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BMW 3-Series (E90 E92) Forum > E90 / E92 / E93 3-series Powertrain and Drivetrain Discussions > N57 / M57 Turbo Diesel Discussions - 335d > Same day 1/4mile drag & road course thrash



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      05-04-2013, 09:22 PM   #1
torqueisking
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Same day 1/4mile drag & road course thrash

I've had my D for a couple months and now that the nice weather has finally arrived, I decided to take it to the track for road course lapping and 1/4 mile drag time trials. Both events were at Toronto Motorsport Park. The road course length is 3km with two straightaways. The only mod on my car is the JBD. It has the factory sport package.

road course lapping:

I was impressed with the brakes. No fade or grinding no matter how hard I hit them. The front to back bias was perfectly balanced. I did hit ABS a few times running into corners a little too hot.

The transmission worked better than I thought it would. I was in DS and shifted manually but I usually found that I only needed to gear down during a corner so I was already in the right gear when I exited. Other than on the straightaway, I let the TCU gear up.

From a handling perspective, I thought the car was perfectly balanced. There was just a hint of oversteer which is my preference. My G-tech meter registered a max lateral G reading of 1.13

Of course the engine makes gobs of power but this is were things became challenging. I could spin the inside rear tire exiting many of the corners. I think this car really needs an LSD.

Tire pressures were around 37PSI front, 42PSI back. I say around because I took air out of them but there were very hot so the reading was inflated ( no pun intended). My numbers are based on my cold pressures and how much air I took out of them.

How fast is it? Of course road course times are VERY driver dependent so it's difficult to say. One also doesn't know if the car they're toying with is stock or modified. I was lapping a little faster than an E92 335i. An E46 M3 was slightly faster on the straightaway but I could stay with him through the rest of the track. A Porsche 996 (non-turbo) clocked similar times to me in my D. Not too shabby for a diesel sedan with an automatic transmission!

1/4 mile drag:

All runs were starting in 2nd gear and manually shifted at ~4500 except for 4th which revved up a little higher through the lights.

Immediately after my last road course session, I staged the car a the 1/4 mile track and made a pass. Traction control was on. It ran a 14.04 at 101MPH, with a 2.178 60 ft time. That's with the JBD at 75% ( as high as can be on my car without throwing a code). I then dropped the rear the pressure to around 33PSI. With no traction control, I lit up the tire launching aggressively in 2nd gear.

I made 4 runs and my trap speed ranged from 99 to 101mph. Just for fun, I removed the JBD and made more two passes. These were all back to back passes. The trap speeds were 97 and 98 MPH. Best case, it looks like JBD adds 4MPH on my car. That's somewhat disappointing.

No matter what I tried, I had a difficult time getting this car off the line quickly. My 60 ft times were between 2.17 and 2.62 seconds. I really wish I had an LSD in this car!

The factory rear camber angle on my car is 1.5deg so that isn't helping my 60 ft time. I may reduce this and take a slight hit to the handling so the car hooks up better.

After those 6 passes, I let the car cool for about 20 minutes. It was now 8:30 in the evening, the sun was down and the ambient temperature was noticeably cooler (~16 Deg C, 59 Deg F)

The next run was my best: 13.94 at 102.6 with a 2.17 60 ft, traction control off. I couldn't top that time but I was able to trap higher: 104MPH. My best traction-control-off 60ft time matched my traction-control-on 60 ft time! Perhaps I need more launching practice!

After reading about stock D's running in the high 13s, I'm a little disappointed with my ETs and the trap speed but overall impressed with the performance of the car.

Last edited by torqueisking; 05-05-2013 at 08:16 AM.
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      05-05-2013, 10:45 AM   #2
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Which tires did you have on? Although I expect you are a lot better driver than I am, your experience with the brakes and handling on your stock suspension were the same as my first (and only) track day. My track was shorter, being only 1.76 km, with two short straights. The longest straight allowed me to get to around 100 mph before braking, and the torque out of the turns leading into the straights was such the the M cars could not overtake before the turn at the end of the straight. I had to wave them on to pass, which was only fair since they were better than me on the twisties. At the time I had the non-sports suspension with the only change being Bilstein B6 dampers. I also found I needed to be judicious in the application of throttle coming out of turns, even with full nannies, because the rear end did want to break free. I do think my OEM RFTs got a bit slippery after a couple of dry sessions though. I say that because the last two sessions were wet, and it was quite slippery for me. But the rear would want to break free even in the dry. I have not been back to the track yet to see how the LSD and reworked suspension and tires will change things. Drag time is surprising. Most guys report that traction is the problem and the difficulty of getting a good launch. Maybe your tires had got a bit slippery too after the track work?
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      05-05-2013, 11:23 AM   #3
torqueisking
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I have Michelin Pilot Sport PS2 ZP RFTs. Sizes are 225/40ZR18 on the front and 255/35ZR18 on the back.

I thought these tires were really good for RTFs. They didn't break loose abruptly and I find them to be quite predictable after a couple laps. I didn't notice any decrease in traction throughout the event. Perhaps it's because the tires only have a couple thousand miles on them.

When it comes time to replace these, I don't think I'll buy RFTs.

I look forward to reading about your impressions of the LSD on the track!
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