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Old 08-01-2010, 04:06 PM   #87
JamesClay
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Join Date: Jul 2003
Location: BimmerWorld
Posts: 183
My Ride: Any BMW with 4wheels
Episode II - The VIR and Summit Point Road Trip/Shakeout/Test

Well, the scheduled Saturday-scheduled update was preempted by me being lazy, so the fun is going to be spread out a little longer. I am going to restrict this update to the performance, observations, and results of the project. I will circle back around in another update to review the build to date and the parts used.

The Ultimate Track Car Challenge was Friday, so we left Thursday afternoon to get there with some sleep. The car is officially a street car with insurance, legal tags, and even an inspection sticker! But I decided to trailer the car to the track anyway since we would be going 2.5 hours to VIR, then Friday night 4 hours to Summit Point, then another 4 hours back home. Too many hours on a car that has had minimal testing and you can never know what to expect in an event like the UTCC where it is run with open passing and a stopwatch to make people a little more greedy for real estate.

I got a call Thursday night from Scott Lear, GRM writer, photographer, and UTCC event planner - he wanted our car in a photoshoot Friday morning. This meant a 6:30AM track arrival to get the car out on track before the day's events started, and since track weekends send me Jekyll and Hyde on sleep, I was up at the crack of dawn ready to rock.

We got to the track, added the event decals to the car, and settled in to our group of 3 cars - a Turbo Cayman and a Ferrari Challenge car. We arrived on the street tires intended to allow us to go around the track to "make sure nothing falls off" - our normal mantra for a new car build. Nothing did, everything worked flawlessly, which was pretty awesome, and so we were then ready to start the first session on our real Hoosier track tires.

Picture from Scott at GRM of the car sitting on grid:
BW_E46M3STC (63)

Session 1 - the morning warm-up. This was the chance for everyone to learn the track (all 65 cars at the same time), shake out the cobwebs, break the stuff that was easy to break, and then roughly split the field in a faster and slower group. It was a little messy with a bunch of yellows as things (not our things) did break, but at the end of the session, we were in the fast group, which gives us a better chance to get a good lap without being held up. At the end of the session, I came in and the guys set the hot tire pressures at 31 (low for slicks).

The car worked exactly as I wanted everything felt right, and it was fast. The rear had a little more roll than I anted at turn exit and the couple wasn't quite right. Quick adjustment was +1 on the rear compression, -1 on front rebound (the front felt a tick too flat as well).

During this session, I did get a few 150MPH runs down the back straight and I heard a flapping - I know the sound well, loose splitter. Well not loose, just not supported enough. We used Alumalite on this, which is corrugated aluminum, so stronger than flat sheets, but only in one direction. And since the 4x10 sheets aren't strengthened in the correct direction given our dimensional requirements, you have to add additional supports on the front lip to hold it up given the air pressure developing. Ryan and Matt (my BW support team) went to town fabricating some supports using safety wire and some borrowed washers - all set. This is the reason we use a carbon piece for a splitter undertray - Alumalite is the prototype/quick to make alternative only.

Session 2 - first timed session. The track was reasonably good - only getting hotter but the surface wasn't totally heatsoaked yet. I went out about 1/3 of the way back of the field, which was roughly gridded by speed. We went out under double yellow with a pace car, so no passing - this allowed me to lag and build a gap between me and the couple of Vettes in front of me. Unfortunately I know VIR very well and I come up to speed pretty immediately and was ready to click off a fast lap the first time by. The Vette directly in front wasn't quite as quick and I had caught him at the top of the uphill esses, he motored clear on the back straight, but I caught again in the downhill. I tried to get another lap but he was fast on the straights, slow in turns, I couldn't get a gap to work with, and yellows quickly came out for a car with a blown power steering - so Lap 1 was the fast lap.

Not a bad session - I planned well except for not estimating my traffic properly - the E46 M3, although making great power for a BMW was not in the same league as the other front-runners and "racing" dissimilar cars like this is tricky. I clicked a 2:06.4 and figured I had another 1.5-2 seconds to go. The Motons responded very nicely to the changes. I was a little worried about coming up in rear compression to help my roll issue because I was using a lot of curb and didn't want to jump the car too much, but the high-speed blow-off in the dampers was awesome and kept the car firmly planted as I hammered the curbs in the flat esses, uphill esses, downhill - you get the point... Measuring tire temps after the session showed the results of climbing ambient temps - the track was starting to go away as we approached 100.

Now, a quick note to thank my friends at Red Line Oils. This car is full of Red Line nose to tail - Water Wetter, Engine Oil, D4ATF in the trans and 75W90 in the diff. So in that session, the engine started to get hot due to the extreme ambient temps and drafting to get a higher straight speed - no clean air hurts a LOT. I knew this was likely and we intentionally ran the car with some less expensive cooling upgrades to determine what we could get away with - the answer is we need to get the coolers that we have in production on the car. But for now, as the oil temp climbed to 300 degrees (indicated, which I know better than on that stock idiot dial), I wasn't happy about the temps, but I knew it wasn't a day-ender either. Normal oils don't like that kind of temp, but I know from our racing program that Red Line will take it for a duration of time and the engine will still be well protected - so we soldier on.

Session 3 - second timed session. I grid up a little late to get some of the bigger Hp cars in front of me. This time I have some Subarus behind me which I know from looking at the time sheets I can handle, and I get a little mroe aggressive on making the gap. The car is working right - no changes other than tire pressure from last session. I go for it the first time by the green at the start stand. I am very happy we decided to add aero. I am flat on the throttle from the transition into Turn 5 until the top of the uphill esses which as I sneak a peek before braking, I am topping at over 130MPH. I get a clean lap and now with the ambient temps right over 100 and track temps around 130, it isn't going to get any faster.

If the last session produced a 2:06.4, I think there is a chance I popped a 2:04. But as I feared, unless you really mess up, the fast laps come early in the day and a perfect lap at 1PM is only a 2:05.9 - 0.5 sec faster than a lap with traffic at 10:30AM. Still, we hit my target laptime. a 2:05 puts our street car in the first few rows of a much cooler April BMW club race - not too shabby. Time to load up - after a solo photo shoot with GRM in some flat evening light. Off to Summit!

I will breeze through the happenings at Summit since the focus for me wasn't on the E46 at hand. My CTC co-driver David White took the car out Saturday - I had enough of the 100+ temps at VIR on Friday and wasn't itching to get in a suit and give it another go. I didn't really plan it this way, but this was a great chance to get another impression of the car, and on a much bumpier track than VIR.

David went out to run a few laps. When he got out, he said the car was too bouncy. GREAT! This is an opportunity to work on shock tuning with a new damper I am not overly-familiar with. Compression is typically on the bottom of the damper and I am feeling lazy, so our planned change is -2 all the way around on the compression to see what it does over the bumps, then we can come out of the rebound easily on the pit lane by popping the hood and trunk. Dave drives a few laps in the next session, comes in the pits and tells me it is way better, and we pull out the rebound (-2 all around) to add data to our matrix.

Final result - the compression most directly affected the bumps and the rebound softened the platform up enough to increase grip in some of the tighter turns where we were having trouble. I added some rebound and compression back based on the F/R balance and we both drove the car to verify our work - the car was pretty dead on. To dial the car in for two very different tracks, on consecutive days, without a crew to help, and exerting a minimal amount of effort - perfect! We both drove the car some the following day and besides our little bit of work on suspension tuning, we torqued wheels, added a little oil, and didn't have to do anything else - the perfect example of how I want a street/track car to perform.

If you are keeping track of the score so far, things we have accomplished:
  • VA state inspection, proof that even the state feels we are street legal - check
  • Street manners - minus decals, check
  • Power well over "typical" - check
  • 2:05 VIR laptime - check
Budget isn't on that list... I have done enough of these to know how this one works and since I, as the customer, didn't set a hard line, the project grew a little from my initial plans/expectations, but we are still close enough to my initial thoughts. More on that later...
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James Clay
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