1931 Bentley 4 Litre


  • Year of manufacture 
  • Car type 
  • Lot number 
  • Drive 
  • Condition 
  • Location
  • Exterior colour 


There were a total of just 50 of the immortal Blower Bentleys to be manufactured, split across two specific series. The first batch of 25 cars carried an SM chassis number suffix and were more readily identified by a smooth finish blower casing.

Chassis SM 3925 was the last of this first batch and was originally one of just two cars to wear a Freestone and Webb panelled four-door saloon body, as pictured in Fifty Years of the Marque (Johnnie Green, p. 105 - 3rd Edition)

A reference to Hay's various works, including the GT Foulis Autofolio book on the 4.5 litre Supercharged Bentley's confirms that these cars led a very colourful life in their early years. With so much power and relative lack of stopping authority on the first examples it seems that a handful of cars caught out their pilots on the unforgiving roads of the 1930's. In fact, it lists two chassis within this batch as believed to have been broken up and a further one which has been scrapped. Of the remaining 22 cars, one was written off and later rebuilt without a supercharged engine, and three were crashed within the first three years of their life and were returned to the factory to be rebuilt, incorporating a "reconditioned chassis frame" from stock. SM 3925 was one of these three cars.

On 24th June 1935 the car suffered an accident that required the frame to be changed by the Bentley factory, as documented in the original Factory Service Records. This would almost certainly have been an original heavy gauge, chassis as also fitted to the 4.5 litres from late 1929, but modified to the blower spec by changing the front dumb irons and the cross member - these being the only two items that carried the original chassis number for that particular frame. It is this precise specification, which exactly matches the chassis fitted to the car today. The front axle and some steering components were also changed at this time, with the originals going in to the recycling division for repair and reuse in another car in the future. The original D-Type gearbox was also changed for a Bentley Factory supplied replacement unit - D- 7015 - also recorded in the Factory Service Record in November 1938. At some point, the car's original engine was used for a 3 litre conversion to 4.5 litres - another common practice at the time, ending up in 3 litre chassis HT 1633 for many years, owned by highly respected BDC members Gordon MacDonald then Kay McCosh.

The reconditioned front axle and steering box from SM 3925 were later used in a 4.5 litre - Chassis HT 3196, which was modified with two seater body and raced by Kemp Place throughout late 1940's & 50's These components stayed with the car all the way through until the late 1980's.

In 1984, under the stewardship of its then privateer owner, the decision was made to track down all the surviving components from SM 3925 and commence on a 6-year project to reunite everything and rebuild the car to its former glory.

The starting point was exactly as in 1935, with an original and genuine reconditioned frame, modified in precisely the same way with the front dumb irons and cross member conversion to blower specification. The ex-Kemp Place 4.5 litre competition two seater - HT 3196 - was acquired and gave up SM 3925's original front axle and steering box - both having survived remarkably well decades of competition use without damage. At the same time, the original engine was acquired, fully rebuilt and installed.

The attention to detail was so intense that an original D-type gearbox was sourced that was just 11 numbers out from the 1938 replacement. The rear axle was sourced using the common practice of using an original and genuine Speed 6 unit - the differential unit was originally fitted to Speed 6 chassis number NH 2728 - and the rear axle banjo is from a 6.5 litre saloon - chassis number FW 2602 - which had been subject to a rear axle change at the factory in November 1934, suggesting this axle had been already been recycled, reprocessed and subsequently used in another car in the interim time.

And so to the Supercharger Unit. Clearly the ‘Blower' in a Blower Bentley was to be the most difficult item to try to locate - probably almost impossible, in truth, to find one of the first smooth cased units that were specific to these first cars - and even more so when you see how many cars lost their blowers early in their life when referring to Hay's fantastically detailed records in various publications.

Amazingly, after a worldwide search, blower unit number 121 was located in the USA, acquired - with great difficulty - and fitted. This, in itself, has a great history, having been originally fitted to the original Olympia show car, itself an original Vanden Plas bodied tourer that still exists today and is considered to be one of the most original and important of all the blowers to survive.

With all major components sourced, present and correct, the restoration and rebuild could now be completed to bring the car as close as possible to its pre-war specification.

Given the immortalisation of the Team Car bodies, the decision was made to rebody in the style of a VDP Le Mans Tourer and also to fit an overdrive unit for long distance relaxed touring. Sometime later, the project was finally completed and ready for the road again. The all-important FIVA card was issued for SM 3925 on 6th June 1990, with older style FIA papers dated 14th May 1994 also on file. A new FIVA card was granted in 2012, an essential document to support an application to take part in such blue ribband events as the gruelling Mille Miglia which we've no doubt this Blower could tackle with ease...

This car became a centre piece of the ‘Stradale' collection in 2009 and took part in the 80th anniversary Blower rally in 2010 covering a trouble free 3,000kms and taking in the Le Mans classic on the way home!

Now ready for the next adventure, where's your first stop?....