Best updates for the first generation Audi 4.0t (S6, S7, RS7, A8, S8)
In 2012, Audi revealed the EA824, a four-liter twin-turbo V8 that has been used in the flagship A8, as well as the S6, S7 and RS7. The 4.0t featured a range of power outputs, with different turbos and intake configurations depending on the model. Older cars with this engine are becoming very affordable. Given the sheer power these engines are capable of, they’re a performance bargain.
If you’ve just picked up a new-to-you Audi powered by the first-gen 4.0t, you might be wondering what the upgrade path looks like for that platform. In this article, we’ll go over the best upgrades for the 4.0ti and what power figures you can expect.
The second-generation 4.0t, the EA825, has powered the A8 and RS7 since 2019, and more recently the RS6 Avant, SQ7, SQ8 and RS Q8, as well as some Porsche, Bently and Lamborghini models. This engine is significantly different from the first generation, and we’ll cover the best upgrades in a future article.
Details of the 4.0t engine
The 4.0t engine is a twin-turbocharged V8 engine with a “Hot-V” turbocharger design. In traditional turbocharged V8 engines, the turbos hang from the side of each cylinder head and the intake manifold sits on top of the engine.
Hot-Vee engines are reversed. The exhaust ports are facing inward toward the center of the engine, while the intake manifolds are where the exhaust would normally start. The turbochargers sit in the “V” created by the cylinder heads, and the exhaust travels from the top of the engine to the back and around the transmission.
Hot-V turbo configurations reduce turbo activation time by shortening the distance the air needs to travel. A faster spool results in better throttle response and allows peak torque earlier in the RPM range.
This guide will be divided into two parts. The first half will cover upgrade options for a lower-output 4.0t, and the second will examine the path to the high-performance version found in RS cars and the S8.
Upgrade path 1: S6, S7, A8
The low output version of the 4.0t came in the S6, S7 and A8. Smaller turbos and less aggressive software from the factory resulted in an output of 450 horsepower and 444 lb-ft of torque.
The upgrade path for the low-performance four-litre engine will be very familiar to those who have modified smaller engines from the Volkswagen Group, such as the 2.0 TSI.
Stage 1 ECU Tune
As with other forced induction engines, the absolute best upgrade is an ECU tune. Audi left a lot of power on the table, and a simple remap without additional hardware can produce gains of 80 horsepower and 150 torque depending on the fuel used. Running E-85 can result in even more impressive power gains.
Stage 2 ECU downloads and tuning
Please note that upgrading your vehicle’s downpipes should only be done if your car is being built for track use only! You will not pass emissions tests with downpipe upgrades, and in some areas of the country they are illegal to use on public roads.
To get more power from the stock turbos, the exhaust needs to be modified. High flow downpipes, combined with software, are the next major upgrade that results in significant gains. This combination can result in gains close to 90 hp and 180 lb-ft of torque, depending on the octane and tuning company.
RS Turbos
After doing downgrades, the stock turbos are maxed out. To push the car further, you need to replace them with bigger ones. Similar to other OEM turbo upgrades bolted onto smaller four-cylinder engines like the 2.0 TSI (think IS38 or K04), the low-performance 4.0t needs no internal upgrades when moving to RS Turbos. The robust engine rotating assembly can easily handle the extra power and torque they produce.
Upgrading to RS turbos is not a very invasive process. Instead of replacing the entire turbo, the stock “cartridge” (the compressor housing and turbine wheel) is removed from the exhaust housing. An RS7’s turbo cartridges are installed in the original exhaust housing.
Upgrading to RS turbos allows your low-output 4.0t to have the same power or power over an RS car, depending on the tune. With RS Turbo and downpipes, you can expect more than 650 hp and 630 lb-ft of torque.
If you want to use RS Turbos and keep your car street legal, they can be used with the factory OEM downpipes.
You can get a few horsepower and a couple of exhausts, but it won’t be enough to feel you while driving.
Upgrade path two: RS7, S8
When you’re looking at upgrading an RS7 or S8, you’re starting with bigger turbos. From the factory, this version of the 4.0t makes between 560 and 605 horsepower (the RS7 Performance and S8 Plus get the full 605). The upgrades will be the same as the lower performance engines up to the point of turbos.
Stage 1 ECU Tuning (High Output)
As with the low performance engine, a first stage provides the most bang for your buck. Depending on the octane used, you can see over 110 horsepower and 130 lb-ft of torque gained without any other modifications.
Casualties and stage 2 (high output)
Adding downpipes to free up exhaust flow and combining them with a Stage 2 ECU tune can produce 40 horsepower and 60 lb-ft of torque in Stage 1 on this platform.
Hybrid/large turbos
This update applies to both the low output and high output versions of the 4.0t. Manufacturers like Weistec and TTE take the factory turbocharger housings and turbine and compressor wheels. These turbos are “hybrid” (meaning they retain OEM tuning while delivering power similar to a custom big turbo setup).
The amount of power you can get with a turbo hybrid setup varies significantly. You can generally expect to see more than 800 horsepower at the wheels, with some TTE systems capable of over 1000 horsepower.
Modes of support
At all stages, you can add additional mods for appearance, sound, and some modest power gains. No piece of hardware will have as much impact as the downpipes on this generation of the 4.0t, but these supporting modifications will improve your driving experience.
TCU Tune
Tuning the transmission will not provide any power gain, but it will optimize and improve the way the transmission performs. You can expect faster acceleration, better shift points and more control over the transmission in manual mode.
intake
A variety of intake options are available for the 4.0t. An intake will allow better airflow to the engine, increase the turbo and induction noise you hear while on the throttle. The 4.0t’s twin intake manifolds will look pretty awesome when you pop the hood.
Heat exchanger upgrade
The first generation 4.0t is used to heat the air in the exchanged water to lower the air intake temperatures. When your car makes higher boost pressure and makes more power, upgrading to a larger, more efficient intercooler can help prevent heat from being absorbed.
Cat Back Exhaust System
While upgrading the downpipes leads to more power, they don’t do much in terms of improving the engine sound. Installing a cat-back exhaust system can give you a much more aggressive sound, ranging from a slight rumble to a loud boom, depending on your taste.
Alex’s Autohaus 4.0ta Engine Upgrades
If you’re ready to start modifying your Audi V8, call Alex’s Autohaus and speak with our tuning experts today! Our team will advise you on the software and hardware to achieve the goals you have for your car. Call us or stop by our Midvale, Utah store today!
