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Discussion Starter · #1 ·
I friend of mine is letting me use his bfg's at the track this weekend. They are 255's (not sure what sidewall size) mounted on 16x8 inch wheels.

Is there anything I should worry about? In terms of breaking a halfshaft? Should I not launch hard? What are teh primary causes of broken halfshafts? Should I hold of using them until I get a chance to get polyurethane bushings and the 14mm bolts for the front irs mount?

What tire pressure? Burnout length? Second gear over first? why?

How many of you out there use d/r's without any problems?

I will also be using a friends autotap, I have never used on of them before all I know is that they are a powerful tool to use for datalogging...so what should I datalog?
 

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Unfortunately, I don't think anyone can answer the halfshaft question. I've heard of a guy breaking one on the first pass with a stock car on F1's. I have about 150 runs on mine, quite a few with DR's. There seems to be a wide variability in results. the one consenses is that hop is really bad, if you get hop, let out.

I do a second gear burnout, although I would not recommend it with the stock clutch an no line lock. I think that is what did my stock clutch in. If you do a second gear burn out, watch the speedo on clutch engagement. If it doesn't jump up immediately, you are burning the clutch, not the tires. The second gear burn out gets the DR's hotter, faster with less RPM and hopefully less heat into the IC system.

To verify that, I would datalog IAT 1 and IAT 2 (although I don't think IAT 2 is really called that in autotap speak.)

And timing
Coolant temp
Fuel pressure

I would also log the tach (should make a fun graph).

JT
 

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Discussion Starter · #3 ·
that's the one thing I have heard also, any hop let out immediatly.

JT what do you recommend as a tire pressure for the d/r's?

I'll try a second gear burnout, but doing a 1st gear one is very easy to do, maybe I'll just have to rev it higher to so a second gear one. And the water box should help somewhat also.

As far as datalogging, I will look into all of those, I also want to do absoulte manifold pressure to see how much boost I am getting. I wonder how many things I can datalog...I guess I'll find that out :)
 

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Rage if you have never done a second gear burnout just do first gear my BFG's get plenty hot and there is plenty of tire speed in first and as JT said it easier on the clutch. Back up just at the edge of the water do a 5-6second burnout and come out of the burnout spinning not mashing the gas just maintaining the tire spin, go directly to the line stage as shallow as possible, hold the revs to 3500 and just let out quickly on the clutch meanwhile going to the floor with the gas, dont pop the clutch just come off it quickly. If the track is descent this will get you into the 1.7's for sure. Run 16lb's in the Bfg's and look forward to your best et's yet!:)
 
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