A lot of people cringe at the idea of a "cold-air" intake. Theory has it that a cold air intake has a bigger filter which lets in more particles which kills your engine life quicker. And that they don't offer that much of a performance benefit.
The first part about engine lifespan is blah blah. Unless you have a super cheap filter, your engine longevity will be fine. The second part is true, BUT only for naturally aspirated vehicles. For turbocharged engines, such as the B58, upgraded "cold-air" intakes have tremendous performance benefits. Not only do they alone provide good horsepower and torque gains, they are an essential supporting modification for those looking to further mod their B58's with things like a tuner.
If you don't care about how or why an upgraded/performance intake is better, and just care about which ones are the best for the B58: feel free to use the table of contents below and go directly to the Best B58 Performance Intakes section.
Is the upgraded intake really a "cold-air" intake?
I use the term cold-air intake because a lot of manufacturers still call their intakes that, and a lot of beginner tuners don't know what else they are called.
The best B58 intakes aren't truly "cold-air" intakes. A cold-air intake (also referred to as a CAI) is made to suck in the coldest possible air, as colder air creates more power. CAI's commonly replace the stock intake and re-route the filter to the bottom of the engine bay, usually somewhere in the lower part of the front bumper. The reason is that air at the bottom of the car is going to be cooler since its further away from the engine, and heat rises. You'll commonly see these style intakes on Japanese cars.
However, with the B58, the best intakes actually do not relocate the intake filter. Rather, they remove the stock box and use an open-air design. The stock air intake on the B58 is an enclosed box with a square filter on the inside of it. Upgraded intakes will get rid of the enclosed box and replace the square filter with a larger cone filter.
Ultimately, because the intake isn't re-routed, you're not going to see a huge decrease in air intake temps. You will maybe see a few degree drops, but nothing huge. You will not see hotter air temps at idle or full throttle, and you will not see increased heat soak. People always love to debate this, so please hit us up in the comments if you're up for the challenge!
More Air and the Effect on Turbochargers
More air might get you an extra 3-5hp on a naturally aspirated engine. On a turbocharged engine, more has a much more drastic effect.
A turbochargers job is to compress air, and to compress enough air to not starve the engine of oxygen (air-to-fuel ratios). The less air you have flowing through the intake inlets into the turbo, the lower the pressure of the air is. Because of the low pressure, the turbo has to work harder, spinning its compressor wheel faster, to compress enough air for the engine.
When you send more air into the inlets, the air pressure increases, which means the turbo doesn't have to work as hard compressing the air. The end result is a more efficient turbocharger which can pump compressed air into the engine more quickly, creating more power.
If you are going to add a tune to your B58 and increase the turbo boost pressure (psi), then a high-flow intake is even more important. Tuning the engine and running higher boost requires more air to be drawn into the engine. Without more air flowing in, at high boost levels, your turbo isn't going to last very long as it's going to have to be working overtime to compress enough air.
Benefits of an Upgraded/Performance B58 Intake
- Sweet "intoxicating" engine sound
- Increased air flow and less restriction
- Quicker throttle response
- Faster turbo spool
- 10whp+ bone stock
- 16whp and 27wtq when used with a JB4
As mentioned, the B58 stock intake is an enclosed box with a filter in it. The enclosed box is very restrictive to airflow as it has a limited volume capacity and can only move air through it so quickly. With an upgraded intake, you are removing the restriction created by the box, allowing for more air to be sucked in more quickly. Additionally, performance intakes will include larger cone shaped filters which are capable of swallowing significantly greatly volumes of air.
More air equals more combustion.
The Best B58 Upgraded Performance Intakes
Here is a list of the three best B58 intakes, in our opinion.
Burger Motorsports B58 Performance Intake
BMS, Burger Tuning, Burger Motorsports is one of the best BMW tuning companies in existence. Their products are extremely high quality, well manufactured, and engineered for performance. Their B58 intake upgrade is a simple plug-and-play install. The intake keeps most of the OEM air intake features, simply removing the main box housing and replacing the OEM filter with a US-made inverted cone filter.
The sound increase from the BMS intake is awesome and they provide a good performance increase, especially when coupled with the JB4 tuner.
BMS Intake Link: BMW B58 BMS Performance Intake
Horsepower Gains: 8whp stock, 16whp with JB4
Torque Gains: little to slightly negative impact stock, 27wtq with JB4
Price per Horsepower: $22.38/hp stock, $11.19 with JB4
Agency Power B58 Short Ram Intake
The Agency Power intake completely removes the stock intake box, rather than just removing half of it like the BMS intake does. Additionally, it features a "heat shield" instead which is designed to block hot the hot air coming from the engine from entering the intake system.
The kit uses a high-flow aFe intake filter, instead of a SB filter used in the BMS intake. Both of these filters are of comparable quality, which makes the only real difference on the AP intake the heat shield. In our experience, the heat shield doesn't quite do enough to warrant the extra $120 of cost on one of these compared to BMS. But, if you are concerned about intake temps, then this might provide some additional comfort.
The AP intake is well received on the market, and highly used on the market. The AP intake is known to be a lot louder than BMS, if sound matters to you.
Horsepower Gains: approx. 8whp, can't find any dyno's to confirm
Price per HP: $37.50/hp
Dinan Carbon Fiber B58 Intake
For those of you who love carbon fiber, or don't believe in getting rid of the enclosed box design, the Dinan intake might be the best option for you. To improve air flow, the Dinan box has a 30% larger volume air box compared to stock, and a 34% bigger filter. Enclosed inside the box is a cone-style filter, similar to what's found on the BMS and AP intakes.
The Dinan intake boasts the highest horsepower and torque gains at +13whp and +11wtq. However, it comes at the highest price and offers the least sound increase. Despite the uptick in performance numbers, which do appear to be backed up by dyno's, the Dinan intake has the highest price per HP given its $600 cost.
Horsepower Gains: 13whp with no other mods
Torque Gains: 11wtq with no other mods
Price per HP: $46.15
Summary on B58 Performance Intakes
Upgraded intakes are a fantastic mod for improved power, and quite frankly a necessity for anyone looking to mod their car further with a tune. There are a number of intakes on the market which we didn't mention such as aFe, MagnumForce, Momentum GT, etc. At the end of the day, all of these intakes perform the same task: delivering more air to the engine. In our opinion, which one you pick really comes down to how much your willing to pay, how much sound you want, and the looks you want in your engine bay. BMS is our favorite, but to each their own - you can't go wrong with any of the ones we mentioned here.
An upgraded intake is really going to unleash its full performance potential once you couple it with a tune, such as the JB4 or MHD. Any of these intakes will do the job and provide sufficient air flow for further modification.