Saturday 11 February 2012

4.5 Litre 'Birkin' Bentley

Tim Birkin was one of the racing drivers known as the "Bentley Boys" in the 1920s.  Birkin added an Amhurst Villiers supercharger to a 4.5 litre Bentley fitted with a slim body, an offset single seat and a large streamlined radiator cowling.


This car captured the outright lap record at Brooklands at the 1930 Easter meeting when it lapped at 135.33 mph. The car used a gallon of fuel every 59 seconds and it developed 240 bhp.


So this is my choice as the racing partner for the Stutz Blackhawk, against which it historically competed at Le Mans.  Like the Stutz, this is a kit from Penelope Pitlane and comes with the resin body, metal chassis and small parts, motor, and running gear.


With the body cleaned up and the chassis put together, it looks like this:


When it raced at Brooklands, the car was painted red but I found out that it was originally painted French Blue - not a colour usually associated with British racing cars - so I thought I'd paint it that colour instead.  First the undercoat in grey:


And then the French Blue, using Humbrol's gloss spray acrylic paint:


I then painted up the chassis parts, fitted the fuel caps, exhaust, supercharger and windscreen, and put it all together.


Tim Birkin apparently wore a blue scarf with white spots when racing:


And here's a view of the supercharger which made this the "Blower Bentley".  W.O. Bentley was hostile to forced induction and believed that "to supercharge a Bentley engine was to pervert its design and corrupt its performance."  He refused to allow the engine to be modified to incorporate the compressor, which was therefore placed at the end of the crankshaft, in front of the radiator - which didn't help the understeer!


So now I have two Penelope Pitlane models ready to be raced:


Sunday 5 February 2012

Pull over and put your hands where I can see them

A while back, I blogged about a police car I'd bought to chase the General Lee around the track.



A great car but it niggled me that the red light on top was just for how.  So I re-wired it!  Maplin sell a flashing LED for a quid which operates up to 14V.  My layout runs at 16V so a bit of O Level physics with Ohm's Law suggested if I stuck a 200 ohm resistor in series with the LED, it should drop the voltage enough to avoid it blowing.  It works - kind of.  It flashes away when I test it but on the track itself it's pretty much constantly on.  But I guess that's better than nothing.


In the photo, the car is sat on my latest contraption - a little test bed made from a cut up piece of track with a 9V battery box soldered to the rails.  A nice quick way of testing a car and portable enough that I can stick it in my back pocket next time I go to a Swapmeet to test second-hand cars before buying them.

I also bought another police car cheap on eBay last week - a twenty-five year old Rover SD1.  Someone had already replaced the tyres on it, so I just oiled and greased it, and cleaned up the paint work to get it back in good condition.  It's lost its wing mirrors but still has its bumpers and the transfers are perfect.  It has a working flashing light but the siren doesn't work any more.  I've wondered about trying to fix that but suspect it get a bit annoying after just a few laps!