760 rwhp 6.2L Swapped Twin Turbo Sleeper 4WD Silverado!

This has been a very special build for us.  If you’ve ever dreamed of going absolutely crazy on a build, and making something absurdly fast that was never designed to – check this one out!

Just imagine the look on that proud Z06 owners face when you demolish them from a light in an unassuming Silverado.

This truck started life as a 2017 Silverado 4WD 5.3L V8 single cab pickup.  Since, we had a customer looking for a 5.3L engine for his Hot Rod build, we used this as an opportunity to upgrade this truck to the 6.2L that was never offered in a single cab Silverado.  Once we took delivery of our brand new 6.2L – it was time to open it up and install a set of Diamond Pistons, Oliver Rods, an LT4 Crank, GPI Heads, and a custom cut GPI Turbo Cam.

Next, it was time to install the new power plant, and bolt up a Armageddon Twin Turbo System.  Due to the fueling limitations of the DI motors, we opted to also upgrade to the LT4 pump and injectors, as well as a direct port methanol system from ProMeth.

After wrapping it up – we strapped it to the dyno, and were pleased to see it made 760rwhp on the dyno, and is proving to be a formidable opponent to most high performance cars on the street.

Check out these videos to see more…

Ready to start building your L83 or L86 powered truck?

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!)


  • Direct L86 Manifold & TB Swap on L83: 9 RWHP / 6 RWTQ
  • Ported L86 Manifold & TB Swap on L83: 17 RWHP / 9 RWTQ
learn more

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!

Purchase Manifold & TB Swap Kit:

Camshafts and Install Packages


  • Low Lift Cams: Up to 60 rwhp / 30 rwtq
  • High Lift Cams: Up to 90 RWHP / 45 RWTQ
shop l83 / l86 cams

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.

Purchase L83 / L86 Cam Install Package:

L83 (5.3L)

L86 (6.2L)

L83 (5.3L) & L86 (6.2L) Cylinder Heads


  • L83 Heads: Up to 25 rwhp / 15 rwtq
shop l83 heads
  • L86 Heads: Up to 30 rwhp / 15 rwtq
shop l86 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.

Purchase L83 / L86 Cylinder Heads:

From: $1,395.00 $1,095.00

LT1 / LT4 / L86

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)
6l80 converters 8l90 converters

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!

Purchase 6L80 / 8L90 Converter:

Drop-In Pistons (for supercharged / turbo / nitrous applicaitons)

This kit includes:

  • Support up to 1000 RWHP applications
  • 6.125 Compstar Connecting Rods
  • Heavy Duty Pin, Locks, and Ring Package
  • Diamond Pistons with 2618 Forging Material
  • Maintains OE Compression of 11:1
  • Thick Wall, Heavy Duty Wrist Pins
  • No Balancing Required! Drop In Piston and Rod Upgrade!!
shop l83 pistons shop l86 pistons

Much like our well-known LT1 Drop-in Piston/Rod package, we’re developing 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!

Purchase L86 Drop-In Pistons:

Top Seller

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:

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

We’d love to help!

We’d love to help!  If you have any questions – just shoot us an email at support@gwatneyperformance.com or call us at (501) 985-4947!

21 thoughts on “760 rwhp 6.2L Swapped Twin Turbo Sleeper 4WD Silverado!

  1. Avatar
    Wyatt says:

    I have a ‘15 Silverado 6.2 with the 8l90 that is putting down 680 rwhp at the moment…We have a Pro Series Circle D converter in it as well. I’m having issues keeping the transmission together. Have you guys had any issues like this…are you upgrading the transmission as well when you do the builds?

    • Avatar
      Jared Cissell says:

      I am in this situation as well. 750 at the wheels and 37″ tires is taxing transmissions. Also running a circle d 258mm triple disc and it has always slipped the tcc in upper gears. My fluid temps reflect this and I am thinking its caused accelerated wear on the clutches. I’m swapping in my third 8l90 at the moment and I’m going to go back to a stock converter for the time being.

  2. Avatar
    Brett says:

    When doing the cam/heads package, what else needs to be done to the 6L80 transmission besides the convertor? I know from experience these transmissions have enough trouble holding up to bone stock engines over 100k miles.

    • Gwatney Performance
      Gwatney Performance says:

      Brett, in our experience they hold up pretty well with lower mileage. Over 100K miles, you may want to consider building the trans – which typically, you’d be looking around $2200-$2400 for parts/labor on the trans build. Of course, if it turned out there was something damaged, etc… inside the trans, the cost of that would increase.

    • Gwatney Performance
      Gwatney Performance says:

      I would suggest doing a cam/head package. I would stick with a low lift cam, like our L83 STG 1 cam, which is designed to work with the factory torque converter. The cam and heads (we have a great L83 head porting program) will help increase both the HP and torque, which will help with towing.

  3. Avatar
    Cody says:

    Will the 6.2 work with the 6l80 in the reg cab? Are the harnesses the same for the L83 and L86? Is there anything extra needed for just a straight 5.3 to 6.2 swap aside from recalibrating the ecm? Thanks.

  4. Avatar
    Adam says:

    Hi i would like to do a build like this. I havea 17 silverado 1500 crew cab with the 6.2. How many hours of labor did it take to do everything.?

  5. Avatar
    Chad Hildebrand says:

    What are you using for Fuel? The highest Octane I can get in my area is 91. Also, you mentioned the Cost was around $30k for this Build, does that mean you offer to do this for anyone for $30k? Thanks, chad

    • gwatneyperformance
      gwatneyperformance says:

      It could vary wildly based on configuration. A spec like this would be around $30k w/ the 6.2L swap. You could safely make a little less power w/ the 5.3L and save quite a bit.

      This being said – we don’t cut corners, so this is the cost of doing it right. Many will say it “could” be done for less – and we agree.

      • Avatar
        Matt says:

        I disagree I have a twin turbo 5.3 with crew cab w/6” lift and 35’s 4×4 and I have 20k since the build. The 6 speed has held up great and I can demolish any diesel build I’ve raced and most coupe corvettes etc… it’s more than enough power, yet in the time I’ve had mine I’ve seen 3 different 6.2s blow up. I was contemplating the swap and everything I’ve seen in real world testing points to the 6.2 not holding up long time… Although with your internal work this might be the exception, but I can’t imagine needing more power as I can break my larger tires loose going 40 mph and smoke pretty much any mustang on the road.

  6. Avatar
    Will says:

    I’m wanting to do the same 6.2 swap into my 5.3 2015 Silverado I have a complete 6.2 with the 8l90 but there’s no info out there on what is needed to swap. Did you guys have to reflash the ecm and the for it to even turn on and run in the truck? Would love to just take my truck to you guys but I’m in Houston, so any info you could share with me on this would be great.

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