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Dissecting the Lancer Evo 7

We take an in-depth look at the awesome Mitsubishi Evo 7...

By Michael Knowling

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This article was first published in 2002.

If you thought that the Australian-delivered Evo 6.5 was something good, take a look at the Evo 7 - it's arguably one of the most advanced production cars ever seen. Here we take you on a technical tour of what makes the VII so great...

The Engine

The Evo 7 uses the same basic engine design that was first seen in the Galant VR4 - a 2-litre, DOHC, 16-valve in-line four-cylinder with an intercooled turbo.

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The current Evo engine (known as 4G63 D4) features hollow camshafts, revised intake manifold and intake port layout (reducing restriction by 20 percent), and a larger oil cooler giving 15 percent additional heat exchange capacity. The static compression ratio has remained the same since the 1996 Evo 4 - 8.8:1. High-octane premium unleaded fuel is mandatory.

The turbocharger found on the GSR version of the Evo 7 is a TD05HR-16G6-9.8T featuring a twin-scroll turbine housing with an Inconnel wheel. The competition-spec RS version uses a TD05HRA-16G6-9.8T twin-scroll housing with an alloy/titanium turbine wheel. It's claimed that reducing the turbine nozzle area (from 10.5cm2 to 9.8cm2) has resulted in "a more stable torque band." An aluminium compressor wheel is used on both the GSR and RS.

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Over the previous Evo VI, exhaust backpressure has been reduced using a large diameter, straight-through pipe design with a dual stage rear muffler. A variable backpressure valve reduces noise at low rpm and opens to give maximum flow at higher rpm.

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Cooling the intake charge is a front-mount air-to-air intercooler that's 20mm wider than in the Evo 6 Tommi Makinen Edition. Cooling fin angles and end-tank shapes have also been revised.

A water spray (with three nozzles instead of the previous two) is aimed at the intercooler core to give additional heat exchange capacity. There are 2 operating modes - automatic and manual over-rode. In automatic mode, the spray operates in two second blasts at 5-second intervals.

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With these engine modifications, the Evo 7 generates (a nominal) 206kW at 6500 rpm, and 383Nm at 3500 rpm. Due to Japanese regulations, the claimed power output is no different to the Evo 6 Makinen, but peak torque is up from 373Nm at a lower 2750 rpm.

Drivetrain

The all-wheel-drive Evo 7 GSR has two separate driveline control systems - AYC (Anti Yaw Control) and ADC (Active Differential Control).

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Active Differential Control makes its first appearance on the Evo 7 GSR. The system sees a computer-controlled, hydraulically-actuated multi-plate clutch apportioning front-to-rear torque, instead of the much more usual centre viscous coupling. The big advantage of this approach is the flexibility that it gives - ACD actively varies its differential limiting force to suit all environments and driver inputs.

Under hard acceleration, for example, the ACD 'locks up' to ensure more torque is transmitted to the wheels with the most traction. Also, note that the multi-plate clutch system can deliver up to three times the differential limiting force of a conventional viscous coupling. In other words, the chance of wheelspin is very slim.

Conversely, the ACD has the capacity to go into an effective 'free spinning' state; this improves turn-in performance, reduces understeer and enhances steering feel.

Activation of the handbrake also automatically un-locks the ACD, enabling proper rally-style handbrake turns...

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In addition to its active variations, the ACD also has three driver-selectable modes - tarmac, gravel and snow. These alter the centre diff characteristics to best suit the current driving conditions.

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Alongside its new ACD, the Evo 7 GSR also carries AYC - a system that first appeared on the Evolution 4 GSR. Active Yaw Control sees a computer-controlled, hydraulically-actuated torque transfer mechanism integrated into the rear differential body. Its purpose is to vary the amount of torque going to the left or right rear wheel, depending on driving input and chassis attitude.

Under hard cornering acceleration, for example, the system reduces understeer by transferring torque to the outer rear wheel. When decelerating through a corner, the system enhances stability by transferring torque to the inside rear wheel. AYC also improves traction on slippery surfaces.

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This diagram shows how the combination of ACD and AYC performs on the road.

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To reduce weight and complexity, a joint computer controls both AYC and ACD systems. This overview shows the system inputs and its integration.

The Evolution 7 RS

Interestingly, the competition version of the Evo 7 - the RS - foregoes the GSR model's driveline wizardry. Instead of having ACD and AYC, the RS receives just a mechanical front diff to replace the GSR's helical unit. It's that simple.

So it could be argued that the driveline set-up of the GSR is really aimed at fast road drivers... something which we think it succeeds at brilliantly.

Finally, the Evo 7's driveline has increased strength over previous models.

The Evo 7 uses a W5M51-type 5-speed gearbox with higher strength steel used for certain gears. First gear ratio is quite short (to improve off-the-line performance), while fifth gear is relatively tall (to make the most out of the engine's significant on-boost torque). The RS comes with an optional close-ratio gearset.

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The clutch and flywheel are increased in diameter and the pressure plate load has been increased (to 9320N). Optimisation of pressure plate shape - and various other components - has reduced rotational inertia.

Completing the list of strengthened driveline components are the hypoid gear, drive pinion teeth and taper bearings, prop shaft, CV joints and driveshaft output shafts - not to mention the AYC mechanicals. Reinforcing ribs also strengthen the front differential case.

Suspension

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The Evo 7 is based on the Japanese-market Mitsubishi Lancer Cedia platform.

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At the front are MacPherson struts with increased bump travel (giving a total 90mm bump and 85mm rebound travel), the track is widened and the roll centre height has been "optimised". The steering box has also been lowered to give increased linearity in toe changes (ie reduced bump steer) and improved cornering stability.

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The rear uses a multi-link strut arrangement with double wishbones. Bump travel has - again - been increased (giving a total 110mm of bump and 75mm of rebound travel), the track is widened and roll centre height is er, again "optimised".

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As you'd expect, the Evo has its own spring, damping and bush characteristics - each is firmer than the lesser model Cedia. Swaybars measure 24mm at the front and 22mm at the rear.

The GSR Evo rides on 17 x 8-inch alloy rims wearing high-grip compound 245/45 ZR Yokohama Advans. The RS competition version comes with only 15-inch steel rims wearing basic 205/65s (purpose-specific replacement is obviously expected!).

These are the standard wheel alignment settings for both the GSR and RS...

Toe - Front
Rear

0mm
3mm toe in

Camber - Front
Rear

-1 degree
-1 degree

Castor (front)

3 degrees, 55 minutes

Brakes

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Slowing the Evo 7 GSR are '17-inch' ventilated front discs with Brembo 4-pot calipers, teamed with '16-inch' ventilated rear discs with 2-pot Brembo calipers. (These diameters are based on the Japanese policy of nominating the smallest wheel that will fit over the brakes, rather than the size of the discs themselves.) A larger 8+9-inch tandem booster and revised 4.0:1 pedal ratio are also specified. Under-tray brake cooling ducts (that lead right up behind the front discs) are available as a dealer option.

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Standard EBD (Electronic Brake force Distribution) apportions front-to-rear braking force depending on road surfaces and vehicle load distribution.

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Also featured is Mitsubishi's latest 'sports' anti-lock braking system. Now taking a steering angle input, the system correlates this with wheel speed, longitudinal and lateral G-sensors to apportion the correct amount of braking effort to each individual wheel.

Chassis Stiffness and Weight Reducion

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The body of the Evo 7 has 50 percent more flexural rigidity than the basic Lancer Cedia.

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The upper frame and A-pillar joint is reinforced, the door openings are stiffer (thanks to 200 additional spot welds), the C-pillar has an added brace, the rear parcel shelf has reinforcements, a cross member is added to the rear facia, while the front suspension, rear trailing arm and upper control arm mounts are all strengthened.

Light weight has also been a priority.

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The engine valve cover is die cast magnesium, the induction pipes are aluminium, the power steering pump bracket is aluminium, camshafts are hollow and the exhaust is straighter (for reduced length). Front and rear door glass is 10 percent thinner, the roof panel is thinner, the bonnet and front guards are aluminium, and both the B-pillar reinforcement and front side member uses different gauge panels mash seam welded together. The blistered rear guards are integrated to eliminate any additional components and joiners, and the wicker has also been removed from the rear wing.

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Inside, the GSR's front Recaro seats shed a total of 6kg, and the RS-spec comes standard with no airbags.

All up, the Evo 7 GSR weighs 1400kg, while its stripped out RS variant is some 80kg lighter. In comparison, the Evo 6 Tommi Makinen weighs in at 1360kg.

Exterior

The Evo 7 body looks dramatically bigger than the previous model - but it's surprisingly similar. It measures 1770mm wide (the same as the Evo 6 Makinen), 4455mm long (an extra 105mm) and 1450mm tall (up 45mm). Wheelbase is 115mm longer than the Makinen, at 2625mm.

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At the front there's Mitsubishi's so-called 'diamond cut nose' (which is shaped to give better visibility and manoeuvrability), multi-lamp headlights, blistered guards, large heat extraction vents and a NACA duct in the bonnet and a lower bumper extension. Out of sight, a large under-tray reduces front-end lift and drag.

Extracting the heated air from behind the engine oil cooler are side-exit slats in the bumper. The Evo's clean side flanks - in particular the side skirts - aid discharge from these slats.

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The rear-end features blistered guards melded into the doors, 3-lens taillights, and a rear wing larger than its predecessor's.

Is the Evo 7 really slower than the Evo 6 Tommi Makinen?
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According to official Mitsubishi literature, the Evo 7 has proven faster than its predecessor around a racetrack in Japan.

The Evo 7 (the RS version) stopped the clocks at 65.5 seconds, while the Evo 6 Tommi Makinen Edition trailed at 65.9 seconds. We're not sure how the GSR version would fare.

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These graphs also show the Evo 7's improved steady-state cornering speed and reduced understeer.

Maybe, just maybe - despite being bigger - the Evolution 7 can out-strip its raw-edged older sibling...

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