Hennessey reveals the McLaren 600LT’s rear-wheel performance thanks to a new video of the performance vehicle on the dyno.

McLaren makes the best transmissions in the business. How do we know? Because they lose very little power between the engine crank and the rear tires.

Let’s take the McLaren 600LT. Under the hood is a 3.8-L twin-turbo V8 engine which produces 592 hp and 457 lb-ft at the crank. That gets fed through a 7-speed dual-clutch transmission to the rear wheels and helps propel the car from zero to sixty in just 2.9 seconds.

Now this is where Hennessey comes in. Before they perform any upgrades to a car, they put it on the dyno to see just how much power it actually makes. Here we see the McLaren 600LT roar its twin turbos out and eventually produces a number.

At the rear wheels, the 600LT produces 574.79 hp. That’s just 18 ponies lost between the engine at the rubber, which is just over 4%. Compared to a normal road-going car, which is around 10-15% power loss, and that’s an incredibly efficient drivetrain.

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Now there’s one mystery here. According to the dyno chart near the end of Hennessey’s video, the torque produced at the rear wheels is 493.88 lb-ft. That’s actually more than the 457 lb-ft McLaren advertises. Unless that figure is actually in Newton-meters, which works out to 367 lb-ft, and it seems impossible for the drivetrain to lose only 18 hp but also lose 90 lb-ft of torque.

So either that dyno is wrong, or McLaren is lying about their torque figures. Or Hennessey has already upgraded this 600LT without telling anyone.

Hennessey has three upgrades for the 600LT to choose from: the HPE700, HPE800, and HPE1000. The HPE700 just gives you new air filters, an ECU recalibration, and a stainless steel exhaust upgrade. The HPE800 and 1000 both give varying degrees of tweaks to the twin turbos and ECU, as well as an intercooler and transmission upgrades.

We’re not sure what this 600LT is set to become, but one thing is for sure: there’s no way it will be anywhere near as efficient by the time Hennessey is done with it.

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