The folksy, friendly, wily Texan who’s hoping to set a significantly higher top speed record for a production car unveiled his 1,600-hp, 1,300-lb-ft twin-turbocharged 7.6-liter pushrod V-8 at The Quail show during Monterey Car Week. We caught up with him after the show to get a bit more detail on his entirely bespoke and ever-so-American engine.
Our very first question was “why pushrods?” Of course Hennessey has loads of experience with this engine type, specializing as he does in extracting vastly more power out of pushrod V-8 Small Blocks and V-10 Viper engines. There’s also no more dense way to package power in terms of an engine’s exterior dimensions. And with the power peak at a lofty 7,200 rpm and an 8,000-rpm redline, this retro valvetrain has been proving itself to be well up to the task of hypercar motivation during more than a year of dynamometer testing.
About that billet block—this is the way real racers do engine blocks. The metallurgy of a forged aluminum block typically boosts tensile strength (how hard it resists being pulled apart) by 30 percent or more and yield strength (the force at which it comes apart) by as much as double that percentage relative to a similar cast aluminum block. Weight typically drops a bit as well. Another benefit—the cylinders tend to stay more perfectly round in a machined block, reducing ring friction (note that the Venom F5 engine uses pressed in steel sleeves as well). The big downside is cost and the fact that it takes bloody hell forever to machine a billet block into a form that’s ready for coolant, lubrication, and combustion. “Days, not hours,” was Hennessey’s rough estimate of total computer-numerical-control (CNC) machining time invested in a single Venom F5 block. Please note that at least a few minutes of that time are frittered away engraving the Hennessey logo on the sides of the block and F5 on the front.
For now the cylinder heads are cast, but John doesn’t rule out a switch to machined billet for the heads as well. He claims his two-valve setup flows 400 cubic feet per minute of air. And of course there are those two Precision Turbo snails force feeding the engine with 24 psi of boost. That boost is generated with help from 76mm turbine wheels and 77mm billet machined compressor wheels running on ball bearings. The turbo headers are made of stainless steel.
Oh, and as for that “production car” stipulation—construction of 24 Venom F5 hypercars is planned and 15 have reportedly been pre-sold. Scrape together your $1.6 million and get your order in fast!
The post More Details on the Hennessey Venom F5’s Twin-Turbo 7.6-Liter V-8 appeared first on Motor Trend.
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