RMS Rolling Road Day April 2015 Afterthoughts

[gsportcars]

Yeah you get transmission losses when in neutral except for maybe the loss of the input shaft spinning depending on setup but it's a minimal difference. Still gives a good indication of flywheel power.

The problem with shifting directly into neutral on these newer boxes is that there is no mechanical direct connection from the shifter to the box for selecting drive/neutral/reverse/park. So it takes you to do a little quick shifting in two different directions with the shifter in a split second while at redline lol.
I'd say it can be done ok but again due to time constraints and the worry of shifting to the wrong position by accident I didn't feel overly confident doing this. I'd rather spend a little time to 'get to know' the behaviour of the box before trying something like that.

The M4 was really handy in this respect as all I had to do was select the gear and when at redline I held the shifter to the left which dropped it directly into neutral. This was how WSM informed me it could be done.

 

[Boydie]

@gsportcars would that be the same case with me regarding going into neutral on the wind down with DSG/Stronic?

 

[gsportcars]

@gsportcars would that be the same case with me regarding going into neutral on the wind down with DSG/Stronic?

Yeah pretty much. So long as you can drop into neutral for the coast down you'll get a good indication of flywheel power. On autos that are slow to shift it can be clearly seen on the dyno graph where the first part of the coast down (high rpm just after letting off throttle) has a huge negative spike in bottom (losses) area while the gearbox holds onto the gear for a second or so before disengaging the drive. The v8 soarer on the day did exactly this. But once in neutral the losses measured are more accurate.


Edit...
Just seeing again the 'dsg'. I know the basics of these but as you have essentially 2 gear sets and 2 clutches I'm not sure how that would equate. You may find you only get half the losses measured as it ignores the second gear set etc. But to be honest at this point I'd need to research it a little to find out the finer details of operation.

 

[Andy044]

Hang on, Marcus didn't get charged?
Fairly happy with the results the soarer made, given the doubt over what its supposed to be standard! Still, small power for a V8, its maybe time I went back to something turbo'd

@gsportcars let me know about that 14a

 

[gsportcars]

@Boydie
A quick trip over to Wikipedia found me this simple illustration...

Going by this, the input shafts are split into 2 with a clutch for each input shaft. The output shaft seems to be the one piece so in theory, 'yes' is the answer to your question.
If you can drop straight into neutral at redline then it should disengage all gears and give the same result as a normal auto on coast down in neutral as neither of the double input shafts are spinning. In fact, you should actually get a slightly more accurate flywheel figure as the box will only ever use one input shaft at a time which is less inertial weight that 'isnt' being accounted for. On a traditional box you would have a heavier 'full single' input shaft that wasn't being measured so the figures are that little bit less accurate.

 

[WSM]

@gsportcars would that be the same case with me regarding going into neutral on the wind down with DSG/Stronic?

My M4 is a DCT and flicking it left into N seemed to work so I'd imagine it should be similar?

 

[Coog]

It is surely, it even says so in the towing/recovery section of the manual IIRC.

 

[Boydie]

Cool, I didn't know

 

[Coog]

Oh and the Revo dsg map also improves this. Its truely manual not some sort of faux manual that decides when to change anyway (ie you can nail it from zero to the limiter in any gear and it'll actually stay in that gear). Was one of the biggest improvements for me with that map

 

[G N K]

After meeting you on Saturday @gsportcars im pretty sure you went with me to view a golf a few years back at a house out towards your workshop. I'd know Matt pretty well, and maybe the mysterious Gavin I have stored in my phone is you lol.

Was happy with the run my cat got, stage one has seen my power increase from 200 standard to 246bhp and almost 300ftlb torque

 

[gsportcars]

That sounds vaguely familiar lol. You could be right. And I can be mysterious sometimes lol.

 

[G N K]

That sounds vaguely familiar lol. You could be right. And I can be mysterious sometimes lol.

Haha, you were too busy to be talking crap on Saturday so didn't say much but yes I don't know any other Gavins and it not my number saved so must be you lol. The golf turned out to be dung with cracked alloys and terrible bodywork it was a dent guy selling it too lol.

 

[WSM]

Oh and the Revo dsg map also improves this. Its truely manual not some sort of faux manual that decides when to change anyway (ie you can nail it from zero to the limiter in any gear and it'll actually stay in that gear). Was one of the biggest improvements for me with that map

DCT in the M4 let's you do this in S3 Drive Logic mode (or some balls it's called) so you can basically rev right up to the limiter in any gear. It's nice

 

[Deckz]

Decent power figures there from a TD ZR @maxpower_ireland

 

[marcusplowman]

Thankfully all the ding donging and flashing lights and warnings on the dash and iDrive were gone a few miles down the road Stupid electronics in cars these days!

 

[gsportcars]

Thankfully all the ding donging and flashing lights and warnings on the dash and iDrive were gone a few miles down the road Stupid electronics in cars these days!

It's amusing seeing the look of horror on some people's faces when they get in the car after a dyno run lol.

 

[marcusplowman]

The steering lock one was the best

 

[Ricky302]

Looks good to me

Do you actually think your transmission losses are 166HP?

 

[pablo]

Lol. No.

 

[Ricky302]

Ha! I was wondering that even BMW couldn't build transmissions that inefficient!

 

[marcusplowman]

Do you actually think your transmission losses are 166HP?

Its 367hp standard...I doubt whether the remap, exhaust and ramair scoop have put it near the 400 mark never mind that Gav explained the whole transmission thing and time wasnt on our hands especially not with me being the second car to run in the morning. I did a bit of investigating online and what a few have done is kept the traction control off, Sport button on, shifter in D and used the wheel paddles to select the desired gear for the run then when reaching peak stuck the shifter down to N. @jessy this might be worth a try with yours...then if it all goes a bit 7175 up Ill know not to try it

 

[WSM]

Anyone happen to get a good video of the M4 on top end run?

 

[marcusplowman]

We should take a run round the tunnel out of the City airport and make some

 

[WSM]

Port Tunnel Dublin!

 

[marcusplowman]

City airport tunnel...5 miles away
Dublin port tunnel...100 miles away