By: IOL Motoring Staff
Some say everything in Texas is bigger, louder and faster - and that certainly applies to their cars. The late Carroll Shelby was a Texan, as is John Hennessey who, since 1991, has dedicated his life to making fast cars go a lot faster than their makers intended them to.
Now he's turned his attention to one of the few street-legal cars on the market that can claim to have genuine Formula One DNA - the McLaren MP4-12C.
You'll understand that, being a Texan, Mr Hennessey doesn't ask permission to climb inside a supercar's ECU; if a customer brings him the car and is willing to pay the freight, he just goes ahead and does it.
In this case that meant first cracking the code of the McLaren's control-module software, since Ron Dennis' Woking whitecoats weren't exactly about to give him the keys to the 3.8-litre turbo V8's kingdom - in fact, when they found out he'd succeeded, it caused what Hennessey describes with somewhat un-Texan understatement as “something of a kerfuffle” at the McLaren headquarters.
PIGGYBACK MODULE
Having accessed the programming, Hennessey piggy-backed an upgrade module on to the factory ECU, installed a larger-capacity intercooler and two, rather than the original single, intake air-filters.
A stainless-steel free-flow exhaust system took care of breathing out, while the turbo waste-gates were screwed down until peak boost hit 1.55 bar (up from on factory's 1.4).
Finally, to avoid detonation under at full throttle, a water/methanol injection system was neatly fitted into the luggage compartment in the front of the car, delivering a 50/50 mixture to nozzles upstream of the MP4-12C's throttle bodies, starting at 0.5 bar of boost and reaching full flow at one bar.
The result was electrifying - seat-of-the-pants testing confirmed that the Hennessey HPE was able to knock a full second off the standard car's acceleration time from 100km/h to 200km/h - from 8.15 down to 7.15 seconds. 0-100km/h took all of 2.8 seconds and the standing quarter mile was disposed of in 10.3 seconds at a terminal velocity of 219km/h.
CHASSIS UPGRADES - WHAT CHASSIS UPGRADES?
But the McLaren stability control program wouldn't let the car rev out on the dyno if the front wheels were standing still, so Hennessey had to source an all-wheel drive dyno to quantify power and torque.
The results? Power was up from 459 to 515kW at 7500rpm (704 horsepower in the old language, hence the badging on the modified McLaren), torque from 600Nm to 815Nm at 5800rpm.
Figuring that a company with half a century a of Formula One experience to its credit probably knows more about suspension and brakes than he does, Hennessey wisely left them alone.
Then he earned monumental karma credits by leaving the body untouched as well, other than a few discreet badges to let you know this is one 3.8-litre McLaren MP4-12C that doesn't back down for any street-legal Ferrari or Porsche.
Nice one, John. Or should that be, “Yee-Haaa!”