OM604 OM605 OM606 Built Engine Power Limits – 400, 500 and 700 Horsepower Explained

How much power can a built OM604, OM605 or OM606 engine reliably produce? Fred covers stroker kits, displacement options, realistic power targets and why 100 horsepower per cylinder is the reliable maximum for these engines.

OM606 built engine power limits are simpler than most people think. One rule covers all three engines in this family – 100 horsepower per cylinder is your reliable maximum.

Why Build an Engine?

Building an engine gives you options. A freshly built engine produces slightly more power than a worn 30 year old unit. That means you can run less boost for the same power level – or run the same boost as your friend and make more power. Both are good outcomes.

Building also gives you the opportunity to make modifications that are difficult or impossible with the engine in the car. Head bolt upgrades, camshaft swaps, displacement changes – all of these are far easier during a full build.

Displacement Options – Stroker Kits

The most significant option available during a build that cannot be done any other way is displacement increase. The stroker kits developed for these engines are based on original Mercedes components and open up significant displacement increases:

• OM604 2.2 litRE → 2.3 litRE
• OM604 2.0 litRE → 2.3 litRE
• OM605 2.5 litRE → 2.9 litRE
• OM606 3.0 litRE → 3.5 litRE

Going from 2.5 to 2.9 litres in an OM605 or from 3.0 to 3.5 litres in an OM606 is a significant upgrade. These engines are already strong on torque but the larger displacement wakes them up in a completely different way – especially at low RPM where the additional cubic capacity makes an immediately noticeable difference.

The CDI hacks producing 2.7 litre OM605 or 3.2 litre OM606 configurations exist but the engineering math has never added up clearly. Making a 2.9 litre OM605 or 3.5 litre OM606 using the proper stroker approach is actually simpler and more straightforward than these alternative configurations. If you have proven data on the CDI displacement hacks post it in the comments – genuinely interested to see it.

Reliable Power Targets – Built Engines

For normally built engines at standard displacement the reliable power targets are:

• OM604 four cylinder → 400 horsepower
• OM605 five cylinder → 500 horsepower
• OM606 six cylinder → 600 horsepower

That's 100 horsepower per cylinder. Simple, consistent and proven.

The difference between a built engine and a standard engine running these power levels is not primarily about peak power. A standard engine can often achieve similar numbers. The difference is consistency, longevity and peace of mind. A built engine starts and does the same thing tomorrow. And the day after. It lasts longer and runs smoother.

Maximum Power – Pushing Beyond the Limits

Squeezing everything possible out of these engines adds approximately 100 horsepower more than the reliable targets:

• OM604 maximum → 500 horsepower
• OM605 maximum → 600 horsepower
• OM606 maximum → 700 horsepower

Beyond these numbers? Theoretically possible with compound turbo setups and extreme modifications. But nobody has shown a properly documented, reliably operating engine producing more than 700 horsepower from an OM606. If you have one – post the dyno graph. A real dyno graph showing a proper power curve, not one where torque and power intersect at exactly the same RPM which is physically impossible and a clear sign of a fake result.

Building is More Accessible Than You Think

You don't need to be an engineer to build one of these engines. Disassembly and assembly can be done in your own garage. The specialist machining work goes to a machine shop. The knowledge is available. The parts are available.

And honestly – building an engine in your garage is one of the best ways to spend time. Sometimes you need to escape and spend quality time doing something you love. Building an engine is exactly that.

Summary

• OM606 built engine reliable power limit is 100 horsepower per cylinder
• OM604 reliable 400hp, maximum 500hp
• OM605 reliable 500hp, maximum 600hp
• OM606 reliable 600hp, maximum 700hp
• Stroker kits increase displacement significantly – OM606 from 3.0 to 3.5 litres
• Built engines offer consistency and longevity at the same power levels as standard engines
• Beyond 700 horsepower from an OM606 has not been reliably documented

Wait three days for the next video. Love you all. Bye!