Makes › MG › J4 · Factory competition · 1933 Ultra Rare
MG
J4
Pure racing version of the J-type Midget
Still being researched: full specifications. Everything shown is checked against the cited sources. Know more? Send us a source.
Photo: Alexander Migl · CC BY-SA 4.0
Contents
01Overview
At a glance
- Built
- 9 Built
- Years
- 1933
- Engine
- Four-cylinder with front-mounted supercharger · 746 cc / 0.7 LFactory: 746 cc
- Power
- 52.2 kW / 71 PSFactory: 70 hp · converted
- Top speed
- Not yet verified
- Body
- Not yet verified
- Designer
- Not yet verified
- In this archive
- Not yet verified
- Surviving
- Not yet verified
Sources and any conflicting figures are in the sections below.
Why it matters
The J4 was the out-and-out racing member of MG's J-type Midget family, combining a supercharged 746 cc engine with a doorless body. Only nine were built in 1933.
How rare is it?
Six separate kinds of rarity – never combined into one number.
Each kind of rarity is rated separately and never combined.
Photos
Exterior, interior and detail photos with their licences.
MG J4 (Wikimedia Commons search)
Photo: Alexander Migl · CC BY-SA 4.0
MG J4 (Wikimedia Commons search)
Photo: Alexander Migl · CC BY-SA 4.0
MG J4 (Wikimedia Commons search)
Photo: Alexander Migl · CC BY-SA 4.0
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02Production & history
Production
Every figure says what it counts.
| What is counted | Figure | Basis | Status |
|---|---|---|---|
| Total model productionJ4 racing cars produced | 91 | Factory production | Independently researched |
Independent counts (e.g. engine and colour) are never combined into a calculated figure. Surviving examples are never presented as original production.
History
Built between March and July 1933, the J4 took the C-type's engine and ENV gearbox, added a fully counterbalanced crankshaft and a front-mounted supercharger, and put it in a doorless version of the J2 body. Output was around 70 bhp depending on tune. An unsupercharged derivative, the J5, was planned but never built.
Variants
How each version differs from the standard J4.
No variants documented yet. Have a source? Contribute it.
03Specifications
Technical specifications
Engine
| Engine family | Not yet verified |
|---|---|
| Engine code | Not yet verified |
| Layout | Four-cylinder with front-mounted supercharger2 Registry reported |
| Displacement | 746 cc / 0.7 LFactory: 746 cc2 Registry reported |
| Bore | 57 mmFactory: 57 mm2 Registry reported |
| Stroke | 73 mmFactory: 73 mm2 Registry reported |
| Compression ratio | Not yet verified |
| Fuel system | Not yet verified |
| Power | 52.2 kW / 71 PSFactory: 70 hp · converted2 Registry reportedApproximate, depending on tune (registry gives bhp). |
| Power at | Not yet verified |
| Torque | Not yet verified |
Transmission & drivetrain
| Gearbox | ENV gearbox (as C-type)2 Registry reported |
|---|---|
| Gears | Not yet verified |
| Driven wheels | Not yet verified |
Chassis, body & dimensions
| Chassis | Not yet verified |
|---|---|
| Front suspension | Not yet verified |
| Rear suspension | Not yet verified |
| Brakes | Not yet verified |
| Steering | Not yet verified |
| Body construction | Not yet verified |
| Wheelbase | Not yet verified |
| Length | Not yet verified |
| Width | Not yet verified |
| Height | Not yet verified |
| Front track | Not yet verified |
| Rear track | Not yet verified |
| Kerb weight | Not yet verified |
| Dry weight | Not yet verified |
Performance
| Maximum speed | Not yet verified |
|---|---|
| 0–100 km/h | Not yet verified |
| Fuel tank | Not yet verified |
“Not yet verified” means no source has been checked for that value yet. Nothing is estimated to fill a gap.
04Colours & options
Factory colours & interiors
Original paint and trim, with the number of cars in each where a source gives it.
Not yet documented. Have a source? Contribute it.
Factory options & codes
Codes are shown exactly as written by the manufacturer.
Not yet documented. Have a source? Contribute it.
05Individual cars
Chassis register
Every documented car, with its colours, history and where it is now. Open a row for the full record. Known chassis are not automatically authenticated originals.
Not yet documented. Have a source? Contribute it.
Competition history
Every race result of the individual cars, in date order. Click a chassis number to open its full record in the register.
Not yet documented. Have a source? Contribute it.
Auction & sale history
Documented public sales of the individual cars. Click a chassis number to open its full record in the register.
Not yet documented. Have a source? Contribute it.
See one in person
Museums where an example of this car can be seen.
No example is documented on public display yet. Have a source? Contribute it.
06Reference
Identification guide
How to tell an original from a replica or later conversion.
A J4 differs from the J3 by its doorless J2-type body, front-mounted supercharger and fully counterbalanced crankshaft. It uses the ENV gearbox rather than the Wolseley four-speed of the touring J-types, a 7 ft 2 in wheelbase and 12-inch cable-operated drum brakes.
Sources
Each number links to the exact facts it supports.
-
1
MG Car Club Triple-M Register – J-type profile Level A
- 9 J4 racing cars produced
-
2
J-Type profile Level A Triple-M Register
- a front mounted supercharger
- capacity 746 cc
- Bore 57 mm, stroke 73 mm
- approx 70bhp, depending on tune
- same engine and ENV gearbox of the C type
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