The Big Kahuna! Chevrolet LS6 454 Engine

Chevrolet has done a pretty good job over the years of making desirable powertrain components available via its Chevrolet Performance Parts operation. Some of the products offered are pretty close to what was originally available, while other components are a bit more ginned up in their level of sophistication and power. What we have for your review today is a 1990 era 454 CI big-block V8 engine known as RPO-LS6. This “rat” motor is located in Reno, Nevada and is available, here on craigslist for $7,800. Thanks to rex m for this tip!

This replacement engine hails back to Chevrolet’s 1970 450 gross HP, 454 CI V8 engine that was offered in the Chevelle and El Camino SS that year. It was a sort of one and done, though it did return for model year 1971 now sporting a reduced 425 gross HP rating and only available in the Corvette. The legend has it that it was supposed to be available in the Chevelle, Camino, and Monte Carlo that year but it never saw the light of day in any of those applications – supposedly. The early ’71 El Camino sales brochure listed the LS6 option but it was quickly revised to reflect otherwise. And there is a claim that two Caminos were actually built with the engine and I have witnessed, via a magazine article, one of those two rare birds. It was in a high-end collection and I cannot recall, now, what lengths the article went to in offering proof of its legitimacy.

As the seller states, the casting date of L020 does equate to December (L – 12th month), the second day (02), 1990 (0), and the part number, 366250, does identify an early ’90s LS6 as referenced on the Chevelles website. As for the engine casting number, 10069286, it too checks out according to Scream and Fly. The discussion gives a rather mixed view of this motor, however. Being a 1990 vintage puts this engine at the end of the original Mark IV, big-block run – they were updated to a slightly different design, known as the Gen V, in 1991 and have since been updated again to Gen VI specifics.

The biggest difference between this crate engine and the original LS6 is the compression ratio. Originally pegged at 11.25:1, this replacement engine offers a more pump gas friendly 10.2:1. As to whether the horsepower rating has changed as a result of the compression ratio decrease is unknown. Chevrolet, today, offers a trio of 454 CI engines, all in varying states of tune with HP ratings of 438, 440, and 480. As a point of comparison, Summit Racing offers a 438 HP, long-block crate engine for $6,722, while a 480 HP variant, in complete engine form, will set you back $11,500.

This subject motor is a bit of an inbetweener. It’s not a true vintage piece from the early ’70s, one that would reflect the exact characteristics of the original, and it’s not a modern crate engine, one that has become ubiquitous and probably better engineered. Additionally, there are various copycat manufacturers that build and sell new crate engines in both big and small block design form – and their pricing is pretty aggressive. Still, I wouldn’t discount this version of the vaunted 454, you have to remember what was going on thirty years ago and how bleak things had been for performance enthusiasts essentially since the early ’70s. This crate offering was probably a breath of fresh air back then, wouldn’t you agree?


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  1. Terrry

    Nice! Now I just have to peruse Barn Finds and find a rusty Chevy to put the engine into!

    Like 6
  2. George Mattar

    Nice write up. If it was a 70 LS6, the price would be 3 times a much and probably be in serious need of a rebuild. And with all the hoopla about 70 LS6 Chevelles, some guy would be trying to find the car to which it belongs.

    Like 10
  3. Dave

    I have to admit that today’s order-up/bolt-in engine power choices are, for lack of a better word, staggering. 1,000 bolt-in horsepower just leaves the cars of yesterday in the museum.

    Like 10
  4. Steve R

    These were not marketed as “replacement” LS-6 engines, they were sold over the counter as drop in performance engines. They may have predated the factory’s performance crate engines, but that was in name only. These were advertised in many publications, locally it was the Diablo dealer, at the time by performance oriented dealerships. I had several friends that bought these and installed them in their muscle cars because it was cheaper to buy one of these than do a performance rebuild on their original engine. In the mid to late-80’s they sold for a little over $2,000, that was a bargain and thus were a popular upgrade.

    Well before this engine was produced the casting numbers on the blocks and heads had changed. Anyone that installed one of these engines into a 1970 Chevelle/El Camino and tried to claim it was a replacement engine would be laughed at by a knowledgeable buyer.

    Steve R

    Like 9
    • Jim ODonnell Staff

      Not in the sense of a correct “warranty replacement” and the seller does hedge on that “Open to debate, however, in my opinion, the only correct crate motor for 60’s/70 Chevrolet performance cars“. But let’s face it if you owned a twenty-year-old LS6 Chevelle (in about 1990) and the engine was trashed beyond a reasonable rebuild, this would have fit the bill. The insanity over originality, matching numbers, etc., as it exists today, was nowhere near this “heightened” level 30 years ago.


      Like 17
  5. Papa Bear

    A guy that lived close to us had a 69 SS 396 ElCamino and in the early 70’s went to Berger Chevy and bought an LS6 to put in it. He still has the ticket from Berger.853 dollars for the brand new LS6 they put in the ElCamino. Camino is long gone and the motor ended up in a Chevelle, still running around Belleville.

    Like 11
  6. mainlymuscle

    This reminds me , I have an early LS-7 on the original shipping crate ,in my shop,and in the way LOL.Monster engines that apparently would run low 11’s in a properly set up Chevelle.High compression requiring race fuel has kept me from putting it in anything.Many of them ended up un boats from what I hear.Anyways ,The ask here is about what I paid ,and would probably sell it for that now.It will need to be gone through obviously , but its never been run.

    Like 3
  7. Ed Casala

    Chevy built a crate motor in 1990 that made 450hp? Learn something new every day. Wonder what those aluminum ZL1 heads from 1970 on my Vette are worth?

    Like 1
  8. Howie Mueler

    Posted 18 days ago, would be nice to see the carb intake and other things taped up.

    Like 2
  9. bull

    Vastly Overpriced!

    Like 1
  10. KDogg

    you can buy a new version with a warranty for about the same or less

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