Hennessey tunes the McLaren MP4-12C to make 704 horsepower.

The McLaren MP4-12C is the latest project from Hennessey Performance Engineering, and the folks tweaking the British supercar's twin-turbocharged V8 have given it 704 horsepower through an engine management software upgrade, intercooler upgrade, new stainless steel exhaust system and dual air induction filters.

The software upgrade is the main contributor to the resultant HPE700 MP4-12C's power boost, raising turbo boost pressure to 23 pounds per square inch from the stock car's 21 psi to stuff more air - and fuel - into the combustion chambers. The new intercooler, with a water/methanol injection pump fitted downstream before the twin throttle bodies, keeps intake air cool and dense, and the intake and exhaust upgrades help to move air and exhaust into and out of the engine as smoothly as possible. The water/methanol injection, mixed in equal parts, starts its cooling charge at seven psi of boost and reaches full flow by 15 psi, allowing the twin-turbo V8 to produce 704 reliable horsepower.

Hennessey took the stock MP4-12C to the track to perform testing for some baseline numbers, and it was able to pull from 60 miles per hour to 130 mph in 8.15 seconds - quick enough to give a Ferrari 599 GTB Fiorano and Lamborghini Murcielago LP670-4 Superveloce runs for their money. After the Hennessey upgrades were fitted, the HPE700 MP4-12C did the same run a full second quicker. The car can also accelerate from 0-60 mph in 2.8 seconds and do the quarter mile in 10.3 seconds at 137 mph.

Taking jarringly fast supercars down the diabolical path to 700+hp seems to be the norm at Hennessey these days, as evinced by the recent HPE700 Twin Turbo Ferrari 458 - also capable of 0-60 mph in 2.8 seconds - we just hope the apocalypse holds off long enough to squeeze in a comparison test (or at least a drag race).
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Hennessey HPE700 Performance Upgrade

• 704 Horsepower @ 7,500 rpm
• 538 lb-ft Torque @ 5,800 rpm

• 0-60 mph: 2.8 sec.
• 1/4 mile: 10.3 sec. @ 137 mph

HPE700 McLaren MP4-12C Upgrade Includes:
• Engine Management Software Upgrade (external from factory ECU)
• Intercooler Heat Exchanger Cooling Upgrade
• Dual Air Induction Filters
• Stainless Steel Exhaust System Upgrade
• Professional Installation
• Dyno Tuning & Road Testing
• Serial-Numbered Dash & Engine Plaques
• HPE700 Exterior Badging
• Hennessey Exterior Badging
• 1 Year / 12,000 Mile Limited Warranty

McLaren MP4-12C: Making Woking's Wonder Quicker
It's good to be back in a McLaren MP4-12C, if only briefly before Hennessey's ECU neurosurgeons unlock the secrets of even more power. The last time for me was at Spring Mountain Motorsports Ranch in Pahrump, Nevada, doing a comparison test for Road & Track with the Ferrari 458 Italia and Corvette ZR1 using the facility's 1.5-mile Radical Loop.

For cars with such explosive power and speed, the track's tight-radius corners and short chutes made for a bit of a bull-in-a-china shop experience, but we all came away impressed with the McLaren's ability to put power down in lower gears. On the sweeper leading on to the back straight, you could feel the MP4-12C's high-speed stability as it powered over a sizable crest that can be the undoing of cars with less aero downforce and suspect suspension kinematics. It did tend to plow a bit more than either the more highly strung Ferrari or the ZR1 (with its borderline-streetable Michelin Pilot Cup Sports) on the track's tightest right-hander, but its suspension offered a nice combination of both suppleness and control. It's said a car's character directly correlates to the environment in which it's developed, so it follows the McLaren would be the ideal automotive tool to devour England's narrow, undulating B-roads, with a couple of roundabout skidpad laps thrown in for dessert.

At Hennessey, we're in the process of upgrading a customer's MP4-12C with our exclusive tuning, with the end goal of making 700 bhp at the crank. We'll soon perform a dyno pull to establish baseline horsepower and torque numbers, and if the R&T test was any indication we ought to see north of 500 rwhp from the 3.8-liter twin-turbo V-8 straight from McLaren's Woking factory. We did a couple of 60-130 mph runs to establish baseline performance as well, with the console-configurable Powertrain settings on "Track" for the quickest possible shifts and the rear wing in the intermediate downforce position. The beauty of this test is that it takes launch variables out of the equation and showcases pure power. An average of two runs was 8.15 seconds, which puts it in the exclusive company of the Ferrari 599 GTB Fiorano and Lamborghini Murciélago LP670-4 SuperVeloce.

It's a beautiful car that assaults each and every sense. The sounds are deeper, more burly than you'd expect from 3.8 liters, the capsule-like cockpit is redolent with fine leather, and the composite bodywork-while not chiseled to the point of inflicting flesh wounds, like the Lamborghini Aventador's for example-looks powerfully coiled and ready to spring. The mere act of getting into an MP4-12C is full of specialness and ceremony; swipe the underside of the intake channel cut into the door (it pivots up and forward), negotiate the formidable carbon-fiber sill and settle into an exotically sculpted bucket that clings remora-like to your backside. And how cool is that airbrake that pops into full-downforce mode above 60 mph when you get hard into the brakes? We can't wait to sample more thrust in this already formidable rocket.

McLaren MP4-12C-HPE700 package complete!
Whilst we may have created something of a kerfuffle over at McLaren with our code-cracking of its supercar's engine-control computer, we at Hennessey Performance are overjoyed with the results of the HPE700 upgrade. We calculate a stout 704 horsepower at the crankshaft, based on a dyno pull that saw 571.6 horsepower at the rear wheels. That's a significant gain over the 2012 car's 616 crank horsepower from its 3.8-liter twin-turbo V-8. A gain of nearly 90 horsepower is, to use another British expression, the dog's bollocks.

It wasn't without a little angst, though, as the McLaren's stability-control nannies intervened on our attempts to generate a baseline dyno pull at our Southern California shop. Without the front wheels moving, the computer throws a red flag, thinking the car is sliding, spinning or otherwise up to no good, and cuts power drastically. Ultimately, after the Hennessey Performance ECU upgrade was installed, we sourced a Mustang AWD 500 SE dyno to generate the numbers.

Performance means little if it's short-lived, so with an eye toward avoiding any detonation we also fitted a water/methanol injection system whose pump and tank fit neatly in the front luggage compartment. All told, The HPE700 upgrade raises boost pressure from 21 to 23 psi, so the system starts cooling the charge at 7 psi with maximum flow achieved at 15 psi and upward, delivering a 50/50 water/ methanol mixture through nozzles located just upstream of the MP4-12C's twin e-throttles.

We can tell you that the McLaren rips a far more ragged hole through the atmosphere in the 60-130 mph acceleration test. The display on our VBox GPS data recorder backed up our finely calibrated inner-ear accelerometer-a 7.15-sec. two-way average, a full 1-second improvement over the stock car. If other published numbers for this contest are to be believed, that puts the McLaren (whose 2013 list price is $239,400) into the realm of far pricier supercars including the Ferrari Enzo and Porsche Carrera GT. In any language...even the Queen's English...that's flat-out, scalding fast.

Doug Kott, Communications Manager for Hennessey Performance, brings 25 years of automotive journalism experience and vehicle evaluation skills to his current position.