K Series Midgets are giant-killer sports-cars, combining traditional appeal with performance way beyond the maker's intention. In fact, the faster KSeries Midgets approach Porsche 911 levels of performance – but with exceptional economy and ease-in-use.
Any Midget can be upgraded to KSeries power, easily attaining Lotus Elise / Honda S2000 acceleration figures, but without the associated costs and most importantly retaining the car's character – the reason we became Midget enthusiasts in the first place.
Unlike its contemporaries (the MGB Tourer and MGB GT), the MG Midget increased its performance over nearly 20 years of production through 4 engine upgrades: 948cc and 46 bhp, through 1098 (55/59 bhp), 1275 (65 bhp) and finally to 1498 with 65 bhp. In this manner, the car's abilities remained acceptable for the period. From the outset, enthusiasts modified their engines to improve performance - mainly through cylinder head, camshaft and carburation changes – better to exploit the fine handling and road-holding of the standard car.
In the early 1960s, the Healeys, the MG factory and some enterprising companies sought significant increases in performance through engine swaps, e.g. by installation of MGB power units (in the case of a factory racer) or by using a Coventry Climax FWE OHC alternative (Healey and Brabham); this advanced engine surely was the 'KSeries' of its time, being lightweight with OHC.
The factory couldn't stop the 3rd party conversions – but would not sanction the Healey's Climax-engined car for sale, possibly because its performance exceeded that of all of its other sports cars in the MG and Austin-Healey range. Apart from a small number of Atlantis (Ford 1600) conversions, engine swaps were rare; most enthusiasts needing more performance chose conventional A-series upgrades.
Fast forward to the early 1990s: Rover has developed and is using an advanced, lightweight, twin-OHC, fuel-injected engine in its saloon cars - ideal for MG's agile and lightweight classic sports-car. By the end of the 1990s, two companies were providing converted cars and parts for home conversions: the KSeries Midget was born.
Any model of MG Midget can be used as the basis for a conversion. Some notes:
All KSeries engines have the same major dimensions and weight, but it's suggested that the 1100cc version should be ignored (bhp for effort is not attractive). This leaves:
Notes:
In general terms, you can expect 5% more torque and 5-10% more peak power from your engine installed in a Midget based on free-flow exhaust and inlet configurations, and free of catalytic converter. With an after-market ECU, expect overall 10% more torque and 15-20% more power. For example:
Engine |
Standard Rover |
K-Midget with Rover ECU |
K-Midget with after-market ECU |
1400 MPi |
103 bhp |
110 bhp |
115 bhp |
1600 MPi |
110 bhp |
120 bhp |
125 bhp |
1800 MPi |
120 bhp |
130 bhp |
135 bhp |
1800 VVC |
145 bhp |
155 bhp |
160 bhp |
The following performance figures have been calculated using a simulator, based on converting a standard 1275 (with notional 62 bhp DIN and 740 Kg weight); the conversions all have 5-spd boxes. You would need a strengthened transmission, suitable tyres to provide traction, and plenty of practice to replicate the following standing-start times (but the in-gear figures should be easily attained):
PERFORMANCE ANALYSIS
Engine size |
1.4 |
1.6 |
1.8 |
1.8 |
1.8 |
BHP |
110 |
126 |
154 |
180 |
209 |
Acceleration: |
|
|
|
|
|
0-30 mph |
2.1 |
1.7 |
1.4 |
1.6 |
1.5 |
0-40 mph |
3.8 |
3.3 |
2.7 |
2.9 |
2 |
0-50 mph |
5.2 |
4.4 |
3.6 |
3.8 |
3.5 |
0-60 mph |
6.8 |
6.6 |
5.3 |
4.8 |
4.3 |
0-70 mph |
9.7 |
8.4 |
6.6 |
6.7 |
5.2 |
0-80 mph |
12.3 |
10.6 |
8.9 |
8.3 |
7.3 |
0-90 mph |
15.9 |
14.4 |
10.9 |
9.9 |
8.7 |
0-100 mph |
22.4 |
18.5 |
14.4 |
13.1 |
10.3 |
¼Mile |
15.5 |
14.8 |
13.7 |
13.6 |
12.9 |
@mph |
89.2 |
91.1 |
98.2 |
102 |
107.7 |
Top Speed |
116 |
122 |
128 |
141 |
148 |
30-50mph: |
|
|
|
|
|
2nd Gear |
2.7 |
2.1 |
1.6 |
1.9 |
1.7 |
3rd Gear |
4.0 |
2.9 |
2.2 |
2.9 |
2.7 |
4th Gear |
5.7 |
4.0 |
3.1 |
4.2 |
3.9 |
5th Gear |
7.9 |
5.5 |
4.2 |
5.8 |
5.3 |
50-70mph: |
|
|
|
|
|
2nd Gear |
- |
- |
- |
- |
1.8 |
3rd Gear |
4.5 |
3.4 |
2.5 |
2.9 |
2.7 |
4th Gear |
6.2 |
4.3 |
3.1 |
4.2 |
3.8 |
5th Gear |
8.2 |
5.4 |
4.0 |
5.6 |
5.1 |
As you might expect from a modern fuel-injected engine and 5 speed box, the fuel consumption is improved compared with the 'iron' engines: you should expect up to 40 mpg overall and up to 50 mpg touring – assuming your ECU is reasonably calibrated.
Anthony Cutler
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