One and Done: GM Discontinuing Its 755-HP LT5 Engine

One and Done: GM Discontinuing Its 755-HP LT5 Engine

09/16/2021

Well, we could hardly believe the news a few months ago when it was announced that Chevrolet’s supercharged LT5 would be discontinued after one year of production, but it appears to be true. The LT5 is officially discontinued. This was GM’s most powerful engine, and in the midst of a horsepower war between the Big Three, it just seemed odd to kill off such a capable 755-horsepower/715-lb-ft performer.

We guess one-and-done is a good phrase for the LT5, as it was only stuffed into the insane, record-breaking 2019 ZR1 Corvette. The ’19 ZR1 fielded the LT5, and Chevrolet wanted that car so bad that it built it even though the taller LT5 blower (compared to the LT4) meant it couldn’t be sold in Europe. We imagine it was pretty expensive to develop the LT5, and it was installed in fewer than 3,000 vehicles.

But while the 2019 ZR1 Corvette was cool, we’re here to talk about the demise of Chevrolet’s most potent crate engine. With production stopped, most of the existing LT5s are gone from dealership inventories. You can still find them around, so if you have about $19,000 laying around and you want one for your hot rod swap project, then you had better get busy, as we’re pretty sure the price is only going to go up as the remaining supply dwindles.

What’s the Difference Between an LT5 and LT4 Engine?

Think of the LT5 as the big brother of the LT4, with most of the changes in the blower area. The LT5’s supercharger grew from the LT4’s 1.7 liters to a newly developed R2650 Twin Vortices 2.65-liter supercharger, which was largely designed by GM’s Small-Block Group working with Eaton’s engineers. The LT5’s four-lobe compressor rotors are larger in diameter and longer, with a tighter 170-degree helical twist than the LT4’s 160-degree-twist rotors. The LT5 produces 14 pounds per square inch of boost, compared to the LT4’s 9.4 psi. The passenger-side rotor is driven by the crankshaft pulley through an 11-rib belt (three ribs more than the LT4) with a pulley ratio of 2.4 to 1 for 15,860 rpm compared to the LT4’s ratio of 3.1 to 1. All of the changes were good for 105 horsepower and 65 lb-ft more torque compared to the LT4.

Will the LT5 Be Used in the C8 Corvette?

Although discontinuing the LT5 after such a low volume of production doesn’t make a lot of financial sense, we really can’t see GM stuffing it into the C8 mid-engine Corvette since GM seems to be moving in the direction of turbos and technologies such as flat-plane-crank engines for the Corvette. This would mean the C8’s naturally aspirated LT2 will be the only pushrod mill powering a Corvette, with future Corvettes getting power from new engine designs, not the LT5.

What’s Chevrolet’s Most Powerful Car Being Sold?

The death of the LT5 makes the 650-horsepower LT4 the big stick in GM’s arsenal, and with that, the ZL1 Camaro is GM’s sole offering, for now, making more than 600 horsepower. We were really hoping for an LT5-powered Z/28 sixth-gen Camaro, but with Camaro production ceasing in a few years, we guess Chevrolet just didn’t want to put in the effort needed to stuff the LT5 into the Camaro, which is a crying shame. We can only hope that GM has some new big-power mill in the works, but we will have to wait to find out.

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