BMW's S65 engine in the 2008-2013 E90/E92 M3 is well-known for its amazing sounds and high-revving ability. With 414 horsepower from the NA V8 it's no slouch, even by todays standards. However, some look to bolt-on performance mods to take the S65 M3 to the next level. In this guide, we'll discuss a few of the best engine mods for the S65 V8 powered M3.
S65 M3 Bolt-On Mods
In this post we will primarily discuss the following performance mods that we believe are the best for naturally aspirated M3's:
- Test Pipe / Exhaust
These 4 mods offer some of the best results for the dollar while remaining NA. We'll break down each of these mods below. At the end we'll briefly discuss a few other options for the S65 engine. Things like forced induction and stroker kits. It's probably stuff that we will expand into posts of their own in the future. Anyways, let's dive in and discuss the best BMW S65 engine modifications.
1) BMW S65 Test Pipes & Exhaust
We're lumping exhaust in general into this section. However, the primary focus is really the test pipes ("cat-delete pipes"). This is where the actual performance gains come from when it comes to S65 exhaust systems. The rest of the exhaust may offer some power, but full exhausts can get pricey and are more for sound than anything else. We won't get into the specifics here. If you want a full M3 exhaust simply find the one that you believe sounds best. Those who don't care about sound as much and just want performance should go straight for the test pipes.
S65 test pipes actually allow you to cut out the restrictive catalytic converters. The test pipes then bolt onto the portion of the exhaust you cut away. S65 horsepower gains can come in the ballpark of 15-25whp and wtq. It's an impressive power gain for a pretty cheap mod on a NA V8 engine. Why do BMW S65 test pipes add so much power?
Back-pressure from the cats is counter-productive to making power. This is especially true on the E9x M3 due to its very high-revving nature. Removing the cats allows the engine exhaust gases to escape faster and more efficiently. Power gains are to be had throughout the entire rev range, but they're definitely most impressive towards the top-end.
Drawback to S65 Test Pipes
Unfortunately, the impressive power gains don't come without a flaw. Removing the cats may cause issues passing emissions testing. You'll also notice a SES light which can be corrected with a tune or other software. This may save you during emissions inspections if your state or country simply checks the OBDII. However, tailpipe emissions testing will quickly fail. Additionally, the lack of cats will be noticeable during a visual inspection.
This may be avoidable for some while it will cause a headache for others. S65 test pipes are still debatably the simplest, cheapest, and most effective performance mod for the M3.
S65 Test Pipes Sound
You'll also notice a slightly deeper, more aggressive exhaust note with the test pipes. Most will find the sound still remains modest for daily driving and highway cruising. However, it can quickly get pretty loud depending on other S65 exhaust mods. Stick with just the test pipes if you want to keep the S65 sounds modest.
Buy Here: VRSF S65 Stainless Steel Test Pipes
$ Per HP: $12 - 20 per HP
2) S65 M3 Tuning Mods
Tunes are another highly effective mod to squeeze more power from the E90/E92 M3 engine. They're a bit pricier than the other primary S65 mods on this list. However, tunes come with many added benefits on top of the power they offer. For one, they'll help unlock the full potential of other mods like the test pipes or an intake. Most tunes also offer the option to raise the rev limit to 8,400 - 8,600 RPM's.
S65 tunes increase power in a few ways. They change many parameters like fueling, timing, VANOS, etc. These little tweaks can help pick up about 10-20whp on the S65 engine. Not too bad. On top of that, they may unlock some extra power from other mods. If you're looking to do several mods we highly recommend going with at least the intake, test pipes, and a "stage 2" tune. Typically stage 2 S65 tunes require those two mods at least.
Overall power gains with a stage 2 tune, intake, and test pipes can often fall in the ballpark of 40-50whp. Those coming from or familiar with forced induction may snarl at those gains. However, it's highly impressive for a few basic mods on the NA S65 engine. Some NA engines only manage to pick up 10-15whp before needing much more expensive mods.
Best S65 M3 Tunes
There are quite a few offerings out there for S65 tunes. However, we believe the following tunes offer a good balance of performance, quality, and price:
- BPM Stage 1 & 2 Tune
- Turner Motorsports Stage 1 & 2 Tunes
Both of these tunes are well known and proven on the S65 M3. Prices come in around $740-920 depending on stage 1 or 2 and other possible add-on options. They both require cat-delete test pipes for their stage 2 tunes. You'll also notice the best results with these stage 2 tunes that are setup to account for the additional mods. Expect the stage 1 tunes to fall on the lower end of the spectrum at 10-15whp. Stage 2 tunes will typically pick up somewhere around 15-20+whp.
S65 Tuning Price: $740 - $920
$ Per HP: $45 - 90 per HP
3) BMW S65 Performance Intake Mods
Upgrading your S65 intake is another great way to pick up some extra power. You may also hear S65 performance intakes referred to as intake kits, cold air intakes, etc. They all essentially mean the same thing and accomplish the same goal. Help the S65 M3 breathe air in more efficiently. It's a great mod to couple with the test pipes and tune as we discussed above.
After all, air and fuel are really the recipes to making more power. Get air in and out as quickly and efficiently as possible. Then adjust the cars computer to accurately account for these changes with a tune. Intakes for the S65 M3 provide power gains in the ballpark of 5-8 horsepower. Not quite as impressive as the above two mods, but not bad for a relatively simple and cheap intake.
Intakes are a pretty simple mod that almost anyone can install at home in their driveway pretty quickly. Most are also familiar with S65 performance intakes so we'll leave it at that for now.
Best BMW S65 Intakes
As with tunes, there are plenty of great options out there. Most S65 intake mods will accomplish the same goal, so we recommend shopping by your preferences. Some may prefer the cheapest option to squeeze out a bit more power. Others like the more expensive options that add some awesome looking carbon fiber to the engine bay. Either way, as a starting point - check out some of the following S65 performance intakes:
- Dinan Carbon Fiber Intake System - $700
- Eventuri Carbon Fiber Intake Kit - $965
- Magnum FORCE Pro 5R Stage 2 Intake - $350
Again, there are other options out there. The above list gives an idea of the price points of some different intake systems. Fancy carbon fiber intakes like Dinan or Eventuri often run $500+. Simple intakes like Magnum FORCE can be found much cheaper, but don't offer the same eye-candy.
S65 Intake Price: $250 - $1,000+
S65 Intake $ Per HP: ~$30 to $100+
4) S65 M3 Upgraded Pulleys
Underdrive pulley kits are another relatively simple, inexpensive mod to pick up some extra performance from the S65 engine. To be honest, we're a bit less familiar with these mods as it's not a common discussion for turbo engines. However, the S65 V8 engine can see gains in the ballpark of 5-10 horsepower with an underdrive pulley upgrade.
The idea behind S65 pulley upgrades is to limit drag from the accessories. This helps the engine run more efficiently and transfer more of the power back to the M3's rear wheels. Basically, the accessories require less power to turn.
Anyways, if there were one mod on this list that we would personally skip it would be the underdrive pulleys. That's primarily since we're more comfortable with the above mods since it's stuff we deal with all the time for the turbo BMW engines. Either way, there's a little power to be had from upgrading your S65 M3 pulleys.
Any option from a quality, reputable company is going to be basically the same thing. You can find these pulley kits for about $275-350. Check out options from Macht Schnell, Active Autowerke, etc.
S65 Pulley Price: ~$300
S65 Pulleys $ Per HP: $30 - 60 per HP
Other BMW S65 Performance Upgrades
We'll keep this section pretty short as we mentioned initially. We're just tossing out a few other ideas for those looking for bigger HP gains on the S65 M3. These mods are typically a lot more expensive, involving, or complex. Or a combination of all those things. We'll revisit these mods in posts of their own down the road. Anyways, consider the following S65 M3 upgrades if you're looking to make serious power:
- Forced induction (superchargers or turbos)
- Stroker kits
- NOS or WMI
An S65 supercharger or turbo kit is going to allow for highly impressive performance gains. However, depending on how far you want to go you may also need some internal upgrades, supporting mods, etc. The price of these kits often start around $5,000 to $10,000. By the time all is said and done you'll probably end up spending about 2x the cost of the kit.
Stroker kits increase the S65 displacement to 4.4L or 4.6L. There are lots of other cool things you can add or modify while the engine is out for these mods. You'll also have on heck of an awesome naturally aspirated engine. However, costs are likely going to end up in the $10,000 to $15,000+ ballpark.
Nitrous and water methanol injection are much cheaper than the two previous mods. However, these upgrades come with risks of their own and a proper, safe setup is important. As such, these S65 mods should be left to the knowledgeable owners.
S65 M3 Bolt-On Engine Upgrades Summary
The BMW S65 is a fairly potent power-plant straight from the factory with 414 horsepower. It also responds pretty well to power mods compared to many other naturally aspirated engines. A few basic S65 mods like test pipes, tunes, intakes, and pulleys can pick up about 40-50whp. Not bad at all. However, those looking for more power will find themselves spending a lot on S65 forced induction, stroker kits, or other options.
E9X M3's with the S65 V8 engine are excellent all-around cars. However, straight-line performance and big power aren't really the focal point of the M3. They're definitely not slouches in that regard, though. That said, if power and straight-line performance are the end goal there are much better platforms out there. Regardless, a few basic bolt-ons can really wake up the S65 M3. It can also make plenty of power for those willing to spend the money.
What mods do you have on your S65 M3? Are you considering any?
Drop a comment and let us know!