When we asked when it would be available, we were told by an Eaton spokesperson that “Only after it was introduced via an OEM, would we see it on the aftermarket.”
Back in 2016, the C7 ZR1 was still very mysterious, but we had a hunch that it would have a big supercharger and wondered maybe GM was the OEM and the recipient was Corvette.
Fast forward 18 months and Autoweek, reports a funny anecdote about the 2019 ZR1’s development via Corvette Chief Engineer Tadge Juecther and LT5 Chief Engineer, Jordon Lee, and we vowed never to doubt our finely honed automotive instincts again.
According to Autoweek, “The engine that powers any ZR1 is special. You could say that the new LT5 engine is the ultimate Chevy small block. It’s amazing to look back at the original 255-cid V8 that started the whole Chevy small block thing in 1955 and try to trace this new block’s lineage. But even compared to the 638-hp LT5 engine that powered the 2009 sixth-generation ZR1, the new 755-hp LT5 in the 2019 ZR1 is a big leap forward in power, torque and efficiency.
First off, it’s not completely all-new. The 2019 Corvette ZR1’s new LT5 shares a lot of parts with the LT4 V8 used in the Z06.
The engine architectures are the same, said Lee. The block, the head, the pistons, the connecting rods are all carryover from the LT4.
It does have an all-new supercharger, an all-new throttle body — the biggest throttle body GM has ever done at 95 mm compared to the LT4’s 87-mm throttle body — a dual fuel system, two engine controllers to control the fuel system, modifications to the lube system, a different crankshaft material made of a higher-strength alloy and a shaker hood.”
Without oversimplifying or nullifying the work of our hallowed Chevy Engineers, the single most important element of the LT5 is the big supercharger. So big that, the motor was nicknamed “BAS” for Big Ass Supercharger internally.
Autoweek continues, “It’s 52 percent bigger than the unit atop the LT4 block, and it’s the reason for the shaker hood. It displaces 2.65 liters of air for every rotation. It has a 170-degree helix rotor set, the twist in the rotor set. It’s more efficient than the 160 degrees in the LT4.
That 170 degrees compared to 160 degrees for the LT4 is mostly done to improve the efficiency of the rotors,” said Lee. “As they’re compressing air, you want to make sure you don’t get any leakage past those rotors. 170 degrees ensures a tighter seal.
The supercharger actually spins slower than the one on the LT4: 15,860 rpm versus 21,000 rpm. The boost is 13.9 psi at peak.
We wanted to slow the supercharger speed down to introduce a lot less heat, said Lee. So running slower is more efficient.
Nonetheless, the LT5’s supercharger is drawing 110 hp to keep it spinning. That’s so much that it needs an 11-rib drive belt to accommodate the extra energy required to spin it. The LT4 only needs eight ribs on its drive belt. So effectively, this engine’s making 865 hp according to Lee.”
Don’t get crazy thoughts about tweaking with this Motown masterpiece, you laptop horsepower junkies.
“The aftermarket’s gonna be chompin’ at the bit to bring in a smaller pulley and overdrive this thing,” said Juechter. “That invalidates the warranty. We designed this engine to be robust on the track, but it’s all optimized the way it’s designed now. Anybody throwing new parts at this, they’re taking their own risk. We stand behind it the way it’s built in Bowling Green.”
Corvette Online was at the LA reveal of he ZR1 and we can vouch for the ZR1’s luscious body mods from the A-pillar forward that tenderly and coolly cradle the new LT5 motor. With 13 heat exchangers crammed under that new sculpted front clip, the ZR1 should escape the dreaded heat soak that has bedeviled it’s older sibling.
One might think of the ZR1 as a Z06 with a 100 more horsepower and that wouldn’t be off base, but what a loving, thoughtful and clever iteration of the fantastic C7 architecture and truly, a “King Of The Hill ‘Vette” worthy of the name.