Alright, this is a tough article to write after we've written so much of this content for turbo BMW engines. The N52's performance potential is often overshadowed by that of the N54 and other turbo BMW engines. When it comes to N52 bolt-on mods, many will simply say, "buy a turbo BMW". However, in this guide, we will discuss a few of the best performance mods for the N52. And then at the end we'll tell you to buy a turbo BMW. Nonetheless, let's jump in and discuss the best power mods for the BMW N52 engine.
1. BMW N52 3-Stage Intake Manifold Upgrade
We're starting off with one of the simplest and best N52 performance mods to increase power. However, if you're a 330i N52 owner then you already have this "mod" straight from the factory. The 330i makes 252hp from the factory whereas the 325i and 328i come in at 215hp and 230hp, respectively. They're all the same exact engine, however the 325i and 328i received a "de-tuned" intake manifold.
Simply replacing the intake manifold with the OEM 330i intake manifold will take any N52 into the 250hp ballpark. As such, 325i models may pick up 30-35hp and 328i models may see gains up to 20-25hp. It's also a direct bolt-on upgrade since it comes directly from an N52.
How 330i Intake Manifolds Add Power
The 3-stage 330i intake manifold uses two differential air control valves (DISA valves) to direct the incoming air to the proper cylinders. As some may understand - not all cylinders are on the same cycle. Therefore, different cylinders need air at different times. The 3-stage intake manifold directs as much air as possible to the cylinders where the intake valves are open at a given time. This results in impressive performance gains for the N52, especially on the top-end.
N52 Intake Manifold Horsepower Gains: ~20hp (328i) and ~30-35hp (325i)
Buy Here: N52 330i 3-Stage Intake Manifold
2. BMW N52 Performance Intake Upgrade
The second N52 mod we're discussing is a performance intake. BMW's N52 engine uses an intake designed to minimize noise rather than maximize airflow. There are certainly gains to be had with an upgraded intake. However, we don't buy into some of the quoted horsepower gains. This states the aFe N52 intake provides gains up to 12hp and 15tq. We're calling complete BS on that. Full bolt-on twin turbo N54 engines with dual cone intakes would be lucky to see power gains in that ballpark. No way the N52 is picking up that kind of power. Sorry.
Realistic horsepower gains with an N52 performance intake fall in the 0-5hp ballpark. You'll probably pick up a few horsepower, but even 5hp is pretty optimistic. That said, you may gain a bit more than 5hp in the lower RPM range, but don't expect massive peak torque gains. Intakes are still a solid overall performance mod for the N52. Even just a few horsepower gain is respectable for a naturally aspirated engine with a basic bolt-on part.
N52 Performance Intake Power Gains: 0-5hp
3. BMW N52 Tunes
Tunes are often at the forefront of discussion when it comes to getting more power out of your BMW. They're showcased all over the place for their ability to pick up 50-100+ horsepower on certain turbo BMW engines. However, tunes are a bit different on naturally aspirated engines. One of the most popular tuning options for the N52 engine is the Active Autowerke's N52 performance tune. Gains of up to 15hp are possible with the AA N52 tune. The N52 BMS Power Box Performance Tuner was once a popular option as well with gains up to 10hp. This product is now discontinued, however you may be able to find some used examples.
Ultimately, the N52 AA tune is one of the most common and best tuning solutions for the N52 engine. The tune may also assist in maximizing the performance benefits of other mods, such as intakes, headers, and 3-stage manifolds. Most should expect tuned N52 horsepower gains of around 5-10hp. Again, more power may be possible with the full list of performance mods. All things considered, this is a respectable power improvement for a $459 tune on a naturally aspirated engine.
N52 Tune Horsepower Gains: Up to 15hp (most will likely pick up 5-10hp)
4. BMW N52 Headers Upgrade (Exhaust Manifold)
Following the 3-stage intake manifold, headers are generally the second best bolt-on N52 mod. The factory exhaust manifold is highly restrictive and results in a build up of back-pressure. Reducing that back-pressure with an upgraded exhaust manifold helps the engine run more efficiently. This is because a reduction in back-pressure allows exhaust gases to escape faster. In turn, the engine is able to get more fresh air into the cylinders. We don't want to get too technical, but reducing back-pressure essentially reduces exhaust gas reversion. This is the process of exhaust gases actually being pulled back into the cylinder, which reduces torque created during the combustion process.
Active Autowerke once again makes an excellent product for the N52 engine. The AA N52 exhaust headers are capable of picking up 15-20whp (~20-25hp). Pretty darn impressive gains. As with most other N52 mods, the upgraded headers will show their most impressive gains when coupled with the 3-stage intake manifold.
Additionally, an upgraded exhaust manifold adds some excellent sounds to the N52. As if BMW's naturally aspirated inline 6 engines don't already sound good enough. Most say the upgraded headers are pretty modest sound-wise with an otherwise stock exhaust. It definitely adds a deeper, aggressive note, though. However, upgraded headers combined with our next mod may be too loud for some.
BMW N52 Exhaust Headers Horsepower Gains: 15-20whp (20-25hp)
5. N52 Exhaust System
Full exhaust system performance gains can be up for debate (as with the N52 intakes). Even on the twin turbo N54 engine we are hesitant to recommend exhaust for performance benefits. Part of that, though, is due to the fact the N54 can pick up so much power with cheap mods. Exhaust is relatively expensive on the N54 for the modest power gains.
When it comes to the N52, power gains will also be modest. However, even small gains on naturally aspirated engines can go a long way. A fully catless exhaust may pick up roughly 5-7hp. Although, fully catless exhausts definitely aren't for the faint of heart. The sound will be very loud and you'll likely piss off the neighbors. Also expect some drone so a fully catless exhaust isn't always a great option for daily driven N52's.
Of course, there are tons of different ways to setup an aftermarket N52 exhaust system. The possibilities are endless with different mid-pipes, cats, mufflers, etc. However, any form of catted performance exhausts will likely only pick up 2-3hp. As such, an exhaust is a great upgrade if you're looking for some awesome and unique sounds. A few horsepower is simply the cherry on top, but we don't recommend this mod for power alone.
N52 Exhaust Horsepower Gains: 0-7hp
BMW N52 "Full Bolt-On" Performance
For the sake of this paragraph, we're going to refer to the above 5 mods as "full bolt-on" (FBO) for the N52 engine. We'll also reference this forum post as it's got some great dynos and comparisons with different mods. Dynos are meant for baseline comparisons so it's tough to compare different cars on different dynos. Nonetheless, that 328i with a tune, 3 stage intake manifold, and headers made an impressive 240whp. If you factor in a standard 15% drive-train loss that puts the 328i at about 282hp. That's a pretty good result to pick up roughly 50 horsepower on a naturally aspirated engine.
Assuming the owner also had an intake and exhaust (to make the N52 FBO) we would expect power to maybe be about 5whp more. Again, the biggest N52 power gains really come from the headers, manifold, and tune. Intakes and exhaust may add some power, but they're probably better mods for those looking for improved sounds.
Ignore Everything We Just Wrote
Now, we have to do this. My first car about 11 years ago was a 1993 Mercedes 300e. I loved the car, but being a young person I wanted the car to be more than it was. I asked for advice on performance mods on several Mercedes forums. No one was particularly helpful and everyone said it wasn't worth doing performance mods to that car. It made me angry. However, I eventually realized they didn't tell me what I wanted to hear. Rather, they told me what I needed to hear.
It's time to say what some people need to hear about the N52 engine. It's not a performance engine. However, N52 powered BMW's are awesome all around cars. Fun, sporty, respectable handing, decent styling, OK power for a naturally aspirated engine. Don't try to make the N52 something it will never be. It's not a straight line, powerful engine. Stick to suspension and/or weight saving mods, or move onto a more capable engine.
The only reason we say this is because many of us are hit with the power bug. It's an endless cycle of always wanting more. If you think this might be you - just buy an N54, N55, or any other larger, forced induction engine. Otherwise, you may find yourself $3,000+ deep in mods only to realize the N52 will never meet or exceed your goals. Of course, the easy way out is stating the N54 is too unreliable. That's not totally true. For the amount you'll spend on the five N52 mods listed in this post you can knock out a vast majority of preventative maintenance on an N54 or N55. The cost to buy the cars up-front isn't all that different.
BMW N52 Performance Mods Summary
Generally, the 3 best bolt-on engine mods for the N52 are headers, the 330i 3-stage manifold, and a tune. These mods alone will likely put the N52 in the ballpark of 270-280 horsepower. Pretty respectable gains for an older, naturally aspirated engine. Two other popular mods are exhausts and intakes, however the performance gains may be up for debate. You may pick up a few extra horsepower with each, but the cost may not justify the performance gains alone. As such, we believe exhausts and intakes are best suited to those looking for sounds.
All things considered, N52 powered BMW's are fun, sporty cars. However, the N52 is not a performance oriented engine. We know some will hate us for saying this, but stick to suspension or weight saving mods. Alternatively, if you're interested in power, find a car and engine better suited to performance mods.