After breaking-in the new...
After breaking-in the new clutch, we returned to Modified by KC's Dynojet 224x for more testing
In part 10 (et 7/09) of our '97 Me project we installed a BimmerWorld stage 2 clutch kit and have subsequently put an easy 500 miles on the odometer as suggested to break it in. For the first 100 miles, the clutch seemed a little grabby. But as time passed, the clutch started to feel like a stock unit. We're also pleased to report there's virtually no flywheel chatter. In fact, the owner of Modified by KC (who fitted it for us) decided to order the same parts for his own E36 M3.
There have been no issues with the UUC short shifter installed by MKC at the same time either.
Clutch Testing
Since the clutch affects power transfer to the rear wheels, we decided to test it. And since a lighter rotating assembly usually means faster acceleration, we figured the dyno would show it, especially in the lower gears.
By looking at first and second gear testing on the first dyno graph, it's apparent there are gains to be had with a lightweight flywheel. Although short-lived, there's a peak power gain in first gear of 11hp, which is a 7% improvement!
We expected smaller gains in second gear, but a peak 6.7hp still helps.
The theory behind a lightweight flywheel is the loss of drivetrain inertia, which shows up as a power loss between shifts. Because a heavier flywheel stores more energy, that neck-snapping first to second gear shift becomes slightly more docile with a lighter flywheel. Our test showed this as a momentary 12hp loss as soon as the throttle was re-applied in second gear.
While we didn't expect to see gains in third gear, we were pleasantly surprised with a rise from 228.9 to 232.7 wheel hp.
On reflection, the Bimmerworld clutch is a worthwhile investment for a street-driven car.
Fluids Test
People who modify their cars usually reach a point where the marginal rate of the horsepower-per-dollar diminishes. Initially, 10hp might be easy to find, but later the same increase requires a bank loan. They're left with the decision to either stop looking for power or going to the dark side with forced induction.
Remembering that good drivetrain lubrication means a free-spinning drivetrain, which can lead to more rear-wheel power, we decided to see whether we could find power with synthetic drivetrain fluid.
To start an accurate test, we needed a new baseline on Modified by KC's dyno. We first made a run using our original NGK BKR6EIX Iridium plugs, which are in the OE heat range. We then swapped them for new BKR7EIX NGK Iridium plugs, which are one step colder and recommended by both Active Autowerke and BimmerWorld on normally-aspirated modified M3s. This established a new baseline free of potential spark problems for our fluid test, plus we were able to see if going one step colder would hurt performance. It's evident it did not.