| Engine | Car | BHP @ RPM |
CR | Valve Timing |
Remarks |
|---|
| 85 | 400 | 75 @ 4200 | 7.4:1 |
10:50:50:10 |
A straight-six engine with OHV and a single AAPI dual-port carburettor.
Contemporary manual quotes CR later increased to 7.5:1. Very rare. |
| 85A | 400 | 80 @ 4200 | 7.5:1 | Used triple D2
type SU carburettors, interconnected & with auxiliary starting device; oil
cooler in cylinder block. |
| 85B | 400 | 85 @ 5000 | 7.4:1 | ? |
Contemporary manual refers to “sports model fitted with special
camshaft”, but no valve timing data. CR later raised to 7.5:1. Few made. |
| 85C | 400-402 | 85 @ 5000 | 7.5:1 | 10:50:50:10 |
Oil cooler in block was blanked off on later engines; triple Solex 32 B1
type carbs. Substantial production. |
| 100A | 403 | 100 @ 5000 | 7.5:1 |
15:65:65:15 |
Had large “stepped” oil sump, larger inlet valves, lightened
valve gear; crank pins were of larger dimensions. Rubber torsional damper.
Last few had CR raised to 8.5:1 |
| 100B | 404, 405DH, AC | 105 @ 5000 |
8.5:1 |
Single six-branch exhaust manifold; big-bore exhaust system; Girling
viscous damper |
| 100B2 | 405 | 36:72:72:36 |
Two 3-branch exhaust manifolds; twin pipe small-bore exhaust system |
| 100C | 404 | 125 @ 5500 | 9.0:1 |
40:80:80:40 |
Offered as alternative to 100B, but few chose it, hence very rare |
| 100D | ACE, ACECA | 128 @ 5750 | 9.0:1 |
The triple Solexes were fitted with accelerator pumps, and the Big Nose
crankshaft had a Holset viscous damper. A powerful yet reliable engine,
much sought after |
| BS1 | Cooper | 132 @ 5750 | 9.5:1 | ? |
Larger mains than road models; lighter valve gear |
| BS1A | ? | ? | 10:1 | ? |
As BS1 but cyl. head skimmed to increase CR |
| BS1 Mk2 | Arnolt | 130 @ 5500 | 9.0:1 | 40:80:80:40 |
8.5pt sump; full flow oil filter |
| BS1 Mk3 | ? | 142 @ 5750 | 9.5:1 |
? |
As BS1 except: Girling viscous crankshaft damper; carburettor butterflies
streamlined; redesigned small nose crank; twin rocker box breather pipes;
no oil filter; sports type oil sump |
| BS1A Mk3 | ? | 148 @ 5750 | 10:1 |
As BS1 Mk3 but without dynamo or starter |
| BS4 Mk1 |
? | 142 @ 5750 |
9.0:1 |
As BS1 Mk3 except: Girling or Hobson viscous crankshaft damper; anti-surge
baffles in sump; polished and blended ports |
| BS4 Mk2 |
As Mk1 except oil filter was fitted; gear-driven camshaft,
side-mounted magneto drive or distributor |
| BS4A Mk2 | 155 @ 6000 | 11:1 |
As BS4 Mk2 except new pistons give CR of 10.5:1 or 11:1; jockey pulley
as belt tensioner; no air cleaners, dynamo, starter or engine torque brackets;
distributor drive by bevel gears at front |
| BSX | 450 | 155 @ 6000
170 @ 7000 |
9.2:1
11:1? |
As BS4A Mk2 except: Twin-choke Solex carbs with accelerator pumps;
air straighteners; 1.56" diam. inlet valves; 12-port head; additional
water pump; special multi-pipe exhaust. More power from engine
as finally developed, with higher octane and higher CR. |
