LT’s are the new LS’s!
The performance truck market continues to grow at a staggering rate – with huge popularity going back to the early LS trucks.
The L83 (5.3L) and L86 (6.2L) performance potential is especially promising due to these modern generation LT engines offering so much more power and technology than its predecessor in a factory trim. For instance, a L83 powered 5.3L truck starts out 50 HP stronger than it’s 5.3 LS counterpart – giving you a much better starting point with these engines!
That being said – there is always room for improvement right?
Intake Manifold & TB Upgrade (a MUST L83 Upgrade!)
During our R&D process with the L83 (5.3L) engine, we discovered that the intake manifold and throttle body from the L86 (6.2L) was a direct bolt-on application for the L83 (5.3L)! The ports lined up perfectly, with the main difference between the two being: runner length and plenum design.
We immediately picked up 9 RWHP and 6 RWTQ. After noticing great gains in simply bolting on the L86 (6.2L) intake manifold and throttle body, and observing significant obstruction in the manifold stands, we decided to port the intake manifold and test again. (Note that we did not port the throttle body, just the intake manifold.) Testing the ported version, we were able to pick up another 8 RWHP and 3 RWTQ, for a total gain of 17 RWHP and 9 RWTQ!
Camshafts and Install Packages
All of our Direct Injected camshafts incorporate a larger fuel lobe, going with the informal industry standard of 32% larger. We’ve specifically ground these cams to utilize our GPI Phaser Plugs (in either a 4° or 0° block-out).
With our truck cams, we’ve stayed with our proven low-lift cam design. We have found – the majority of our customers want the sound and added power, but still want to retain that 100,000 mile durability. Our low-lift cam grinds are more gentle on valvetrain, yet still offer great gains in power. These low-lift cams are designed to work with the factory pushrods and run on a factory LT1 valve spring.
Of course, we do offer all of these cams in a high-lift version as well, for those seeking an all-out performance build! The high-lift cams offer the same drivability mannerisms as their low-lift counterparts, but offer an increase in power due to the higher valve lift.
L83 (5.3L) & L86 (6.2L) Cylinder Heads
When it came to designing a cylinder head package for our L83 (5.3L) truck customers, we kept the ports small in order to emphasize port velocity. This has allowed us to see significant power increases under the curve, not just in the high RPM range.
Our L86 (6.2L) cylinder heads utilize our proven CNC porting program that we run on our LT1 cylinder heads, while we developed a new porting program for the L83 (5.3L) cylinder head.
Several milling options are available, and we highly recommend that piston-to-valve clearance is properly checked in any milled application.
During our porting process, we want to ensure that we provide you – the customer – with the greatest and most reliable product that we can. This is why we install guide liners and precisely grind the liners to achieve optimal valve-to-guide clearance. All of our cylinder heads also receive a valve job – grinding the valve seats to custom angles. In addition to the cylinder heads being cleaned, deburred, etc., the bowls are hand-blended on every set of cylinder heads.
Torque Converters
Converter Recommendation
- 258mm Converter for both 6L80 and 8L90 (for most applications)
- 245mm for all out track builds
- 3000-5000 stall based on driving style (lower improves street manners / higher improves 60ft times)
When it comes to converter options for the DI trucks, we relied on our history and relationship with Circle D Converters to choose the perfect converter for these applications. As a standard, we recommend a 258mm converter, with stall speeds between 3000-5000 on a “B” stator.
In lighter, race applications, the 245mm converter is still a viable option as well!
Drop-In Pistons (for supercharged / turbo / nitrous applications)
Much like our well-known LT1 Drop-in Piston/Rod package, we’ve developed a drop-in package for the 5.3 L83 engine as well! These new pistons will feature a Diamond Racing piston, forged from 2618 alloy, and come complete with pins, clips, rings, and valve reliefs. They will maintain a factory compression ratio of 11:1 and utilize the same Compstar rods as our LT1 package. Of course, all of this will be a zero-balance install for a true drop-in application! Look for this new package in the coming weeks, along with a “how-to” video illustrating the proper way to file-fit the rings!
Recent L83 (5.3L) Build
One one of our recent L83 builds we were able to observe significant performance gains from our L83 (5.3L) cylinder heads, camshaft, and intake manifolds.
On the baseline pull our test truck began with 308 RWHP and 338 RWTQ.
Here’s the complete list of mods:
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OEM L86 (6.2L) Intake Manifold and Throttle Body Swap for L83 (5.3L) Trucks (2014-Up GM Truck)$328.98
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GPI – L83 Cam Kit for 2014-2019 Silverado & Sierra 5.3LFrom: $0.00
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GPI – Ported OEM L83 (Gen V 5.3 DI) Cylinder Heads PackageFrom: $1,095.00
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Kooks – 2014+ GM 1500 Series Truck / 2015+ GM 1500 Series SUV 1 7/8″ X 3″ Header (28602402)$1,466.24
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Airaid SynthaFlow CAD Intake Systems (200-285) 2014+ GM Truck 5.3L$449.99
After completion, we ended with 402 RWHP and 396 RWTQ, for gains of 94/58 respectively. Our peak HP was observed at around 6400 RPMs, with peak TQ at around 4800 RPMs.
Before and After Dyno
L83 Head & Cam (Stage 3) Idle Sound
Rather build a turbo truck?
We’ve got you covered too!
Ready to start building your L83 or L86 GM Truck?
We’d love to help! If you have any questions – just shoot us an email at [email protected] or call us at (501) 985-4947!
With a build for your 402 rehoused, can you tune this to go with a stage 2 magnusen supercharger? What you think the final rwhp/rwtq be?
Hey Jason, we certainly can tune for the Maggie setup in house, we don’t remote tune power adder applications remotely though.
With the addition of 7-8 psi you likely would be in the 550-575 whp range on this same setup. Drop in pistons and rods certainly recommended from a durability and longevity standpoint.
I just got a junkyard 2020 l83 with a 6l80.
I plan on swapping it into a 1985 c10
What all parts do I need?
The 2020 engine/PCM is more complex with the dynamic fuel management and ECM unlock requirements. Tuning is going to be far more expensive firstly, and the cam kit is going to be different than previous years. I would recommend looking for a pre-19 setup to transplant due to better parts availability and tunability.
I have a 2015 5.3 Silverado. What would be your best recommended full setup to achieve up to 450hp safely?
This same setup with our high lift version of the Stage 4 cam/ported heads and increase in compression. Flycutting will be needed. Flex fuel and supporting bolt on mods of course.
I have a 2019 chev silverado 5.3ltr, I would like a cam for street driving, would like to stick with stock converter, what is the most cam that you would recomend
Our stage one. But the afm kit is different on 19-up. Our camshaft will work, currently we do not offer complete cam kits for this application.
I have a 2018 Silverado 5.3 4×4. It’s good at stock but I would like to make some extra power. What would yall recommend for it and if going to high would I need to get the trans built for it to handle a lot of power?
With good tuning the trans should live a long happy life. Some of the easiest power gained would be headers, cai, flex fuel, and tuning. That is an easy 50 rwhp in modifications. From there our cam kits and head porting service offer substantial gains of another 50 plus rwhp.
Thank you for sharing! Is it true the current LT series of GM engines are ticking time bombs around 100k? The root cause being GDI, lifter and cam issues from cylinder deactivation plus burning oil? Thanks again.
I have a 2014 silverado with 205,000 – no problems yet. So I would say the 2014s are ok.
I have a 2016 sierra, do you have an estimate for total cost including install time?
Not from our experience. With GDI there are certainly issues with carbon/oil deposit buildup on the valve, but that can be maintained with routine cleaning. Otherwise the engines are reliable. We have seen some cases of some faulty valve springs from the factory, but that has been isolated to the newer run over the last year or so. I personally have a 17 model with almost 70k miles of cruising and towing and could not be happier with how it performs and how efficient it is!
With the L86 manifold & TB swap kit (for L 83) get rid of the throttle lag?
What you are feeling is Torque Management. It can be helped in the tune.
How bought Your stg1 cam on a l83 with a procharger around 14psi with LT1 injectors and upgraded intank pump..really like to keep stock converter.what do you think bout this combo an where do you think I would be power wise?
That cam will work well with a Procharger.
At 14 psi you should be in the 700 area roughly with adequate fueling and octane.
I have a 2015 Silverado 5.3 with a pedal commander. What would I need to reach 400 +hp. I noticed you guy never mentioned MSD upgrade. Thanks
Probably because MSD is garbage.
How about a 6.2 with a 4.8 crank
That would be great if you want a dedicated high RPM setup. Would be custom pistons, and the factory computer will only rev to 8192. The short stroke is going to shift the power and torque upward.
Could i get 450 hp to 500 hp from a built up 5.3 motor?
450 is possible. It would take more compression, flycutting valve reliefs and at a minimum a L86 intake. We would likely do a high lift version camshaft.
450 is very achievable.