Yesterday I flew to Arizona to pick up the ESS Supercharged RS-46 stroker motor. Late the night before, Roman called to inform me that ESS wanted to make one last change to the basic kit, and that might take most of the following day to complete. When I arrived in Arizona I called Roman to come and pick me up at the airport. The only question on my mind was "did everything go as scheduled today?" So I was very pleased to hear Roman tell me "I'll be right there...I'm driving your car."
With Roman in the driver's seat, it seemed like we drove half-way across Arizona to get to the shop where I needed to drop him off. It was beginning to rain, and the road was not suitable for any real full-throttle performance demonstrations.
Power Delivery of the ESS Supercharger:
Power delivery of the ESS Supercharger was very nice and linear. When I first drove Roman's car, I was overwhelmingly impressed with how smooth the power was delivered. I guess this was to be expected because it's not a turbo. But nonetheless, the power delivery was very smooth and linear.
None of that changed with the ESS Supercharger and stroker motor. Power was smooth, linear, but overwhelmingly STRONG! When hard accelerating, the only thing going through my mind was whether or not I would chicken out and pull my foot off of the gas before hitting redline. There's a good reason for saying that.
Earlier in the day even though the road appeared dry, hard acceleration caused the back end to float around a little. Apparently the road wasn't as dry as I thought -- because during my 60-130 runs (more on that later), the car travelled perfectly straight and the rear-end didn't hunt around at all.
Since it was raining when I picked up the car, I was really afraid to push the car very hard. Until I had a chance to acclimate myself to the new car, I didn't want to push it so hard that I wrapped it around a pole. But when the weather dried out, my driving settled into a very nice rhythm.
As one would imagine, first gear is mostly useless at full throttle. However, second gear is very usable -- mainly due to the extra tall gears. Even though third gear radically broke traction all on its own at 100 MPH (see 60-130 runs below), third gear was still great at full throttle (with TC off). Due to the speeds involved, I never had a chance to push the car very hard in 4th gear -- because doing so would take me above 175 MPH.
With the extra power of the ESS Supercharger, freeway driving didn't matter what gear I chose. I could drive in 3rd, 4th, 5th, or 6th. I could punch it hard or gradually accelerate in any gear, and the ESS Supercharger would deliver enough power that downshifting was never needed in any situation.
But how does it really drive?
461 miles just flew by. The combination of the stroker, supercharger, and extra tall final drive made it all a perfect package. The stroker motor alone already provided an extra 110 ft/lbs of torque. In NA form, the extra torque was enough for anybody who ever drove the car to say "this is the car BMW should have created." But as my dyno graphs have shown, the torque on the stroker is much more peaky than the perfectly flat torque curve of the factory motor. After 5000 RPMs, the stroker torque decreases, which means the horsepower gains above 5000 RPMs aren't as dramatic as the stock motor. This also means the horsepower peaks lower on the stroker than it does on the stock motor.
The ESS Supercharger is the perfect antidote for the stroker torque curves. By adding the ESS Supercharger, all of the power lost above 5000 RPMs is now regained. The supercharger/stroker combination never stops giving power -- all the way up to redline.
Now, when you couple the increased torque of the stroker, and the additional power provided by the ESS supercharger with a much taller set of gears, you end up with an absolutely perfect package. Without the extra torque of the stroker, the taller gears wouldn't be nearly as driveable on a supercharger-only package. But with the ESS supercharger, stroker and extra tall gears, it's a match made in Heaven -- the perfect sports GT.
60-130 MPH Runs:
After leaving ESS and getting some food for the road, I punched in my destination address (461 miles away), called my wife, and told her I was on the road. By now, it was raining pretty hard and I'm deathly afraid to hit the throttle very hard. Along the way I called some friends, spoke for a long time (because I had a lot of time to kill), and by the time I got to the California border it was night, but the roads were dry.
Immediately after crossing into California, I stopped at Starbucks and hooked up the VBox. My plan: take some 60-130 runs. I pulled off the freeway and waited on an onramp for the traffic to clear. I gradually launched into first, short-shifted into second, then hit the gas pretty hard. Due to my much taller gears, I shifted from 2nd to 3rd at 80 MPH, then at 100 MPH something happened. It seemed like I lost all power, or at least 100 HP of it. My first instinct was that the Supercharger belt must have come off, and before I panic, I needed to figure out which accessories are powered by that same belt. From my previous experiences (when a belt schreded), I knew the "other belt" ran the power steering and everything non-important. That means that this belt must run everything that IS important -- so that means it's time to panic and call Roman.
Roman: "Hello, did you break down yet?"
Robert: "Well, maybe! Here's what happened..."
As luck would have it, even though I was in the middle of the desert, only one mile ahead was an exit with a service station. For those of you who are familiar with the California deserts, you know how lucky this was for me. As I drove the next mile, I didn't get any warning lights, and I made sure my water temperatures were not increasing. When I finally popped the hood, I saw that everything was perfectly fine. So, what happened?
After shifting at 80MPH and accellerating up to 100MPH, the ESS Supercharged-Stroker broke traction so hard (at 100 MPH!) that traction control kicked in to save me from myself. Doh! I forgot to take off traction control.
After taking off traction control, I was out on the road again. I ran 60-130 runs at a variety of altitudes from 300ft, to 1600ft. When I got home to analyze the data, I discovered that all but one of the runs ended before 130 MPH because I took my foot off the gas at 129 -- almost every time.
The one good run was 8.34 seconds on a slight incline (0.31%). Even though the other runs were cut short, the data I accumulated told me exactly what I needed to know. The best time was 60-128.95 @ 7.92 seconds. This tells me that this car definitely break under 8 seconds 60-130 -- even with stock PS2 rubber and power-eating 20" wheels.
Due to my gears, I can perform a 60-130 run with zero or one gear shift. The best times were all using one shift. Just to confirm this fact, I did perform a single 60-130 run using zero shifts (actually, it was 60-128.86) and the result was 8.66 seconds. 8.66 was the worst of all of the 9 runs I attempted (even worse than the run at 1600 ft altitude) -- thus proving that a zero shift 60-130 will hurt my time more than help it.
Other Tidbits of Info:
I always thought my oil consumption of the stroker was a little higher than I wanted. At first build, the stroker would consume a quart of oil for every thousand miles. Eventually, that settled into 1-qt for every 1400-1600 miles. I'm told by MANY sources that both consumption numbers are within BMW specifications, but it was still higher than I wanted. Once the ESS Supercharger was installed, in 600 miles of driving home and around town, the electronic guage did not change at all.
I always keep a very good eye on my oil and water temperatures though my BMW Performance (toy) steering wheel. Whether it was pre-stroker or post-stroker, my oil temperatures always remained constant at 100-103 degrees (C). Yesterday, they remained at a steady 95 degrees.
Before the taller gears, the stroker would get 16 MPH on the highway. After installing the taller gears, that increased to 20 MPH. With the addition of the ESS Supercharger, my highway gas mileage increased to a very nice 22 MPH.
Pictures and Graphs:
Sorry I didn't have time to prepare any pictures and graphs. Last night, Jason (one of the M3Post regulars known to Northern and Southern California) came to meet me when I got into town. I took him for a ride. He also took plenty of pictures. Maybe he can post them up as a response.
I also got a text message from my brother-in-law earlier today, saying the following video was on YouTube. This video was shot this morning -- when I was driving the car to AutoTalent.
Sorry for the long post...but I figured you guys would like to see an update and my first hand driving impressions of the ESS Supercharger and RS-46 stroker motor.