LSXrt 6.3L Install on the Silverado

In May I went all crazy. Yep. All crazy. As a life long dream and goal, I’ve always wanted to own a hot rod and building the Silverado all these years has been part of the goal. From the RideTech and DJM suspension, to the Monster Transmission, paint job, custom roll pan and exhaust, electric fans, lights too finally here at the custom engine.

That’s right. The full meal deal on a Texas Speed LSX 6.3L stroker motor was ordered. Up to this point, the blood, sweat, tears, and money has all been worth it.

To start, let’s go into social media for a second.

A question I’ve been getting a lot on Facebook is: Why did I choose the 5.3L platform versus a 6.0L or larger platform? Pretty simple actually.

This Silverado came factory with a 5.3L LM7, a cast iron block 5.3L, and it made sense to go with Texas Speed’s 6.3L stroker since it started life as a 5.3L LM4. Choosing this setup allowed factory components to be used which kept costs down. Factory items used:

  • Oil pan
  • Oil valley pan
  • Valve covers
  • Factory fuel rails with updated brackets
  • New, factory replacement high volume water pump
  • A/C Pump and brackets
  • Alternator and brackets
  • Power steering and brackets
  • New, factory replacement motor mounts
  • Factory belt tensioners
  • New, factory replacement high torque mini starter

In addition, here is quote from TS’s website:

The GM 5.3L aluminum engine block is a very popular choice to use in 347, 383, and 395 CID applications due to its lower cost. It has excellent benefits, such as bay-to-bay breathing, that make it very durable to use in the build.

My mechanic, and all-around badass, Dayzed50 did the majority of the work while I handed wrenches, did some smaller misc here and there, and exercising the demons by drinking the cold ones.

The overall assembly was straight forward since the motor arrived as a long block.

As seen in the pictures below, the headers and intake were fitted outside the truck and glad we did too. In coming videos, it will be seen that there was some sanding on the passenger side head’s gussets for header clearance. The sanding didn’t affect any structural integrity as those gussets weren’t being used by this application.

After all fitment was done, the motor slid right into her new home with the headers lining up perfectly to the collectors. There was zero fighting. We didn’t even have to loosen the lower exhaust. Jackpot.

The major pain in the ass was installing the ATI Super Damper as the tools being used just quite wouldn’t work. However, with some modifications to those tools, the damper went right on. We decided to install the damper after dropping in the motor as it provided more clearance when lowering the motor into place.

*In hind sight, we’d probably have pulled the radiator and fans and installed the damper outside the vehicle.

The FAST LSX RT intake installed smoothly and using adapters that accommodated factory fuel rails and injectors (the 24lb injectors are in during break in and will step up to 42lb afterwards. More on in a later blog) the intake was done. Dayzed did tap some vacuum and sensor locations yet no modification were done to the factory wire harnesses or sensors.

Also, I absolutely love the dry intake versus previous GM generation engines as all the o-ring gaskets make installation clean.

Upon bolting on the accessories and giving it a test fire, no oil pressure was to be had. Dammit to hell! I mean … it was a bit stressful. Dayzed50 conducted extensive internet research and we did some testing before deciding on the next plan. Dayzed50 chose a method he had heard about that kept coming up online – Packing the oil pump with Vaseline. Being petroleum based and thick, the Vaseline created enough vacuum for the oil pump to prime. Using a stopwatch, we timed the priming which took less than 5 seconds. It was dam near immediate.

Celebrating success with a high-fives and cold ones, the remaining engine accessories went on, the engine was filled with fluids, and a double-double check-check on fasteners was completed.

A second test fire was in order and oil pressure rose with no issues and the Silverado purred at idled. I was told to vary the RPM for a few minutes while things broke-in and then shut down for an oil change.

The next 300 miles clicked off easily with having to drive up to the Stevens Pass ski cabin and then to Roy’s for an oil change. Folks at Roy’s asked a bunch of questions and the truck literally shook their walls. LOL Winning.

Now the Silverado is sitting at approximately 500 miles and I’m ready for more.

Next to come will be the dyno tune session. Stay tuned.

2 thoughts on “LSXrt 6.3L Install on the Silverado

  1. Dude, that is turning into one badass truck. I love the way everything looks. Can’t wait for a video to hear the sound of that V8.

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