The great S50B30-S50B32-S50B30US-S52B32US debate

[MrBlonde]

One of the longest enduring pieces of misinformation on the internet is the BMW M3 engine codes.

Here are some facts to help you sort the truth from the rumour:


The European-spec (non-USA) S50B30
Though based on the regular production M50 24-valve inline-six used in many BMW models of the era, the European version of the S50B30 engine has a number of unique components developed by BMW Motorsport (later renamed BMW M). These include:
-Increased bore (to 86mm) and stroke (to 85.8mm) for a total of 2990cc
-Increased compression to 10.8:1
-Ported and polished cylinder head
-Individual throttle bodies for each cylinder
-Heavy-duty valve springs
-Continuously-variable VANOS valve timing on the intake stroke
-Bosch Motronic M3.3 engine management control
-Dual mass flywheel
-Free-flowing intake and exhaust systems

In this guise, the S50B30 produces 286 hp (DIN) at 7,000 rpm and 236 lb/ft of torque at 3,600 rpm. These engines are equipped with dual catalysts for all markets.

How do the U.S. and European versions of the S50 engine differ?
The European and U.S. versions of the S50B30 powerplant share similar cast iron engine blocks and have an identical capacity of 2990cc. However, the U.S. version (known as the S50B30USA) retains the less complex head design and two-stage (non-stepless)VANOS valve timing system of the normal M50 engine upon which it is based. It also does without the European-spec model's individual throttle plates for each cylinder. Compression is slightly lower at 10.5:1. One benefit of the U.S. version is that it retains hydraulic lifters, thus periodic valve adjustments are not needed.

The S50B30USA is rated at 240 hp (SAE) at 6,000 rpm and 225 lb/ft of torque at 4,250 rpm.

How did the U.S.-spec version of the E36 M3 come about?
When the E36 M3 made its European debut in 1992 there were no plans to produce a North American version. Sales of the previous M3, the E30 of 1988-91, had amounted to just under 5,000 units and BMW’s only other North American-spec M car at the time, the E34 M5, was not selling in large enough quantities to justify the addition of another M model in the American market. However, a letter-writing campaign initiated by the BMW Car Club of America sparked such an overwhelming response by the enthusiast BMW community that BMW of North America decided to reconsider. The main issue was price: BMW NA was determined to keep the MSRP down to around $35,000, about the same as the last of the E30 M3s. The only way to meet this price point was to develop a specific version of the S50 engine without the costly individual throttle bodies and continuously variable VANOS valve timing system of the European-spec motor. Just such a car entered production in February, 1994 (as a 1995 model) and went on to be produced in almost equal numbers to the European version despite a production run of only half as many years.

The European-spec (non-USA) S50B32
For the 1996 model year, BMW M replaced the E36 M3 3.0 with the faster and more refined 3.2-liter version. For the European market, this model was fitted with the new S50B32 engine, an evolution of the S50B30, as well as a six-speed manual gearbox and detail refinements to the chassis. For the U.S. (and later Canadian) market, the M3 received its own powerplant, the S52, plus ASC+T traction control and a host of chassis upgrades. Both versions were also treated to a few cosmetic alterations.

How is the Euro-spec M3's 3.2-liter engine (S50B32) different from the previous version (S50B30)?
When creating the 3.2-liter M3 engine, BMW M relied upon much of the experience it had gained when designing the V12 engine for the McLaren F1 supercar. In the end, the S50B32 incorporated the following improvements over the S50B30 engine used in the original Euro-spec E36 M3:
-Increased bore to 86.4mm (from 86.0mm) and lengthened stroke to 91.0mm (from 85.8mm) for a total capacity of 3,201cc (from 2,990cc)
-Increased compression ratio to 11.3:1 (from 10.8:1)
-Advanced BMW/Siemens MSS50 engine management system able to compute 20 million instructions per second
-Double VANOS continuously variable valve timing on both intake and exhaust strokes
-Lightweight pistons
-Improved dual-mass flywheel
-Graphite-coated conrods
-Larger inlet valves
-More efficient intake and exhaust systems
-Second oil pump

The result of these changes boosted horsepower from 286 hp (DIN) at 7,000 rpm to 321 hp (DIN) at 7,400 rpm. Maximum torque also increased from 236 lb/ft at 3,600 rpm to 258 lb/ft at 3,250 rpm. This was the first street-legal BMW engine to achieve over 100 hp per liter.

How is the North American 3.2-liter M3 engine (S52) different from the 3.0-liter (S50B30USA)?
Unlke the Euro-spec S50B32, the S52 powerplant is an evolution of the standard production M52 engine. However, it incorporates the following changes over its S50B30USA predecessor:
-Increased bore to 86.4mm (from 86.0mm) and increased stroke to 89.6mm (from 85.8mm) for a total displacement of 3,152cc (from 2,990cc)
-More finely balanced camshafts
-Valve lifters, springs and spring seats with reduced mass
-Revised intake and exhaust systems
-OBD II (On-Board Diagnostics, version II) compliance
-Horsepower unchanged at 240 hp (SAE) at 6,000 rpm
-Torque increased to 236 lb/ft at 3,800 rpm (up from 225 lb/ft at 4,250 rpm)

Summary
Only the USA ever got the S52 engine, which is nothing like the S50B32 VANOS 3.2 litre engine the rest of the world got. The US engine is nowhere near as good.

The early model E36 M3s got the S50B30 engine everywhere except the USA. The USA got the S50B30USA engine which is nothing like the S50B30. It is nowhere near as good.

We have S50B30s (3 litre) and S50B32s (3.2 litres). We never had S52s. Our engines are full BMW Motorsport engines. The USA engines are cheaper, less powerful derivatives from the standard BMW M50.

[cplagz]

To clarify this is for the E36/E36-7 (M-roadster/coupe) chassis only correct Kenny? As the E46 then got the S54B32.

[MrBlonde]

Originally Posted by cplagz

To clarify this is for the E36/E36-7 (M-roadster/coupe) chassis only correct Kenny? As the E46 then got the S54B32.

Marc, yes this is for E36 M3, and early model M Roadster and M Coupes.

The E46 M3s all have the S54B32 engine (worldwide). The US M Roadster and M Coupes after I think 2001-2002 also had the S54B32 engines whereas this was never an option in Australia.

[Aaron318iS]

Excellent write-up Kenny Might try and save this thread in the Tuningwerks thread for future reference

[StuttGartDTM]

Top class mate, great read for me atm cheers.

[Kaotiq]

Erm

looks like a cut and paste from parts of the FAQ at www.bmwmregistry.com (great site) dunno where they got it from.

Cheers,
Iain

[Mpower///_tyron]

thank you very much I've always wanted to know the difference but could never find it

[MrBlonde]

Originally Posted by Kaotiq

Erm

looks like a cut and paste from parts of the FAQ at www.bmwmregistry.com (great site) dunno where they got it from.

Cheers,
Iain

Iain, yep that's where it is from, a very good site for this stuff. Also has details on special M3 models like Australia's M3R and special E30 M3s.

The only place I've found that is accurate. Most sites refer to the US model M3 engines as S50 or S52, which creates great confusion.

[Kaotiq]

Yeah, when I need info thats one of the first places to look, and one of the places I refer people too.

Very Usefull indeed,
Iain.

[brocky_85]

thanks for the info, ive wondered why the guys in the US only seem to have '95+ e36 m3s, and also why theyre specs are different. nice to know we aussies were getting the real deal all along

[GazM3]

i love it when ppl on the US froum secitions state that thier 240hp version is only like 0.1sec slower over the 1/4 mile

eheh
they should have called the US version either 330i or m330i not an M3. I guess its kinda like devaluing the product. Probably simiar to what they done with the last honda integra "type R", at least they were honest enough to quote the updated one with a "type s".

Perhaps thinking of this in reverse, they should have perhaps offered the US m3 as a 330i in other markets at a price point inbetween the 325i and the M3. Especailly when the 325i/328i had 141/142 kW capacity, an intermediate 180kW bmw would have sold well, say at a price point of around $99.99k