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.

From 2013–2019, the Cadillac ATS 2.0T was one of the more underrated performance cars on the market. Utilizing 272 horsepower through the turbocharged inline-4 LTG engine, the ATS 2.0T could run a 14.0 second ¼ mile and go from zero to 60 mph 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 upgrades you can have your 2.0 ATS competing with the big boys. Read on to find out the best Cadillac ATS 2.0T performance upgrades for the most horsepower and torque. 

Cadillac ATS 2.0T Engine Info

Before we start our Cadillac ATS 2.0T performance upgrades recommendations, let’s look at the engine itself. The engine code is LTG, and it is a 2.0 liter turbocharged, inline-4. Inside the ATS, the LTG produced 272 horsepower and 260–295 lb-ft of torque. In addition to the ATS, GM also put the 2.0 LTG inside a myriad of other vehicles, including the Chevrolet Malibu, Cadillac CT6, and Buick Regal. 

The LTG is part of the third generation of the EcoTecs, , which also includes the larger 4.3 EcoTec, 5.3 EcoTec, and 6.2 EcoTec. It is currently still in production inside the Chevrolet Camaro LS/LT and others. Like other EcoTecs, both the head and block of the LTG are aluminum. This allows for weight savings over traditional cast iron while still maintaining high reliability. Some of the high-points of the LTG are its use of gasoline direct injection and its twin-scroll turbocharger. 

The direct injection allows for finer fuel atomization, which corresponds to better fuel delivery and control, and thus better horsepower, torque, fuel economy, and reduced emissions. The twin-scroll turbocharger allows for an almost instant boost response that will last nearly until red line. From the factory, the LTG uses an air-to-air intercooler to cool the boost, which is located just behind the radiator. 

Cadillac ATS 2.0T Power Limits With Mods

In stock form the LTG is a pretty stout engine, but when you start looking into Cadillac ATS 2.0T performance upgrades things can change pretty quickly. The engine block and crankshaft are very solid and are generally good until at least 600+ wheel-horsepower. That’s about 675 horsepower from the engine

Unfortunately, the internals do not fare nearly as well. Most shops have found that the stock pistons and connecting rods are only good until about 350-375 wheel-horsepower. That equates to only about 390-415 horsepower. If you plan on going past those levels, you will want to upgrade to forged pistons and connecting rods, as well as head studs. 

Still, even on the low end, that allows for upgrades of more than 115 horsepower over stock without needing to upgrade the internals. Considering we’re talking about a small 2.0 liter turbocharged inline-4, withstanding 400 horsepower is pretty impressive for a completely stock engine. 

Cadillac ATS Catch Cans

While not really a Cadillac ATS 2.0T performance upgrade, an LTG catch can is a smart reliability upgrade many people make when starting their ATS builds. 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.

On modern engines, the crankcase is ventilated back into the intake manifold through the positive crankcase ventilation (PCV) system. The gasses are then reburned in the combustion chamber, instead of being vented to the atmosphere, to avoid excessive emissions. On most turbocharged engines, a little bit of oil also makes its way through the PCV and into the manifold. On port injected fuel systems, the little bit of oil is washed away when fuel is injected. 

However, 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.

Even on non DI cars, there can still be some issues with blow-by, so catch cans are used for most boosted applications. They are a relatively inexpensive and simple modification to make, and the top option for the 2.0T ATS is the ZZPerformance catch can linked here

Best Cadillac ATS 2.0T Performance Upgrades

Mishimoto Performance LTG Intercooler

Our top Cadillac ATS 2.0T performance upgrades are:

  • ECU Tuning
  • Downpipe
  • Intercooler upgrade
  • Flex-Fuel E85 Kit

1) Cadillac ATS 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. 

Top 2.0 LTG Tuners

The best option for tuning the LTG is going to be getting a custom rather than canned tunes. Canned tunes, also known as “Off the Shelf” or OTS tunes, are one-size-fits-all tunes that provide minimal performance increases. In contrast, custom tunes are much more powerful and reliable. This is because OTS tunes are generic, whereas custom tunes are dialed in specifically for your car. 

Custom tunes are dialed in through data logging, which allows the tuner to see how your engine is responding to changes in real time. Data logging allows for the most precise tuning possible, and is what makes custom tuning so much better than canned tuning.

The two most well known ATS custom tuners are Vermont Tuning and ZZPerformance. Both of them sell handheld tuning devices and offer custom tuning on top. Vermont Tuning uses EFI Live Autocal, while ZZP uses HP Tuners. Both of them are similar to each other and will offer similar power gains. With just tuning, you can expect gains of 40+ horsepower and 60+ lb-ft of torque from both VT and ZZP.

2) Cadillac ATS 2.0T 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. 

Best ATS LTG Downpipe

For LTG downpipe upgrades, you have two main options: catted or catless. Catted LTG downpipes use a high-flow catalytic converter (HFC), which filters some emissions but is much less powerful than OEM. HFC downpipes are EPA compliant (though not always CARB compliant), making them street legal in most states. They still provide a significant bump in power, but don’t have the negatives of going catless like increased pollution, potential boost creep, and the god-awful smell of raw emissions. 

On the other hand, those looking for the most performance can go with a catless LTG downpipe. These downpipes completely remove the catalytic converter section, making the pipe 100% hollow. They allow for the best possible flow from a downpipe and will add about 10 horsepower more than their catted counterparts. Catless downpipes are also called test pipes by some manufacturers. 

Keep in mind, catless downpipes can be prone to under colder conditions to boost creep, where boost cannot be controlled mechanically, and they also smell awful. They are however usually much cheaper, but are not street legal in most states. 

The top ATS downpipe options are the ZZPerformance catted LTG downpipe and the RPM Motorsports catless LTG downpipe. The RPM catless downpipe will be a little bit cheaper, but both of them will perform pretty close to each other on the stock turbo. ECU tuning is highly recommended for any LTG downpipe upgrade. They can cause the engine to overboost, run lean, and potentially cause engine damage without tuning. 

3) Cadillac ATS 2.0T Intercooler Upgrades

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.

Best LTG Intercoolers

There are two main things that hurt the performance of the OEM intercooler: location and sizing. Being located behind the radiator cuts off the intercooler from airflow, which hurts its ability to cool the fins and coils. In addition, the stock unit is also very undersized. It struggles to perform well in very hot climates, like Arizona or Texas, and quickly becomes heat soaked after repeated runs. 

Heat soaking is when the intercooler becomes too hot to adequately cool the boost, essentially becoming useless. The purpose of upgrading to an aftermarket intercooler is primarily to get a bigger unit that is capable of superior cooling. Aftermarket LTG intercoolers are typically front mounted, which means they are located in front of the radiator rather than behind it. This allows for superior air flow and helps keep the intercooler performing as efficiently as possible. 

The top two units we recommend are the Mishimoto ATS 2.0T intercooler upgrade and ZZPerformance ATS 2.0T intercooler upgrade. Both of these intercoolers are bigger and perform much better than the stock unit. The Mishimoto unit is much bigger and works better than the ZZP unit. But, it is also more than twice as expensive and somewhat overkill for the stock turbo. We suggest the ZZP for stock turbo builds, or the Mishimoto for big turbo builds. 

4) Cadillac ATS 2.0T 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. 

Best LTG Flex-fuel Kits

Flex-fuel kits work by using a sensor installed in the fuel lines to read the ethanol content of the fuel. This sensor is connected to the ECU, and it lets the ECU adjust and optimize parameters to whatever the ethanol content is. More ethanol will mean more aggressive engine mapping, while less ethanol will make it less powerful.

Flex-fuel kits are crucial for several reasons. Not only do E85 pumps sometimes vary widely in their actual ethanol content, but not all gas stations have E85, sometimes leaving pump gas as the only option. With flex-fuel kits, you can run anything from only pump gas to only E85, and anywhere in between (note: most fuel pumps struggle past an E60 fuel mixture). They are very easy to install but must be used with tuning to work.

Earlier we recommended Vermont Tuning and ZZPerformance for LTG tuning, and we also recommend their flex-fuel kits. After purchasing a kit you can get your car tuned for flex-fuel with them, and make even more power. Both the Vermont Tuning ATS 2.0T flex-fuel kit and the ZZPerformance ATS 2.0T flex-fuel kit are similar to each other, with the ZZP being slightly less expensive. With flex-fuel tuning, you can see another 10-15% in gains on top of just standard tuning, making it an excellent ATS 2.0T mod. 

Best Cadillac ATS 2.0T Performance Upgrades FAQ

What are the best Cadillac ATS 2.0T performance upgrades?

The best Cadillac ATS 2.0t mods are tuning, downpipe upgrade, intercooler upgrade, and flex-fuel/E85 tuning. With these mods, you can add more than 25% horsepower to the LTG engine.

How much horsepower does LTG tuning add?

With tuning, you can add 15-20% in horsepower and torque to the LTG engine inside the Cadillac ATS 2.0T. With a flex-fuel kit, you can add even more performance.

How much horsepower and torque can the LTG engine take?

The LTG block is good until at least 600 wheel-horsepower, or about 675 crank-horsepower. The pistons and connecting rods are only good until about 350-375 wheel-horsepower, or about 390-415 crank-horsepower.

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