Requiem for the Rat
By Chris Haak
December 18, 2009 marked a milestone that passed fairly quietly considering its significance in the automotive realm On that day, GM’s Tonawanda, New York engine plant produced its final big block V8 engine – of course, popularly known as the “rat motor.” This clearly marks the end of an era, because that plant produced some 5 million big block engines for GM starting in 1958, some of which were so legendary that their displacement in cubic inches still haunt the dreams of gearheads.
The last big blocks produced by Tonawanda were available only in GM’s medium duty trucks, and were called the Vortec 8100 (they displaced 8.1 liters) in marketing terminology and were known by GM as the L18. The L18 was built in two configurations for the Chevy Kodiak and GMC Topkick, with either 295 or 325 horsepower and 440 or 450 lb-ft of torque. While we don’t have any statistics on the take rate of the big block gasoline engine option in the medium-duty trucks, it’s not hard to see why the engine probably wasn’t terribly popular in them. It surely got poorer fuel economy than the well-regarded 6.6 liter Duramax diesel, yet the Duramax throws down a comparable 320 or 325 horsepower and staggeringly superior 520-620 lb-ft of torque. Heck, even the much smaller 6.2 liter V8 that’s optional in the Silverado produces 403 horsepower and 417 lb-ft of torque.
Of course, just because Tonawanda isn’t producing big blocks anymore for the first time in almost 52 years doesn’t mean that the big block is completely dead. GM still sells a sizable lineup of big block crate engines through its GM Performance Parts subsidiary. Displacements of the crate engines range from 427 cubic inches (7.0 liters) to 572 cubic inches (9.4 liters), with horsepower ranging from 338 to 720 and torque from 444 lb-ft to 685 lb-ft.
Turning back a few pages (or chapters, if you will) in the big block’s storied history, what became an engine available only in medium duty trucks and sold to manufacturers of pumps, power generators, and power boats began its life as a passenger car engine in 1958, evolved into a racing engine, had songs written about it, and became literally the stuff of legends. Ask any guy with gasoline coursing through his veins what “396” “427” or “454” mean to them, and you’re likely to hear something about the Chevy Big Block V8. I don’t pretend to be an expert in all things big block, but these engines have always held a special place in my heart.
The last time I heard a big block was at the beach this past summer in Delaware when a speedboat roared along the shoreline. Knowing what kind of engine I was hearing, the sound was enough to make the hair on my arms and neck stand up. Yes, I’m that much of an auto enthusiast that the growl of a big block-powered boat can raise my pulse.
Digging a bit deeper into the old memory banks, probably my favorite big block memory is riding shotgun in my father’s friend’s 20,000-mile one-owner 1967 Corvette convertible with the 427 cubic inch/435 horsepower solid-lifter L71 under the hood, and of course with factory side exhaust. His friend never babied the engine from the day he bought the car new, and the fact that many of the car’s 20,000 original miles had at least one trip to the 7,000 RPM neighborhood is either a testament to the big V8’s durability, or to the benefits of a regular flogging in keeping things running smoothly. Perhaps it’s a combination of the two. Getting a chance to ride in that ’67 Corvette – usually only once a year – was often one of the highlights of my summer, and (with apologies to Mozart), to my ears, there really is no sweeter man-made sound in the world than a solid lifter, side exhaust-equipped big block at full bore.
I never had much exposure to other big block-equipped cars and trucks through the years aside from some time spent driving a half ton two wheel drive 1972 Chevy pickup with a “400” (really 402 cubic inch) big block on parts runs for my father’s business. But I’d be remiss in not mentioning that, aside from the Corvette big blocks of the mid- to late-60s and early 70s, the 1970 Chevy Chevelle SS 454 is another legendary model that stands out in my mind as one of the pinnacles of big block performance. There were two different 454s available in the 1970 Chevelle SS 454: the top-trim LS6 454 produced 450 (gross) horsepower and 500 lb-ft of torque; both figures put the LS6 at or near the most powerful engines sold to the public during the muscle car era, at least in terms of published horsepower. (Underrating horsepower was a common game in that era, in an effort to dissuade casual buyers from just checking the option boxes with the largest numbers and to encourage lower insurance premiums). GM did the underrating trick with the “430 horsepower” high-compression L88 427, which actually produced over 500 horsepower; so did Chrysler with its 426 Street Hemi.
My sextagenarian father loves large-displacement V8s, and for a while had a solid brown, two wheel drive 1977 Suburban with a factory 454 under the hood. Because you could get that engine in 1977, he had trouble understanding why you weren’t able to get the big block with the half ton in later years, such as when our family got a new 1988 Suburban, or when we got a new 1997 Suburban. But GM did at least partially answer his question with the 1990 Chevy 454SS pickup. No big blocks had been available in half-ton trucks in years, yet GM put a 454 cubic inch (7.4 liter) V8 under the hood of its lightest full-size pickup (regular cab, short bed) in the 1990 through 1993 model years.
Guess whose dad owned one, at least for a while? Yep. His was a 1990 model, which produced only a sorry 230 horsepower from that giant engine, but a healthy 385 lb-ft of torque, piped through a three-speed HydraMatic. The previous owner of that particular 454SS had replaced its exhaust system with a freer-flowing X-pipe setup, and it sure felt fast compared to my 1988 Grand Am SE with a 150-horsepower Quad 4. I loved driving that truck, and to me, the funniest thing about when I was allowed to drive it was that I was generally only allowed to do so on wet roads. Yes, it’s counter-intuitive to give a 16 year old male a pickup with 385 lb-ft of torque and most of its weight not on the drive wheels, but it actually forced me to be tame with the truck and to respect the big block. I was thinking of that experience with the 454SS this morning as I managed to get excellent fuel economy as I feather-footed my way to the office through slippery roads amid an early-morning snowfall while piloting my rear wheel drive, 304-horsepower car shod with all-season tires.
GM never put the big block into another half-ton truck again. In its last decade and a half, the big block was available only in 2500- and 3500-series trucks and larger. The 2007 model year was the last in which the Vortec 8100 was available in the 2500- and 3500-series trucks, leaving only the medium duty trucks to carry the torch. With GM winding down the medium duty business and ceasing production in July 2009, it was only a matter of time before the big block met its demise.
Just because the big block is gone, however, not all is lost. The 3.6 liter V6 in my Cadillac CTS outpowers the 7.4 liter V8 in the 1990 454SS pickup (though doesn’t touch the 454’s torque), and newer engines like the 7.0 liter LS7 big-bore small block (which GM says displaces 427 cubic inches for obvious marketing reasons, though the true number is 428 cubic inches) put most of the old big blocks’ output numbers to shame. And the new supercharged LSA (556 horsepower, 551 lb-ft in the Cadillac CTS-V) and LS9 (638 horsepower, 604 lb-ft in the Corvette ZR1) are two of the most powerful engines that GM has ever installed in production cars.
A new Corvette with the 6.2 liter LS3 small block V8 and the optional NPP performance exhaust is another car that happens to have the ability to make my arm hairs stand on end. But still, there will never be another Chevy big block V8. Rest in peace, rat. I wonder if there are any babied 454SSs on eBay Motors today.
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