Volvo B20 Engine Guide

Volvo’s B20 engine has been highly regarded ever since it first made its way onto the production line for the 1969 model year. The B20 was the successor to the famed Volvo B18 engine, and was in production until the early 1980s. Volvo produced six different variants of the B20 engine, including both fuel-injected and single and double-carburetor versions.

While the younger generations are less familiar with the B20, for many years it was a top-performing engine. It has been out of production since the 1980s, but still graces the street in countless Volvos today – both in cars and howitzers for the Indian military (seriously). In this guide, we’ll go over the Volvo B20 specs, history, reliability, and performance.

Technical Specifications

Engine	Volvo B20
Model Years	1969-1981
Displacement	2.0 L (1,986 cc)
Aspiration	Naturally Aspirated
Configuration	Inline-four
Compression Ratio	8.7:1 – 10.5:1
Bore and Stroke	88.9 mm x 80 mm
Valve Train	OHV 2 v/cy, 8 Valve Total
Fuel System	Carburetor/Fuel Injection
Head/Block Material	Cast Iron
Horsepower Output	90-130 horsepower
Torque Output	103-130 lb-ft of torque

Vehicle Applications

• 1969-1970 Volvo 120 Series (Amazon) (including 123GT)
• 1969-1974 Volvo 140 Series
• 1969 Volvo GTZ (Concept car)
• 1969-1973 Volvo P1800/S/E/ES
• 1974-1976 Volvo 200 Series

The Volvo B20 also powered these non-car applications:

• 1969-1981 Volvo Bandvagn 202/203 (Mk. II) (All-Terrain Military Vehicle)
• 1977-1981 Volvo Laplander C202 (All-Terrain Military Vehicle)
• Bofors Haubits FH77/A Howitzer

Volvo B18 to the B20

In 1969, Volvo bored out the B-series for a third time, creating the 2.0 L B20 engine. The B20 Volvo immediately succeeded the B18 in most applications, making more horsepower and torque. Volvo rated the B20 between 90-130 horsepower and 101-130 lb-ft of torque, decent improvements of 15 horsepower and 18 lb-ft of torque.

Volvo phased out the B20 in cars in the mid-1970s after a relatively short production run. It did appear in several models, including the 120 Series, 140 Series, 200 (240) Series, P1800/S/E/ES, as well as the GTZ concept car. The GTZ was designed to be a high-performance coupe, but only two were ever built, one in 1969 and one in 1970. The 1969 GTZ featured the B20.

The B20 was succeeded by the slightly larger Volvo Redblock engine, also known as the B21. The B21 was not just a bored version of the B20, but also had a different valve train and included several turbocharged versions. Volvo stopped using the B20 in their cars by 1977, and the only continued uses were in military applications.

Military Applications

The Swedish military used the B20 as a successor to the B18 in several vehicles, including the Laplander C202 and Bandvagn 202. The C202 was a civilian-designated vehicle, while the Bandvagn was used exclusively by the military.

The Bandvagn 202 is an all-terrain carrier, and used the B20 from 1969-1981. Not only did Sweden use it, but Canada, Finland, the Netherlands, Norway, and the UK also used B20-powered Bandvagn. The Bandvagn has seen use in climates ranging from the desert in the Middle East to the polar caps in the Antarctic, showing the engine’s incredible versatility and engineering.

You wouldn’t think it from a 2.0 L engine, but the Bandvagn is used to carry as many as 10 troops over a one-ton payload. It makes an estimated 97 horsepower in the Bandvagn, and there are many still in use today.

The company Bofor used the B20 to power the auxiliary drive system in the Haubits FH77/A Howitzer artillery gun. In the FH77/A, the Volvo B20 is connected to hydraulic pumps, which drive the wheel motors, auxiliary wheel, breech closure, and ammunition crane.

Engine Design Basics

The Volvo B20 engine is a 2.0 L inline-four engine with an overhead valve train (OHV). There are 2 valves per cylinder for 8 valves total. It has a bore and stroke of 88.9 mm x 80 mm, making it a bored version of the 1.8 L B18 engine. It is a split-bore center engine, meaning the spacing between cylinders 2 and 3 (the middle two cylinders) is wider than between cylinders 1 and 2 or 3 and 4.

The firing order is 1-3-4-2 anti-clockwise and the oil capacity is 3.75 l, which are both the same as the B18. Volvo carried over the B18s 12v electrical system, but used an alternator instead of a generator now. Volvo gave some versions of the B20 either Zenith/Stromberg or S.U. carburetors, but other versions used Bosch’s D-Jetronic or K-Jetronic fuel injection systems.

Like the B18, Volvo made several variants of the B20. There are six variants in all, the B20 A-F.

Volvo B20A

Volvo used the B20A in the Volvo 140 Series 142 basic and deluxe models, as well as the 145 express and 200 Series. They rated it at 90 horsepower and 119 lb-ft of torque and it utilized a single Zenith/Stromberg carburetor and had a compression ratio of 8.7:1. The B20A was the first B20 Volvo produced.

Volvo B20B

The B20B Volvo is a double-carburetor version of the B20A. From 1969-1970 compression was 9.5:1, Volvo lowered it to 9.3:1 in 1971, and further from 1972-1974 down to 8.7:1. Volvo used the B20B in the deluxe models of the 140 Series and in the 1800S.  They rated the B20B at 97-118 horsepower and 103-123 lb-ft of torque, solid improvements over the B20A.

Volvo B20E

Volvo put the B20E in several models, including the 1800E and 140 Series Grand Luxe models. The Volvo B20E is a fuel injected version of the B20, and used the Bosch D-Jetronic system from 1970-1973, and the Bosch K-Jetronic system from 1974-1975. The B20E made 130 horsepower and 130 lb-ft of torque, and had a very high 10.5:1 compression ratio.

Volvo B20F

Volvo used the B20F from 1972-1976 inside the 1800ES, 140 Series, and 200 Series. Like the B20E, the B20F is fuel injected, and used the Bosch D-Jetronic system from 1972-1973, and the Bosch K-Jetronic system from 1974-1975. The Bosch B20F made 94-112 horsepower and 105-115 lb-ft of torque, and had a compression ratio of 8.7:1.

The B20F was basically a low compression B20E. Volvo fitted some versions of the B20F with a catalytic converter, while others used the carburetor for emissions control like the rest of the B20 series.

Reliability

While the B20 doesn’t quite have the 3 million mile motor reputation as its B18 predecessor, it is still widely regarded as a very solid engine. There are many 200,000+ mile B20 power vehicles still out there roaming the streets today. In addition, civilians and some militaries still use the B20 in their original Laplander and Bandvagn all-terrain vehicles.

The B20 can pretty much be regarded as bulletproof for longevity in its stock form. It is still susceptible to all the problems of any 40-50-year-old engine, meaning all belts and hoses need to be thoroughly inspected. The timing gear teeth can also break from constant wear, and the rear crank seal is known to occasionally leak.

Also, the carburetors need regulator servicing as well as the breather gauzes. The original Bosch D-Jetronic system was problematic, which is why Volvo replaced it with the K-Jetronic system.

Performance and Mods

While you might not think so, the Volvo B20 is actually a very moddable car that is used by many performance enthusiasts. In Norway, a Team Volvo built an incredible modified B20-powered dragster that can blast through the quarter mile in under 9 seconds at over 150 miles per hour. It runs 40 PSI of boost from a massive turbo to help it make the jaw-dropping sprint.

One of the most common upgrades is adding a turbocharger. Volvo used a Garret T3 turbo on several engines in the slightly larger B21 series running between 6-9 PSI of boost. Many people swap over these turbos, or other T3-sized turbos, and run a similar amount of boost.

For turbocharging, you will probably want to start with one of the lower compression models, like the F or B, with the F being preferable due to the fuel injection. You’ll want the K-Jetronic fuel injection to start with, or many people upgrade to a Megasquirt fuel injection system.

Here are two guides (A; B) to restoring and building out B20 engines. Keep in mind, the newest B20 motor you’ll find is still four decades out of production, so it’s going to take some serious work. However, the end result will definitely be worth it if you can make it through.

B20 Volvo Legacy

The B20 engine is one of the top Volvo motors ever created. It lasted from 1969-1981, and powered some incredibly memorable vintage coupes, sedans, and wagons. The mighty inline-four might not have looked like a lot, but it could go for endless amounts of miles without issue. Volvo used the B20 in all kinds of cars, like the 140 Series, 200 Series, and 1800E, as well as military vehicles like the Laplander L3314 and Bandvagn 202.

Hopefully, the spirit of the B20 Volvo will never die – just like the engines themselves. Even though they have been out of official production for more than four decades, they still have a strong enthusiast community and reputation. Here’s to the mighty Volvo B20, an all-time incredible inline-four.