When it comes to performance potential, most people tend to forget about the 325i, 328i and 330i, since these are the less popular siblings of the mighty E90 and E92 335i. While most people would give you the lazy answer of “buy a 335i”, we’re actually going to answer the question of how to make power out of an BMW N52 non turbo six. If you have an E90, you could have as little as 218hp at your disposal from the factory. In this piece, we’ll show you what power mods will easily boost your output to 288hp or more.
We’ll start with the obvious – an intake.
*Please note that many of these modifications are not emissions legal and should only be considered for true track-only race car builds. Be sure to check local and federal regulations for your area.
#1 BMW N52 Intakes
The factory intake isn’t exactly flow-optimized – it’s been designed with minimizing noise in mind.
Moving from one end of the spectrum to the other, we’ll start with Injen Technology’s intake for the N52. Featuring a heat shield, large, high flow conical filter element and streamlined tubing, the Injen Intake for BMW 128i, 328i and 330i yields a gain of 8whp / 6wtq, which isn’t bad at all for a nonturbo car.
Check out how the power is increased across the entire rev band. While it is just 8whp, it is an increase that’s there across the entire rev range.
One of the newest-to-us options that we’re pleased to now offer is from Dinan Engineering. The Dinan Ram Air Intake for E9X 328i is a true Ram Air conversion utilizes your stock airbox, keeping intake air charge temperatures down and enhancing power.
The Dinan Ram Air Intake for E9X 328i is a bit different in that it requires you to modify the factory airbox to convert it into a proper performance part.
Here’s how the airbox looks with the Dinan Ram Air conversion kit installed. Notice that outlet on the bottom? That’s your Ram Air inlet.
The port on the bottom of the airbox is now fed from this metal box located behind the foglight grille, a-la-E9X-M3.
This system is good for 7whp/6tq Not to mention it looks perfectly at home under the hood.
Speaking of things that look at home under the hood, another option for the N52 is offered by BMW Performance. The BMW Performance Intake for BMW E9X 328i features a larger air duct with a carbon fiber lid to give the car a sportier underhood appearance than stock.
Horsepower gains are more conservative than other systems, but darn it looks good.
Last, we have the aFe Stage 2 Si Intake for BMW N52 328i / 330i and 128i models. Offering by far the greatest horsepower gain, the aFe intake yields a power bump of 12whp / 15wtq, which is by no means bad for a naturally aspirated car.
The sealed airbox features a conical type filter element in the housing, increasing surface area, allowing for greater airflow, and the rotomolded airbox with carbon fiber lid looks as good as it performs.
Upgrading with a cold air intake is only half the battle for your N52 – we still need to talk about your intake. Oh, you thought we were done there? Not yet.
#2 BMW N52 330i “HO” Intake Manifold Upgrade
By far, the single biggest horsepower gain for any N51 or N52 is the BMW N52B30H0 Intake Manifold Conversion Kit for BMW 3-Series, 128i & Z4 [E82/E85/E89/E9X]. See, in all the non-M and non-turbo 3-series, BMW used basically the same engine with a detuned intake for lower spec models. Replacing your stock intake manifold with the N52B30H0 manifold will bump your output up equivalent to 250hp from the factory, 260hp if you’ve got a tune for it and more with further modifications.
What makesBMW N52B30H0 Intake Manifold Conversion so awesome is that because it’s an intake manifold from the 2006 E90 330i, it is a direct, bolt-on upgrade to the other cars with the N52 engine – 128i, 325i, 328i, 528i, and Z4 3.0i. While other lower-trim cars used a single-stage intake manifold, the 330 came with a more advanced 3-stage manifold with electronic valves to direct air to the cylinders that need it most, which on a 325i or 328i, translates to a significant power gain.
How The Manifold Makes Power
The 330 manifold uses two electronic DISA valves (Differential Air Control) to direct incoming air to the cylinders that need it most by diverting air away from cylinders that have their intake valves closed. The system works based on RPM range to fill each cylinder with as much air as possible while the intake valves are open. With more air volume and fuel adjustments you can extract more power from those cylinders at any given RPM. The standard and medium output N52 engines make do with the old-fashioned single stage system that only works to boost torque in the mid-range. With the additional DISA system you can extract much more power, especially at high RPM. We did our first development on this system in 2006 and it has been one of our top N52 performance upgrades ever since.
Have questions about upgrading your intake? Ask our team of Mod Experts – give em a call at 714-582-3330, chat live at ModBargains.com
#3 Engine Management (A Tune) BMW N52 330i “HO” Intake Manifold Upgrade
Our favorite engine management option is the BMS Power Box tuner for BMW N52 128i, 328i & 528i models. Good for 8-10whp / 8-10wtq on its own, the Power Box is a plug-n-play tuner that does not rewrite your ECM, thereby leaving no trace on the ECU if you remove it later on – this device remaps the throttle and other ECM settings to get the car to peak performance.
Check out the dyno sheet below.
Unfortunately, if you live in California, this isn’t an option.
However, that’s not to say you can’t tweak things to make them more fun – one of the things we’ve heard people rave most about believe it or not, simply alters throttle response relative to how hard you’re pressing the gas pedal – the Sprint Booster for BMW E9X & E82 1-Series.
From the factory, your throttle pedal’s settings are overly conservative – with these electronic throttles, you’re not getting a 1-to-1 response at the throttle when you stomp the pedal – sometimes you get as little as 70% throttle when you sink your foot to the floor with today’s electronically controlled throttles. So what the Sprint Booster does is alter how the throttle itself responds to the pedal, making it a more direct response, which in turn makes the car much sharper, and a hell of a lot more fun to drive.
Check out the explanation video above, as it kind of needs to be explained, but what we can tell you is that this simple device will give you a serious kick in the pants you’ll definitely notice and much snappier, more responsive car.
Regrettably, without removing the ECM, besides the BMS Powerbox, there really aren’t many options for overwriting the ECM.
If you’re looking at a way to get more out of your N52’s ECU, talk to our team of Mod Experts. Call us at 714-582-3330 today.
#4 Loud Pipes Save Lives – More Power with a HEADER
Reference Photo of Active Autowerke Race Headers Installed on N54 for Illustration Purposes
After the intake manifold, the next biggest source of power for any NA BMW N52 engine build is going to be a header. The header, or exhaust manifold, is what directs exhaust gases out of the motor and into the rest of the exhaust system. The OEM header is extremely restrictive, with hard bends rather than streamlined bends and constrictive tubing with high-density catalytic converters. Replacing the OEM header with an aftermarket high flow header like AaFe Power Catted Headers for BMW N52 328i, 128i will yield a massive gain of more than 16whp/18tq, and will be especially potent if paired with a high flow intake.
A set of aFe Power Catted Headers for BMW N52 328i, 128i is somewhat emissions friendly, in that there’s absolutely no racecar unburnt fuel smell like you’d expect of a un-filtered race header, and they’re street legal for use in much of the USA – of course, check local laws/regulations.
As you can tell from the Dyno graph above, a header makes a serious difference in horsepower, and that’s where you’re going to want to look if you genuinely want to make power. Not only do headers make a ton of power, but they generally sound pretty badass in a way that an exhaust system alone simply can’t do.
As with anything that alters the catalytic converters, check with your local laws and regulations to see what’s street legal in your area, but if you’re building a racecar, this is the way to go. Ready to order? Have questions? Consult the Mod Experts at 714-582-3330 or chat live at ModBargains.com
#5 An Exhaust System
After discussing headers, we can’t help but talk about the obvious – an exhaust. Not only will an exhaust free up horsepower, but an exhaust system gives your car the auditory character that announces you’ve arrived, and visual flair that sets your car apart from the crowd. Check out the sexy quad tips on the E90 328i above (Remus Sport Exhaust for E9X with Quad Tips)- see how great that looks? It’s not often you see quads on a 328i.
The system fits both E90 and E92 models, and can be had in dual exit for quad tips – or single exit as factory.
The Remus Single Exit Exhaust for BMW 328i offers great sound and moderate power gain with those same great looking Remus tip options, but configured in a single exit twin tip setup, as factory for those who prefer that look.
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Another great sounding option is the Active Autowerke Gen 2 Exhaust for E9X 328i
Between the midpipe and exhaust, you’ll pick up 5whp/5wtq approximately across the rev band.
Whatever your taste, there’s an exhaust system that’s right for you that will give you the look and sound you’re after. Consult a Mod Expert for more information – call 714-582-3330 or chat live at ModBargains.com
So that’s five… between an exhaust, a tune, intake, intake manifold and a header, you can easily take a 218hp 325i to 270hp or more, making the N52 the naturally aspirated screamer six it was always supposed to be, something that lives up to the standard of the “Ultimate Driving Machine”.
But let’s say this still isn’t enough for you, and you still really hate your neighbor with a 335i and really want to beat him and just rub his nose in it that your 328i or 128i utterly destroyed him… well, without boost, that’s gonna be hard to do, even with full bolt ons, the N52 will struggle to make 300whp (and that’s a straight up race engine with MOTEC ECU, VTC at full lock, retrofitted E36 M3 ITBs etc) – but lucky for you, that’s not exactly an obstacle.
#??? FORCE FEED THAT SIX
If you’re still not satisfied by NA power, there’s always boost. Yes, there are ways to go boosted, even in a 328i or 128i! One of the best options for this is a supercharger, like the ESS Tuning Supercharger for BMW N51/N52, seen above. Good for a staggering 80-100whp gain, this supercharger puts you very comfortably into 335i territory.
The dyno doesn’t lie – the numbers are there, and technically that supercharger itself is CARB approved, but the street legality of the system is questionable so check your local laws and regulations, but it’s definitely safe for use on tracks anywhere in the USA as the catalytic converters are unmodified.
So that’s it for our rundown of the best power mods for the BMW N52 328i, 128i and 528i – we hope this was informative for you, and thank you for reading.
Interested in changing up the look and sound of your BMW E9X 328i, 128i or 528i? Ask the Mod Experts what exterior upgrades are available for your car to change the style of your ride. Call us at 714-582-3330 for expert car mod advice and schedule your installation at the Mod Auto shop today.
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Story & Photos Nick Gregson