Low drag stock retros (50's to 90-ish)

[HoTWire]

I've been giving some thought to building an Electric hillclimb/sprint/drag car. Idle thoughts at the moment, but you never know how things will pan out (I have a few contacts that build electric vehicles and a desire to go hillclimbing). Obviously being who I am I want to build something out of an old car

My initial thought was to get either a Hillman Imp, or an MG Midget (because you can fibre glass most of it). It got me thinking though, what older cars have good drag coefficient, particularly ones that could be light too

No pictures of anything yet as I'm looking for ideas, but have a picture of the car that inspired my Midget thoughts

[MonzaPhil]

Spitfire might fit the bill too.

Erm.


Thinking.

[ettorebugatti]

For an hillclimb car I would optimize power to weight ratio over aerodynamics.

[spandelly]

Before someone else says it porsche 924

[markbognor]

[scmick]

MATRA-SIMCA Bagheera had quite low drag. Loads of scope for losing weight from the metal structure under the fibreglass.... If that's not already dissolved through rust.

[austinpowers]

Reliant robin. Low weight and less roiling resistance as you have less wheels. Ok the handling maybe a bit curse word in the bends but just think of it as a challenge.

[Midas]

GTM Rossa K3?

Light, mid-engined, slippery and unregistered projects go for around £300







I don't think you are a million miles away from me, more than welcome to have a look at mine if you want.

[freddieh]

If I remember correctly, the Citroën BX has quite attractive drag numbers, and could be very light with a stripped interior etc.

[mikeymk]

The secret to aerodynamics is not in pushing through the air, but in leaving it behind - it is the rear of the vehicle where the science happens. Originally the attempts were made to replecate an aeroplane wing and bring the air to meet, but diffusing the rear of the car so the airflow manages itself proved more successful and i believe a Triumph Dolomite is more aerodynamic than a Jaguar XK120.

Looking at modern cars, and how the diffusion styling is executed will show this. Typically some sort of spoiler or at least ridge at the end of the roof line, now also common behind the rear wheel arch and occasionally built into the tail light or similar to break the flow from swirling around the rear of the car.

Air will sit behind an aerodynamic car and hardly move. Even at 100mph a leaf can hover about behind it for a few seconds because the air behind the car is travelling at the same speed and duplicating a very long thin teardrop of air - an invisible bee-sting spike. This can be seen when a car is driving at speed on a dirty surface, and why the rear of a modern car gets so dirty over use on such roads. The print left from static air can be seen on this Audi..



On this Civic below, the diffusement area is the recessed section of glass between the tail lamps and the plate recess, the lamp and spoiler surfaces being the cut-off. I use this example specifically because Honda didn't quite get this right first time, and had to add little vertical cut-off spoilers just below the tail lamps to stop the air from the side of the car swirling round the rear excessively and damaging the trail flow..



Ford had to do exactly the same thing with the Sierra - the later MK1 got a diffuser down the rear quarter window to stop excessive swirl killing the teardrop and creating a vacuum behind the car..

Without..


With..


If you're looking for an aerodynamic retro, you want a slash-cut rear end. Back in the simple days, that was by far the most effective factor. Like a Spitfire MK4 instead of a MK3, and what Triumph were doing generally in the '70s.. The Lancia Fulvia is also a good example. And look at the rear window recess of a MK1 Golf, and roof tail of most '70s hatches.

But i agree with Ettorebugatti - for a hillclimb car, weight is your biggest enemy. And if you're carrying lead-acid batteries then you'll want them where they'll assist handling and traction - i.e the rear footwell and under the front seats. And if you only need to do a couple of runs, you can keep them minimal (or spend thousands on litium-ion).

[waveman1500]

Frontal area is just as important as aerodynamic drag coefficient, because you're really looking for the lowest total drag. Therefore, something as small and low as possible is good.

If you're allowed to run without the windscreen, then that will help. Herald /Midget with aero screen and tonneau?

Fisher Fury would be good, if it's retro enough for you?
Can you find any old sports racing cars or kits? Ginetta? Mini Marcos?

[MiataMark]

What about a Porsche 356, 550 etc (replica bodies)

[jiminwatford]

Nov 5, 2015 7:22:09 GMT mikeymk said:

Interesting stuff...

Thanks for that

[HoTWire]

This thread has been wonderful so far...

Now dreaming of an electric Matra! ... but suspecting a speedster MG Midget is still the way forwards... maybe with some rear aero mods (thanks mikeymk )

[Frankenhealey]

Nov 4, 2015 21:03:27 GMT ettorebugatti said:

For an hillclimb car I would optimize power to weight ratio over aerodynamics.

What he said ^^^

So how about a lightweight composite car with aerodynamic tweaks by Gordon Murray not costing the earth. I give you

TAA DAA

The Midas



You know it makes sense because I'm always right (except when I'm wrong)

[Midas]

Nov 5, 2015 18:09:31 GMT Frankenhealey said:

Nov 4, 2015 21:03:27 GMT ettorebugatti said:

For an hillclimb car I would optimize power to weight ratio over aerodynamics.

What he said ^^^

So how about a lightweight composite car with aerodynamic tweaks by Gordon Murray not costing the earth. I give you

TAA DAA

The Midas



You know it makes sense because I'm always right (except when I'm wrong)

Oddly enough I've got one of those too, complete with the Murray designed undertrays. For handling, suitability for electric conversion I'd still 'climb the GTM.

[ettorebugatti]

Midas is a very good shout.

There's a Vindicator (seven kitcar) with an EV conversion that occassionally does some hillclimbs.

More modern, but 90s coupes like the Vauxhall Calibra and VW Corrado weren't bad in the aerodynamic department.

A Panhard can be added to the list as well, both light and slippery:

[ettorebugatti]

Or something from Zagato:

[ratchart]

If you're going electric (Judas! etc) that means you can block of the radiator grille which I imagine is a hindrance to airflow in a conventional engined car. 

[mtjm]

Nov 6, 2015 9:01:52 GMT ratchart said:

If you're going electric (Judas! etc) that means you can block of the radiator grille which I imagine is a hindrance to airflow in a conventional engined car. 

There's some good information on things like grille blocks and air dams for aero on the EcoModder site: ecomodder.com/. Might be worth having a look there. They spend a lot of time looking at reducing aero drag. It's mostly more modern cars but there are some 90s ones on there, primarily Honda Civics and Suzuki Swifts.