American Truck Simulator

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About this mod

Adds the CAT 3408 V8 engine with authentic torque and sounds to your game. Works with all SCS trucks and dozens of modded ones too. You will find seven horsepower options for this engine ranging from 400HP up to 800HP.

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Adds the CAT 3408 V8 engine with authentic torque and sounds to your game. Works with all SCS trucks and dozens of modded ones too.


You will find seven horsepower options for this engine ranging from 400HP up to 800HP. It also includes a 15 speed compound transmission with 6 final drive ratio options (from vanilla 3.23 up to 4.63)

1. 3408 T DI: 400 hp @ 2100 rpm, 1200 lb/ft @ 1400rpm
2. 3408A TA: 450 hp @ 2100 rpm, 1460 lb/ft @ 1400rpm
3. 3408B TA: 500 hp @ 2100 rpm, 1616 lb/ft @ 1400rpm
4. 3408B TA: 540 hp @ 2100 rpm, 1746 lb/ft @ 1400rpm
5. 3408E TA: 600 hp @ 2300 rpm, 1950 lb/ft @ 1400rpm
6. 3408E TA: 700 hp @ 2100 rpm, 2250 lb/ft @ 1400rpm
7. 3408E TA: 800 hp @ 2100 rpm, 2600 lb/ft @ 1400rpm

All of these engines are based on official specs and actually existed; None of these are made up. Although it's worth mentioning that only the 3408E model was never used in OTR trucking and was strictly off road (think marine, generators, and rock trucks) where emissions and regulations weren't an issue. Unfortunately I wasn't able to find as much information as I would normally like: I was not able to find a complete torque curve for any of the 3408 models (only some points on the curve), so this mod draws heavily from the larger CAT 3412 engine's torque curve, but adjusted to align with the information I had on the 3408.

About The Engine

Caterpillar introduced the 3408 in the 1970s and discontinued it around 1985. While you definitely saw people run this engine OTR, its size, weight, and fuel economy all worked against it, preventing it from really achieving mainstream popularity. Instead it was especially popular as a marine engine where the weight mattered less and it could be tuned for significantly more power as emissions and noise weren't a problem either. You also found ths 3408 in generators and rock trucks, among other applications. In the US, only the initial 3408 and the A-model were used in trucks, while Canada held on to the 500HP 3408B model for a few extra years. Nowadays it is pretty uncommon to see one still running outside of show trucks, as parts are getting harder to find and emissions regulations are preventing its use in some places.

The 3408, like the 1693, used precombustion chambers which gave it that signature "Clatterpillar" rattle. These chambers also meant the engine could not be fit with a traditional Jake Brake, so instead it received Caterpillar's "brakesaver" hydraulic retarder, which sounds a lot like a modern transit bus. The engine could be fit with an aftermarket exhaust brake if one so desired, but this mod only implements the brakesaver.

Supported Trucks
You can now see the supported truck list for all my engine mods here: