The Guide to Upgrading the Chevy LS3 Intake Manifold. It’s no secret that the Chevy LS3 is a high-performance engine. The LS3 has all of the race-tested frills that you’d expect from a Chevrolet V8 and is found in the C6 Corvette and Camaro SS. As a result, the LS3 is a very well-optimized engine right out of the box. The factory flow statistics are one of the LS3’s strongest points. This is true for the LS3’s rectangular-port heads as well as the stock intake manifold.
The LS3 intake manifold from the factory is widely regarded as one of the best OEM intakes ever made. Not only in GM’s catalog, but throughout. That is quite a compliment. In terms of actual flow figures, the original manifold design is quite difficult to beat. That doesn’t mean there aren’t options to upgrade and redesign, and the LS3 aftermarket community has done just that. There are numerous LS3 intake manifold alternatives available at this point.
Intakes aren’t a simple performance component for the LS3. In the aftermarket intake manifold contest, some engines have a clear winner, but the LS3 is a bit more subtle. Higher flow figures aren’t always the goal of an improved LS3 intake manifold because the stock design is so good. To shift power around the rpm range, some LS3 enthusiasts replace the factory manifold with a new one.
This post will go through the advantages of upgrading your Chevy LS3 intake manifold. We’ll go over some of the most compelling reasons to do so, as well as recommend certain inputs for various applications.
How Does an LS3 Intake Manifold Work Aftermarket?
Before we get into the intricacies, let’s first discuss the role of an LS3 intake manifold. It’s an important one, so be warned. The fundamental function of an intake manifold is to evenly feed fresh air to the cylinders. Air enters the system via the intake, then passes through the throttle body and into the intake manifold. The air is subsequently forced into the intake plenum, a large cavity at the top of the manifold. The air is then discharged into the intake runners, which supply air to the intake valve. While this may appear to be a straightforward operation in general, each individual component of that system has a major impact on engine performance.
Changing the size, shape, diameter, and length of elements in an LS3 intake manifold can significantly alter power and torque profiles. Aftermarket manifolds come into play here. Because 6.2L LS3 engines are used for a wide range of applications, from endurance to drag racing, some fans like to fine-tune the rpm range where power is most noticeable. By varying the plenum size, runner length and diameter, and runner shape, aftermarket LS3 intake manifold providers can provide variable performance characteristics.
Considerations for an Upgraded LS3 Intake Manifold
When considering improving your LS3’s intake manifold, there are numerous factors to consider. Many of these considerations stem from the other internal components that interact with the intake manifold. The length of the intake runner, the size and form of the plenum, the camshaft pairing, and the displacement all have an impact on how well an LS3 intake manifold works with your build.
Length of the LS3 Intake Manifold Runner
The length of the internal runners is one of the most important aspects of an intake manifold. Depending on how you want your LS3 to perform, the length of the intake runner must be carefully evaluated. The length of the runner influences where in the rev range power and torque peak. As a result, different intake manifolds are better suited to different applications.
Intake manifold runners live in a world full of discussion and numbers. Having said that, there are some general factors that make LS3 intake runner length a little easier to understand. Short and wide intake runners, in general, move the torque curve up the rev range. Long and thin runners, on the other hand, move the curve down the rev range. In terms of flow, a manifold with shorter runners will always overflow a manifold with bigger runners of the same diameter. Despite the greater flow, manifolds with short runners do not necessarily create more power. The main distinction is where the power peaks.
The majority of the math connected with this effect is concerned with pressure fluctuations within the cylinders and intake runners themselves. When the intake valves are open, the downward-moving piston creates a low-pressure wave. The low-pressure wave travels through the runners, drawing air from the manifold into the cylinder. The length of an LS3’s manifold runner is proportional to the time it takes for this pressure wave to reach the manifold plenum. Longer runners are thus preferable at lower engine speeds, where the waves have more time to reach the plenum before the intake valve closes. The converse is true for short runners, as the wave has less time to travel and hence performs better at high rpms.
LS3 Intake Manifold Plenum Dimensions
Plenum size is vital to consider in addition to intake runner length, which is definitely the most critical design feature of an LS3 manifold. As previously stated, the intake plenum is where air is kept after entering the manifold via the throttle body. The volume of the plenum is critical because it must store enough air to fuel the engine throughout the rpm range.
Poor engine performance, especially at high rpms, might result from an aftermarket LS3 intake manifold with an undersized intake plenum. The engine can draw in incoming air faster than the manifold can replenish when the plenum is too tiny. As a result, the engine responds slowly or even stalls. A narrower plenum can improve low-rpm performance but degrades as the revs rise.
An LS3 intake plenum that is overly large, on the other hand, can have a negative impact on performance. A large-volume plenum can lower the velocity of entering air greatly, which is also an issue. In terms of manifold design, air velocity is a significant variable. The faster the intake ports and cylinders can fill with air, the higher the velocity. Low rpm engine response is reduced as a result of low air velocity.
The best intake plenum design provides the most capacity while sacrificing air velocity as little as possible. The volume of aftermarket LS3 intake manifolds is typically more than that of the factory 3.7L plenum. Having said that, plenums larger than 5.1L are uncommon. Shape also matters in plenums, as an essential last point. The velocity is greatly influenced by the flow pattern and turbulence of the air entering the plenum. Better air management is frequently associated with improved engine performance.
Fitment of the Chevy 6.2L Intake Manifold
One of the most prevalent improved intake-related issues that Vette owners have is clearance. Aftermarket Chevy Smallblock intake manifolds frequently stretch above the height constraints of the stock hood. This is typically because the manufacturer chose a plenum design that is more vertical than wide. Because the C6 has a fairly narrow frontal profile, there isn’t much vertical area to work with.
There are two common solutions to this problem: acquire a high-profile hood or cut a hole in the existing one. While exact statistics for C6 hood clearance are difficult to come by, it is commonly assumed that a manifold with a vertical profile of more than 6-inches will be too tall to fit under a factory hood. Obviously, if you put an LS3 in a different chassis, the figure will be different. Because manifold clearance is a common issue for the C6, there are a plethora of high-profile hoods available. High-profile C6 hoods available in a variety of shapes and sizes, so it all comes down to personal style and look. Otherwise, a hole in the stock hood would suffice if you want the aggressive look of internal components peering out.
Other Considerations and Factors
Choosing the best LS3 intake manifold involves more than simply the manifold’s performance. The key to selecting the correct intake for your 6.2L LS is ensuring that it works in tandem with your other engine improvements. An improved cam, for example, is a relatively typical LS3 modification because the LS format responds very well to them.
The discussion over cam duration vs runner length rages on in the LS community, and there is no definitive conclusion. There is a strong case to be made for pairing longer runners with a larger cam for improved high-rpm performance. A satisfactory outcome can be obtained by striking a compromise between the increased low-end performance offered by longer runners and the high-end performance provided by longer-duration cams. On the other hand, from a tuning standpoint, the inverse can also be a favorable matchup. When trying to tune for power in a certain area of the rev range, pairing short runners that provide high-rpm performance with a larger cam that favors a high-rpm curve might be a good combination. This is a very simplistic description of ram tuning, and there is much more to it that we don’t have space to go into here.
To some extent, throttle body size influences LS intake manifold performance, especially as system efficiency improves. At some point, the factory 90mm LS3 throttle body can choke performance by not providing enough air to the plenum. A frequent LS3 modification is to install a bigger diameter throttle body. This is especially true when used in conjunction with an improved intake manifold. If you want to understand more about LS3 throttle body possibilities, see our LS3 Throttle Body Guide.
Suggestions for an Improved LS3 Intake Manifold
It should be evident by now that there is no one-size-fits-all intake manifold that is best for the 6.2L Chevy V8. In truth, there are several alternative intakes that operate well with differing runner lengths, plenum sizes, and shapes. It all comes down to where you want your LS’s peak power and torque ratings to be. As a result, we’ll recommend a few LS3 intake manifolds that perform diverse functions.
1) LS3 Intake Manifold Fabricated by Sniper EFI
Power Band RPM: 3,500 – 8,000rpm
5.512″ is the length of the intake runner.
Holley is without a doubt a household name in the realm of LS performance parts. It would be an understatement to say that they have been in business for over 100 years. For increased high-rpm performance, their Sniper EFI Fabricated intake manifold is a good option. It can also fit comfortably under a stock C6 hood.
The Holley intake’s build materials and craftsmanship are one of its hallmarks. The Sniper is constructed completely of 5mm T6061 sheet aluminum and is TIG welded throughout. This combination offers unrivaled dependability and strength. Because of its grade-A construction, the Sniper is a popular choice for LS setups with forced induction.
Aside from the manifold, the package includes a matching fuel rail that connects directly into the runners. The Sniper manifold we’re recommending here is designed to be used with a 90mm throttle body, but Holley also provides the same manifold with a 102mm TB.
Overall, the Holley Sniper is an excellent choice for anyone seeking a manifold with a shorter intake runner length than stock. Because of the shorter runner length, the Sniper operates best at higher revs, which is ideal for people tuning for a high-end power band. It is crucial to note, however, that it will compromise some low-end torque. A bigger cam with the Sniper manifold is a frequent mix that produces good performance.
2) Carbon pTR Adjustable Manifold Performance Design
Power Band RPM: Dependent on runner length
Length of Intake Runner: 6.5,” 8.0,” 9.0″
The Performance Design Carbon pTR LS3 manifold offers a significant design advantage: adaptability. The pTR’s most notable feature is its modular construction, which allows you to change the length of the runners. There are three runner lengths available: 6.5,” 8.0,” and 9.0,” each with a distinct engine performance. The pTR comes standard with the longest 9.0″ runners. The pTR provides peak torque lower in the rpm range since it has a long runner manifold. The modular runners allow you to match the manifold to your other LS3 modifications such as improved cams, heads, and exhaust.
When discussing the pTR, it is equally crucial to discuss building materials. It makes use of several unusual chemicals not commonly seen on LS3 manifolds. The pTR, unlike the other alternatives on this list, is made of both glass-reinforced nylon and carbon fiber. As a result, the part is extremely strong and has excellent thermal dynamics to reduce heat absorption.
The pTR also has a few entertaining party elements up its sleeve. The runners, for example, have nitrous nozzle bosses on both the outboard and valley sides. There are also options to run three various injector body lengths depending on your needs. In a Motortrend test, the pTR performed best when equipped with the longest intake runners.
3) Intake Manifold Edelbrock Pro-Flo XT
Power Band RPM: 1,500 – 7,000rpm
Length of Intake Runner: 6.25″
While the Edelbrock Pro-Flo XT is not the most feature-rich manifold on our list, it is effective. It is also the most affordable while maintaining the Edelbrock pedigree and brand. The Pro-Flo XT has 6.25″ runners that give excellent balance across the rpm range. The Edelbrock has a very broad power and torque band, extending from 1,500 to 7,000rpm. This is an excellent manifold for someone seeking strong mid-range performance.
The Edelbrock will not disappoint you in terms of build quality. It is made of cast aluminum, which maintains weight to a minimum while maintaining strength. The Pro-Flow is intended to be used in conjunction with a factory 90mm throttle body. However, if you want to improve flow, it may be ported to 105mm. The Edelbrock is intended to be used in conjunction with a -8 inlet and outlet fuel rail system, which is available separately. Last but not least, the Pro-Flo XT will not fit under a stock C6 or Camaro hood.
Edelbrock says that their intake manifold produces 16 more horsepower at peak rpm and greatly exceeds the competition. We have no reason to disagree.
Related : The Camshaft Upgrade Guide for Chevy LS3
Summary of Chevy LS3 Intake Manifold Upgrades
For good reason, the Chevy LS3 is one of the most well-known engines in the world. It provides incredible power from the factory in a relatively unbreakable compact. The LS3 has a few significant distinguishing features, but its factory flow statistics and exceptional intake manifold design really emphasize the engineering care that went into it. While the factory LS3 intake manifold is difficult to top, there are some excellent aftermarket choices for those wishing to fine-tune their power and torque curves or adjust their LS3 intake for an increased cam or higher displacement.
The design of aftermarket LS3 intake manifolds has a significant impact on engine performance. One of the most essential aspects is the length of the intake runner, which corresponds directly to where peak power and torque are created. Shorter runners excel at high-rpm performance, whereas longer runners excel at low-to-mid rpm balance. The size and shape of the intake plenum, which is connected to air velocity and volume, also have an impact on performance. Tuning an aftermarket intake to work with an improved cam is critical since they must function in tandem for the optimum results.