Momentum Worx Non-VGT ISX "Lumpy Larry" Camshaft | Single Cam CM2250 / CM2350 | MMWX.3688242

If you’ve converted your Cummins ISX from a VGT to a fixed-geometry turbo, you already know the tradeoff:

You gain simplicity and strong top-end performance — but you lose the additional exhaust restriction the VGT provides during engine braking.

The "Lumpy Larry" Non-VGT ISX Camshaft is a drop-in upgrade designed to improve engine braking performance on single-cam ISX engines running a fixed-geometry turbocharger.

The Problem with VGT to Non-VGT Conversions

Factory VGT-equipped ISX engines use the variable turbine housing to create additional exhaust restriction during engine braking. When the VGT is removed and replaced with a fixed-geometry turbocharger, that restriction is no longer available.

The result can be:

• Reduced engine braking performance
• Weaker braking on long grades
• Less overall braking authority compared to the factory VGT setup

While no camshaft can physically recreate the exhaust restriction of a closing VGT turbine housing, the Lumpy Larry improves braking performance through changes in the engine's valve events.

The Non-VGT Solution

This camshaft profile is based on camshaft designs used in factory non-VGT ISX applications and is specifically suited for engines running fixed-geometry turbochargers.

It is designed to:

• Improve Stage 1 and Stage 2 engine braking
• Increase braking authority with a fixed-geometry turbo
• Help compensate for the loss of VGT-assisted braking
• Provide a more aggressive exhaust note during engine braking
• Install as a drop-in upgrade
• Reuse your existing timing wedges

No special timing wedge setup is required — installation uses the engine's existing timing wedges.

Why It Works

Rather than relying on turbocharger restriction to generate additional braking force, this camshaft changes the valve events to improve the engine's internal braking characteristics.

For trucks converted to a fixed-geometry turbocharger, this provides stronger and more usable engine braking while retaining the simplicity and performance benefits of a non-VGT turbo setup.

And yes — it sounds mean doing it.

Fitment

Cummins ISX Single Cam Engines

• CM2250
• CM2350
• Fixed-geometry / non-VGT turbo conversions