The S63 is already a highly capable engine even with the stock turbos. We wrote about the S63 stock twin turbos abilities in our guide about building a 700+whp S63. However, it's simply not enough for some. A set of upgraded twin turbos has the ability to push the S63tu M5 & M6 into a totally different ballpark. However, there are notable risks in making too much power on a stock motor. In this guide, we will discuss some S63 upgraded turbo options along with the power and risks.
BMW S63tu Horsepower Limits
Before diving into the turbo discussion let's knock out some of the less exciting info. First off, it's tough to put upper limits on any engine. There are a lot of factors at play. Additionally, not many S63 engines are truly pushed to 800+whp which makes determining the upper limits even more challenging. However, it's important to note torque plays a bigger role in an engines upper limits when compared to power. The generally accepted safe limit for the S63tu is about 700-750wtq.
Again, this isn't a perfect science. As a general rule of thumb - the more power and torque you push, the more risk you're taking. There is definitely still risk at 700-750wtq. However, there are a few ways to mitigate the risk when pushing the S63 towards its limits:
- E85, race gas, and/or meth injection
- Good, conservative tune
- Limit mid-range torque
E85 is awesome for high performance applications. However, the S63 isn't as well suited to E85 as some other BMW engines. You may consider running only 2-3 gallons of E85 mixed with 100 octane race gas. Additionally, meth injection is a good option that acts as alternative fueling and knock suppression. Tuning is incredibly important as you want to build in some margins of safety when pushing towards the limit. You want to ensure AFR's aren't leaning out at all, timing isn't too aggressive, etc. Finally, let's discuss mid-range torque in its own section below.
BMW S63 - Limiting Mid-Range Torque
This isn't the absolute best example, but it's something we can work with. First, you'll notice peak power is higher than peak torque. That's good. Additionally, peak power of 809whp occurs right in the ballpark of 6,000 RPM's. We can use the basic equation below to determine the exact torque when peak power occurs:
WTQ x RPM / 5252 = WHP
708wtq x 6000 / 5252 = 809whp
This S63 M5 only needed 708 wheel torque to make 809whp at 6,000 RPM's. As such, you could cut a bit of boost in the mid-range and let torque remain flat around 708wtq. You'll still make the same peak power. However, you will sacrifice some power in the mid-range, so it would be a slightly slower car compared to the above dyno chart. Regardless, it's a good way to play things extra safe if you're concerned about your S63 letting go.
Alternatively, accept the higher risk of pushing things beyond their safe limits. Or spend the money up-front to have your engine built. There's not necessarily a right answer so we won't weigh in on that. Use your own judgement and decide what makes the most sense for you. Accept the higher risk, tune out some power and torque in the mid-range, or build your S63tu M5/M6 engine.
A Few Other Considerations
As a final note, we highly recommend doing things the right way if you intend to get upgraded turbos. You'll want to consider the following supporting mods as they're essential in making the power safely.
You want to ensure the S63tu is breathing efficiently. That means getting air in and getting it out as efficiently as possible. Catless downpipes will help reduce back-pressure and make the turbo and engines job easier. Intakes allow the engine to pull in the necessary air-flow. Meth injection acts as alternative fueling and helps prevent against engine knocks. Finally, the M5 and M6 DCT is known to begin slipping around 650wtq. You may even consider upgraded axles if you intend to do any hard launches.
Lastly, you'll likely want or need new spark plugs and ignition coils to prevent the S63tu from misfiring after the turbo install. We highly recommend opting for 1-step colder NGK 97506 spark plugs.
BMW S63 Upgraded Twin Turbo Options
Alright, with that info out of the way let's jump into the more exciting stuff. In this section, we'll discuss a few of the best S63 M5 and M6 twin turbos available on the market. We'll split this into two sections:
- 700-800WHP Twin Turbos
- 800+WHP Twin Turbos
We always recommend keeping turbos within their efficiency range as to not push them to their absolute limit. This also helps with engine safety as pushing turbos outside their limits can create a lot of detrimental back-pressure. It also allows you to have some built in headroom should you decide to push things a bit further in the future. That said, don't get too much turbo to the point you're sacrificing a lot of turbo spool if you don't intend to use the turbos true potential.
It's just a quick point to consider prior to purchasing S63 twin turbos. Know your goals and choose a turbo that safely meets those goals. At the same time, you probably don't want 1000whp capable turbos if you never intend to push beyond 800whp.
700-800WHP S63tu Twin Turbos Upgrade
This is a solid, modest ballpark for the S63tu on upgraded turbos. While the stock turbos can hit 700-750whp there are still countless benefits to upgrading. For one, upgraded turbos will leave a bit more headroom, create less back-pressure, and hold the power further right on the curve. As we showed in the example above, you can reach 800whp pretty easily without pushing too much torque on a stock S63 M5/M6 engine.
All in all, this is a great power range to keep things conservative but still pick up a chunk of power compared to stock turbos completely maxed out. Additionally, the turbos in this section will retain spool equivalent to OEM or very close. Solid power and quick spool.
1. S63 Weistec W.3 Twin Turbos (750-800whp)
We've written about Weistec turbos for a few other BMW engines, too. Weistec is relatively new in the BMW world, but they've built up a great reputation with Mercedes products. As with most turbos we'll reference in this section, the S63 Weistec W.3 option uses the stock turbo housings. They're then machined to accept larger 5-axis CNC machined impeller wheels.
Weistec claims these S63tu turbos are good for up to 890 horsepower. Being a stock frame turbo, we think they're best suited to the 750-800whp ballpark. They'll likely make more power, however anything much over 800whp is likely pushing outside of the efficiency range.
2. S63 Vargas Turbo Tech Twin Turbos (750-800whp)
Vargas (VTT) has been around the BMW turbo game for quite some time. They were a newer company in the earlier days of the N54, and have come a long way since then. Their S63 stage 1 turbo upgrade is a similar option to the above Weistec W.3 turbos. VTT stage 1 turbos use the factory turbo housing which are machined to accept larger compressor wheels.
Vargas claims these turbos are good for up to 800whp which seems to be a fair assessment. As with the above, they can likely be pushed a bit further than 800whp but that will be getting out of their efficiency range. Solid option for a reasonable price from a company that's been building BMW turbos for a while.
3. S63 Pure Stage 1 Upgraded Turbos (750-800whp)
Credit to Pure for the above dyno image. We'll circle back around to the dyno in a minute. Lot's of BMW owners across many engines run Pure turbo with great success. Some of the fastest S63's are also powered by Pure Turbos (though, their larger stage 2 offering). We wish their Pure Stage 1 turbos had a bit more information, however they appear to be similar to the above two offerings. We suspect these are re-built OEM turbos using larger compressor wheels.
As seen, this S63tu is making 820whp with the Pure Stage 1 offering. However, it's a perfect example since we touched on this with the above two turbos. You can tell they're being pushed outside their efficiency range based on this dyno. Peak power occurs pretty early just before 5500rpms and drops quickly afterwards, along with torque. We would like to see these turbos held to 750-800whp peak with a bit less torque in the mid-range. Quality product with proven results for a very good price.
800+WHP S63 Upgraded Twin Turbos
Some of the turbos in this section will be capable of making 900-1000+whp. However, few S63's have ventured into that territory. Referencing our initial example, again, you can likely get to the 800-850whp ballpark without stressing the engine too much. At least from the perspective of torque. These turbos will also be capable of making a lot of mid-range torque. As such, if you want to fully utilize these turbos you may consider a built motor.
Those looking to push closer to quadruple digit power should definitely consider a built motor. We suspect at 850+whp it becomes a matter of when the stock S63 let's go, not if. Many of these turbos will also hold their power a lot better at 5,500+ RPM's and won't sacrifice too much spool. Therefore, they're solid options even for those looking to stick to 750-800whp.
1. S63 Weistec W.4 Upgraded Turbos (850-1000+whp)
We'll open up this section with an offering from Weistec once again. Right off the bat - you likely noticed the price point of these S63 W.4 turbos is tough to swallow. It's a huge jump from the turbo offerings in the previous section. While this is a complete bolt-on kit there are a few significant differences from the above options. These are no longer stock frame turbos. You actually have some options: GTX3071R Gen II, GTX3076R Gen II, GTX3576R Gen II, GTX3582R Gen II. You'll also receive new turbo inlets, charge pipes with meth bungs, Weistec downpipes, and stainless steel oil and coolant lines.
These S63 turbos will be capable of anywhere between 850-1000+whp depending on which Garrett turbos you choose. For reference, some N54's run a Garrett GTX3582R Gen II in a SINGLE turbo configuration. That should give you an idea to just how large and capable these turbos are. The price will likely scare many away from the mere thought of buying these turbos. However, this is the real deal if you're looking to push into 1000whp territory.
2. S63 Pure Stage 2 Twin Turbos (800-850whp)
This list wouldn't be complete without mention of S63 Pure Stage 2 turbos. These turbos power all of the fastest S63/S63tu M5 and M6's in the world. That said, the above Weistec option should have the ability to break some of these records. Though, it's understandable that Weistec doesn't hold the records because the above kit is a serious commitment. We're not even sure how many, if any, of the Weistec kits are out there.
Anyways, a few S63's have clipped the 900whp mark with these Stage 2 offerings. However, we believe that was accomplished with NOS. Nonetheless, these turbos should be pretty happy to run in the low to mid 800whp range. Also, the price is appealing for that kind of performance. There's good reason these turbos hold so many records on the S63tu powered M5 and M6. Proven performance for a good price.
BMW S63 Upgraded Twin Turbo Summary
If you're in the market for upgraded turbos on your S63tu M5 or M6 then the above options are some of the best choices on the market. However, upgraded turbos don't come without notable risks. 700-750wtq is generally a safe limit for the S63. It's possible to make 800+whp while limiting mid-range torque to keep the engine within its safe range. However, even then, the risks are still there.
Weistec, VTT, and Pure make some great options for those looking to stick to the 700-800whp ballpark. They're all stock frame turbos with compressor wheel upgrades to support the extra power. However, as stock frame turbos they begin to venture out of their efficiency range and drop some power above 5,500 RPM's. Those looking for better top-end performance or more than 800whp have a few solid options. The Weistec W.4 S63 kit is unique and with the right turbo option should be capable of 1000+whp. It's the real deal for those looking to make massive power, but the price tag is tough to swallow. Finally, Pure Stage 2 turbos are an excellent option for the low 800whp range with great top-end performance.
It's tough to go wrong with any of the above options. Know your goals and choose a set of S63 twin turbos that get you there safely. Most importantly, mod away and have fun.
Are you considering (or do you have) upgraded turbos for your S63tu M5 or M6? Leave a comment and let us know.