Cosmo Sports/Mazda 110S and it's 10A engine
Introduction / Cosmo
L10A / Cosmo L10B / Specifications
brochure / Racing / 2002 Cosmo?
/ More information
The COSMO SPORTS, or for later export versions the MAZDA 110S was officially launched on 30 May 1967. The world's first two rotor production car, it beat even the NSU Ro80 to market by three and a half months (Note, Mazda paid NSU hefty licence fees for the use of the Wankel design. All Mazda rotor housings have "NSU licence" cast into them).
The start of the Cosmo project was in December 1962, with Mazda's first two rotor engine prototype in July 1963. The first prototype cars were produced by August 1963, and in October 1963 the head of Mazda, Tsuneji Matsuda drove the prototype known as 'Project L402A' to the Tokyo motor show. See picture below where they are returning from the motor show, judging by the smiles on their faces this car was a real hit!
This car used the prototype engine known as the L8A (or 0353), with 2x398cc and a combination of peripheral and side intake porting.
The L8A evolved to the L10A (or 0810-pictured below), with 2 x 491cc and size intake ports. The peripheral ports were dropped* and the engine size increased to give better operating characteristics (Better torque at a lower RPM). All production Mazda rotary engines since have used side intake ports.
The prototype engines and cars progressed and in April 1966* a pre-production run using of 80 Cosmos were made (L10A engine), 60 of which were sent out as evaluation models to Mazda dealers in Japan, accumulating over 600,000km in 6 months.
The design was finalised in late 1966 and production would have commenced
soon after for the 30 May 1967 launch date.
Cosmo type L10A and it's engine.
N.B. 1587x2200 version of German magazine file to be fixed
The L10A name was shared by both the car and the engine.
While the car was mostly conventional late 60s sports car, it boasted several 'high tech' items, such a de-dion rear suspension, front disc brakes and an 'aircraft inspired' dashboard. (With Tachometer, Speedometer, Oil Pressure gauge, Water Temperature gauge, Ammeter and Clock).
The L10A Cosmo was only sold in Japan.
The engine is the main point of technical interest.
Called the L10A (or 0810).
The rotor was made from cast iron and featured twin side seals and triple oil seals (today's 13B has a single side seal and twin oil seals). Apex seals were aluminium impregnated carbon - found to wear under 1.0mm in 100,000km driving. Before this "new" apex seal design the rotor housings had severe "chatter" marks, so Mazda was overjoyed to solve that problem. The eccentric shaft was made from expensive chrome-molybdenum steel.
Most of the other techniques used in the engine are standard practice today - oil spray to cool the rotors, oil cooler, gear type oil pump, oil metering pump to put a small amount of oil into the intake, axial flow water cooling etc. Ignition timing was Leading 2 degrees ATDC / Trailing 7 degrees ATDC
The engine weighed 102kg (225lb) and was 508mm long x 594mm wide x 544
Cosmo type L10B and it's engine.
As with the earlier model, the L10B name was shared by both the car and the engine.
This model was started production on 13 July 1968.
The newer version of the Cosmo was slightly updated, with a 5 speed gearbox,
power assisted brakes and optional air conditioning fitted behind
the seats on the rear parcel shelf, the wheel base was lengthened
by some 150mm (5.9 inches), which tended to make the car look more balanced.
The car was also given a much larger radiator grille (probably to improve
cooling). Larger 15 inch steel wheels were used. The overall weight
was up by 50kg to 990kg.
None were officially sold in Australia, however one was officially imported for evaluation and about 5 have been privately imported - see below for information about one on display in Melbourne.
Interestingly the exported cars were fitted with the earlier Cosmo's L10A 110hp
engine, 4 speed gearbox, 14 inch steel wheels, presumably avoid maintenance
With 130bhp (20 more than the earlier Cosmo), the L10B was even faster, it's 400m/quarter mile time of 15.8 seconds is comparable to sporty cars such as the 2001 BMW 330i at 15.9 seconds.
Notes about the above table:
There are several "used car" magazines in Japan that occasionally have a Cosmo Sport advertised for sale. IF you can find one they cost around $US20,000 - $30,000 depending on condition. Other than that, I have NO IDEA where you would look for one!!
The 'De-Dion' axle arrangement can be thought of as being halfway between a conventional live axle and fully independent suspension - the differential is mounted to the car's frame, with allows less unsprung weight for better handling. The two wheels are solidly locked together by the de-dion axle. The two wheels are therefore not independent.
Regarding the L10A's slower top speed claim, 200 km/h (124mph) was the measured top speed, however Mazda de-rated this to "guarantee" 185 km/h (110mph), as well as be safer on the specified tyres.
Cosmo Sales Brochure
They are original copies of sales literature for the Cosmo
Sport. The postcard is of the earlier L10A model, and the Brochure
is of the L10B model.
Mazda sent several L10A Cosmos to Nurburgring in Germany to prove the reliability of the cars and particularly the engine. I am looking for more details about this.
Mazda Cosmo 21
At the (January) 2002 Tokyo Auto Salon there was a "new" Cosmo! Styled to
look like the original Cosmo on this page, it is in fact an MX5(Miata) with a body kit
plus an RX8 engine - I understand that it was built by "Mazda Sangyo"
which seems to be a subsiduary company that does engineering work, ambulance
Rumour has it that the Cosmo 21 is going on sale in Japan (hmmm.. it looks too over the top to be anything but a show
car, but there have been a lot stranger Japanese cars than this in the past),
great news if it does as there might be hope for a rotary MX5. At the show there
was also a new Coupe version of the MX5 with a non-removable roof - a rotary MX5
coupe would be close to the original RX7 in concept.
The specs in Japanese alse eluded to ABS and the like. I can't read Japanese,
there were other items but they are probably of little consequence.
For those wanting to see a Cosmo, I have confirmed (March 2001) that there is one on display at:
Further reading and acknowledgements:
Other relevant reading at Craig's Rotary Page (Please go via the INDEX
Other relevant sites on the Internet (Please go via the LINKS
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This page last updated 17/3/2002
17/3/2002 - Added Cosmo 21
16/3/2001 - Major revision of text; re-wrote some sections. Added information about Max Kirwan Cosmo. Converted all text to new standard (Headings as Heading1, Some sub-headings (e.g. tables) as 14 point normal bold italic, Most text as Normal, Internal page links at top not all uppercase)
11/3/2001 - Minor content update (Spelling mistakes, tidy up). Background image changed to PG00_02B.JPG
26/4/1999 - Previous known update (May have been some before this)
This site is online at tripod (The large images on many pages don't
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