by DaveT » Fri May 10, 2019 8:20 am
In terms of desirability, there were only a few hundred DS7 engines made by Austin, around 50 of which were used in the first batch of 541Rs (1 in the last interceptor). The production run of the DM7 / DS7 Austin princess was only around 200 cars. It has been suggested that the engine suffered from severe overheating and quite a few early 541Rs have subsequently been fitted with XK engines either to overcome this or to overcome poor spares availability.
The cylinder head design of the DS7 provides better engine breathing with no siamesed ports vs the DS5. The result of this being higher quoted BHp figures and higher top speed in the contemporary road tests, although road testing of the 541R with DS5 engine (circa 143 cars vs the circa 50 with DS7) seems to have been ignored by the press - it was a slightly backward step after all. Both engines are pushrod overhead valve with inlet and exhaust ports side by side on one side of the engine (I.e. not cross flow)
So reliability and spares availability vs power output - it is clear that a DS7 engine that has seen almost constant use throughout its life is unlikely to suddenly develop overheating problems due to the design of the engine, but a DS7 restoration project could uncover unresolvable engine issues...possibly explaining why the car was taken off the road in the first place.
Re power output, the race prepared 541R seen in recent years competing at goodwood etc has a highly developed DS5 engine, so it is possible to make up all the difference and some. A DS7 engine could be given the same treatment but with spares being short on the ground and the knowledge in race preparing early Austin Healeys being slightly less relevant, I am not sure this would be a good idea.
Other thoughts welcome.
Dave
Dave Turnage
Colchester
JOC 8674
JOC 541 Registrar
541S, 100/1061
541R, 6002/387 (now in lots of pieces!)
Alvis speed 25 DHC