OM606 Supercharger Only Guide – Running an OM606 on Supercharger Without a Turbo

OM606 supercharger running alone – episode six and the bonus addition to the five part boosting series. Today we cover the standalone supercharger option, why it suits specific applications and what boost levels are realistically achievable.

Why One Bar Doubles Your Engine

The fundamental boost principle applies directly here. Atmospheric pressure is one bar. Your OM606 running on atmospheric pressure makes approximately 150 horsepower with a good injection pump.

Add one bar of boost from a supercharger and you double the pressure acting on the engine. The engine receives twice the air mass per cycle. Result: approximately 300 horsepower. The engine effectively thinks it is double its original size.

This is rule of thumb – individual results vary based on engine condition, pump specification, temperature and efficiency. But the principle is consistent: one bar of added boost doubles the engine output.

Supercharger Options and Boost Limits

Eaton superchargers – M62, M90, M112 – are the most accessible option. Available cheaply from scrapyards. Maximum efficient boost is one bar. Above one bar efficiency drops rapidly and the rotors begin contacting each other under pressure. One bar, 300 horsepower on an OM606. For many builders this is sufficient.

Modern screw superchargers from specialist manufacturers offer higher boost capability. A Swedish manufacturer that produces superchargers for Magnus and other American V8 applications has confirmed two and a half bar is achievable on these engines – beyond the manufacturer's standard warranty but technically possible with their hardware.

Two bar from a supercharger equals approximately 450 horsepower on an OM606. Two and a half bar reaches approximately 500-525 horsepower. For the majority of builders who want a strong, reliable daily driver these numbers cover every requirement.

Beyond two and a half bar the manufacturer becomes reluctant to commit. Three to three and a half bar requires significant persuasion to even discuss. Two and a half bar is the agreed practical maximum for standalone supercharger use on these engines with current available hardware.

The Character of Supercharged Power – Linear and Predictable

This is the most important distinction between supercharger and turbocharger power delivery.

A turbocharger builds boost progressively with RPM and load. Below boost threshold the engine is relatively soft. When boost arrives power increases significantly. The character changes between off-boost and on-boost driving.

A supercharger provides boost linearly from idle. If you have 200 Newton metres of torque at idle you have proportionally more at every RPM point throughout the range. There is no on-boost moment. No threshold. No sudden increase in power delivery. The engine simply feels bigger across its entire operating range.

The Natural Aspirated Myth

Natural aspirated enthusiasts often claim immediate power response as the advantage of NA engines. This is a misconception worth addressing.

A Ferrari 360 Modena makes approximately 360 horsepower. A BMW M3 E46 makes approximately 343 horsepower with 360 Newton metres of torque. Both are considered highly responsive NA engines.

A 23 year old Saab 9-5 with a 2.3 litre petrol turbo makes 230 horsepower and 401 Newton metres of torque with maximum torque arriving at approximately 2400 RPM.

The BMW M3 makes maximum torque at approximately 5800 RPM. Cruise along in the M3 and press the throttle – nothing meaningful happens until the engine is well into its RPM range. The Saab responds immediately because the turbo is already partially spooled at cruising speed and torque is available from low RPM.

Natural aspirated cars have no torque advantage over turbocharged cars at low and medium RPM. The advantage exists only at the top of the rev range after the engine has been driven hard. A supercharger provides exactly the low RPM torque multiplication that turbos provide – but linearly and without any threshold.

Why Supercharger Suits Drifting and Specific Applications

For drifting the supercharger has a genuine advantage. The engine always behaves consistently. There is no off-boost to on-boost transition that can upset chassis balance mid-corner. The driver always has the same effective engine size available regardless of RPM or throttle position history.

For road use the linear power delivery is pleasant and predictable. The engine never feels flat. Power is always available proportionally to throttle input.

For maximum peak power the turbocharger remains superior. The supercharger cannot match a turbo at the same boost level for efficiency – it consumes engine power to drive the compressor rather than using exhaust energy.

Installation – Simpler Than Expected

BMW M30 or similar performance headers work well as a starting point. The flange dimensions differ by only two to three millimetres from Mercedes specification. Weld a Mercedes flange to the header and bolt it to the engine. Route the supercharger around the intake and connect to the inlet.

The supercharger noise – that distinctive whine – is an excellent bonus. Different from a turbocharger, immediately recognisable and genuinely impressive.

Summary

• OM606 supercharger alone: one bar doubles engine power to approximately 300 horsepower
• Eaton M62 M90 M112: one bar maximum, cheap and widely available
• Modern screw superchargers: up to two and a half bar achievable, approximately 500 horsepower
• Power delivery is completely linear – no boost threshold, no on-boost moment
• Natural aspirated engines do not have inherent response advantages over boosted engines
• Supercharger suits drifting because of consistent predictable power delivery throughout the RPM range
• Installation uses modified BMW M30 style headers with Mercedes flange welded on
• For maximum peak power turbo remains superior – supercharger trades efficiency for linearity and simplicity

Six episodes out of five. Love you all. More content coming. Hang on!