Roll speed

[Niko1414]

Yesterday did some very unscientific testing vs my tuned c63 for the upcoming airstrip event. I found 2nd gear roll at 40 mph with RPMs 5.5k gave me a big jump on roll. What surprised me is rolling at about 60mph roll with the RPMs at about 5k in 3rd gear I just don't pull as hard right away.very delayed and c63 stays with me till about 90. Tested this 3x and delay was there.



Thoughts or recommendations ?

And I had a passenger in the m5. C63 did not

[Used2be]

Originally Posted by Niko1414

Yesterday did some very unscientific testing vs my tuned c63 for the upcoming airstrip event. I found 2nd gear roll at 40 mph with RPMs 5.5k gave me a big jump on roll. What surprised me is rolling at about 60mph roll with the RPMs at about 5k in 3rd gear I just don't pull as hard right away.very delayed and c63 stays with me till about 90. Tested this 3x and delay was there.

Thoughts or recommendations ?

And I had a passenger in the m5. C63 did not

Assuming your large diameter 1, 3, 5, and 7th gear clutch isn't slipping, perhaps the M5 2nd gear is lower than the 2nd gear of the c63 and gives you that jump? And the 3rd gear in the c63 may be lower than the 3rd of the M5? Just thought, is the M5 a manual? If so, ignore the clutch, but the gearing could still come into play.

[NISFAN]

Yes, the C63 only hits about 90mph in 3rd, M5 goes over 100mph, 107mph indicated. That is the issue with the M5, it has ridiculously long ECO gearing. 7th gear is massively overdriven 320MPH at 8000rpm.

For airfield races at 60, start in 2nd.

[Charlie Brown]

Assuming no mechanical issues.. This is a test of acceleration. Acceleration is determined largely by how much power can be applied (used) to accelerate the vehicle. For any given RPM, greater mechanical advantage through selection of a lower (numerically higher) gear ratio will provide greater available torque for a given power output (meaning a given RPM) and thus acceleration. All this assumes the engine doesn't redline and has the ability to spin at the Desired RPM. So, you can expect that with all other things being equal (available RPM, traction. etc..) that the car will accelerate faster from 5k RPM in 2nd gear than it would in 3rd gear at 5k RPM. Thus your results are to be expected... It would be interesting if you used an app on your phone to measure your acceleration in terms of force applied such as measuring "Gs". Seat of the pants works as does your approach of using the C63 as a constant. But an app will tell you where you get the greatest acceleration.

[Timberwolf]

I'd love to have a boost gauge to know exactly how much boost the car makes where.
2nd gear feels like it gets the totality of boost right off the bat, versus 3rd where it's smooth progressive delivery.

[Used2be]

Originally Posted by Timberwolf

I'd love to have a boost gauge to know exactly how much boost the car makes where.
2nd gear feels like it gets the totality of boost right off the bat, versus 3rd where it's smooth progressive delivery.

This piece might do it for you. I haven't gotten one yet, but it looks like it might give good info on a variety of things. Others on here have it, but I haven't talked to them to know if it really has practical uses.

http://www.p3cars.com/bmw-5-series/p...tal-interface/

[Timberwolf]

Originally Posted by Used2be

This piece might do it for you. I haven't gotten one yet, but it looks like it might give good info on a variety of things. Others on here have it, but I haven't talked to them to know if it really has practical uses.

http://www.p3cars.com/bmw-5-series/p...tal-interface/

All my ESS Supercharged E9X buddies run that gauge and seem pretty happy with it. I would love something that reads out on the Nav screen like the GTR! Cause a constant read digital readout gets tiresome. Be nice to have some diagnostic capabilities like IATs, Engine oil, Boost, Timing, etc on the Nav screen. That's a product I'd want

[M54ccibo]

Originally Posted by Niko1414

Yesterday did some very unscientific testing vs my tuned c63 for the upcoming airstrip event. I found 2nd gear roll at 40 mph with RPMs 5.5k gave me a big jump on roll. What surprised me is rolling at about 60mph roll with the RPMs at about 5k in 3rd gear I just don't pull as hard right away.very delayed and c63 stays with me till about 90. Tested this 3x and delay was there.



Thoughts or recommendations ?

And I had a passenger in the m5. C63 did not

Funny, last week I was driving one of the local toll roads very late at night and did some runs from 60, solo, with nobody out. I too found exactly what you stated. So I practiced some rolls from 60 in 2nd.

The problem with 2nd gear 60 rolls are the very short time before your first shift. Definitely doable just need to practice

[Niko1414]

Ha! Ordered a p3 last week just came in today. I'm going to insist on 40mph rolls and or practice rolling at 50/60 in 2nd gear. 3rd is out of the question... Maybe that is why we see videos of people loosing in M5 race they roll in 3rd ???

[NISFAN]

Originally Posted by Niko1414

Ha! Ordered a p3 last week just came in today. I going to insist 40mph rolls and or practice a bit rolling at 50/60 in 2nd gear. 3rd is out of the question... Maybe that is why we see videos of people loosing in M5 race they roll in 3rd ???

Yes M5/6 DCT has a very long ratio box, 3rd is a 107mph gear

Start in 2nd at 60, you won't be in it for long, but will pull harder. This is only DCT, never driven MT M5.