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Reader's contribution: a tribute to the B2x4 engine

Reader's contribution. Recently, we appealed for articles and photos of interesting SAABs. We have received this fascinating contribution from a reader who wishes to remain anonymous. Only minor changes have been made to the article for publication on the web. Enjoy!

When driving a Saab, crowds seldom gather to gawk from the side of the road, street, or for road workers to give the thumbs up when you drive past or for fellow motorist to simply stare with their mouths wide open, since there really isn’t anything special or exciting in a Saab, often perceived to be more farm equipment than car, or could there still be “something”?

Reader's cars: the 666BHP SAAB 9-3

On the outside of these cars, there is seldom “anything”, nor has there been any really spectacular models released from the factory to write about either, but underneath the bonnet there is a “hidden” treasure, the B2x4 series motor, waiting to be freed from its misery.

Of the existing potential in these B2x4 engines the majority are unaware of, unlike the case of those engines found in Nissan Skylines, Toyota Supras, 911 Porsches etc, known to be capable of supporting incredible amounts of horsepower per litre many can only dream of.  Within the smallish group of Saab enthusiastis, the B2x4 motors are well known for their durability and of the potential they have, but for the larger audience these capabilities are often unknown.

Apart from a carbon effect bonnet, there is little to betray the awesome power of this very special SAAB 9-3

Unmodified, these engines are capable of supporting up to 500bhp with suitable externals (turbo, exhaust, fuelling…) and with minor modifications far more.  The following is a write-up of one 9-3 Saab which was pushed far, far beyond this level.

Firts, take on entirely standard B204 engine...

The engine in this 9-3 is a Saab B204L, a 1985cc, 4-cylinder, 4-stroke engine with 4 valves per cylinder, twin overhead camshafts and 2 balancer shafts.  Cylinder bore 90mm, stroke 78mm. 

Even the main bearing shells and caps are entirely standard components, unmodified in any way

This engine was originally introduced in the early 1990’s to NG900’s and 9000’s and produced 154 - 200bhp, depending on the Saab model and version it was used in. The 9-3 used the B204 engine until production ceased in 2001, when the B2x5 series engines replaced the B2x4. 

Pistons, connecting rods and caps are all standard B204 parts, albeit carefully checked for defects and cleaned thoroughly

Internal modifications in this 9-3 were kept at a minimal level and the only those components which were a must were changed.  The B2x4 block, being a bullet proof cast iron “lump” was used without modifications, thus requiring only honing and cleaning.

The cylinder head has benifited from polised ports but retains standard SAAB valves

Cylinder head was mildly ported from canals. Valves, however, are Saab original size: 32mm intake, 29mm exhaust, stem 7mm.

The cylinder head uses special camshafts with ajustable camwheels but head gasket and bolts are all standard B204 components.

276° duration 10.4mm lift camshafts were installed, among with 20% stiffer valve springs and adjustable cam sprockets to help with breathing at higher rpm, where the original Saab cams are insufficient. Hydraulic lifters, head gasket and head bolts are all Saab. Intake manifold, throttle body were kept Saab original too.

The project uses a Holset HX 40 super turbocharger

The turbo came from Holset, a model called the HX40 super. Compressor inducer 60mm, turbine exducer 65mm, with #18 turbine housing. Compressor flow rated to 70lb/min.

Special tubular exhaust manifold and 60mm EWG

Exhaust gases are taken care of courtesy of a 42mm outside diameter tubular manifold, while the downpipe too is considerably larger than the standard fitting.

Note that the car is fitted with a 3.5" custom front downpipe and exhaust

The standard B204 engimne management system has been replaced with a Tatech sequential ignition and injection system. This means that the Direct Ignition is ditched in favour of a distributor with Audi COP coils providing the sparks to the plugs.

Trionic 7 gives way to Tatech management. Note non standard fuel system!

The fuel system uses a Walbro lifter pump from the original tank to a 1.5l hopper tank, while a pair of Bosch -044 main pumps feed a modified original fuel rail with Bosch 1000cc injectors.

A custom larger, high flow intercooler and silicon hose complete the turbocharger circuit

Tune: Gear dependant boost control to maintain traction. 3rd gear mapped against traction limit, 4th and 5th gear to max power. Peak boost 2.2-2.3bar.

Performance was monitored with data loggers and in standing mile competitions.


0-100 km/h: 6s, 0-200 km/h: 12.65s, 0-250 km/h: 17.8s, 0-300 km/h: 27s
Dyno performance:
666bhp@7458rpm, 690Nm@5993rpm (601whp), (Bhp per litre 334)
Standing mile record:

Now, see the car in action:




SeriousSAAB thanks the author for sharing this write up with our readers


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