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Saab B engine

From Alfawiki
Saab B engine
Company typeEngine
IndustryAutomotive
PredecessorTriumph slant-four engine
Founded1972
FateProduction wound down in 1981
Headquarters
Södertälje
,
Sweden
ProductsInline four-cylinder petrol engines (2.0 liters)

Template:Infobox engine

The Saab B engine is a four-cylinder inline petrol powerplant created by Saab Automobile. It represents a reengineered version of the earlier Triumph slant-four engine, featuring a displacement of 2.0 liters and making its debut in 1972. This engine was installed in the Saab 99 and later the Saab 900 models. Production of the B engine began to wind down in 1981.

History

During the early 1960s, engineers Rolf Mellde, Per Gillbrand, and Karl Rosenqvist initiated development of a new 1.2 liter inline-four engine intended for the forthcoming Saab 99.[1] The UK-based engineering firm Ricardo was engaged in this effort and was aware that Triumph Motor Company was simultaneously developing a comparable engine. Saab concluded that creating an entirely new engine would be prohibitively costly and risky, leading Ricardo to facilitate contact between Saab and Triumph.[2]

Triumph consented to supply Saab with 50,000 engines for the new model.[1] Initially, the displacement stood at 1.71 liters before being increased to 1.85 liters later on. For several years, Saab maintained exclusive rights to use the slant-four engine.[3] Saab engineered a unique transaxle design that incorporated the transaxle casing as an oil sump. The original Triumph power unit was rotated by 180°, positioning the clutch and flywheel at the front.[4]: 47, 48  This arrangement caused the front-mounted water pump to face the firewall or bulkhead, rendering it inaccessible and necessitating its relocation atop the cylinder block.

In 1972, Saab transferred production of this engine to their own Scania division located in Södertälje. A letter to the editor—though unverified—cites a Saab press release from July 1970 indicating that this move had been planned from early on.[5] Subsequently, Saab undertook a comprehensive redesign resulting in the B engine with an increased displacement of 2.0 liters; notably, its bore diameter was reduced by approximately 0.3 mm (0.012 in) compared to the Triumph’s equivalent 2.0 liter unit.

A further redesign occurred in 1981 when Saab introduced the Saab H engine.

Technical characteristics

Although the B engine retained elements such as bore spacing and bearings from the original Triumph design, it represented a major reengineering effort. Similar to the Triumph slant-four engine it was based on, the B engine features a cast iron block with cylinders inclined at 45° from vertical. The earlier engine's 78 mm (3.07 in) stroke remained unchanged, while the bore diameter was expanded to 90 mm (3.54 in). Additional modifications compared to the Triumph slant-four included a redesigned cylinder head with larger valves, expanded intake ports, a reshaped combustion chamber, and an improved camshaft assembly optimized for enhanced lubrication.[6] Saab 99 intake configurations had incorporated fuel injection as early as the 1970 model year, a trend that continued with the B engine alongside both single- and dual-carburettor options.[7]

The initial B engines featured a lowered compression ratio of 8.7:1, down from 9.0:1 in the Triumph unit, yet power output reportedly increased.[6] The distinctive water pump setup was preserved, consisting of a cast opening in the block housing the pump shaft, bearing, seals, and impeller, all pressed into place; however, seal design improvements were implemented. The pump is driven via a jackshaft and helical gear. Subsequent B engines employed a fine-tooth gear that is prone to damage, representing a vulnerable component within an otherwise dependable engine.Template:Fix/category[citation needed] Notably, the early B engine was among only two engines (alongside Honda's CVCC) capable of meeting California's strict 1975 emissions standards without utilizing a catalytic converter.

16-valve

During the mid-1970s, Swedish engineer Gunnar Axelsson created a DOHC cylinder head featuring 16 valves for the B engine block.[8] This configuration was estimated to deliver approximately 220 hp (164.1 kW).[8] The engine saw limited application in Saab's rally vehicles.

Turbo

File:Saab99turbo-engine.jpg
B engine installed in a 1980 Saab 99 Turbo

Saab launched a turbocharged variant of the B engine in the 99 Turbo model in 1978. Per Gillbrand played a pivotal role in developing this turbocharged powerplant and earned nicknames such as Turbo-pelle (Turbo-Pete) in Swedish and Mr. Turbo in English due to his expertise with forced induction.[9][10] The development team also included Mellde, along with Bengt Gadfelt—who brought experience from turbocharging Saab-Scania trucks at Scania—and Geoffrey Kershaw from England, an apprentice at Rolls-Royce who later founded Turbo-Technics Ltd.[1]

Saab prioritized enhancing torque output over peak horsepower.[1] The turbocharged B engine distinguished itself from earlier turbo setups by employing a compact, low-inertia impeller capable of rapid spool-up and introducing an innovative wastegate to regulate boost pressure.[11][12] A unique feature of this early Turbo model was Saab’s use of exhaust manifold pressure to control the wastegate, enabling boost pressure to taper gradually at high RPMs. This provided a wide and practical torque band.[13]: 469, 470  Compared to its naturally aspirated counterpart, power increased by 23%, while torque rose by 45%.[11]

Modifications specific to the turbocharged B engine included lowering the compression ratio to 7.5:1 using specially designed pistons, incorporating sodium-filled exhaust valves, revising the camshaft profile, installing an oil cooler, and fitting a Garrett AiResearch T3 turbocharger equipped with oil-cooled bearings alongside the externally controlled wastegate.

This turbocharged version of the B engine powered both the Saab 99 and early Saab 900 models.

Dual-fuel

The Saab 99 GL was offered in an alternative-fuel variant known as the Petro, developed through the collaboration of Saab-Valmet and manufactured at Valmet's facility in Uusikaupunki. This particular model featured two separate fuel tanks—one designated for gasoline and the other for either kerosene (referred to as "petroli" in Finland) or turpentine, the latter being derived from byproducts of Finnish paper mills. Notably, Finland was the exclusive market for this vehicle.[14] The engine initially started on gasoline before automatically switching to the secondary fuel, although drivers could manually override this to use gasoline exclusively. This version utilized low-compression pistons borrowed from the Turbo model alongside electronic ignition technology. Introduced in 1980, the Petro’s engine delivered 85 hp (63.4 kW) at 5600 rpm when running on 67 octane kerosene. Production totaled 3,756 units of the Saab 99 GL Petro.[15]

B engine variants

Compression ratio Induction Power output Torque Years
8.7:1, 9.2:1, 9.5:1 Zenith-Stromberg 175 CD single carburettor 95–100 hp (70.8–74.6 kW)
@ 5200 rpm 		157–162 N⋅m (116–119 lb⋅ft)
@ 3500 rpm 		1972–1981
9.2:1 Zenith-Stromberg 150 CD-25 dual carburettors 108 hp (80.5 kW)
@ 5200 rpm 		164 N⋅m (121 lb⋅ft)
@ 3300 rpm 		1976–1980
8.7:1, 9.2:1 Bosch D-Jetronic
Bosch CI mechanical FI 		110 hp (82.0 kW)
@ 5500 rpm
118 hp (88.0 kW)
@ 5000 rpm 		167 N⋅m (123 lb⋅ft)
@ 3700 rpm 		1972–1974
1975–1981
7.2:1 Turbocharged, Bosch CI mechanical FI 145 hp (108.1 kW)
@ 5000 rpm 		236 N⋅m (174 lb⋅ft)
@ 3000 rpm 		1977–1980

Motorsports

In the realm of rallying, driver Stig Blomqvist secured victory at the 1976 Belgian Rally Boucles de Spa piloting a specially modified Saab 99 with a 16-valve engine.[8] He continued his success by winning the Swedish Rally in both 1977, driving a B engine-equipped 99 EMS, and again in 1979 behind the wheel of a Turbocharged Saab 99. The triumph in 1979 was historic as it marked the first time a turbocharged vehicle won the Swedish Rally. Saab ceased its official rally involvement in 1980.[16]

Additionally, Saab 99 models powered by B engines competed successfully across various classes within the SCCA.[17]

External links

  1. ↑ 1.0 1.1 1.2 1.3 Cite error: Invalid <ref> tag; no text was provided for refs named colebook
  2. ↑ Cite error: Invalid <ref> tag; no text was provided for refs named scjun-jul84
  3. ↑ Cite error: Invalid <ref> tag; no text was provided for refs named aronline
  4. ↑ Cite error: Invalid <ref> tag; no text was provided for refs named valebook
  5. ↑ Cite error: Invalid <ref> tag; no text was provided for refs named msmjul76
  6. ↑ 6.0 6.1 Cite error: Invalid <ref> tag; no text was provided for refs named saabnet76
  7. ↑ Cite error: Invalid <ref> tag; no text was provided for refs named veteranerna
  8. ↑ 8.0 8.1 8.2 Cite error: Invalid <ref> tag; no text was provided for refs named msm-aug76
  9. ↑ Cite error: Invalid <ref> tag; no text was provided for refs named hemmings-per
  10. ↑ Cite error: Invalid <ref> tag; no text was provided for refs named skaraborg-per
  11. ↑ 11.0 11.1 Cite error: Invalid <ref> tag; no text was provided for refs named hemmingsturbo
  12. ↑ Cite error: Invalid <ref> tag; no text was provided for refs named autonews
  13. ↑ Cite error: Invalid <ref> tag; no text was provided for refs named turbobook
  14. ↑ Cite error: Invalid <ref> tag; no text was provided for refs named petro1
  15. ↑ Cite error: Invalid <ref> tag; no text was provided for refs named longbook
  16. ↑ Cite error: Invalid <ref> tag; no text was provided for refs named saabmuseumrally
  17. ↑ Cite error: Invalid <ref> tag; no text was provided for refs named soundings19
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