L8P for a C10

The latest LT offering is here. For just over a decade, the cutting-edge LT platform has served as the fifth generation of General Motors’ storied Small-Block V-8. Now, the 6.6L crate engine* known as the L8P makes big power and big torque. This fresh, large-displacement engine is derived from the L8T engine offered in current-generation Chevrolet Silverado 2500HD and 3500HD models. The high-strength L8T was also previously introduced as a crate option,* and today, the “P” in the L8P version means “Performance.” 
 
With that kind of pedigree, it’s only fitting that the Chevrolet Performance team has installed one of the first L8P engines in a 1967 Chevy C10. The truck has showcased a variety of Chevrolet Performance crate power plants* since 2017, and this year it will make the rounds on HOT ROD Power Tour. The engine is also currently available to customers.

“The L8P provides good, usable horsepower and torque curves, it's very drivable and it sounds good,” says Jeff Trush, General Motors Group Manager, Pace Car and Specialty Show Vehicles. “It’s kind of neat to me that it's actually a 6.6L truck engine that's out of one of our modern trucks and it goes into one of our vintage trucks. That is kind of a cool tie from modern day back to our classic history … This truck was built in 2017 for SEMA and to be able to modernize and upgrade it to some of our latest and greatest technology is pretty neat.” 
 
The L8P makes 523 horsepower and 543 lb.-ft. of torque. Like the L8T, the engine features a forged steel crankshaft, a variety of high-strength parts, high-flow heads and a composite intake manifold. However, the L8P engine combines the substantial strength and large displacement of the L8T with several valvetrain upgrades to provide impressive performance capabilities.

Among them is the use of a billet-steel hydraulic roller camshaft based on the LT2 engine that powers the eighth-generation Corvette Stingray. The cam features additional lift and duration over the L8T version to draw more air and fuel into the engine. Enhanced valve springs and intake valves in the aluminum cylinder head complement the camshaft. 

Although the engine is currently represented in a classic truck – one of today’s most popular options for enthusiasts – the engine can be utilized in a wide variety of builds despite its large size. In fact, the Chevrolet Performance team has also installed both the L8P and L8T engines in Cadillac CTS-V models. 

“It's no different than installing anything from the LT family in my mind, the mounts are all similar,” says Jeff Walker, General Motors Engineering Group Manager – Performance Software and Calibration. “For the CTS-Vs it just bolted right in. As long as you’ve got the clearance to the oil pan, you should be good. You can bolt it in, you can buy Gen V LT swap parts.

“With the LT family being out there already there are a lot of aftermarket [parts] to support conversions, and that was kind of our path on the ’67. If we don't offer it, what can we get off the shelf that just bolts right in?” 
 

The two Jeff’s teams work hand in hand.

 At the GM Performance and Racing Center in Pontiac, Michigan, and the nearby Milford Proving Ground, Walker’s group handles extensive calibration, tuning and testing. They dial in engines and components until they have wrung out both the best possible performance on the dyno and proper drivability. For the C10 build that also included calibrating the SuperMatic 6L80-E six-speed automatic transmission that is paired with the L8P. 

Then, Trush’s team installs the parts and builds vehicles to the most up-to-date configuration, including all sub-systems, in Milford. 
 
“Jeff’s group helps by providing the crate engine components, the crate engine and calibration support, and we're essentially responsible for the vehicle build and the crate motor installation,” Trush explains.

Walker says that in essence, Trush is the first customer. 
 
In addition to demonstrating the engine in a popular build, projects like the L8P in the C10 provide a test bed for Chevrolet Performance.  

“Not only does it become the show property, but it also becomes a learning tool for us to be able to utilize that truck to potentially refine or evaluate the package in a classic vehicle beyond what we've already done,” Trush says. 

The L8P provides customers with an engine based on architecture that has been extensively tested and proven both by engineers and by hundreds of thousands of grueling miles on the road in heavy-duty trucks. In production trucks, many of those miles involve towing trailers or other activities requiring the utmost in durability and lots of torque. Now, enthusiasts can get all of those characteristics plus performance enhancements.  
 
In addition, they get the benefit of General Motors’ extensive resources and the knowledge of some of the best engineers in the business. 
 
“It's all production-built, the same engine plant that builds the [production] L8T is building [the L8P] for us as well,” Walker says. “It's a low-volume build, but you're doing it in a production facility that builds thousands of engines, so being able to implement this into that facility has been perfect. You get all the checks and balances from the huge volume of the L8Ts going into the G-vans and heavy-duty trucks that we sell. Those engines have to be perfect and now we're leveraging all of that to build the L8P.”  
 
According to Walker, the L8P feels very refined while still being massive fun to drive.

A 1967 C10 seems like a perfect fit. 

Be sure to keep watching The BLOCK for coverage of this year’s HOT ROD Power Tour and many Chevrolet Performance builds from events across the country.
 
*Because of their effect on a vehicle’s emissions performance, these engines are intended exclusively for use in competition vehicles. These engines are designed and intended for use in vehicles operated exclusively for competition: in racing or organized competition on courses separate from public roads, streets or highways. Installation or use of these engines on a vehicle operated on public roads, streets or highways is likely to violate U.S., Canadian, and state and provincial laws and regulations related to motor vehicle emissions. 

Classic builds are not available for purchase.