engine option
Hi Hal,
You might like to consider the 3-litre Humber Super Snipe/Imperial engine as it has several historical connections with Bristol.
It was developed, maybe jointly, with Armstrong-Siddeley Motors as a development of their Sapphire 3.4 hemi-headed straight six.
Several racing versions of the 346 engine were built c. 1953, producing c. 190bhp with iron head & twin Zenith single-choke sidedraughts or c. 230bhp with alloy head & triple Webers.
Two engines went to Allard for Tommy Sopwith's "Sphinx Allard" and two were allocated to Frazer-Nash for 550F Le Mans Prototype. AC were also approached, but declined.
These engines were developed for the AS Hunter sports car project that might have been an XK-beater, but was shelved.
When Hawker-Siddeley & Bristol Aero bit merged to become Bristol-Siddeley at about same time that car division were looking to cease production of BMW derived engine in favour of more powerful off-the-shelf lump, they found themselves with an alternative engine in-house.
It is believed that Bristol took 4 Star Sapphire 4-litre engines + auto boxes for fitment in prototype 407s, of which one is known to survive. One engine was also fitted in "Project 240 mule", but proved far too heavy & messed up the handling. I'm pretty sure this car was the "Bullet" on which the Blenheim Speedster was based, as it is known to have been used to test various engines, as well as being light enough to have handling affected by big lump (& Star engine was extra heavy)
Its descendant Humber engine was much lighter, with shorter, lower block & thinner castings, but just as tuneable. There's a racing Sapphire 346 in Northern Ireland & no apparent problems with unleaded without hardened valve-seat inserts in iron head.
There are rusting Humber hulks all over the place, in danger of being weighed in for scrap...........................
Good luck,
Rob
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