While GM intake manifolds are generally known to be top-notch, the factory LS2 manifold is an exception. Thanks to bad production techniques, the LS2 has one of the most restrictive intake manifolds in the entire LS lineup. For that reason, an intake manifold upgrade is one of the best performance mods that you can do to see more power, more torque, and better throttle response from your LS2 engine.
Benefits of an Upgraded LS2 Intake Manifold
- 20-25 Horsepower and 25-30 wtq gain
- Noticeable increase in midrange power/tq
- Improved throttle response
- Very good horsepower per dollar ratio
- Simple installation
- Does not compromise drivability in any way
There are quite a few pros when it comes to intake manifold upgrades. That goes for most naturally aspirated American V8s, but even more so on the LS2. As a side note, not all LS engines benefit as much from intake manifold upgrades, like the LS6 and LS3, as many of those engines already have very high flowing intakes from the factory.
The most obvious reason for an intake manifold upgrade is the power and torque gains. In most cases, ported factory LS2 intakes and quality aftermarket intakes will yield somewhere in the ballpark of 20-25whp and 25-30wtq which is mighty impressive from a bolt-on part that you can throw on in less than an hour.
It adds the additional power to the rev range where you want it to be as well. Upgraded intake manifolds shift power and torque curves right, meaning that you’ll see noticeable gains in midrange power and torque, just what you want on the track or strip. Improved intake flow also has the benefit of improving throttle response. That’s even more noticeable when paired with other complimentary upgrades like a ported throttle body.
When it comes to bang-for-buck mods, an intake manifold upgrade is arguably the best you can do. While cam upgrades come close, installation is much more difficult and costly if you don’t do the work yourself. Also, unlike with large, lopey cams, intake manifold upgrades don’t affect drivability at all.
Think About Other Supporting Mods Too
An intake manifold upgrade isn’t typically the first step in an LS2 build plan. That is because an upgraded intake provides much more significant benefits when paired with other mods that complement it. Most C6 owners typically go the route of a cold air intake, long tube headers, a cam upgrade, and an intake as the finishing touch. That will yield the best results in terms of gained horsepower and torque.
Most enthusiasts prefer to start their build with simple bolt-ons that won’t immediately require a tune. A cold air intake and long tube headers fit that bill perfectly while providing noticeable gains themselves. The factory LS2 intake is rather crappy, so you can generally pick up around 10 horsepower from an upgraded CAI. Long tube LS2 headers are one of the most popular mods for sound and performance gains, generally yielding around 20-30 horsepower and similar torque. You can also throw in a ported throttle body here too, as that improves intake flow even more for later down the line. None of those mods requires a tune, but the benefits are more pronounced with one.
Then, after most of the smaller stuff is out of the way, a cam upgrade enters the discussion. Obviously, there is a lot to discuss on that topic, which is why we wrote a dedicated article on LS2 cam upgrades. But, regardless of whether you are building a big-cammed drag build or a moderately-cammed street build, both will benefit massively from improved intake flow. Ideally, you’d do a cam upgrade and intake manifold upgrade at the same time so that you only have to tune the engine a single time for both performance upgrades at the same time.
Choosing The Right Intake Manifold
Choosing the right intake manifold for an LS2 is pretty straightforward, but there are a few things that you should know prior to pulling the trigger. For one, it is important to mention that LS2 intake manifolds are interchangeable with other LS manifolds that share the same cathedral port style, meaning that most LS1 and LS6 intakes will also work on the LS2. However, throttle body size is also another aspect that you have to take into account.
The LS2 uses a 4-bolt 90mm throttle body from the factory. Many enthusiasts choose to upgrade their throttle body to a larger one for increased airflow, especially when going for a high horsepower build. If you have upgraded your throttle body to a larger one, you’ll also need an intake manifold with a throttle body opening to match. That can get confusing sometimes too, as some aftermarket manifolds, like the popular FAST intake, have a 102mm TB opening but will still work with the factory throttle body.
Lastly, it is important to get an intake manifold that matches the final goal of your build. For instance, there are a number of really good polymer intake manifolds on the market which are good for high horsepower naturally aspirated builds. However, polymer isn’t the best material when it comes to withstanding the pressures generated by forced induction builds. In those cases, a quality aluminum manifold is a better choice.
Porting the Factory Intake Manifold
GM is generally pretty dang good at designing intake manifolds. The intake manifolds of most LS engines are so well designed that upgrading to an aftermarket one isn’t even worth it. Unfortunately, that isn’t the case for the LS2. GM first experimented with using sonic welding on the LS2, and didn’t do a very good job with it in the beginning. The bad welds allowed a minuscule amount of air to leak internally past the welds, which hampered air flow significantly.
Since the flaw had to do with the design of the manifolds themselves, most people would just swap them out with aftermarket ones. However, there is an option that works just as well, which is porting the factory LS2 intake manifold.
Porting is done to remove excess material or smooth the internal surfaces of the intake manifold, in this case, in order for there to be less internal turbulence, allowing air to flow more freely. The additional airflow is what adds the power. Additionally, the smoother internal surface is what also leads to improved throttle response. Backed up by dyno results, ported manifolds produce a bit less power yields than other aftermarket options, typically around 10-12 horsepower. The other benefit is that porting the factory intake is much less expensive than purchasing a new, upgraded one.
Generally speaking, porting is a pretty straightforward, yet intricate, service that many machine shops offer. However, there are a number of reputable shops that have made a name for themselves in the LS2 community. Gwatney Performance Innovation is perhaps the most popular option for those who don’t have access to a local shop.
Best Aftermarket Intake Manifold Options
If you aren’t a fan of porting the factory intake manifold, using an upgraded aftermarket intake manifold is another option. While there are a number of good LS intake manifolds on the market, there are only a couple that enthusiasts inside the LS2 community recommend. I’ll list two good polymer manifold options and one aluminum one for the forced induction guys.
FAST 102mm Intake Manifold
The FAST intake manifold is unquestionably the most popular aftermarket intake manifold available for the LS2. It’s the one that everyone defaults to in the forums because it really is the best one out there. It is important to mention that there are two FAST manifolds available for the LS2 including a 90mm and 102mm version. While it might seem like the 90mm one is the way to go if you have a stock throttle body, everyone says that the 102mm manifold has much better airflow properties and still works with the factory 90mm TB.
The FAST manifold is made from the same type of polymer as the factory manifold, which has good heat dispersion properties. Fitment is exact to factory specs, so installation is extremely easy. Most people with little experience say that you can throw it on in less than an hour. It also comes with pre-installed nitrous bungs if you’re trying to go crazy in the future.
Compared to a ported factory LS2 intake and most of the other options out there, the FAST intake provides the most significant power and torque gains. Most people who have dyno’d their car after installing the intake say that you can expect anywhere between 15-20 horsepower and 20-25 torque from it. Since it doesn’t come ported from the factory, there is even more performance on the table if you opt to port the FAST intake as well.
MSD Atomic Air Force Intake Manifold
Outside of the FAST intake, the MSD Atomic Air Force intake is truly the only other polymer manifold worth recommending. While there are other options like the Doorman manifold, the FAST and MSD are on another level in terms of quality and performance. Like the FAST, the MSD intake is made from a polymer material to dissipate heat, reduce weight, and eliminate heat soak.
The MSD intake utilizes bell-mouthed runner entrances to maximize airflow and minimize shrouding. I’m not sure what ‘minimize shrouding’ means but user testimonials back up the maximum airflow claim at least. Another benefit to the MSD intake is that it is a two-piece manifold which makes it easier to access the runners for porting. While it is advertised as a 103mm intake, the MSD accepts both 103mm throttle bodies, as well as standard LS2 90mm throttle bodies. Either one works.
There isn’t nearly as much proven dyno information about the MSD intake as there is for the FAST, but there is a lot of support for MSD intakes in the LS7 community. While it isn’t necessarily fair to compare the cathedral port design to the rectangular port design, at least MSD has a good reputation somewhere. If I had to guess, I’d say that it would stack up pretty evenly against the FAST.
JEGS Fabricated LS Intake Manifold
The final LS2 intake manifold option that I’ll throw out is the JEGS fabricated LS manifold. This manifold is made primarily for boosted applications as it is fabricated from high-strength T-6061 aluminum. If you don’t have a boosted build and aren’t planning on having one in the future, best to stick with the previous two options, as they’ll provide better gains.
The JEGS manifold comes with a couple of cool perks including a fuel rail kit, intake seals, LS3-style map sensor port, and vacuum port fittings. All of those will prove to be necessary with a high-horsepower turbo build. According to JEGS, the manifold was built to withstand 750+ horsepower, so you should be set. Regardless, this is the manifold to go with in lieu of a cheap fabricated Chinese manifold on eBay if you want your build to hold up over time.