The E30 M3 Sport Evolution was essentially a racing vehicle modified for street usage. Built to exacting specifications to comply with the FIA's Group A Touring Class regulations that required an initial run of 500 road cars, the original E30 M3's main purpose in life was to win races on the track.
It got the job done.
BMW essentially gave its Motorsport division free rein to build a winner. The M10 Formula 1 block was used as the starting point for its S14 plant and the cylinder head design was essentially a sawed-off 2.3-liter version of the 3.5-liter inline-six unit from the M5/M6 line. A Bosch Motronic injection system fed the beast.
The engine ultimately cranked out a 192 hp at 6750 rpm, which was quite respectable in its day, and was linked to a close-ratio five-speed dogleg gearbox hooked to a limited-slip diff.
The basic 3 Series suspension package was augmented with thicker anti-roll bars, firmer springs and shocks and lower ride height. Extra-fat fenders were installed to accommodate larger running gear, and a pronounced spoiler and wing aided aerodynamics.
BMW advanced the EVO program until its short four-year run ended in 1992.
Gustave Stroes, a Ph.D of mechanical engineering, has picked up where BMW left off. With pieces from the factory bin, and parts he developed on his own, he has continued the development of his 1988 M3 and created what is arguably the finest street/club racer around.
"Since I first acquired my M3, I considered converting the engine to a 2.5-liter 'EVO III-style' unit," says Stroes. "That day came when I spun my number three rod bearing at Laguna Seca in November 1999."
Now the engine is fitted with an EVO III crank with a longer 87mm stroke (stock is 84mm) to enlarge displacement to 2.5 liters and increase torque. The internals include forged 95mm JE pistons with Total Seal rings and Pauter rods linked with ARP fasteners. The block is a "seasoned" unit with polished crank journals to reduce stress risers, and the timing chain tensioner is an uprated and preloaded BMW S52 unit from an E36. The compression ratio is a heady 11.35:1.
The 16-valve head was ported by Don Fields and retains stock intake valve sizes to retain flow velocity at lower rpm. According to Fields, the porting job is aggressive but not over the top. Stiffer EVO III valve springs handle the higher lift of the Schrick 284/276 cams. A Turner Motorsport adjustable cam gear allows additional fine-tuning of the torque curve.
Fields then enlarged and ported the throttle bodies 2mm to EVO III specs-48mm butterflies-and matched them to the larger EVO III intake trumpets. The carbon-fiber intake plenum is one of only three BMW Motorsport units ever produced. It weighs a paltry 1.5 pounds. A larger EVO III airflow meter works with BMW "Big Green" injectors and specially tuned TMS/Conforti Software.
To solve another problem, Stroes developed his own GSP Magnecor ignition wire kit featuring a low-crossfire design.
"The ignition wires on the E30 M3 have always struck me as odd-the way they're crammed into that small, hard plastic loom does not seem like a very good idea. Moreover, they tend to rub up against each other at various points along their path," says Stroes.
The bracket is made from 2024 aluminum alloy and treated with hard black anodizing to prevent scratching and to keep it from acting as a pathway to ground. MSD wire separators and mounts are also part of the solution.The Magnecor wires use a metallic inductive-suppressed conductor to transmit spark energy rather than copper.
The M3 exhales through an EVO III exhaust header and a custom GSP 3-inch stainless-steel exhaust with a Borla Y-pipe. The header is connected with a 0.5-inch GSP oversize flange. GSP also supplied the gapless exhaust clamps that feature band clamps welded to stout stainless-steel tubes.
Stroes says the engine produces 225 whp with 173 lb-ft of twist, and it has the reliability of a framing hammer.
The oiling system was augmented with a Canton Mecca remote cooler, mounted under the air intake, and an Accusump 3-quart quasi-dry sump system mounted in the trunk. Stroes retained the factory radiator but modified it with a 318ti fan switch. The A/C and mechanical fan and clutch systems were removed for additional weight savings.
The suspension is comprised of Ground Control's height-adjustable spring package, which uses Eibach 450-pound springs in front and 700-pound springs out back. Koni adjustable dampers reside at each corner. Ground Control provided the front camber plates, spherical-bearing control arm pivots and heavy-duty rear shock mounts. Aluminum front control arms and reinforced rear trailing arms are supplemented with the original anti-roll bars. BMP's spherical-bearing drop links have been adjusted for zero bind at static ride height.
The transmission is based on the European close-ratio "dogleg" box, held in place with BMW E28 transmission mounts. A UUC short-shift kit makes shifting chores more precise and offers an adjustable height lever. The entire assembly sits about 0.5-inch lower, thanks to BMW 750iL engine mounts.
A BMW Motorsport limited-slip diff features a 75-percent lockup, runs a 4.10:1 ring and pinion and includes an M Coupe finned rear diff cover. The driveshaft was modified with an E35 M5 "guibo," a flex disc much more robust than the factory unit.