I was naturally very interested to read the Connaught articles, especially the one in your January issue concerning the B Types.
I purchased B5 just after the disposal sale at the works from Brian Naylor, and proceeded to race it during the 1958 and 1959 seasons. I had to smile when I read about the 240 bhp obtained on the test bed, as I always considered the figures a joke. B5 was heralded at the sale as developing 224 bhp at recent tests on alcohol fuel; but as we had to use Avgas for the 1958 Formula One season, I removed the engine from the car straight away and fitted it on to my test bed. I well remember that it produced 199 bhp on alcohol, and after some adjustments it peaked at around 215 bhp at 6,200 rpm.
I then converted the engine to run on petrol, fitting somewhat lower compression pistons and experimenting with different camshafts and timings. After many many hours of bench testing, the maximum output I obtained was 210 bhp at 6,300 rpm. My two engines both gave the same output, which I considered very modest, but it was impossible to get any more from the existing design. I was in the test house at Send one day, and I noticed that the rev counter used on the bed was the Smiths Chronometric direct drive instrument as used in the car with a 90-degree drive box. The chronometric tacho with a direct drive cable is supremely accurate, but not so when used with right-angle drive and inaccuracies in the gears.
I removed the set-up from B5 and cross-checked it against my electric-master rev counter on the test bed. At 6,000 rpm the Smiths instrument showed up 250 bhp which would account for a near 20 bhp optimistic reading. I operated just ten miles from Heenan and Froude’s Worcester works, so it was no trouble to have my bed tested. I even had a correction factor for the rev-counter. As a result, my test house figures were very conservative.
These comments may be of some interest to your readers, and In some ways explain why a delightfully designed and built car did not do better, and cried out for a more advanced engine.
GEOFFREY RICHARDSON Hartlebury, Kidderminster