such a big leap?

My worst case scenario is that I end up with a car that is faster and lighter (and more expensive) than my Fisher Fury R1.

[robcollingridge]

One simple example of what I'm talking about is this indicator stalk/switch I've fabricated using carbon fibre this weekend. I can do this because I'm using clever electronics, which also mean much of my wiring loom can be 7/0.2 wire (which weighs just 3.5g per meter). This indictor switch will be mounted on the carbon fibre paddle shift and it weighs just 8g.



I'm not saying 400Kg is an easy target to reach but, these are the kind of things I'm doing to make it happen.

Rob

[robcollingridge]

The main reason for not modifying an existing car (such as my Fury), is simply that I want this car to also be jaw-droppingly beautiful. I figure that I'm only going to do something like this once in my lifetime. Because this car will be purely about driver involvement and not lap times and downforce, I've also set myself the much harder objective of creating the most beautiful car I've ever seen.

And people thought hitting the 400Kg weight target was the difficult bit! ;-)

Rob

[robcollingridge]

rhinochopig said:

At that weight I would look at using bike rotors and callipers with a bespoke mounting bracket instead of willwoods. I would also look at something like a Rial wheel at 4.9kg http://www.fluke-motorsport.co.uk/rial-challenge-1... as a good balance of price vs weight.

Thanks for the link but, the Compomotive CXR alloys on my Fury are lighter at 4.6Kg.

Rob

[robcollingridge]

GnuBee said:

ISIS, MoTeC PDM, OBM or something else?

None of these. The bike engine comes with it's own loom and in my Fury R1, I treated it like a black box. I did rather nervously cut out all the unwanted parts of loom though, to reduce the weight of the loom. Amazingly, it still worked! :-) Didn't use any bike instruments.

The rest of the electrics are really very basic stuff and there simply isn't enough sensors and devices to warrant anything other than simple switches and wires. Even with this stuff though, I've done some clever things to reduce the amount of wiring and the current ratings required. Because the battery is now in the engine bay (mid-engined), it's a long way to the front lights, horn, etc. which use the most current. I'm planning a shared power line, with remote relays and very thin control wires, again to save weight.

All the dash switches are low current (weigh 4g each) and work really well in my Fury too.


I used the ETB DigiDash 2 in my Fury:


I'm planning to use a bespoke 7" OLED dash display and custom hardware and software to drive a 720p/1080p dash with custom graphics:


It will also do all the data logging, GPS, etc. Basically the guts of a 7" tablet running a real-time OS.

I'm seriously considering have an Ethernet network running from front to back too, primarily for telemetry, multiple IP video cameras for video/audio recording. This will connect to the Internet via a Smartphone, using Wi-Fi tethering. This stuff is all very cheap and very light now.

[robcollingridge]

I can save over 3Kg, just by using a Lithium Iron Phosphate battery :-)
http://www.robcollingridge.com/400kg/design/electr...

[robcollingridge]

I guess they don't last as long and you don't want to keep things connected such as alarms and clocks. Don't have or plan such things though. My normal lead-acid battery only lasts 5 years and as such is a consumable item. And that's with an Optimate III connected regularly.

[robcollingridge]

My current battery is less than 4Kg. With a Lithium battery, I can get below 1Kg. It costs about £90, twice as much as my lead-acid battery. If ever Kg lost was as cheap, I'd be a very happy man!

[robcollingridge]

GC8 said:

Only £90? The last time that I looked (admittedly a while ago) they cost the best part of £1,000!

Where from, if you dont mind me asking?

Link on my website:
http://www.robcollingridge.com/400kg/design/electr...

Rob

[robcollingridge]

Sorry, I should have been clearer, I'm using a motorbike engine and motorbike battery. I didn't look for replacement car batteries on that website. Yamaha R1 recommended equivalent is £93 and 851g :-)

[robcollingridge]

ajprice said:

That had a bike engine, the sort of similar Brooke Double R is 550kg with a Cosworth 2.3. What's the weight difference between a bike engine and a Cosworth 2.3?

Lots! My 2003 Yamaha R1 engine was 60.5Kg dry. And that includes the clutch and gearbox, alternator/starter, fuel injection rail, air box, air filter, water/oil pump, etc.

I'm guessing that this engine is over 120Kg alone as a K-Series 1.8l is 96Kg on its own. Then you have to add gearbox and all the other bits :-(

Rob

[robcollingridge]

Found some nice aluminium LED number plate lights today.

Should save a bit more weight ;-)

[robcollingridge]

LOL! Since I posted that part, I've decided to just mount the LED in the bodywork. Seriously ;-)

[robcollingridge]

GC8 said:

Using all LED bulbs you can lighten the wiring loom significantly.

That is the plan but I'm going further than that:
http://www.robcollingridge.com/400kg/design/electr...

Thoughts on lighting so far are here:
http://www.robcollingridge.com/400kg/design/lighti...

Rob

[robcollingridge]

Looks like McLaren have something similar in mind. Not sure what their target weight is though.



Article here: http://www.autocar.co.uk/car-news/design/mclaren-e...

Rob