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Published 1/31/24

The 525 RLB Crate Engine is Here



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The 525 RLB, the latest sealed racing crate engine* from Chevrolet Performance, is a long-block assembly based on the circle-track specific CT525* and developed for universal sanctioning bodies.

Among its many uses, it is an ideal fit for spec-based off-road racing.

The engine comes in a long-block configuration.

Robert King, the proprietor of Klein Engines, is among those who was heavily involved in the development of the 525 RLB.

King’s Phoenix-based shop was founded by Tom Klein in 1974 and King took over the reins close to 14 years ago. The two men share a close relationship, with King having driven Sprint Cars for Klein for several seasons. The shop has worked on projects ranging from dirt and pavement circle track engines, to INDYCAR development, to engines for off-shore boats, twin-turbo sand rails and off-road desert racing.

Brad England, parts manager at the GM-specific AutoNation Parts Center Phoenix, supplies King with the engines that Klein builds into race car power plants for a wide variety of racing disciplines. In fact, it is common to see the AutoNation Crate by Klein Engines logo at tracks and on race vehicles.

Among Klein Engines’ diverse slate of projects is heavy involvement in the off-road space.

“I was already building the off-road engine for these guys and we're trying to make it more economical and less work for the consumer,” King says of the 525 RLB.

A version of the Chevrolet Performance 525 RLB crate engine* made one of its first public appearances during the 2023 BFGoodrich Tires Mint 400. Klein Engines aided in the engine’s development.

Per the Chevrolet Performance catalog, the LS-based engine cranks out 533 horsepower and 477 lb.-ft. of torque when used with a four-barrel carburetor and intake manifold. Among the engine’s highlights are forged pistons, heavy-duty connecting rod bolts and LS3 rectangular-port cylinder heads offering impressive airflow. In addition, the assembly includes a coil-on-plug ignition, SFI-certified balancer, six-quart racing oil pan and more to get the most performance out of the high-revving, high-strength engine. Racers will simply need an induction and ignition system to complete the power plant.

In many spec-based off-road classes, racers utilize a version of the Chevrolet Performance LS376/525, but with some upgrades allowed to the engines before they are sealed. As a result, engine shops swap out items like camshafts and oil pans, potentially adding parts costs and labor in what are designed to be budget-friendly classes. The 525 RLB helps offset those expenses. Plus, many of the parts upgraded by the shops are included in the 525 RLB anyway.

“Since this package is already done, we take all the labor rates away from that and the parts are already there,” King explains. “That's why it'll help the consumer save money.”

The 525 RLB is an ideal choice for a variety of trucks competing in off-road spec classes.

In addition to his relationship with England and the team at AutoNation, King works closely with veteran road racer Jeff James, a Chevrolet Performance parts and performance specialist based in Westlake Village, California. James has worked with General Motors since 2007. Through his time in the field and in talking with King, James found that there was an opportunity to build upon the CT525 for racers, while also providing sanctioning bodies with a package that could simplify rules across the board.

“Let's give them a more durable package that is more cost-effective and is more verifiable,” James says. “Each sanctioning body can package their rules [their own way], but if this guy wants to come run with this other group, he’s legal without having to make a bunch of engine changes, or having to take this motor out and put this open motor in or something like that.”

The Unlimited Off-Road Racing sanctioning body is among those embracing the new engine, having specified the 525 RLB for use in the Unlimited Truck SPEC class in its events. They include the Parker 400 in Parker, Arizona; the Mint 400 in Primm, Nevada; and the California 300 in Barstow, California.

Hall Racing campaigns a truck in the Unlimited Truck SPEC class at events like the BFGoodrich Tires Mint 400. The 525 RLB is now written into the rulebook for Unlimited Off-Road Racing events.

The aforementioned events taking place from January to mid-October are some of the most highly regarded in the off-road world. What’s more, at each of the three in 2024, AutoNation Chevrolet Gilbert will provide a new 525 RLB crate engine to the winner in Unlimited Truck SPEC. The only eligibility requirement is that an AutoNation/Klein Engines decal be displayed on both sides of the truck.

But the 525 RLB goes much further than cost-effectiveness or a way to unify rule books. It is also a very stout piece with internals that are ideal for engines that face as much stress as those found in off-road competition.

“By us building something that’s tailored to them, all they have to do is basically put a front-end accessory drive on that fits their application, and put an intake manifold on in their configuration, and go,” James says.

Since the engine comes as a long block, it can be used for a variety of racing disciplines outside of off-road as well.

“It will also be an excellent replacement for some of the circle track guys that are adopting our 525,” James notes.

Plus, the long-block nature of the RLB allows racers to utilize either carburetors or a fuel-injection system.

The 525 RLB is one of many crate engines offered by Chevrolet Performance.

Regardless of usage, all the 525 RLB crate engines will feature tamper-proof seals, an important component of leveling the playing field. The 525 RLB includes an encrypted cap and seals that can be read with a phone app by a series’ tech team.

James, King and England all envision the engine having the same effect on the off-road space as GM’s now legendary circle track engines did in that discipline. In essence, they have allowed lower-budget racers to be more competitive without needing to absorb the costs and time associated with high-dollar built power plants.

“I certainly don't want to hurt or affect the business of these other engine builders, I just want everybody on the same page,” James says.

The 525 RLB also offers options in the ever-evolving motorsports landscape, particularly as it continues to move from carburetion to fuel injection, while also furthering General Motors’ commitment to internal combustion engines.

“Everybody's pushing for EVs, and EVs are very practical for many applications,” James says. “But we’re not going to see very many off-road EV packages anytime soon. So, I just really want to make sure that the racers and the hot rod and performance enthusiasts know that we’re here to stay. We’re not going anywhere. We still do Small-Blocks, we still do Big-Blocks, we've developed new packages in all of those areas over the last few years and we're going to keep going forward there.”

Robert King of Klein Engines (left) and Chevrolet Performance’s Jeff James.

For King, a longtime racer himself, the reasons for his involvement in the sport are just as much personal as they are professional.

“This is supposed to be a fun hobby, a sport, and if [the racers are] not having fun and they're not spending money, we're not there,” he says. “That's what my job is; I care. I want the guys out there racing.”

The 525 RLB gives them that opportunity.

Keep watching The BLOCK for much more on Chevrolet Performance and all motorsports disciplines.

*Because of its effect on a vehicle’s emissions performance, this engine is intended exclusively for use in competition vehicles. This engine is 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 this engine 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.