As I’ve mentioned in a previous post, my car is feeling down on power since moving to the high altitude of Colorado. According to most reliable sites, my BMW E36 has 20% less power at my current altitude (~6000 ft) than at sea level. It left the factory with 189 hp, so best case it’s only making around 150 hp now. That just won’t do!
The BMW E36 chassis being 25+ years old, there are many proven things that people have done to increase power. These methods can be broken down into three main categories:
- Engine Swap – Actually replacing the complete engine in my car with the engine from another car
- Engine Build – Installing new components in the engine such as pistons, rods, cams, head, etc
- Forced Induction – Installing a supercharger or turbocharger system on the engine
Let’s take a look at the various options within each of these categories, along with the major pros and cons.
One great thing about the BMW E36 chassis is that the engine bay is pretty cavernous. Since a longitudinal inline 6 cylinder came standard from the factory, you can actually fit up to a V12 in the engine bay! Now a V12 is definitely not very common (or practical) but it is possible.
Here are the most common (and documented) engine swaps that people perform on the BMW E36 chassis:
- BMW S50 – 3.0 liter six cylinder from E36 M3 (240 hp / 225 lb/ft torque)
- Pros – Identical in all exterior features to my M50 engine so it’s a complete drop-in replacement, uses same OBD1 computer system, relatively low cost for a complete engine
- Cons – Not that much more power than my current engine, not that different future modification potential from my current M50
- BMW S52 – 3.2 liter six cylinder from E36 M3 (240 hp / 240 lb/ft torque)
- Pros – Identical in most exterior features to my M50 engine so a relatively easy drop in replacement, relatively low cost for a complete engine
- Cons – Not that much more power than my current engine, OBDII computer system more difficult to integrate into the car, not that different future modification potential from my current M50
- BMW S54 – 3.2 liter six cylinder from E46 M3 (333 hp / 262 lb/ft torque)
- Pros – Identical in most major exterior dimensions to my M50 engine so a medium difficulty swap, good power, good future potential modification for more power
- Cons – Computer system and sensor integration more involved, medium cost for a complete engine
- BMW S62 – 4.9 liter V8 from E39 M5 (400 hp / 369 lb/ft torque)
- Pros – Great power
- Cons – All custom mounting and integration as we’re now out of the inline six cylinder family, not much future modification potential for more power, high cost for a complete engine
- GM LSX – 5.3 liter to 6.0 liter V8 from many different GM and Chevrolet models (300 – 400+hp / 350 – 400+ lb/ft torque)
- Pros – Great power, great future modification potential for more power, some variants are lighter weight than BMW engines
- Cons – Need a lot of parts to make it fit well (mounts, exhaust headers, transmission, driveshaft, computer system, etc), medium cost for a complete engine
- Ford 5.0 – 5.0 liter V8 from Ford Mustang or Ford Explorer (220 – 300 hp / 300 lb/ft torque)
- Pros – Good power, good future modification potential for more power some variants are lighter weight than BMW engines, low cost for a complete engine
- Cons – Need a lot of parts to make it fit well (mounts, exhaust headers, transmission, driveshaft, computer system, etc)
There are many very cool engine swaps that have been completed on E36 BMWs that I’d love to do. However, most are very involved and can take a long time to get right. Specialized tools, welding, lifts and great tuning skills are some of the challenges that full swaps can bring.
If I were to do a swap, I would probably go with a GM LSX V8 swap as it’s the best bang for the buck even though it’s a fairly involved process. But a swap just isn’t for me, too complex.
The BMW M50B25 engine can be built into a larger displacement and higher compression engine with parts available from several sources. This can provide a high horsepower (350+ hp) and high revving (7,500+ rpm) engine. You’d basically be installing the following main components that would yield the noted result:
- Pistons – Strengthened units that would withstand higher cylinder pressure
- Rods – Longer rods that increase the displacement of the motor (up to around 3.3 liters is possible, from a stock 2.5 liters), increase the compression ratio of the engine (from around 10.5 to 12.5+), and withstand the higher cylinder pressure that’s being created
- Crankshaft – Longer throws that allow the longer rods to achieve full travel. Also strengthened.
- Camshafts – Different profiles that allow more air to fill the combustion chamber and more exhaust gases to escape
- Bearings – Higher strength to withstand the higher forces being created
- Valve Springs – Stronger and stiffer to withstand the higher lift created by the camshafts and to increase the rev limit
As you can see, you’re basically replacing the entire rotating assembly in the engine. As such, this is not a cheap endeavor. VAC Motorsports offers an amazing 3.3 liter stroker kit (pistons, rods and crankshaft) for the BMW M50B25 engine but it costs over $7,000!
There are also components that can be combined from other BMW engines to create a stroker engine of sorts but the end results are mixed. There doesn’t seem to be a straightforward way to build up my M50 engine to get high compression and large power without spending a ton of money. Not for me!
Forced induction is all about pumping in more air (and supporting fuel) into an engine that can be drawn in by the engine’s vacuum alone. Superchargers and turbochargers, first developed in the early 1900’s, are the main ways to do this. Both methods compress atmospheric air and thus raise the amount of oxygen molecules per volume, however they go about spinning the compressor in two different ways.
A turbocharger uses exhaust gases to spin a turbine, which is connected to a compressor via a common shaft. A supercharger uses the engine’s crankshaft to spin a pulley (via a belt) connected to a compressor.
The M50B25 engine in my particular BMW E36 car is actually very well suited to forced induction. It uses a robust iron block that can withstand high boost pressure and thus a lot of horsepower. Many people have used the stock rotating assembly (pistons, rods and crankshaft) to produce fairly high horsepower when paired only with the proper head gasket and stronger head studs/nuts (such as ARP brand). There’s an article, in the September 2018 issue of Performance BMW, on a 1000+ hp turbocharged BMW E30 drift car, owned by Jim Olofsson, with the stock M50B25 block (but with other upgraded engine parts). The upper extreme of what my engine can be built into!
Turbocharger systems in the BMW E36 chassis are fairly widespread but they’re very complex and tight fitting. They’re also very expensive in true kit form in the few places that offer them. Most systems are just custom built by the car’s owner. Ultimately they can provide the highest horsepower (when compared to supercharging) but I just think that they’re not worth the effort or expense for the end goals that I would have in mind.
Supercharger systems, specifically centrifugal superchargers, are offered in complete kit form for the BMW E36 by a few different manufacturers (VF Engineering, Dinan, Active Autoworke, etc). Most of these kits feature the Vortech V2 or V3 centrifugal supercharger. They’re relatively affordable and offer a fairly straightforward installation. The superchargers themselves are capable of supporting nearly 700 hp but that would obviously require extensive supporting engine and driveline modifications. They maintain the feel of a naturally aspirated car as they gain boost as the rpms increase. This seems like a logical path for more power that can be easily implemented!
I’m guessing you can see which way I’m leaning at this point. Stay tuned for a future blog post where I reveal my plan and the implementation of the direction I take!