IanH's C6 RS6 - 955hp & 1200nm - Updated 09 Feb '24

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VaudiGR
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Re: IanH's C6 RS6 900+ spec - Updated 15 Oct 21

Post by VaudiGR » Mon Oct 18, 2021 2:22 pm

Quick question about gearboxes. Is it worth investing in upgrading parts within the gearbox for peace of mind, or would a gearbox that doesn't exceed exceed 1000Nm mark should / would work forever given regular oil changes?

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IanH755
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Re: IanH's C6 RS6 900+ spec - Updated 15 Oct 21

Post by IanH755 » Mon Oct 18, 2021 6:35 pm

As a "not-an-expert" I'd say that the lower the torque the longer the box would last but, even with continual servicing, these OEM GB's will start to fail as the mileage creeps up, even on completely stock cars and at which point I don't even know if you'll be able to get replacement OEM boxes any more.

If you fit uprated parts I would suggest that it'll "reset the clock" on how long a GB will last as the OEM parts which wear out first are replaced during the upgrade.
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Re: IanH's C6 RS6 900+ spec - Updated 15 Oct 21

Post by VaudiGR » Tue Oct 19, 2021 5:17 am

I see your point. So sourcing a GB and keeping it aside even upgrading it would be a good idea if the plan is to keep the car longterm

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Re: IanH's C6 RS6 900+ spec - Updated 15 Oct 21

Post by IanH755 » Tue Oct 19, 2021 9:46 am

Reading my post back I realised it sounded like I was saying "OMG, you won't be able to fix these boxes ever again.........." which isn't right looking back and might make you feel the need to spend extra money on something you may not need.

Instead what I meant to say was that you should still be able to find ZF specialist who can replace any worn OEM internals which would solve the vast majority of issues caused by old/worn parts. However it really is only if you physically "break" the gearbox, i.e. there's bits of metal missing from the metal casing, holes ripped through it etc that at that point - where you can't just repair it, but now need a complete replacement - I think you'd struggle as these "custom-made by ZF for the RS6 only" boxes are pretty rare in the UK (only a few hundred available).

Again, if it's just replacing something thats just worn-out like clutch packs etc (which it would 95%+ of the time) you'll be fine as any ZF specialist can fix that, but only if its something more catastrophic which ruins the box, might it be far harder to find a replacement box.

So to answer your question - ***IF*** you are keeping you car for long time (say more than 10 years) I would suggest that you don't have to buy a spare box "just in case" as they'll still be able to fix 95% of worn parts for a long time yet. However, if you still want a spare anyway then by all means buy one if you have the financial ability, but I would say it's not something that you absolutely 100% need.

Sorry if it sounds like I'm flip-flopping with my opinion, I just realised how pessimistic I sounded in that first post and wanted to clear-up what I said.
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Re: IanH's C6 RS6 900+ spec - Updated 15 Oct 21

Post by IanH755 » Wed Oct 27, 2021 9:12 pm

Ah my life is just effing great :(

During a quick pop around to my folks I suddenly noticed a raw/wet fuel smell when stationary (not exhaust). Nothing with the car seemed "off" (no hesitation, missing etc) but I pulled over anyway to check and found a fuel line quick disconnect in the engine bay has had a 20p bit of plastic locking tab decide to fail, causing the quick disconnect to partially fail and introduced a small fuel leak of about 1 drop per second at idle. The black plastic "cap" in the middle on the bottom picture should be flush with the metal pipe on the right but is clearly popped out and now won't reseat so the quick disconnect is now partially open, allowing a small amount of fuel to drip out.

I spoke to MRC and sent them the pics below, they've seen this failure before and have already ordered the replacement part but it'll take a few weeks to get here so my trip down to MRC on Friday has been delayed slightly!

It's in the pipe in the top centre/left -

Image

The black plastic protective coating was removed by me at the side of the road so I could check for any cracks/leaks from the metal pipe underneath (none found) -

Image
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Re: IanH's C6 RS6 900+ spec - Updated 15 Oct 21

Post by IanH755 » Sat Nov 20, 2021 7:09 pm

Soooooo, fuel leak issues all sorted (new fuel-line and quick connect) plus some TLC with 10 new spark plugs, 10 new coil packs & a new fuel filter then a little extra safety/fun with an uprated in-tank fuel pump fitted (Walbro) as the old OEM one was starting to drop the rail pressure from 5 BAR down to 3 BAR at 6k+ RPM which could have risking a Lean situation if it dropped any lower so it's now running a stable 4.9BAR all day long.

Having the fuelling sorted certainly helped with the MPG (LOL-PG anyway - 3.6MPG at full throttle, 12MPG around town, 24MPG on a 60mph run) and, in combination with a nice strong new spark, it helped drop my 100-200kph Dragy time down from 6.25 sec to just 5.4 sec (about the same as the Koenigsegg CCX supposedly) so I'm guessing the fuelling issue was maybe more hindering that initially thought.

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Re: IanH's C6 RS6 900+ spec - Updated 15 Oct 21

Post by RMC83 » Wed Nov 24, 2021 8:24 pm

Great info there Ian.

Are you planning on another dyno run to see the effect of these fuelling mods? Knocking almost a second off your 100-200 time is quite a jump, so you would think that would also be noticable on the dyno graph.

Cheers
Roy

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Re: IanH's C6 RS6 900+ spec - Updated 15 Oct 21

Post by chunky79 » Wed Nov 24, 2021 9:55 pm

Good work again Ian. That's certainly a beast.
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Re: IanH's C6 RS6 900+ spec - Updated 15 Oct 21

Post by IanH755 » Thu Nov 25, 2021 6:11 pm

RMC83 wrote:
Wed Nov 24, 2021 8:24 pm
Great info there Ian.

Are you planning on another dyno run to see the effect of these fuelling mods? Knocking almost a second off your 100-200 time is quite a jump, so you would think that would also be noticable on the dyno graph.

Cheers
Roy
Hi Roy, my guess would be the previous 100-200 runs (which were done after the new 930hp map) were hurt by the fuel problems which started during the mapping so while I'm not sure if all the new fuel stuff would make more than 930hp, since fitting it all it's very noticeable that I'm back to getting 930hp with every full throttle press whereas with the fuel pressure/leak issues it would feel like 930hp one time then 730-ish the next time the back to 930hp the next so once that happened I didn't go near FT until everything was fixed.
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Re: IanH's C6 RS6 900+ spec - Updated 15 Oct 21

Post by welwynnick » Sat Jan 01, 2022 10:35 pm

IanH755 wrote:
Sun Oct 17, 2021 3:23 pm
IanH755 wrote:
Sun Oct 17, 2021 1:10 am
1st just bogs down low then spins up high i.e. the TC can't get the rev's high enough for a proper launch so the car bogs down right at the start and then, once on boost, the car wheelspins hard into 2nd gear on a normal road.
I did a Dragy run and you actually see this happen in the acceleration graph - there's a little spike at launch followed by a dip as the car bogs, then a massive dip at 1st-2nd gear change (it just stops accelerating shown as the line dropping back to 0g) and then it takes 0.25 to 0.5sec to get back to full acceleration. I'm quite impressed by the Dragy's plotting software TBH as it makes describing what I "feel" during the event much easier to understand with a visual line to point at.
Most of the speeds and time are almost (or exactly) the same as previous so thats pretty consistent between runs using different devices, which is nice.
Image
https://www.autotrader.co.uk/car-detail ... 2190651411

That's an interesting chart Ian, and makes a revealing comparison with a modified S8 that's come up for sale on Autotrader. That car has upgraded turbos, 1100Nm torque (similar), 800bhp (rather less) and probably weighs about the same. But of course it has the 8 speed gearbox. Although it's slightly slower to 200kmh, the launch is better, maintaining close to 1g acceleration from standstill through to second gear, then tails away gradually with little interruption from gearshifts. It's not often you get information like this to show what's going on.

Nick
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Re: IanH's C6 RS6 900+ spec - Updated 15 Oct 21

Post by IanH755 » Sun Jan 02, 2022 9:13 pm

The C6's 6 speed ZF box changes gear in approx 300ms and the newer ZF 8 speed does it around 150-200ms and that difference really shows looking at the smoothness of that S8 graph compared to mine. Plus that extra time spent during gear changes on the older box will slightly add to the overall time so, for the 10.78sec @ 129mph run above - ZF6 uses 4 changes to reach 129mph = 1.2sec approx vs ZF8 using 5 changes to reach 129mpg= 750ms to 1.0sec.

It felt like quite a big step when I went from my C5 RS6's ZF5 gearbox to the C6 RS6's ZF6 box so I'm guessing it'd feel the same going from the ZF6 to ZF8. I mean I'd absolutely love a ZF8 box dropped into my C6.
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Re: IanH's C6 RS6 900+ spec - Updated 15 Oct 21

Post by stevo55 » Mon Jan 03, 2022 10:47 am

That S8 defines ‘a lot of car for the money’ but for the love of Christ look at the interior colour!
Looks like a 1970’s disco sofa.
Good job you’ll be going so fast no one will notice at least some of the time.


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Re: IanH's C6 RS6 900+ spec - Updated 15 Oct 21

Post by welwynnick » Mon Jan 03, 2022 3:05 pm

IanH755 wrote:
Sun Jan 02, 2022 9:13 pm
I mean I'd absolutely love a ZF8 box dropped into my C6.
You'll be the first to hear, Ian.

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Re: IanH's C6 RS6 900+ spec - Updated 15 Oct 21

Post by RMC83 » Tue Jan 18, 2022 7:17 am

IanH755 wrote:
Sat Nov 20, 2021 7:09 pm
Soooooo, fuel leak issues all sorted (new fuel-line and quick connect) plus some TLC with 10 new spark plugs, 10 new coil packs & a new fuel filter then a little extra safety/fun with an uprated in-tank fuel pump fitted (Walbro) as the old OEM one was starting to drop the rail pressure from 5 BAR down to 3 BAR at 6k+ RPM which could have risking a Lean situation if it dropped any lower so it's now running a stable 4.9BAR all day long.
Hi Ian,

Quick question....how did you find out that the LPFP was dropping the pressure to 3bar? Was the pressure being logged during the dyno run or was there an issue that when looked into, it was found found that the pressure was low?

Also, i'm very keen on getting multi maps programmed in aswell, do you know the history behind this, ie why you can get them now programmed in the ecu and not 6yrs ago? Is this just to do with map delevopment by mrc, or is there something else available now that wasn't 6yrs ago?

Cheers
Roy

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Re: IanH's C6 RS6 900+ spec - Updated 15 Oct 21

Post by IanH755 » Tue Jan 18, 2022 7:46 pm

RMC83 wrote:
Tue Jan 18, 2022 7:17 am
Hi Ian,

Quick question....how did you find out that the LPFP was dropping the pressure to 3bar? Was the pressure being logged during the dyno run or was there an issue that when looked into, it was found found that the pressure was low?

Also, i'm very keen on getting multi maps programmed in aswell, do you know the history behind this, ie why you can get them now programmed in the ecu and not 6yrs ago? Is this just to do with map delevopment by mrc, or is there something else available now that wasn't 6yrs ago?

Cheers
Roy
Hi Roy,

LPFP - Yeap. spotted during the dyno runs.

Multi-Map - No idea why/how the change came about but you can now have 3 maps held on the same ECU as previous but now all at the same time.
***OLD*** Daytona C5 RS6 Avant - MRC'd - 500HP & 820NM (PistonHeads Link).

***NEW*** Daytona C6 RS6 Avant - MRC'd - 955HP & 1200NM (PistonHeads Link)

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