Cadillac ATS 2.0T LTG downpipe

Top Cadillac ATS 2.0T Performance Upgrades Guide

Chandler Stark

Meet Chandler

Chandler is an automotive expert with over a decade of experience working on and modifying cars. A couple of his favorites were his heavily modded 2016 Subaru WRX and his current 2020 VW Golf GTI. He’s also a big fan of American Muscle and automotive history. Chandler’s passion and knowledge of the automotive industry help him deliver high-quality, insightful content to TuningPro readers.

The Cadillac ATS 2.0T was one of the more underrated performance cars on the market during its time. Utilizing 272 horsepower through the turbocharged inline-4 LTG engine, it could run a 14.0 second quarter-mile and go from zero to 60mph in just 5.4 seconds. However, compared with the higher spec V6 engines, the 2.0 turbo seemed vastly underpowered.

Luckily, with just a few performance upgrades you can have your 2.0 ATS competing with the big boys, producing nearly 400hp. In this guide we’re going to discuss tuning, downpipes, intercoolers, E85 fueling, and catch cans as a great bolt-on mod list for the Cadillac ATS. First, we’ll cover engine power limits to give you an idea how far you can push the 2.0L LTG engine without need serious upgrades.

2.0T LTG Power Limits

The biggest limitation on the 2.0 LTG engine is the internals. The stock pistons and connecting rods can only handle around 350-375whp before they need upgrading. If you want to push beyond these levels you will need a set of forged internals and some head studs.

Outside of the internals the engine is very strong. The block and crankshaft can handle more than 600whp so with a set of forged internals you can take these engines pretty far. Our list of modifications is going to cover your basic bolt-on upgrades. The five mods we list below can easily put you within the power limit of the factory internals so upgrading beyond that is a bit less common due to the costs associated with internal and turbo upgrades.

Best Cadillac ATS 2.0T Performance Upgrades

  • ECU Tuning
  • Downpipe
  • Intercooler upgrade
  • Flex-Fuel E85 Kit
  • Oil catch can

1) ECU Tuning

For the first of our Cadillac ATS 2.0T performance upgrades, we’re looking at ECU tuning. ECU tuning is one of the best ways to increase horsepower and torque on the LTG without making any physical bolt-on modifications. With just tuning alone, you can add 15-20+% horsepower and torque to the LTG in minutes. In terms of hp/$, tuning is by far the most cost effective Cadillac ATS 2.0T mod. 

For those who are unfamiliar, tuning involves rewriting the programing on the engine control unit (ECU or PCM for powertrain control module). This is done through “flashing” (or installing) new software that has upgraded programming. The new software is called a “tune,” and optimizes parameters like ignition timing, boost pressure, camshaft timing, and more. The optimization provides for increases to horsepower, torque, and sometimes even better fuel economy. 

In addition, for those with automatic transmissions, you can also get tuning for the transmission control unit (TCU). TCU tuning can improve shift logic, shift timing, and make the transmission perform much better for high performance driving. We also highly recommend a wideband O2 sensor for tuning, as the ATS does not have one stock. 

2) Downpipe Upgrades

After you start tuning your LTG, the next of the Cadillac ATS 2.0T performance upgrades is a downpipe. The downpipe is the part of the exhaust system that bolts directly to the turbocharger. Downpipes collect the exhaust gasses exiting the turbo and directs them into the rest of the exhaust system. 

The stock downpipes are restrictive for two primary reasons: The diameter is too small and creates too much back pressure, and it contains a catalytic converter. Both of these are done for emissions purposes, but they really restrict performance. The catalytic converter in particular is the biggest restriction for power. OEM cats are pretty efficient and powerful to filter emissions, but they choke off the turbo from proper airflow. 

3) Intercooler

Next up on our list of Cadillac ATS 2.0T performance upgrades is the LTG intercooler. The OEM intercooler for the LTG is an air-to-air unit that is located just behind the radiator near the front bumper. The purpose of an intercooler is to cool down the boost or “charge air” before it reaches the engine. The LTG is a turbocharged engine, and turbochargers rely on hot exhaust gasses to function. In addition, compressed air becomes hotter as it compresses, adding more heat. 

Hotter air has less oxygen than colder air, which means it will produce less horsepower and torque. The point of the intercooler is to improve the oxygen content of the charged air so it produces more horsepower and torque inside the engine. Besides providing more power, intercoolers also help mitigate detonation or engine knock. 

The OEM unit is an air-to-air intercooler, so it works by using ambient air for cooling. As air rushes into the intercooler it passes through a series of fins or coils. These help dissipate the heat, and are cooled by ambient air passing over it. Intercoolers are crucial for turbocharged systems, as they improve performance and prevent engine damage from detonation, and they are very popular LTG mods.

4) Flex-Fuel E85 Kit

The last of our Cadillac ATS 2.0T performance upgrades is flex-fuel tuning. LTG flex-fuel kits go right along with ECU tuning. They can really turn the 2.0T ATS into a completely different car. One of the things that makes the LTG such a great engine is its use of direct injection fueling. A benefit of modern DI systems is that they are also usually fully capable of running E85 – like the LTG. 

E85 is a mixture of 15% gasoline and 85% ethanol, and can be found at a limited number of gas stations throughout the country. Besides being cleaner for the environment, costing less at the pump, and being a renewable fuel source, E85 is great for making horsepower and torque. That’s because 85 has an effective octane rating of about 105, which is a significant improvement over the 91/93 available at the pump.

Higher octane means better knock resistance. E85 tuners can lean out the air-to-fuel ratio, increase boost pressure, and advance ignition timing much more than on pump gas, without encountering detonation or engine knock. This means a lot more horsepower and torque compared with pump gas. The downside to E85 is its lack of availability in many places, reduced gas mileage, and sometimes problems with starting in cold weather. 

5) Oil Catch Cans

While not really a performance upgrade, a catch can is a smart reliability upgrade when starting an ATS build. Catch cans are used to fight blow-by, which happens in most engines. Blow-by is when combustion gasses or pressure “blow” past the seal of the piston rings and enter the crankcase. These gasses need to be ventilated in order to stop serious engine problems from occurring.

Direct injection systems have the fuel injector located in the combustion cylinder and not the intake manifold. As a result, the extra oil stays in the runners and can build up to excessive levels, preventing airflow. This is where catch cans come in. Catch cans sit between the PCV and intake manifold, and they “catch” any oil before it reaches the manifold. This keeps the manifold clean and prevents any oil buildup.

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