Prepping for the 2008 NASA Championships

Update by Scott Lear to the BMW 325is project car
Oct 29, 2008

Tires don't like stopping a car sideways in the gravel; fortunately we didn't flip over, but we did end up with rocks in our tire bead.
The ThermalSound Direct trunk matting is a box of sticky and surprisingly heavy goodness.
We replaced the missing OEM trunk matting with the ThermalSound stuff, adding nearly 25 pounds to the car in the process.

Last year we had a pretty terrible event racewise, as we were plagued with brake issues that forced us to retire before the checkered flag flew. We were optimistic about our chances this year as we prepared for the big September 11-14 event.

The punt at HyperFest might have ended our race, but we were still enjoying a pretty positive season in our Spec E30. The car has been running well, and thanks to the recent addition of a radiator fan, it seemed more ready than ever to take on the daunting schedule at the 2008 NASA Championships in Mid-Ohio. Last year we had a pretty terrible event racewise, as we were plagued with brake issues that forced us to retire before the checkered flag flew. We were optimistic about our chances this year as we prepared for the big September 11-14 event.

We neglected to mention it in the last installment, but our punt-induced spin at Summit Point produced another side effect: A bit of runoff-area gravel wedged in where the tire bead of our Toyo Proxes R888 meets the wheel. The right-rear tire’s side had taken the brunt of deceleration as it dug into the gravel pit; the other three tires were free of debris. Naturally, driving around with the gravel packed in there wasn’t going to do the wheel or tire any favors. So, we removed the wheel and the valve stem as soon as we noticed the problem, depressurizing the tire completely to relax the sidewall. A local service shop was able to quickly dismount the tire, remove the stowaway gravel bits, and put it all back together.

As we discovered at HyperFest in June, running a full tank of gas was the best way to avoid our issue with fuel starvation in right-hand turns. As a result, we abandoned our ultra-heavy spare tire solution and went with a borrowed wet-weather spare, which was fine for shorter sprint races since we weren’t burning more than a few gallons of gas per session. The Summit Point scales during HyperFest told us we were at 2781 pounds with a full tank. This gave us 31 pounds of fuel to get through a sprint race, which we felt was a comfortable margin. In fact, the way the numbers lined up, it looked like our home scales were reading about 15 pounds lower than the scales at Summit Point and Roebling Road.

The NASA Championships culminate with a 40-minute race, and we were bound to burn off a good bit of fuel in such a long duration. Based on our prior experiences, we made an educated guess that the fuel starvation issue would surface with about 7 gallons of fuel burned, which equals 45 pounds using an upper-limit fuel weight estimate of 6.5 pounds. Some say 6 pounds is a more accurate estimate, but it’s better to come in a few pounds heavy than a few pounds light. Also, our own spare tire is a bit lighter than the one we borrowed at HyperFest, so it was time to revisit our weight one last time before the Championships.

We put our stock spare in the trunk and put the car back on our Longacre Computerscales. All weights are in pounds, with a full-to the-brim gas tank and the driver in the car.

LF 748723 RF
LR 671608 RR
Cross: 50.69 %TOTAL: 2750 lbs.

From a consistency standpoint, we’re glad to see that we’re right back where we were before; the 3-pound loss can be attributed to the removal of the power steering pump. Keeping in mind that we had noticed our own scales reading 15 pounds low, we needed to add about 30 pounds to the car to keep above a post-race minimum weight of 2750 pounds for the long NASA championships race. Since the root of our low-weight problem was the removal of the ultra-heavy OEM trunk matting back from when we first prepared the car, we decided to put this right by reinstalling some OEM style trunk matting. ThermalSound Direct makes all kinds of OEM-style matting for heat and vibration control, and they had a box of double-sided adhesive matting left over from a special project. Their regularly available Q-mat is essentially the same material, except one side of it is coated in foil. Adam Doskocil (866-926-6548) has quoted a price of $8.97 per sheet for GRM readers. With the BMW on the scales, we applied layers of this very sticky matting to the trunk in the OEM locations. After laying it on pretty thick—the OEM matting weighed 53 pounds, after all—our corner weights looked like this:

LF 744723 RF
LR 685621 RR
Cross: 50.8 %TOTAL: 2774 lbs.

After factoring in 15 pounds of leeway for our low-reading scales, the trunk matting gave us about 40 pounds of fuel weight to play with. This would be more than enough for a 40-minute sprint race, even when we account for warm-up and cooldown laps. Besides, if we did end up dropping below the minimum weight, it would happen at about the same time that fuel starvation kicked in, at which point our race would be doomed in any case.

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View comments on the GRM forums
scotaku New Reader
11/12/08 3:58 a.m.

Sorry to see the project come to a close, Scott. All the features and the project blog were and will continue to be a help to me as I get healthy and finish my car finally.

I am curious how those E3 sparkplugs ever checked out (circa Mar 07). The M20 junkies out in the ether swear nothing runs better than the stock spec Bosch W8LCR. Did the E3's really make much of a difference? Good enough not to notice? Fire and forget? :)

Scott Lear
Scott Lear
11/12/08 9:02 a.m.

Actually, the E3s were a victim of the insanely rich running conditions we suffered early on, the plugs got fouled badly over a couple of months. They did seem quite resistant to fouling, however, with the increased surface area for potential spark. It's got some Bosch plugs in it now, I believe, we threw them in at the track after the fuel issue was resolved.

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