OM606 Necessary vs Unnecessary Upgrades – Injectors, Pre-Chambers & Camshafts

Not every modification on an OM604, OM605 or OM606 is worth doing. Fred breaks down which upgrades are genuinely necessary, which are a waste of money and which depend entirely on how you use the engine.

OM606 unnecessary upgrades cost builders time and money every day. Today we go through injector nozzles, pre-chamber modifications and camshafts – what's worth doing and what isn't.

Injector Nozzles – Unnecessary Upgrade

The best injector nozzles for OM604, OM605 and OM606 engines are the stock ones. There is no aftermarket nozzle upgrade that improves performance on these engines. The spray pattern and flow characteristics of the original nozzles are already correct for what these engines need.

If your nozzles are worn out and the spray pattern is degraded then yes, replace them. But as a performance upgrade – no point.

Lucas vs Bosch Injectors – This Matters

There is one important injector distinction to make. The OM604 came with Lucas injectors. Visually they look identical to Bosch injectors, the parts appear interchangeable and the common belief is that they perform the same way.

They don't.

We tested this together with Diesel Mekano and the results were clear – Lucas injectors do not perform the same as Bosch injectors despite appearances. If you have Lucas injectors throw them out and replace them with Bosch. This applies particularly to anyone who has bought injectors online and may have received Lucas units thinking they were Bosch.

The OM605 and OM606 came with Bosch injectors from the factory. Only the OM604 has the Lucas units but it's easy to end up with the wrong injectors when buying parts online.

Pre-Chamber Modifications – Unnecessary

Pre-chamber ball replacements – the stock units are made of extremely hard material and essentially never fail under normal use. Aftermarket replacement balls in alternative materials exist and are fine if you want them but as an upgrade there's no real point.

Pre-chamber drilling – people drill additional holes in the pre-chambers believing it improves flow, reduces EGT or increases power. Show me dyno data and EGT measurements proving it works and I'll believe it. Until then it's an unnecessary modification. The pre-chambers are very well designed from the factory and flow whatever fuel you give them without restriction.

Camshafts – Depends on Your Goals

This is the one upgrade on the list that genuinely depends on what you're doing with the engine.

The OM605 and OM606 are available in naturally aspirated and turbocharged versions. The turbo engines have different camshafts than the NA versions. The NA camshafts – sometimes called M8 cams – are happy to rev to 7000 RPM. The stock turbo camshafts are not.

If you're running your engine to 5500 RPM or below – camshaft upgrade is probably unnecessary. If you want to rev higher – it becomes a worthwhile upgrade. Cheap, simple and effective.

Remember – torque multiplied by RPM equals power. If you can rev 2000 RPM higher with the same torque you make significantly more power. The camshaft controls where in the RPM range your engine makes its best power.

Stock turbo cams give full power around 5500 RPM. NA cams move this up slightly. Stage 1 cams push maximum power up to around 6500 RPM. Stage 2 cams push it to around 7000 RPM.

If maximum power is the goal you need to rev and if you need to rev you need the right camshaft.

Exhaust Manifold – Necessary

Not an unnecessary upgrade. Covered in detail in a separate video but a proper tubular exhaust manifold is always better than the stock unit on a performance build. Faster spool, better heat management, more power. Worth doing.

Summary – Necessary vs Unnecessary

Unnecessary upgrades:

• Injector nozzle upgrades – stock is correct
• Pre-chamber ball replacements – stock never fails
• Pre-chamber drilling – no proven benefit

Important distinction:

• Lucas injectors on OM604 – replace with Bosch immediately

Depends on your goals:

• Camshaft upgrade – unnecessary below 5500 RPM, very worthwhile above it

Always necessary on a performance build:

• Proper exhaust manifold

Most of this stuff is unnecessary. Strange but true. Love you all. Bye!