12 replies to this topic

[ERault]

I would like to learn about the 8 cylinders 1500cc OM Grand Prix cars (Tipo 865 I believe ?). I thought I had an article somewhere (perhaps in MotorSport), but I can't find it. What I know is that two cars started in the 1927 European GP at Monza, driven by OM regular Minoia and Morandi. One then found its way to England through R.F. Oats who had strong ties with the factory. He raced the car himself at Brooklands, before handing it over for 1931 to swedish driver Henken Widengren (who confusingly also raced a 8C 1100 Maserati).

How many cars were built (two or more ?), did they survive ? Who designed them and how advanced were they ?

Thanks !

[David McKinney]

I'd like to know more, too

As far as designers are concerned, Corrado Orazi was head of engineering at the right time, and the six-cylinder 665 had been designed by Odoardo Fuscaldi (with engine developed from a design by Lucien Barractouché), but I don't know if any of these were responsible for the 865

I believe the model's first appearance was in the 1926 German Grand Prix, in which Minoia made fastest lap before retiring

I wasn't aware (or had forgotten) that the cars raced in England by Oats and Widengren were GP models

[fuzzi]

According to "Italian High Performance Cars" by Anthony Pritchard and Kenneth Davey (published by: George Allen and Unwin 1967):

"In 1926 OM produced a team of Grand Prix cars ... These were supercharged 8-cyclinder 1477cc (56x77mm) with twin overhead camshafts and roller bearings".

"One of the cars ran in the German GP at Avus but retired for unspecified reasons. After this the cars were entered in a number of races without actually appearing, but they eventually ran in the 1927 Italian GP at Monza, where, after the retirement of much of thefast opposition they finished second and fourth. These cars can hardly, however be regarded as successful, as their performance was hampered by a three-speed gearbox, excessive weight (1764lbs dry) and inadequate roadholding. ... One of these 8-cylinder cars was brought to England by the concessionaire Rawlence, where it was modified by the development engineer R.F. Oats. It ran quite well in Brooklnds handicaps, but failed to finish in any of the long-distance events for which it was entered."

"Rawlance imported over 350 OMs to England and Oats developed an Ohv version of the Tipo 665 of whch six were built to permit qualification in the 1929 TT."

Rawlence were associated with M.C.Morris who handled Maseratis in England and Widengren had his 1100cc car prepared by them.

Hope that helps.

[Roger Clark]

Motor Sport April 1964 contained a Competition History of the O.M., including:

Chassis development by the O.M. works was minimal; even the three Grand Prix cars had ordinary tourer frames, suitably shortened and lowered. These G.P. cars first appeared in 1927. They were " one-and-a-half-seaters," the engines of which were straight-eight twin-overhead-camshaft 1,477-c.c. 1 1/2 -litres, supercharged by Roots blower blowing through the carburetter. The big-end bearings were roller, the mains ran on ball bearings. Triple valve springs were used. The cylinder blocks were made in two fours (someone had been looking at a Bugatti!) and were completely fabricated from welded sheet-steel. The cylinderhead bolts passed right through the block and into the crankcase; this, it is reported, necessitated four days' hard labour if any work had to be done on the head. T h e camshafts were driven by gear train at the front of the engine, and gears at the rear of the block drove the Bosch magneto, which lived on top of the gearbox.

The car which came to England was first fitted with a normal Roots blower, then, later, it was modified to take four twin-choke R.A.G. carburetters. This was quite a successful modification but the peak performance came when Oats fitted a JamiesonVilliers blower in 1931.

The engine of the 8-cylinder car peaked at 6,500 r.p.m., useful power being developed at about 6,000 r.p.m. The final b.h.p. figure was 117. T h e car weighed 12 cwt., quite a percentage of which was attributable to the lead which Oats poured into the inverted U-section frame forward of the scuttle in a desperate but successful attempt to improve the road-holding.

A 3-speed gearbox was used, this being adequate for Brooklands (90 m.p.h. in 2nd gear) but which would have handicapped the car had it been developed for road racing.

The 1.5 litre straight-eight cars were but a brief excursion into Grand Prix design and it seems that O.M. sensibly valued simplicity and reliability rather than high speed produced by expensive complexity.

Edited by Roger Clark, 13 March 2011 - 22:17.

[Roger Clark]

I believe the model's first appearance was in the 1926 German Grand Prix, in which Minoia made fastest lap before retiring

The Motor Sport article I referred to above says that Minoia non-started as the track was wet and the car handled dangerously.

[David McKinney]

The car's participation is mentioned not only in Cyril Posthumus's book on the German GP, but also in a contemporary report in Der Motorwagen

[Vitesse2]

The car's participation is mentioned not only in Cyril Posthumus's book on the German GP, but also in a contemporary report in Der Motorwagen

... and also in Automobil Revue, which says he retired on lap 7 with unspecified mechanical problems.

[ERault]

... and also in Automobil Revue, which says he retired on lap 7 with unspecified mechanical problems.

Michael Müller in this thread http://forums.autosp...php/t26715.html had expressed some doubts Minoia's car at the german GP was the Tipo 865 grand prix car.

Thanks to Roger, I have now found the article in MS. The car is indeed given for 12 cwt (that is 610 kg for regular people if I trust my internet conversion tool...) and 117 bhp. According to Pomeroy, the minimal weight in the GP regulation was down to 600 kg (from 650 kg) for 1926, and rapidly raised to 700 kg for 1927. Pritchard's figure of 1764 lbs dry quoted by Fuzzi (800 kg) was probably closer to the truth. More alarmingly, by 1927 the Talbot had 160 bhp at 7000 rpm, and the Delage probably more than 170 bhp. One wonders if the bhp quoted for the OM could have been without the blower ?

The article also states the ex-Oats / Widengren car then went to Jersey for sand racing and "it is believed that the engine of it may still exist". That would be make a nice found !

[fuzzi]

Ah that business of the Channel Isles rang a bell. I have a note from the Autocar in 'The Sport' 4 November 1938:

"Frank Le Gallais has just been supplied with a 1½-litre GP roller-bearing OM engine for racing in Jersey. The engine was supplied by Grimsdell of the Spares Bureau which had the old team engine for sale."

[Michael Müller]

Michael Müller in this thread http://forums.autosp...php/t26715.html had expressed some doubts Minoia's car at the german GP was the Tipo 865 grand prix car.

My doubts came from reports covering the Italian GP at Monza 2 months later saying that the OMs had been not ready yet. On the other side the German press talked about a "8 cylinder supercharged engine", so it MUST have been the tipo 865. Strange that obviously OM had withdrawn the cars for more than 1 year after AVUS 1926, possibly for improvement.

Comparing the OM with the Talbot 700 and the Delage 15S8 is comparing apples with pears. The Delage engine was a technical miracle, with expenses bringing the company near to bankruptcy. And also the T700 was not far from that, remember that these cars had been capable to win voiturette races still in the 30's. The yardstick for the OM 865 should be the Bugatti T39 which had similar power putput. But if the OM really had a standard road chassis not much could be earned.

[ERault]

Ah that business of the Channel Isles rang a bell. I have a note from the Autocar in 'The Sport' 4 November 1938:

"Frank Le Gallais has just been supplied with a 1½-litre GP roller-bearing OM engine for racing in Jersey. The engine was supplied by Grimsdell of the Spares Bureau which had the old team engine for sale."

MotorSport for june 1937 has an interesting story : Arthur Baron (better known for racing Bugattis) has been asked by a customer to build a special for racing in South Africa. The car will use the OM chassis, the straight eight supercharged engine being replaced with a less exotic Ford V8.

I don't know if this project was ever completed (no trace of an OM Special in Ken Stewart's "Sun on the Grid" index), but it could explain the availability of the OM engine as posted above bu Fuzzi.

[David McKinney]

...no trace of an OM Special in Ken Stewart's "Sun on the Grid" index...

It was more than likely entered as a Ford V8 special...

[Steve L]

Could anyone point me in the direction of photos of the OM Grand Prix racing car which ran at Brooklands please?

I seem to remember seeing a picture of it running with a front radiator cowl but cannot locate this!