What Dinan Adds to BMW M3 #179

Adapted from Larry Webster's article in C&Driver 2003. https://www.caranddriver.com/reviews/a15134452/dinan-s2-m3-specialty-file/

It's hard to imagine anyone even trying to improve on the M3, but Dinan says his $17,798 package of engine and suspension mods does indeed do just that. This is not a new experience for us.

Dinan acknowledges the inherent dangers of such ventures and is well aware that in stock trim the M3's 333-hp, 3.2-liter six-cylinder engine, for example, is already highly tuned, and there aren't a lot of inexpensive things he can do to significantly increase horsepower. That's why the list of new power parts has just three items on it: an airbox, an airflow meter, and a muffler.

The airbox is larger than the stock unit and also has a snorkel that inhales cold air from the area between the top of the front grille and the hood. In addition to the less restrictive airflow meter, the package includes the relocation of the intake-air-temperature sensor so it's closer to the six throttle bodies, a move Dinan says provides the engine computer with more accurate intake-air-temperature readings.

The throttle bodies are also bored out for further airflow increase, larger 3.5" air filter/intake, 3.5" throttle body boot, wiring harness adapter, OBD2 wiring harness and ECU, appropriate software tune, and higher flow fuel injectors all to accommodate the M3 compatible Porsche MAF..

The exhaust system is also modified for maximum efficiency. The standard M3 uses a muffler that has two outlets, so from the rear of the car there are two pairs of exhaust pipes sticking out. Dinan's muffler uses only one larger, smoother outlet because he says more air is able to flow out. A dummy pair of exhaust tips retains the stock look.

Finally, Dinan reprograms the M3's engine computer, which controls a great many engine functions, including the intake- and exhaust-valve timing, spark timing, fuel flow, and throttles. In addition to adapting those engine parameters to the new parts,

Dinan increased the rev limit by 200 rpm to 8200 (we redline at 7,000 for HPDE He also removed the top-speed governor. Car and Driver don't top-speed-test modified cars, but Dinan says the S2-M3 is good for 189 mph.

All the modifications added a claimed 28 horses to the power bank, an 8.4-percent improvement. That's not enough for a customer to sense a thrilling boost in power, so as part of the package, Dinan also puts in a shorter final-drive ratio (#179 is 3.73:1 versus 3.62:1) to make for sprightlier corner exits.

It is also interesting to note that thanks to the higher rev limit Dinan's car clears 60 mph in second gear, the same as the stock car.

Dinan feels the greatest improvement he's made over the stock M3 is in the suspension department. As we do, he thinks the M3 is too stiff, but he goes even further, contending that the handling benefits don't justify that hard ride. So the S2-M3 package includes new 12-position adjustable shocks and anti-roll bars, stiffer springs, front camber plates, front and rear strut-tower braces.

Dinan claims his car rides about as well—or not—as the stocker but has a lot more grip. Its 0.96-g skidpad figure is a bunch more than a stock M3's. We've tested three stockers, and the numbers have ranged from 0.84 to 0.87.