The new BMW B series modular engines went in a new direction for charge air cooling. BMW changed to a top mount air-to-water intercooler design. As such, the B48 does not use a traditional FMIC. Whether or not these upgrades are worth it on the B46/B48 is up for debate. Worry not, though. In this article, we discuss the B48 charge air cooling system and mention a few possible heat exchanger upgrades.
*The B46 and B48 are basically the same exact engine. We may refer to it in this post as either B46, B48, or both.
B48 Charge Air Cooling
In the past, BMW stuck with front mount intercooler systems. A lot of true racing applications use the air-to-air FMIC designs. This is because air is easier to cool. It's a great design, however it has shortcoming of its own. BMW moved to air-to-water intercoolers on the B48 and B58 for good reason. Air is easier to cool, but it also heats up a lot faster.
That's why heat soak was such a common issue on the N54 and N55 engines without an FMIC upgrade. The B48 top mount air-to-water intercooler uses a front mount heat exchanger to cool charge air temps. Basically, coolant circulates through the heat exchanger for cooling and then runs into the top mount IC to cool the charge air.
Benefits of B48 Top Mount Intercooler
- Better cooling capacity
- Shorter intake path
Water and coolant take a lot longer to heat up compared to air. This helps prevent against heat soak on the B46/B48 engine. The top mount system also allowed BMW to shorten the intake tract which helps response and turbo spool. All great things thus far.
However, the problem with an air-to-water system presents itself with long, aggressive driving. Once the water/coolant mix gets heat soaked it takes a long time to cool back down - unlike air which cools quickly.
B48 Heat Exchanger & IC - Worth It To Upgrade?
Most B48 owners likely have no need to upgrade their heat exchanger or IC. It's also a good time to note - the heat exchanger would be the first upgrade. We don't believe an intercooler upgrade even exists yet. Therefore, we'll mostly be focused on the B48 heat exchanger for the rest of this article.
Back on track. Is it worth it to upgrade the B48 heat exchanger? For most B48 owners there likely isn't any need or benefit in upgrading the heat exchanger. If you plan to track the car often then it's probably a worthwhile upgrade. The same can be said if you plan on upgrading the B46/B48 turbo and running 350+whp.
Otherwise, you likely won't see any notable benefits. You might see slightly cooler IAT's with an upgrade, especially on back to back pulls. However, the benefits aren't worth the cost for most as it won't be a drastic improvement.
Best B48 Heat Exchanger Upgrades
Again, we're skipping intercoolers. There may be an option or two on the market, but the first weakness will be the heat exchanger. Even then, most B48 owners won't have any need to upgrade the exchanger. We'll come back and upgrade this post in a couple years. As more and more B48 owners look to upgrade the turbo and push the car further we'll have some extra info. For now, heat exchanger upgrades are not commonplace. As such, options are pretty limited. Nonetheless, we'll discuss a few solid options on the market.
1) BMS B48 Heat Exchanger
Burger Motorsports (BMS) offers some excellent products for many BMW engines. Their heat exchanger upgrade will fit most B46, B48, and B58 engines. We're not aware of any results on the B48 engine. However, it is a proven product on the larger B58 engine. Again, most performance gains will only be had by those really pushing their B48 hard.
We're confident the BMS heat exchanger will get the job done for those looking to keep their charge air temps in check. It's also an excellent price at $429. However, it's expensive relative to the benefits for a modest B48 setup.
BMS Heat Exchanger Price: $429.00
Buy Here: BMW B48 Heat Exchanger
2) Masata B48/B46 Heat Exchanger
Masata is a UK based company which makes their heat exchanger an excellent option for folks based internationally as these products are heavy and expensive to import. Masata heat exchanger provides significant cooling improvements over the factory system and is available for all models with the B46 and B48 engines.
While this is a great heat exchanger we recommend it only for International folks as the initial cost plus cost of shipping it to the US makes it less attractive than the BMS option.
Buy Here: Masata B46/B48 Heat Exchanger
3) B46/B48 CSF Racing Heat Exchange Upgrade
CSF Racing is a well known brand in the world of cooling products. We run some of their radiators on our BMW's. As with the above BMS option this part will fit most B46, B48, and B58 engines. Again, results are mostly limited to the 3.0L B58 engine. It's a bit more expensive at $599, but it's a solid product from a reputable company.
CSF Heat Exchanger Price: $599.00
Buy Here: CSF Racing B46 Heat Exchanger
B46/B48 Heat Exchanger & IC Upgrade Summary
Unfortunately, there isn't much solid info to discuss when it comes to B46 intercooler and heat exchanger upgrades. However, it's also a good thing. The B48 charge air cooling system is very effective straight from the factory. Most stock turbo B48's won't see any huge benefits from upgrading the exchanger or IC. It may be a different story if you're tracking the car or doing back to back to back pulls often.
As far as we're aware there aren't even any top mount intercooler upgrades around yet. They would be overkill, anyways. The heat exchanger upgrade is the more common option and will help maximize the B48's cooling capacity. Burger Motorsports and CSF Racing make some great products for a reasonable price. Check out those options if you're set on upgrading your B48 heat exchanger.