Everyone has their own opinion about which muscle car engine was the best muscle car engine - because we each have our ideas about what it takes to be the best. For some, it's all about peak horsepower numbers - even if the engine was barely streetable. For others, it's about wild designs - canted valves, cross-ram intakes and multiple carbs (or fuel injection). But when the parameters are defined more closely - and the question is, which muscle car engines were also great street performance engines - the following contenders deserve a tip of the hat:

* 1970 Buick GS 455 Stage 1

Don't be misled by this engine's seemingly mild 360 horsepower rating - be thrown back in your sport bucket by its stupendous 510 ft-lbs. of torque - more torque than any other engine of the muscle car era and all of it available at just 2,800 RPM. And torque, not horspower, is what moves a street car (especially a two-ton muscle car) down the quarter mile like a scalded cat. In the case of Buick's 1970 GS, that would be a searing 13.8 seconds flat at more than 100 mph through the traps - and 0-60 in 6.5 seconds. Those numbers make the '70 GS Stage 1 455 one of the quickest factory stock muscle cars ever built, bar none. And it delivered that performance with air conditioning and power windows, through an automatic transmission - and with civility few similarly high-powered muscle cars of the era could hope to match. The Stage 1 engine featured a cold-air induction hood scoop/dual-snorkel air cleaner, high-flow Quadrajet four-barrel carb, large valve heads and a hotter camshaft, among other upgrades. It represented the pinnacle of Buick performance - and a record that would not be challenged until the mid-late '80s and the introduction of the turbocharged Regal Grand National and GNX.

* 1973-1974 Pontiac SD-455

The SD-455 is considered by some to be the last hurrah of the classic muscle car era - and that it was. Even when it was a brand-new engine, it stood virtually alone; Ford, Chrysler and even the rest of GM's divisions (including Chevrolet) had killed off most of their true performance engines - and even the cars that once housed them. The 290-310 horsepower (net) SD-455 Trans-Ams and Formula Firebirds were truly the last of the line. But they were also the most potent Pontiacs ever offered to the public - besting earlier bruisers like the 1970 Ram Air III 400 equipped GTO and the even more radical (and rare) Ram Air IV 400-equipped '70 Trans-Am. And they did it with low (8.2:1) compression, a fairly mild hydraulic cam - and radical round port heads that flowed more air than all the politicians in Congress combined. A stone stock SD-455 was capable of low 13 second quarter-mile runs and top speeds approaching 140 mph - with a non-overdrive three-speed THM400 automatic transmission (or non-overdrive 4-speed manual). Uncork the factory exhaust, shoe the thing with drag slicks and dial up the ignition timing a bit and SD-455 cars were reportedly high 12-second machines. That is fast by any standard - even today's. A new Corvette Z06 is only slightly quicker - and it is advertised as having more than 500 horsepower and has the benefit of a modern six-speed gearbox and massive tires to hook it all up. One wonders what the true output of the '73-74 SD-455 really was. And how fast it might have been with a bit more development - and better tires to put all that grunt to the pavement instead of brutalizing the overmatched 15-inch rubber that came on the cars of that time.

* 1970-1972 Chevy LT-1 350

When the 350 small-block Chevy V-8 appeared (along with the also-new Camaro) for the 1967 model year, it was as a mid-performance engine - above the Camaro's standard inline six, but several steps below the big-block 396 that was available in the Camaro SS. By '69 (final year for the first-generation Camaro) it was still playing straight man to hot dogs like the Camaro Z28's race-intended 302, which could be ordered with exotica such as a cross-ram four-barrel intake, with cowl induction on top of that - and tube headers and chambered pipes in the trunk. But as wild as it looked - and as great for high-RPM SCCA roadracing as the 290 horsepower 302 may have been - it sucked on the street. It wasn't very driveable, didn't work with an automatic transmission - and wasn't even especially quick (stock '67-69 Z28s were generally good for low-mid 15 second quarter mile times). All this - and the stolid reputation of the 350 - would change in 1970, when the LT-1 appeared in the Corvette and as the new "second generation" Z28's standard engine. Though it still offered high-performance special equipment like the previous year's 302 - including an aggressive solid-lifter camshaft, high-compression pistons, four-bolt block and an aluminum high-rise intake with a Holley carb on top - the extra cubic inches gave it both superior horsepower (370, according to the press releases) and streetability. It was also a better performer than the old 302 - at least, quarter-mile wise. The new Z28 was noticeably quicker (solidly in the mid-low 14s) and had much more part-throttle punch. Buyers now had their choice of either a 4-speed manual or three-speed turbo-hydramatic, too. Unfortunately, the LT-1 had a brief life due to ever-increasing emissions regulations and was replaced just a few years after it was introduced by the much milder L-82, which tried hard but wasn't half the engine the LT-1 was.

* 1966-1972 Chrysler 440 Magnum/Super Commando

The 426 Street Hemi may be Mopar's rock star engine, but like so many other extreme engines of the muscle car era that were basically race car engine "detuned" for the street - and put into production to legitimize their use in race cars - the Hemi was not at its best idling in traffic. In fact, it wasn't really happy outside of its native environment - the high banks of NASCAR super speedways like Daytona or ripping up the asphalt in quarter-mile bracket racing. Hemi cars still get the big bucks today as collectibles, too. But back in the day, savvy street brawlers knew the virtues of the 440 - in either Magnum (Dodge) or Super Commando (Plymouth) forms. Its rated peak horsepower - 375 at the peak of development - was not too far off the pace of the Hemi's 425 horse rating (though admittedly, the Hemi was probably laughably under-rated). And on-paper numbers or no, the 440 delivered heroic performance in 4,000-lb sheetmetal dreadnoughts that had no business being fast. And yet, fast they were. Blisteringly so, in the case of several examples. The single four-barrel 440 was a tough customer, but for a few years, one could up the ante with a three carb setup known as the Six Pack (or Six Barrel) which pushed the rated output of the mighty engine to within striking distance of the vaunted Street Hemi - on the street, at least. The three carb set-up got cancelled after '71, however - and though the 440 block continued in production through the mid-late '70s, it got crippled up after '72 and continued to lose special parts (and performance) until the end, when it was just a big engine for big boats, all hollowed out and barely belching out 200 honest ponies by the end.

* Ford 289/302

Ford has built a number of standout V-8s over the years, including legends like the 427 and 428, the 390 and 351 Cleveland - to name just a few. But unlike virtually all the muscle engines of the '60s, Ford's sweet small block - the 289/302 - lasted as a production engine for decades after the original muscle car era ended. It was in fact still powering Mustang GTs as recently as the mid-1990s - and was only retired after Ford concluded it could no longer be tweaked to meet constantly tightening emissions and fuel efficiency diktats. (The 4.6 liter overhead cam V-8 took its place in the Mustang for the '95 model year - and though not a bad engine, it lacked the low-speed grunt and muscle feel of the old Five-Oh.) Like Chevy's also-excellent small block V-8, the 289/302 was a very versatile little engine that could be built for economy and smoothness (in two-barrel form, with mild cam - just like Chevy's 307, 305 and even a few 350s) or it could be set up as a full-tilt screamer with a 6,000 RPM-plus redline and more horsepower than it had cubic inches. Early Mustangs with the K-code 289 "Hi-Po" (and its advertised 271 horsepower) are among the most desirable of '60s-era muscle machines - capable of quarter mile times right there with the big block bruisers (14.68 seconds, according to one road test of the time). Ford's small V-8 also held the line during the darkest days of the mid-1970s, keeping at least the idea of V-8 street performance alive (if not the actuality). And when the second muscle car era flickered to life in the early 1980s, it was Ford's Mustang GT - powered by a 5.0 liter "Boss" - that lead the way.

Again.