Guide

Turbo/Supercharger Build.

 

DIFFICULTY LEVEL: Easy

 

APPLICABLE MODELS:

5 Series (1988-1995)

 

Walkthrough

The design of a turbocharger is very similar to that of the supercharger. The difference is that one is exhaust-driven(turbo) and the other is belt-driven(supercharger). The general rule is that a turbocharger maximizes your powerband at a higher RPM, because it is powered by the amount of exhaust being forced through it. On the other hand, a supercharger has better lowend torque, since it is controlled by a belt directly connected to the crankshaft. A supercharger is already injecting air into the system, even at extremely low rpm. Generally, superchargers cost a little more than turbo kits, but a turbo kit is tougher to install, as you must typically route your exhaust system through the turbocharger as well as add an intercooler.

There are tradeoffs between both systems. In theory, a turbocharger is more efficient because it is using the “wasted” energy in the exhaust stream for its power source. On the other hand, a turbocharger causes some amount of back pressure in the exhaust system and it also tends to provide less boost until the engine is running at higher RPMs. Superchargers are easier to install but tend to be more expensive.

 
Supercharger:
A supercharger is much like a turbocharger, with the biggest differnce being that a supercharger is connected directly to the crankshaft with a belt. A supercharger is matched to an engine by its displacement and belt ratio. It can provide excess airflow at any engine speed. The concentrated charge of air provided by a supercharger results in a more powerful combustion stroke in the engine’s cylinders, resulting in improved engine performance. A supercharger is a self-contained unit, while the turbocharger relies on the engine’s exhaust system- and, often, an intercooling system to function.

European Supercharging Systems:

Model
Stock HP
Supercharged HP
Boost
520i
127hp – 147hp
215hp
6 Psi
525i
168hp – 189hp
285hp
6 Psi
’93-’95 530i
215hp
335hp
6 Psi
540i
282hp
420hp
6 Psi

Pros:
– New 2-year/unlimited mileage warranty program for ESS assembled main Supercharger units.
– Supercharger is perfectly balanced to ensure super-smooth running and long durability.
– Unique SilentDrive belt-driven step-up system, very low noise (inaudible with hood closed).
– Easy installation, due to self-lubricated design which means no oil lines from the engine.
– 100% maintenance free.
Cons:
– Maximum recommended boost level is 12PSI. (higher boost levels than 8 PSI require extensive engine modifications.)
– Price: From $4200 to $5000.

Dinan supercharger stage 3:

Model
Stock HP
Supercharged HP
Boost
540i
282hp
439hp
? Psi

Not enough info.

 
Turbocharger:
A turbocharger is an air pump designed to operate on the normally wasted energy in the engine’s exhaust system. The exhaust gases that would normally flow out of the tailpipe are instead routed through a turbocharger unit mounted adjacent to the engine.
Inside the turbocharger are two back-to-back turbines. On the exhaust side, a turbine uses the exhaust gases flowing through it to spin. When the exhaust-side turbine spins, so does the other turbine, forcing air into the intake of the engine. The exhaust output controls how fast the turbine spins, so at slower revs the turbine spins more slowly and forces less air into the intake of the engine. If the force of the exhaust gases is low enough, the turbo will barely spin, if at all. As the engine rpm increases, the turbine spins faster and forces more air into the engine’s intake. This is why turbos tend to work better at higher rpm and why turbochargers experience what is called turbo lag(the delayed time it takes for the turbine to spool up). Some companies use twin turbo systems, which compensate for the low/high-end sacrifice by dedicating one turbo to each situation.

Turbocharger Dynamics:
I have seen it running on a 535i. 400 Rear wheel HP (without an intercooler, 475RWHP with intercooler) with a single turbo, no turbo lag, great setup.

Korman Mosselman Turbo Systems:
Not much info there, the kit is available for BMW 525i (M20 single cam), 535i, 735i, iL.

– Low Boost System, 5.5-6.0 psi
– No ECU reprogramming, injector change, or air flow meter change is required. No changes to factory tuning specifications.
– Adjustable Wastegate.
– Water Cooled Turbine Bearings, Oil Lubricated.
– Price: $4650.00

New M30 power: 265 Hp