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MTM Audi TT Bimoto - Terrific Twin MTM's TT Bimoton

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MTM Audi TT Bimoto - Terrific Twin MTM's TT Bimoton

Post by LhYnxz on Thu May 22, 2008 4:43 pm

*I first drove the MTM Audi TT Bimoto back in the spring of 2002, when it was painted bright yellow and its bodywork looked a lot more standard than it does today. Back then, it had a mere 652 hp, but its 215-mph top speed was enough to leave the then-new Lamborghini Murcilago in its dust.





Unlike the Lambo, the Bimoto's power comes from eight cylinders rather than 12. And they're spread across two engine bays. This is the world's first twin-engine Audi TT, created by MTM's Roland Mayer in the village of Wettstetten, just 10 miles from Audi's Ingolstadt HQ.

Since then, the Bimoto has evolved, becoming faster along the way. Mayer's objective from day one was to crack the 350-kph (217 mph) barrier in a road-legal car. When the Bimoto achieved 371 kph (231.9 mph) at the highspeed Nardo track later that year, he raised his sights to 400 kph-around 248 mph.



The following year, the Bimoto returned to Nardo with a few tweaks and managed 374 kph (233.8 mph). After that, the project went on the back burner as Mayer concentrated on additional buildings and technical facilities to take his rapidly expanding company to the next level.



In September 2006, the Bimoto was wheeled out again with some new parts and 430 hp from each motor, achieving 384 kph (240 mph) at Papenburg, the highspeed proving ground in northern Germany.



The boat-tailed TT is not exactly known for its inherent high-speed stability and, at these speeds, positive downforce was more than just desirable, it was a matter of safety. The Bimoto has a front splitter, a flat carbon fiber undertray, rear spoiler and rear underbody diffuser. Now, however, a critical point had been passed where directional stability was a big issue, so the next step was to fit a large vertical fin to the rear. This makes the car look like a mutant cross between the TT, a Le Mans Jaguar D-Type and a jet fighter. You could liken its aerodynamic evolution to the time when pioneering airmen ran into the compressibility phenomenon.

In the meantime, the engines also reached their peak point. Surprisingly, capacity has stayed at the stock 1.8 liters-Mayer says this is for reliability. Each has received uprated lightweight pistons, polished and balanced connecting rods and high-lift cams. The heads are gas-flowed and hold specially ground camshafts with solid lifters and strengthened components that can run safely to 8800 rpm.

Bigger KKK turbos, built to MTM's spec, sit on new exhaust manifolds. Downstream of each turbo, massive intercoolers drop intake temperature significantly, allowing high boost to be maintained with safety under the stress of a top-speed run. Low backpressure is encouraged by a stainless steel free-flow exhaust system with semi-race catalytic converters. Each engine gets one exhaust pipe and the center pipe is for the wastegates.



One of MTM's specialties is engine management. The perfect amount of fuel from the larger injectors and spark from the high-powered ignition packs allow each engine to produce 505 hp and 382 lb-ft of torque. Combining these figures makes 1010 hp with 764 lb-ft. That's Veyron power in a car weighing 1100 pounds less.

The
tall gearing (allowing the theoretical 248 mph top speed) comes from a
VW Golf diesel's top gear ratios. At the beginning of development,
these chosen ratios allowed a theoretical 237 mph at 7000 rpm in sixth
gear. This was why the motors were modified to run to past 7400 rpm.
Two six-speed gearboxes are linked mechanically, but state-of-the-art
electronics take care of engine synchronization. Mayer is the first to
admit that without drive-by-wire throttles, this would be physically
impossible.
With all-wheel drive, traction off the line is
excellent and the car grabs the tarmac and rockets to 62 mph in 3.1
seconds, 124 mph in 8.9 and 186 mph in 19.8, even with the tall final
drives. These figures were taken in July 2007 at Papenburg, where the
Bimoto was clocked at 245 mph. In the topspeed pecking order, that
makes it officially faster than the Ferrari Enzo, Porsche Carrera GT
and McLaren F1, but slower than the Koenigsegg CCX, Bugatti Veyron and
the SSC Ultimate Aero TT. The Bimoto requires a two-wheeldrive
gearbox with each engine rather than one all-wheel-drive unit. An
electronic differential controls power distribution between the front
and rear axles, and each end has its own limited-slip differential. The
front unit has a 25-percent lock-up, with 50 percent at the rear.Wheels
are MTM's forged 19-inchers-strong, light and sized to do the job
without imposing too much drag. Tires are ContiSportContact Vmax, the
only production road tire rated to 223 mph.
Unlike a race track,
high-speed tracks like Nardo or Papenburg have no corners and so do not
require a car to slow down quickly. So 14-inch front and 12.7-inch rear
rotors with four-pot calipers are adequate and keep unsprung weight
down. However, if a customer wants a road car with extreme stopping
power, then MTM can fit 15-inch discs with eight-pot calipers at each
corner.
Open the engine bay and it's obvious where the hundreds
of man-hours were spent. The tubular steel cage around the hatch
opening stands out, as does the 22-gallon fuel tank nestled between the
cabin and engine bay. With the loss of the rear floorpan, structural
strength was regained with a 1.6-inch-diameter tubular steel rear frame
that follows the inner hatchback profile. A perimeter frame made from
square-shaped steel (its metal being 3mm thick) reinforces the sills
and front and rear bulkheads, with the front bar crossing under the
dashboard.
The transmission tunnel is also strengthened with two
square-section bars joining the front and rear bulkheads. The rear
engine/gearbox and subframe are production TT spec with the steering
system removed. The suspension's lower arm bushes (that create passive
toe effect on a standard TT) are replaced with solid items to prevent
undesirable rear-steering in this application.
Up front,
MacPherson struts have been replaced by race-style coilovers using
external reservoirs, with adjustable height as well as bounce and
rebound control. Ride height has been set up at 30mm and 25mm lower
than stock, front and rear respectively.

Driving the Bimoto is a
unique experience. Turn the ignition on and hit the chromed button that
says 'Eng 1.' Then hit the 'Eng 2' button next to it to fire up the
rear engine. At low speed, the Bimoto is hardly louder than a stock TT
and does not attract undue attention (apart from its lurid paint
scheme). Inside, however, the stripped-out interior is only shielded
from the rear engine bay by a sheet of carbon fiber, so the cabin's
sound level is much higher than normal. The hydraulic clutch ensures
that pedal effort is hardly more than a standard TT and the gearshift
action is barely heavier too.
Thanks to its engine management,
the Bimoto is fairly tractable-despite huge turbos and wild cams. But
fullthrottle acceleration is stupendous. Once boost arrives, thrust is
strong and unrelenting. It's almost impossible to watch the twin rev
counters, digital speedometer and the road at the same time. The car
gathers speed so fast that watching the road is definitely the most
important. Despite the side intakes that draw cooling air into the rear
engine bay and the booster fans which help to vent the rear intercooler
and radiator, the temperature gauge for the back motor always indicates
slightly higher than the front.
Thanks to a 52/48 percent weight
distribution, crosscountry handling and grip are simply amazing, and in
the dry can lay down as much power as you like once the car is set up
for a corner exit. If you lift off sharply while cornering on the
limit, you can feel the weight in the rear trying to move the tail
outward. This was very pronounced with the stock bushings in the
suspension lower arms, but since the uniball joints were substituted,
the tendency to oversteer has largely been eradicated.


At
Nardo last October (the Autobild Sportscars/Continental High Speed
Event), the Bimoto was the quickest car by far, at 390 kph. Nardo has
steeper banking than Papenburg. On a flat autobahn with no wind, the
Bimoto should be capable of a genuine 400 kph, a smidgen short of 250
mph.Now the car has won the last couple of high-speed events at
Nardo and come close enough to 400 kph on a banked track, Roland Mayer
thinks he's proven his point. The Bimoto can be retired to its place of
honor in his small private collection, which also includes a genuine
Audi Quattro S1 rally car. A family Of Twins

*The
push-pull idea of having one motor at each end of a vehicle is not new
and heavy-duty locomotives still use it to this day. But in road-legal
cars and motorsport prototypes, its use has always raised eyebrows.
While a rearwheel- drive car can be made into a four-wheel-drive with a
front transfer case and extra driveshafts, the engineering required to
install two engines of the original type into a reardrive car is quite
daunting.
That's not the case with front-wheel-drive cars, as the
engine, gearbox and driveshafts come neatly packaged and just require
duplicating at the rear. The advent of front-wheel drive in
mass-production cars spawned some creative engineering. Even the lowly
Citron 2CV received twin powerplants in a limitedproduction factory
version for use in desert conditions.
In the 1960s, John Cooper
was nearly killed when his twin-engine Mini prototype desynchronized
and flung itself off the road. Throughout the 1980s, Volkswagen
Motorsport flirted with twinengined cars based on the Mk I Golf
floorpan.
Golf, Jetta and Scirocco
prototypes were built to explore this concept as a possible Group B
rally weapon to beat the all-conquering Audi Ur-Quattro from the same
stable. Twin-engine Golfs competed in the famous Pikes Peak hillclimb
event from 1985 to '87, finishing in the top 10 each year.
Some
aftermarket tuners have built twin-engined cars based on VW
mechanicals. In the late 1990s, British VW tuner Dubsport made a
scorchingly quick twin-engine Mk III Golf using a pair of turbocharged
VR6 motors. Physical installation of two engines is the easy part of
the story. Synchronizing them is the tough bit. Only with the advent of
drive-by-wire throttle management in recent years has throttle
synchronization been made a little easier.

MTM Audi TT Bimoto
-Engine
Dual transverse 1.8-liter inline four-cylinders, turbocharged and intercooled, electronically linked
-Transmission
Dual six-speed manuals, linked
-Suspension
KW coilovers, solid bushings
-Brakes
Four-piston calipers, 14-inch rotors (f), 12.7-inch rotors (r)
-Wheels And Tires
MTM forged alloys, 8.5x19
ContiSportContact Vmax, 235/35
-Performance
Peak Power: 505 hp @ 7420 rpm (x2)
Peak Torque: 382 lb-ft @ 6300 rpm (x2) 0-62 mph: 3.1 sec.
Top Speed: 393.6 kph (245 mph)
Curb Weight: 3,285 lb
-Price
600,000 Euros (about $880,000)

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LhYnxz
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