Mercedes C43 AMG Performance Upgrade Guide

After nearly a two decade hiatus, the C43 AMG made its triumphant return to the Mercedes-Benz lineup in the 2016 model year. It featured a new look, new engine, massively upgraded tech, along with the classic performance of its predecessor. It quickly earned rave reviews from critics and enthusiasts, who praised it as refined but very enjoyable.

Still, the AMG C43 feels a little underpowered from the factory, and the DE30LA engine is just begging for more horsepower to be unleashed. These engines are strong, capable of handling about 500whp before needing internal upgrades. Fortunately, just a few bolt-on performance upgrades like tuning, an intake, downpipes, methanol injection, and an intercooler can get it to those power levels. In this guide we’re going to dig into each of these mods in-depth and teach you how to build a 500whp C43 AMG.

M276 Power Limits

The Mercedes-AMG C43 responds incredibly well to performance upgrades. The only real question with the M276 is how much power the internals can really handle. It features an aluminum block with forged pistons but cast connecting rods. This makes the rods the weakest point in the engine.

Approx. 500whp is the the upper limit for the connecting rods. That’s about the max you’ll want to push without sacrificing reliability and asking for bent rods. For those serious about making big horsepower, fully built blocks and completely forged internals are a must.

If you would rather consume this content via a video, check out our How to Build a 500WHP C43 AMG video below:

C43 AMG Performance Upgrades

• Tuning
• Dual Intake Upgrade
• Downpipes
• Water-Methanol Injection
• Intercooler

1) ECM Tuning

By far the biggest bang for your buck upgrading the AMG C43 is going to be ECU tuning. It is our top choice for the 5 best AMG C43 performance upgrades, and it really brings the car to life. Tunes generally increase performance by increasing boost pressure, optimizing air-to-fuel ratios for power, and advancing ignition timing. Adding just a few pounds of boost and a couple of degrees of timing can seriously alter the power output of an engine.

Tuning Benefits

• + 90-120hp (75whp-100whp)
• + 120-150tq (100wtq-125wtq)
• Increased turbo response
• Larger power band
• Reliability when adding other mods

You can easily add 90-120hp (75whp-100whp) and 120-150tq (100wtq-125wtq) to a completely stock car with just tuning. Tunes can also help account for other modifications made to the car, including intakes, exhausts, and alternate fueling. Not only will they make the car more responsive to other upgrades, but it will also help the engine run safer after they are installed, too.

Besides just peak power increases, tuning also provides a larger overall power band and vastly increased turbo responsiveness. The C43 pulls longer and harder after tuning, and it is much quicker off the line and out of corners. Tuning also allows for live data logging and monitoring for some tuners, which lets you check how your car is doing post-tuning.

2) Cold Air Intake Upgrade

The stock intake for the C43 flows okay, for stock power levels, but on more powerful builds they start to become choke points.

An intake by itself on the DE 30 LA will net around 10-20whp/wtq, and it will gain even more with a tune. In addition, you will also see improved throttle and turbo responsiveness. The turbo will spool a little bit quicker due to increased airflow, which will result in earlier peak power and a larger power band.

Intake Upgrade Benefits

• +10-20whp/wtq
• Improved throttle and turbo response
• Increased airflow over stock
• Improved engine bay aesthetics

3) Upgraded Downpipe

Downpipes are another great performance upgrade. They connect to the turbos and one of the most crucial parts of an exhaust system. Unfortunately, the stock downpipes are restrictive and impede flow while creating a lot of backpressure. This reduces exhaust scavenging and increases EGTs, which strangles performance on back to back runs. Aftermarket downpipes reduce this issue by allowing for greater flow and reduced backpressure.

Power gains are around 10-20whp/wtq with downpipes, and they require tuning on this platform. Without tuning, C43s can actually lose power because the engine will not compensate for the reduced backpressure. However, upgraded downpipes allow for tunes to run more boost, resulting in more power.

Downpipe Upgrade Benefits

• + 10-25whp/wtq
• Increased turbo and engine sounds
• Increased scavenging
• Decreased backpressure
• Reduced EGTs

4) Water-Methanol Injection (WMI)

Methanol injection is a fueling upgrade to help support the factory fueling system, allowing it to produce more power without significant upgrades.

These injection kits work by injecting a 50/50 solution of water and methanol into the charge pipes that connect to the intercooler. This has two purposes: not only does it reduce the temperature of the air going into the engine, but the methanol itself increases the octane rating of the fuel. IATs can be reduced substantially by injecting water-meth, and octane ratings can increase by as much as 20 points.

Proper tuning is crucial to taking the full performance advantage of water-methanol kits. Still, they offer increased detonation protection even without tuning. The massively reduced charge air temps from the methanol sufficiently decrease cylinder pressures through cooling, reducing EGTs and the likelihood of potential detonation events. This reduces engine wear and tear which increases longevity.

Benefits

• +20-80hp
• Increased detonation protection
• Increased fuel octane rating
• Reduced charge air temperatures

5) Larger Intercooler

The C43 uses a water-to-air intercooler, which utilizes water and coolant to cool the air passing through it. The OEM unit is good for stock power levels and smaller builds, but anyone living in hotter climates or looking at larger builds should really consider an upgraded intercooler.

The larger core allows for increased cooling but with a smaller pressure drop. Pressure drop is when boost loses compression during its path from the turbo to the engine, and the larger the pressure drop the bigger decrease in performance. The larger the pressure drop the harder your turbo has to work to produce sufficient boost, which increases wear and raises intake and exhaust gas temperatures.

Upgraded Intercooler Benefits

• +10-20whp
• Reduced intake temperatures
• Reduced pressure drop
• Optional WMI integration for simplicity

Summary

The M276 engine inside the Mercedes C43 AMG is a stout engine that is more than capable of handling some performance upgrades. The stock block and internals can take a lot of power before they need to be replaced, and are known for their incredible engineering. These cars can easily take gains of 120whp/wtq without breaking a sweat.

Tuning is by far the best bang for your buck horsepower and torque wise, but we understand that not everyone is looking to remove the factory ECU settings. Intakes and downpipes are great ways to increase flow in and out of the engine, which not only adds power but also aids in reliability. Finally, water-methanol injection kits are great upgrades that balance increased performance with increased reliability.