Jan 25, 2013
Dave Walter
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History of the Corvette LT1

As is no big surprise by now, the next Corvette is on its way and the world is a better place for it. The C7 aims to be a better than the current Corvette in just about any way it can, and from the looks of things, it just might accomplish that goal. One of the biggest contributors to any vehicle’s success or failure is, of course, its engine. And when it comes to sports cars, the engine factor is exponentially more important than in say, your average entry-level subcompact.

Designated as the LT1, the heart of the C7 certainly looks like a success on paper — an all-aluminum 6.2-liter pushrod V8 (thank the heavens), variable valve timing, an amazing 11.5:1 compression ratio, direct-injection (which is a first for a pushrod engine), and of course the matching 450/450 horsepower/torque rating which is nothing short of glorious. All of these figures, you are bound to see over and over in the coming months, and the LT1 will be heralded as the crown jewel of the Corvette kingdom. What you may not know however, is exactly where this LT1 sits in the GM small-block lineage, and just how far back the General harked for its newest engine’s name.

The new 2014 LT1 fits into two of GM’s historical engine categories. The first is where it sits in terms of engine “Generations” (denoting major mechanical changes in an engine of the same size). The new LT1 is the fifth generation of the small block V8. Generation 1 was in 1955 and was given many name designations, but essentially was the same engine for four decades. Generation 2 didn’t come along until 1992 and was named the LT1 (more on that in a second). That engine carried on for 15 years until the LS1 debuted as the Generation 3 in 1997, and then the LS2 made its entrance into the automotive world beginning the Generation 4 series of engines in 2005. Now the new(er) LT1 will denote the beginning of the Gen 5 engines, and it’s anyone’s guess how long it will stick around.

That however, isn’t the only historical series the LT1 fits into. The LT1 designation has come along, not one, but two other times in the history of the Corvette. As previously mentioned, the most recent was in the 1992 Corvette. That LT1 was a technological marvel, it displaced the same 350 cubic inches, but had an iron block with aluminum heads, and it introduced a reverse-flow cooling system (a first for GM), in which the engine’s temperature management was designed to cool the heads of the engine first (as opposed to the more traditional block-first-then-heads cooling pattern), which kept cylinder temperatures down thus allowing the engine to run at much higher compression ratios (flash forward — you can start to understand why the 2014 motor may have been given the LT1 designation, considering its 11.5:1 compression ratio). In 1996, GM decided to upgrade the LT1 with a host of performance parts, including a more aggressive camshaft, better flowing heads, and other go-fast goodies. There were so many tweaks to the LT1 that GM decided this high-performance LT1 needed its own designation, and introduced us to the LT4. Any Corvette equipped with a manual transmission got the 330 horsepower LT4 standard issue, while automatic Vettes still retained the 300 horsepower base LT1. GM also did bring back another name — the ZR1. The ZR1 was a second generation Corvette that ditched the LT1 and used a 32 valve all-aluminum Dual Over Head Camshaft (DOHC) engine that was designed by Lotus and built by Mercury Marine called the LT5. This monster motor produced 375 horsepower in 1990-92 and jumped to 405 horsepower from 1993-1995, so don’t be surprised if we see the next Corvette ZO6 sporting a resurrected LT4 monikered engine, or the return of the LT5 in the next ZR-1.

The first installment of the LT1 however, was issued way back in 1970. That first LT1 was again, a highly modified 350 cubic inch engine that used things like solid lifters, a higher-lift camshaft than in the ‘standard’ 350, a Holley four-barrel carburetor, aluminum intake, and surprise, surprise, a much higher than normal 11:1 compression ratio (noticing a pattern yet?). In Corvette trim (as it was used in a few other cars), the first LT1 was rated at 370 horsepower at 6000 rpm and 380 pound-feet of torque at 4000 rpm. Sadly due to a combination of new “net” horsepower versus “gross” ratings, and a lower compression ratio due to the impending gas crisis, the LT1 was detuned to a “net” of only 255 horsepower and 360 lb-ft of torque in 1971, and dropped even further in 1972 to the tune of 255 ponies and only 280 lb-ft of torque. But the LT1 would live on.

The only other point of note in this myriad of numbers and designations is to point out the generation of car that the LT1 will be used in. As evidenced by its name, the C7 is in fact the seventh iteration of the Crossed Flags. The first was in 1953, the second in 1963, the third in 1968, the fourth in 1984, the fifth in 1997, and the sixth in 2005. It is only a presumption at this point, but with a new Corvette typically comes a new Camaro as well and seen as how this current Camaro will have been in production for five years come 2014, we can only presume the next Camaro will be sporting a slightly detuned LT1 as well. That being said, in terms of the Camaro timeline, there have been five generations thus far — the first in 1967, the second in 1970, the third in 1982, the fourth in 1993, and the fifth and most recent beginning in 2009.

That is a lot of Generations, numbers, and engine designations, but as someone who grew up as a die-hard Corvette fan, it isn’t hard to see how some novice owners will get confused very quickly when they try to search “LT1″ in Google for replacement parts in the very near future. So, hopefully the LT1′s legacy is now just a bit more understood, because if you don’t know where you come from, how can you possibly know where you are going — and from the looks of the newest Corvette engine, you’re going to be going very fast.

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