Duramax LML Cold Air Intake Upgrade Guide
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A cold air intake is the second best performance modification for a Duramax LML, with the first being tuning. An intake will provide horsepower and torque gains through airflow increases, but will also increase throttle response and turbo spool, and add about 1-2mpg of fuel economy improvements.
We’ve been installing intakes on Duramax trucks for years and are going to discuss the performance benefits, considerations for choosing an intake, and share our favorite open and closed intakes on the market.
Duramax LML Cold Air Intake Benefits
- Up to 20whp and 60wtq gains
- 30%+ airflow increase
- Faster turbo spool
- Increased throttle response
- 1-2mpg increases
- Sweet engine sound
Power gains I mention are going to be maximum gains throughout the band, you can likely expect closer to 10whp and 20wtq peak power gains. Additionally, gains and performance benefits are going to increase when an intake is combined with engine tuning.
Intakes are great for low-end torque compared to high-end horsepower which makes them a great addition for towing.
Open Intake vs. Closed
The most important intake consideration is whether you choose an open or a closed intake. As the name suggests, open intakes have the air filter open and directly exposed to the engine bay air. Closed intakes keep the air filter enclosed within an airbox, therefore protecting it from the engine bay temps. A lot of open intakes will have “heat shields” that are supposed to protect the filter from the hot engine air. These are pretty much marketing ploys and not really very effective.
Pro’s of Open Intakes
- Provide more airflow than closed intakes since the box on closed systems is restrictive
- Greater power gains due to more airflow
- They are usually a bit cheaper since it’s less material
- Provide more intake “whoosh” sounds (could be a con)
Con’s of Open Intakes
- They draw in slightly hotter intake air temps (IATs) since they are exposed to the engine bay
- See our explanation below on why this really doesn’t matter
We always recommend open intake systems. They provide better power gains, are usually a bit less expensive, and give the greatest airflow increases. The only time we would recommend a closed system is if you wanted less intake noise. But overall, any upgraded intake is an improvement over the stock system. Unless you are planning on going full bolt-on and upgrading your turbo then a closed system will be just fine.
Intake Air Temps (IATs) and Why They Don’t Matter
An open intake might draw in air that is 1-3 degrees warmer than a closed system. However, the air then passes through the turbocharger anyways and gets heated up a lot. Which is why the Duramax LML has an intercooler – to cool the air before it enters the engine.
Ultimately, the factory intercooler is plenty efficient on the LML and therefore intake air temps being a few degrees lower doesn’t actually result in cooler air being sent to the engine.
Best Duramax LML Cold Air Intakes
We recommend open air intakes since they provide the best bang-for-the-buck usually. The most important thing is the filter quality. Avoid the cheap eBay or Amazon intakes since they usually have crappy China filters. Stick name-brand and with a high quality filter and you can’t go wrong.
We’ll provide our favorite open intakes as well as closed intakes for anyone looking for less noise.
Boosted Performance 4″ Open Intake
Our favorite LML intake is the 4″ open system from Boosted Performance. This intakes outflows the factory system by more than 60% and provides some of the best performance gains on the market.
The Boosted Performance LML intake is 4″ system and uses a high-quality S&B brand filter. It allows for a substantial 60%+ increase in air flow compared with the OEM intake, and will boost mpg by 1-2. The intake comes in wrinkle-black finish to reduce heat soak and is a direct bolt-on fit. No tuning is required.
Price: $299
Buy Here: Boosted Performance LML 4″ Intake
2. Closed: S&B or Banks Power
Our closed intake options are Banks Power and S&B, two of the most respected diesel performance brands. Neither offer open intake systems and instead opt for fully-enclosed LML intakes. The S&B system is more affordable at $350, but the Banks Power comes in slightly pricier around $450.
Since these intakes are closed systems they only provide about 30% airflow improvements, whereas the open systems above offer around 60% more flow. However, since they are enclosed they will be a bit quieter which is nice for anyone who makes frequent long road trips.
Summary
Whether your LML is completely stock or tuned, an upgraded intake system is always our first recommended mod. In addition to power increases it allows the engine and turbo to breathe better which improves efficiency, gas mileage, and engine responsiveness. When an intake is combined with a tune you can see around 10whp and 20wtq peak power gains, with significantly greater gains throughout the low-end of the power curve.
We prefer open intake systems since they provide more airflow increases and therefore more power gains. However, unless you are shooting for big power gains and plan on upgrading your turbo, a closed intake system will be plenty effective on the LML. Boosted Performance, S&B, and Banks Power are all well respected intake manufacturers. At the end of the day all of these intake systems are virtually the same and choosing to add a cold air intake is more important than the brand you choose.
