Celebrating 7.0L of American Horsepower (Happy 427 Day!!!)

The king of the 1960s, the legendary 427 was later reborn as the most powerful naturally aspirated LS motor ever made.

Look at the calendar. Today is unofficially 427 Day. And we couldn’t let today pass without paying tribute to a series of engines that all shared one common denominator: seven liters aka 427 cubic inches of tire-smoking American goodness.

From big block fury to setting the benchmark as the highest-revving LS-family engine ever made, the 427 isn’t just one engine. But several. Here’s a quick look back at the historical highlights.

Big Block 427

The 427 was a big block V8 that could be found under the hood of Corvettes from 1966 to 1969. (The one pictured above was recently sold on Bring a Trailer). But, as hardcore enthusiasts well know, the 7.0-liter 427 wasn’t just a single engine; it was several. In 1966, you could opt for RPO codes L36 or L72. Rated at 425 horsepower for that model year, the L72 featured larger intake valves, bigger carbs, and other upgrades. In 1967, one could opt for the L72, now listed at 400 horsepower, or the L89, which was essentially an L72 with aluminum cylinder heads. GM claimed the L89 made 435 horsepower, although this was likely underrated.

The King 427 of the era was called the L88 and was, effectively a blueprinted racecar engine that was also “rated to 435 horsepower.” (Although many believed that number was closer to or even above 500 horsepower.) Here’s how Car and Driver described the L88 in 1967 when the editors literally described being too afraid to test it, opting for the L89 instead:

There is an even more powerful, Instant Immortality engine, coded L88, for megalomaniacs only. The L88 also has the aluminum heads (which feature larger exhaust valves — 1.84 inches vs. the standard 1.72), but with a toilet-sized single four-barrel sitting atop a hogged-out manifold. All the 427s have a suggestive hood bulge, but the L88 alone has an air intake at the rear of the hood which ducts cold air directly on the carb.

The 427s reign came to an end in 1970 when GM bored out the big block to 454 cubic inches. The first variant was dubbed the LS6 (which later became the name of the C5 Z06’s motor). And, crazy enough, GM was planning to unleash an LS7 454 that was supposed to be good for about 460 horsepower. But rising gas prices, insurance rates, and emission standards made the original LS7 dead on arrival… for production cars. Instead, Chevrolet offered the “off-road-use only” LS7 as a crate motor and it was the stuff of legends until its nameplate returned a few decades later.

LS7 

In 2006, it had been 37 years since a 427 cubic-inch engine graced the engine bay of a production Corvette like the one pictured above on Bring a Trailer. But this time around, the high-revving 7.0L V8 was massively different. Revving to 7,000 RPM. Fuel injection and computer controlled only. And it was technically a small block Chevy this time, being a bored-out version of the LS2.

The LS7, as the new 427 was called, featured titanium connecting rods, CNC ported heads with titanium intake valves, and sodium-filled exhaust valves this could be considered a racecar engine. And with 505 horsepower, it had the performance to back up that claim. And even though it was a small block, it made big block-like torque. 470 pound-feet of it to be exact. And the bulk of it is available from 2,400 RPM to 6,400 RPM. A 2006 Z06 could hit 60 mph in just 3.5 seconds. Faster than a 911 Turbo or Ferrari F430 of the day.

This LS7 would stay in the Z06 until 2013. It also was used in the 2014 and 2015 Camaro Z28. It remains the most powerful naturally aspired LS family engine ever produced, and the second-most powerful naturally aspirated Corvette motor of all time.

427 Convertible Collector Edition

GM knew how special the 427 was. They even named one of their commemorative models using the term. In 2013 the Corvette 427 Convertible Collector Edition was released. The car simultaneously marked the 60^th anniversary of the Corvette and paid tribute to that legendary 7.0L V8. At the time it was released it was the fastest convertible Corvette in history. There have been quite a few commemorative edition Corvettes, but the 427 Convertible Collector Edition is one of the best. And a big reason is because of the engine under the hood.

The End of the 427 Era

The world is moving fast to produce nothing but all-electric cars. But the 427 is still fighting the good fight, much like its 1970s ancestor, as an “off-road-use only” crate motor. The LS427/570 crate engine makes 570 horsepower and 540 pound-feet of torque, a major upgrade over the stock variant. But alas, it is, sadly, discontinued. But you may still be able to find one if you contact the right retailer. It remains a great engine for any project car you may be considering.

But you better act fast. The 427 days are quickly coming to a close.

Images: Joe Kucinski; Chevrolet, Bring a Trailer

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