However, competition in WRC's Group A required the homologation of 2,500 production models. No problem. Offered in GSR and RS flavors, 5,000 EVO Is were snapped up between September 1992 and December 1993. Mitsubishi's intent behind the lightweight RS model was to provide a good starting point for building a club-level rally car.
So why include parts that will be tossed later? With that philosophy in mind, RS models were sold with steel wheels, manual windows, and cheap seats. ABS was not offered on RS models, nor was a rear wiper. The GSR, intended to serve street-car duty, included power windows, air conditioning, Recaro seats, alloy wheels and carpets, helping to bring the GSR's total weight to 2,730 pounds, 155 pounds more than the RS. Keep in mind the Japanese weigh their cars with no fuel, spare, or jack, so make a mental conversion over to American-style curb weights.
Throughout the EVO's life, motivation was provided by the VR-4's stout iron-blocked turbocharged 2.0-liter DOHC 4G63 engine. EVO I got a lighter crankshaft, higher compression pistons, new connecting rods, plus a new port geometry, bringing output to 228 lb-ft at 3000 rpm and 247 hp at 6000 rpm; 10 more than the VR-4. The VR-4's established AWD drivetrain and five-speed W5M33 gearbox, with a double-cone synchro added to second gear, were carried over.
The EVO's suspension consisted of MacPherson front struts and a multi-link rear, with pillow-ball mounts replacing the base Lancer's rubber bushings in the control arms and toe-control links. The lowly Lancer chassis was beefed up to cope with the rigors of rally use, giving a 20-percent increase in torsional rigidity. Extra beef equals weight, so undercoating was removed on all Evolution RS models through EVO V.
Evolution II
Chassis Code CE9A
The Lancer Evolution II, built from December 1993 to January 1995, was focused primarily on improving the handling of the EVO I. Though the same fundamental chassis was used in Evolutions I-III, EVO II brought a 10mm increase in wheelbase accomplished by moving the front wheels forward. Vehicle track was increased at both ends to accommodate larger tires (now 205/60-15; up from 195/55-15), while longer control arms in front and a revised swaybar mounting arrangement enhanced steering response. Aerodynamic tweaks like a front air dam and an additional rear spoiler support improved vehicle stability at higher speeds.
Mitsubishi intended to improve power output with each Evolution, and EVO II started the trend. Boost pressure was increased, higher-lift cams were fitted, and detail changes to the exhaust reduced backpressure. Power of the 4G63 was now up to 256 hp, while torque remained unchanged at 228 lb-ft, propelling a vehicle weight of 2,750 pounds for GSR models and 2,600 pounds for RS models.
Evolution III
Chassis Code CE9A
Speeds on tarmac stages were getting higher, so reducing lift and improving cooling performance became priorities in Evolution III. A larger rear wing, a front airdam with brake cooling vents, and rocker panel extensions were fitted and, you guessed it, power was up again.
Ongoing improvements to the engine's breathing were rendering the existing turbo, a TD05H-16G-7, a liability compressor efficiency was taking a dump at higher engine speeds, adversely impacting volumetric efficiency. So Mitsubishi swapped the old 60mm 16G compressor wheel for a more suitably sized 68mm 16G6 wheel and redesigned the exhaust again for less backpressure. With these new lungs and another bump in compression ratio to 9.0:1, power crept to 266 hp at 6250 rpm, while torque stayed at 228 lb-ft.
Selling 7,000 examples from January 1995 to August 1996, Evolution III was the best-selling EVO to date.
Evolution IV
Chassis Code CN9A
The initial production run of 6,000 EVO IVs sold out in three days. EVO mania had hit full force. This latest EVO, introduced in August 1996, was based on an entirely new Lancer platform and had a technology portfolio as long as your arm. A new twin-scroll turbo kept exhaust pulse energy high all the way to the turbine wheel, improving boost response so effectively that the size of the turbine housing was stepped up (from 7 cm2 to 9 cm2). Coupled with a new cam grind, the larger turbine housing promoted better volumetric efficiency at higher engine speeds, while the twin-scroll took care of the low end. To homologate a new anti-lag system, all production models were sold with the anti-lag air injection hardware on the exhaust manifold. With no software to control it, however, street drivers were prevented from shooting anti-lag-induced fireballs out the tailpipe during gear changes. Compression ratio was back down to 8.8:1, thanks to new, lighter pistons, and a new metal head gasket kept combustion pressures where they belonged. Output was now 276 hp at 6500 rpm, while peak torque leaped to 260 lb-ft at 3000 rpm.
Mitsubishi was also forging new production-car territory with its inclusion of Active Yaw Control (AYC), which adjusted rear torque split to minimize understeer and improve turn-in, and, on RS models, a torque-sensing helical limited-slip front differential. As if that weren't enough, buyers were offered a super-close ratio gearbox in addition to the standard five-speed, plus a choice of final drive ratios.
One downside of the new, stiffer chassis and drivetrain goodies was a vehicle weight increase of nearly 200 pounds, with the car now tipping the scales at 2,970 pounds.
Clearly, Mitsubishi was barring no holds in the street adaptation of its rally car. The EVO was highly competitive in WRC and was earning a well-deserved cult following in the rest of the world, while American enthusiasts remained largely ignorant of the World Rally Championship and the fire-breathing offspring it produced.
Evolution V
Chassis Code CP9A
WRC classes were also evolving and by 1997 a new class, creatively named "World Rally Car" class, had emerged. WRC class cars had to abide by Group A rules, but did not require homologation, giving them a more serious purpose-built flavor. Still confident in the efficacy of its Evolution platform, Mitsubishi opted to continue competing in Group A and introduced the Evolution V in January of 1998.
To remain competitive against the WRC class cars, especially in tarmac trim, all areas of the EVO received attention. Vehicle track was increased 40mm in front and 35mm in the rear, with new fender flares and 17-inch wheels to fill them out. Suspension geometry was reconfigured for more travel and lower roll center, and inverted struts were fitted to the front. Both ends of the car got larger brakes. The twin-scroll turbine housing was biggie-sized to 10.5 cm2, and the 4G63's cylinder bore was increased 0.3mm for improved piston-ring sealing characteristics. At 1998.6cc, total displacement remained below 2.0 liters as per class rules.
Peak torque jumped to 275 lb-ft at 3000 rpm. Claimed power remained at 276 hp, an artifact of the Japanese "gentlemen's agreement" of capping peak power quotes, rather than a true reflection of the 4G63's urge in its then-current guise. It's safe to say that the engine was making something over 280 hp at this point.
Despite the changes, total weight increased only 22 pounds over the EVO IV. With an aggressive new rear wing, larger hood vents for improving radiator airflow, a deeper front chin spoiler, and enormous cooling vents in the bumper, the EVO V looked like a rolling street fight.
Evolution VI
Chassis Code CP9A
Further improvements to cooling performance and engine durability were the main focus of 1999's Evolution VI. A new coolant routing path reduced water pump cavitation, and shrunken fog lamps meant even larger openings in the bumper were possible, and the license plate was offset to the driver's side to get out of the way of cooling airflow. New pistons with cooling channels cast in the underside were installed, and a larger oil cooler was fitted, as was a larger intercooler.
Though Mitsubishi did not claim an increase in engine output for Evolution VI, its power delivery improved in RS by using a titanium-aluminide turbine wheel, a world's first in a production car. With lower density than a traditional Inconel turbine wheel, this intermetallic alloy reduced rotational inertia, improving boost response. However, titanium-aluminide is more brittle than Inconel, and to avoid potential durability problems the titanium-aluminide turbo was not available in the street-biased GSR model.
Chassis stiffness was increased further still with the addition of 130 spot welds, strategic reinforcements, and the use of structural adhesive. New regulations limiting the size of aerodynamic enhancements meant yet another new rear wing for the Evolution. To make up for the lost wing area, Mitsubishi simply added a second tier.
Another trim level was introduced, RS2, combining the RS-only hardware specification with a modicum of the GSR's niceties. By this time, American enthusiasts were fully clued into the EVO's overseas presence, and their pleas for a U.S.-spec car were being given consideration.
Evolution VII
Chassis Code CT9A
In 2001, the Evolution VII was introduced. And the Evolution series as a Group A homologation model was dead. For the first time, Mitsubishi would be competing in WRC class, which does not require the sale of homologation vehicles to the public. Evolution VII was based on Mitsubishi's newer Lancer Cedia platform, one size larger than the previous platform, to the chagrin of some hard-core EVO fans. What little it gave up in pure straight-line urge to the lighter EVO VI it made up for with chassis wizardry.
Most significant was the introduction of an active center differential (ACD), an all-new electro-hydraulically controlled multiplate clutch-type limited-slip differential with three times the binding capacity (783 lb-ft compared to 221 lb-ft) of the viscous unit used in the EVO VI. Active Yaw Control (AYC) still regulated torque split in the rear differential, while a torque-sensing helical limited-slip was fitted to the front. With input from a host of sensors, ACD and AYC were both regulated by a single dedicated control unit. Together, ACD and AYC improved turn-in and reduced understeer more seamlessly, allowing controlled tail-out hooliganism and scalpel-sharp steering response.
Structural reinforcements to the donor Cedia chassis increased flexural rigidity by 50 percent by adding thicker sheetmetal and bracing in high-load regions, seam-welding in the B-pillars and front chassis section, and more than 200 additional spot welds in the door apertures. Weight-saving measures like thinner glass, forged aluminum suspension pieces, aluminum front fenders, thinner sheetmetal in the roof panel, a magnesium cam cover, and hollow camshafts kept the total vehicle weight increase to about 90 pounds over the EVO VI.
At 276 hp, quoted power remained unchanged though peak torque increased to 283 lb-ft, this time by way of reworked intake ports, a less-restrictive intake manifold, and a smaller twin-scroll turbine housing (reduced from 10.5 to 9.8 cm2). Paired with a 20mm larger intercooler and a lower-backpressure exhaust, the sauce was spread over a broader range of engine speeds than ever before. Overall, the VII was an even more potent performer-if a more civilized one-than the VI.
The Lancer Evolution series' overwhelming success extends a big middle finger to the focus groups and consumer clinics of the traditional mainstream, lukewarm, carry-your-golf-clubs-in-the-trunk sissy pants approach to car building, and smacks misty-eyed retromobiles upside the head. Prodigious performance envelope aside, that's reason enough to respect it.
source : http://www.sportcompactcarweb.com
