The Mercedes-Benz SL55K has one of the most easily-tunable power plants ever made, designated as the M113K. Enthusiasts enjoy the supercharged SL55K platform for potential reliable and affordable power increases by cranking up the boost with a simple fifteen-minute modification–a reduction pulley on the supercharger.
The M113 5.0L was the mainstream V8 engine from Mercedes-Benz of the late 90s and early 2000s, while the M113K was a 5.4L version of the M113 with a 2.1L Lysholm supercharger bolted to the top of it. It’s a simple design with a single overhead cam and three valves per cylinder, keeping the maintenance to a reasonable level. DIYs are a simple, low-stress process and give owners like me peace of mind, knowing that if something has to be fixed, it won't be beyond my abilities and won't empty my wallet in the process.
Mercedes shoehorned the M133K into the SL55, S55, E55, and CL55 meaning the engine is still simple like before, but it outputs five-hundred thumping horsepower and gobs of torque. The M113K shouts to a 6800RPM redline with supercharger whine up front and deep rumble from the exhaust in the back. When getting on the throttle, the sound mixed with the sheer speed easily achieved, it's almost too much to process.
Even with everything above, there’s another perk of a supercharged engine that stands out with enthusiasts—that's how easy it is to increase boost with a reduction pulley to make huge power. I researched high and low to find the favorite option among enthusiasts and found Victory Road Performance or VRP. I'm glad I did as they're helpful, knowledgeable, and downright awesome to work with. They have years of Mercedes-Benz experience, and the community appreciates their reliably effective upgrades.
Victory Road Performance Reduction Pulley Options
VRP offers reduction pulleys in multiple sizes: 80mm, 76mm, 72mm, and 70mm. I opted for their most mild upgrade, the 80mm pulley.
Why didn’t I automatically choose the 70mm pulley for the most power? One thing and one thing alone. Cooling. A weak spot of the M113K is its ability to keep itself cool. It can manage factory power and even the added power 80mm pulley but requires VRP’s cooling packages past that point. I really just wanted to make my car ‘factory but a little better’.
Victory Road Performance Reduction Pulley Power Output
So, with the reduction pulleys, just how much power can you make with a few hundred dollars and a few minutes of installation? To put it simply, a lot.
- 70mm pulley gains over 100 whp from stock (with full supporting mods and tune)
- 72mm pulley gains 90 whp from stock (with full supporting mods and tune)
- 76mm pulley gains 60 whp from stock (with cooling upgrade and tune)
- 80mm pulley gains 45 whp from stock (with tune)
The difference with any of these isn’t subtle–even the 80mm pulley is enough to laugh out loud when nailing the throttle as if the car didn’t invoke enough of that when stock. It accelerates to a point where the speedometer acts like a tachometer.
If you wanted to run a smaller pulley anyway without cooling upgrades, unfortunately, that really wouldn’t work. You won’t be able to use the additional power because of heat soak, or you won’t have access to the power for long before the car turns into an SL500 to cool down. However, it’s important to stress that the M113K is indeed one of the most bulletproof platforms there is, especially coupled with Mercedes-Benz’s 722.6 transmission that doesn’t bat an eye—even when faced with one-thousand foot-pounds of torque. With that, a reduction pulley and tune are a stress-free way to add power
With all this in mind, what do I recommend? First, get a 55K Mercedes-Benz because they’re magnificent to own and drive. Secondly, do yourself a favor and get a smaller pulley because it’s a riot and can tear down the road with peace of mind that the car is still under-stressed. If you want more oomph and want to keep an otherwise stock car while keeping the cost low, go with the 80mm pulley and tune. Don’t skip the tune either–it’s important to teach the car to cope with more boost; otherwise, it’ll run a combination of too lean and too rich depending on the RPM. If you want more power than the 80mm, we offer VRP split cooling packages. I would also recommend upgrading the stock intercooler pump to the newer Bosch 0392022010 if it hasn't been changed during the life of the vehicle as the stock pumps were weak from the factory.
So that's it. With under a thousand dollars and very little time and effort, you can be driving a 600WHP missile. Right now, we have many Victory Road Performance parts in-stock and are continuously building out our catalog. To view our entire catalog, you can do so here. If there is anything specific you would like to see listed, leave your recommendations in the comments below.