When the musclecar wars from Ford, GM, and Mopar hit us in the 1960s, the popular saying was “there’s no replacement for displacement.” While that may have been true for that era, today we’re seeing smaller engines produce more power thanks to the addition of not only the latest technology, but forced induction as well.
Though we are still seeing some behemoths cross the production line these days, we’re still in awe of some of the biggest engine blocks that found their way between the frame rails of some of the most interesting and powerful cars for their time. We’re going to look at the ten biggest automotive engines that GM has ever produced, according to a recent blog post on GMPartsCenter.
Number 10 – Cadillac Series 90
Cadillac was always known for big engines, and in 1938 it produced a 16-cylinder engine making 185 horsepower from its 431 cubic inches. By today’s standards, that’s a small engine, but still slightly larger than the famed Chevrolet 427 with only half the cylinders.
Produced until 1940, the Series 90 was considered state of the art back then, and Cadillac claimed this engine’s 185 horsepower was found in some of the fastest cars of its time. The Series 90 was a lower, wider 135-degree V angle design with in-block valves, giving it a much lower hood profile than other engines.
Number 9 – Cadillac 452
Slightly larger than the Series 90, the Cadillac 452 was another 16 cylinder engine found in vehicles produced from 1930-1934. With just 165 horsepower, the 452 was found in some of Cadillac’s most expensive cars at the time.
There was a V12 variant that was a truncated version of the V16, with just 368 cubic inches. Some of Cadillac’s heavier cars were seeing as much as 80 miles per hour, with the lighter cars seeing over 100 miles per hour. At 7.4 liters, the 16 cylinder Cadillac 452 had a smaller displacement than the many of the big block offerings from GM in the 1970s.
Number 8 – Chevy 454
The Chevy 454 was found in cars and trucks from 1970-1976, but was a substantially underrated engine when it was first introduced. Manufacturers would often underrate their engines for insurance and EPA purposes, and enthusiasts often found the power output to be a bit higher than was advertised. The Corvette was fitted with the LS5 version in 1970, with a factory rated 390 horsepower and 500 lb-ft of torque, and the LS6 engine was bumped up to 450 horsepower.
You could also find this engine in cars like the El Camino/Sprint, Monte Carlo, Chevelle, and Caprice, and its LS7 version saw 465 horsepower and 610 lb-ft of torque – not to be confused with the 7.0L LS7 found in the C6 Z06 Corvette. The 454 is a popular crate engine from Chevrolet Performance, with the 454 HO delivering 438 horsepower and 500 lb-ft of torque, and the ZZ454/440 delivering a whopping 469 horsepower and 518 lb-ft of torque. An EFI version was introduced in 1987 as the 7.4L 454, found in GM trucks, and later the Vortec 7400 version arrived in 1996. This engine has had a lot of variants and generations throughout the years.
Number 7 – Oldsmobile 455
The Oldsmobile Rocket 455 was considered the beginning and the end of many things with regards to GM performance. It was the first OHV V8 engine for Oldsmobile, as well as the last one to see a carburetor in a production car. From 1968 to 1970, it could be found in the front wheel drive Toronado – cousin to Cadillac’s El Dorado, and from 1973 to 1976 it could be found in the GMC motorhome, which was also front wheel drive.
The Rocket 455 replaced the 425, but with a bumped stroke of 4.25 inches. Output ranged from 275 to 400 hp with the “Rocket” name disappearing from the air cleaner decal after 1974. The Cutlass, Vista Cruiser, Delta 88, 98, Custom Cruiser, and the infamous 4-4-2 were all found with the 455 up until the end of production in 1976. However, the Olds 455 was still produced through 1978 for power equipment use.
Number 6 – Pontiac 455
Anyone who knows Pontiac mills from the musclecar days knows that the Chief didn’t have big-blocks and small-blocks, as the engines were all based on the same block. Unlike its GM counterparts, Pontiac manufactured its own engines from 1955 to 1981, and the biggest displacement came in the form of the 455, used from 1970-1976.
This 7.5 liter beast was never listed on Trans Am shakers as the 7.5L, unlike the later 6.6L 400 cubic inch mill. It was always called the 455 by everyone, and when the Firebird Formula and Trans Ams came out with the SD 455 in 1973 and 1974, they were the cars to watch out for.
The SD 455 had a strengthened cylinder block with four-bolt mains, nodular-iron crankshafts, forged rods, and forged-aluminum pistons. The SD 455 didn’t pass emissions in 1975, so enthusiasts were stuck with the standard 455 mill until 1976.
*NOTE: a slight oversight in the original list we worked from was the Buick 455, which shared only cubic displacement with the Olds and Pontiac engines. All three engines had their own, unique bore and stroke, and were completely different engines.
Number 5 – Cadillac 472
The base engine for Cadillac’s 500 cubic inch version was the 472, with a stock stroke of 4.060 on the 4.300 bore engine. It was considered to be a lower maintenance engine with 10 percent fewer parts and a reduction of 30 percent in gasketed joints.
Used in Cadillacs from 1968 to 1974, the 472 was capable of 375 horsepower and 525 lb-ft of torque with 10.5:1 compression. But EPA regulations brought that power down to 205 horsepower and 380 lb-ft of torque before the engine was taken out of production.
Number 4 – L18 Vortec 496
The L18 Vortec was introduced in 2001 and was made for GM trucks. It has an all-iron block and the same bore diameter as the 7.4 liter big-block, with the stroke upped by .037 inches. The L18 (PN 89017918) has since been discontinued by GM Performance, and most performance sites will list it as such.
It was a V8 truck and SUV engine first introduced in pickups, Suburbans and Yukons in 2001. In production vehicles, it was putting down between 225–340 horsepower and 350–455 lb-ft of torque, with custom builds bringing the power up to 550 horsepower and a stump-pulling 690 lb-ft of torque.
Number 3 – Cadillac 500
Anyone who lived in the 1970s was familiar with the big 500-inch Caddy engine. It was used exclusively in the El Dorado – a front wheel drive luxury boat that could smoke the tires straight down to the rims – until 1975 when it was available in nearly every full-size model.
With a 4.304-inch stroke bringing the 472 cubic inch Cadillac motor to a whopping 500 inches, this behemoth was capable of up to 400 horsepower and 550 lb-ft of torque with compression adjustments up to 10.0:1. But in the years that followed, like its smaller 472-inch sibling, our wonderful EPA forced compression down to 8.5:1, and horsepower dropped to an anemic 190. It still put out a strong 360 lb-ft of torque, despite the power loss.
Number 2 – Chevy 502
The ZZ502 Base is the DIY for those who want a strong bottom end with big torque, capable of 508 horsepower and 580 lb-ft of torque. The HT502 is a solid truck replacement engine good for 406 horsepower and 541 lb-ft of torque to help you tug that trailer up a hill.
The 502 HO is a good all-around performer putting down 461 horsepower and 558 lb-ft of torque at the crank, giving classic musclecars a great street and strip performance engine. The Ram Jet 502 is your EFI long block alternative to carburetors, with a complete MEFI 4 controller and fuel injectors good for 502 horsepower and plug-and-play simplicity.
Number 1 – Chevy 572
Introduced in 1998, this big block was found in the Chevrolet Performance Parts catalog instead of a production vehicle. Known as the ZZ572, Chevrolet created this monstrous crate engine for enthusiasts for use in musclecars or race cars, with one variant built to accept 92 octane pump gas – the ZZ572/620, and the other built for race gas – the ZZ572/720R.
You can find this crate engine under the hoods of some pretty cool builds. This is the most powerful crate engine that Chevrolet Performance has ever offered with 620 horsepower for the street, and 720 horsepower in race trim. It’s also the largest displacement engine that GM has ever produced, and along with the other crate engines listed, it can be found in the Chevrolet Performance Parts catalog.