A question of bhp/litre


I was intrigued to read in last month's (November) Motor Sport a paragraph of a letter to you from S. Dear, Chairman, MMM Register, in which he stated that the 750-c.c. Q-type MG had the highest b.h.p. per litre output in the world pre-War.

He goes on to say that the K3 engine produced 202 b.h.p. at 7,500 r.p.m., which gives a power output of 185.8 b.h.p. per litre.

Therefore is he suggesting that the 750-c.c. Q-type produced around 190 b.h.p. per litre? My information on the Q-type engine shows that it produced 151.47 b.h.p. per litre at 7,200 r.p.m. (113 b.h.p. from 746-c.c.).

This compares with the 1935 twin-cam 744-c.c. Austin Seven engine, designed to run at 12,000 r.p.m., which produced 155.92 b.h.p. per litre at 8,500 r.p.m. on sprint fuel, though during the o.h.c. Q-type's period, 1934, Austin 750-cc. racers were, of course, using side-valve engines.

It is not mentioned in S. Dear's letter that amongst the records held to this day by Austin Sevens is the 750-c.c. Brooklands Mountain Lap record of 77.02 m.p.h. by Dodson (October 1936). Perhaps it is significant that the ban he mentions on official MG racing by the company occurred in 1936, the year after the introduction of the twin-cam Austin Seven,

B. H. PEGUM – Shrewsbury.