IanH's 955hp V10 Audi RS6 - Another Car Diary!
Discussion
So I took the plugs out of the other 3 easily accessible cylinders and checked both the plugs and the bores.
The plugs all looked fine (all the same as this)
I did a quick boroscope of the 3 cylinders and found a "little" amount of shallow scoring on all but nowhere near as much as on the No 1 Cylinder and I also found that all the pistons had that same "missing" section in the piston crown so thats the design of the piston and not an issue in the No1. Here's a few random pics of the other cylinders showing the same "missing bit in the No2 an No4 and showing some of the bore marks and the No 2-3-4 cylinders.
So I cleaned up fouled plug, rebuilt the engine putting the No1 cylinder plug/coilpack into cylinder 3 to see if they were fine and put the working No3 plug/coil into cylinder 1. Started the engine and there is still a misfire on Cylinder 1 (No3 runs fine so plug/coil OK) and, now I've got bore pics from 4 cylinders to compare, it's pretty obvious that the No1 has 1 if not 2 deep scores about 180' apart so I'm fairly sure it's lost compression
It gets taken up to Unit20 next week so I'll let Grizz take it apart and see how bad the damage is, cry a little and then prepare my anus for the bank manager/Audi!
The plugs all looked fine (all the same as this)
I did a quick boroscope of the 3 cylinders and found a "little" amount of shallow scoring on all but nowhere near as much as on the No 1 Cylinder and I also found that all the pistons had that same "missing" section in the piston crown so thats the design of the piston and not an issue in the No1. Here's a few random pics of the other cylinders showing the same "missing bit in the No2 an No4 and showing some of the bore marks and the No 2-3-4 cylinders.
So I cleaned up fouled plug, rebuilt the engine putting the No1 cylinder plug/coilpack into cylinder 3 to see if they were fine and put the working No3 plug/coil into cylinder 1. Started the engine and there is still a misfire on Cylinder 1 (No3 runs fine so plug/coil OK) and, now I've got bore pics from 4 cylinders to compare, it's pretty obvious that the No1 has 1 if not 2 deep scores about 180' apart so I'm fairly sure it's lost compression
It gets taken up to Unit20 next week so I'll let Grizz take it apart and see how bad the damage is, cry a little and then prepare my anus for the bank manager/Audi!
Edited by IanH755 on Saturday 31st December 15:04
IanH755 said:
These aren't Audi injectors from a 2L, they're custom made specifically for the 900+ C6 cars MRC have done, but again they'll be taken out and tested just to be sure as, being custom-made, their reliability may not be as good as Audi's own.
Yes im aware of that.I mean that injector failure is pretty common on these engines and the results are similar to what you have.
Just trying to offer some advice.
I'm not convinced about the "missing bit" on the pistons, even though it's present on several.
I've seen a very similar issue on my own car (488bhp Fiat Coupe) - it was caused by the combustion process running slightly too hot and starting to melt the top edge of the piston. Sadly, mine was worse and the combustion process had got down the sides of the piston as far as the rings and caused the rings to jam into the ring lands. The result was a misfire, a loss of compression, lots of oil smoke and very oily plugs....
Is the "missing bit" under the exhaust valves?
I hope I'm wrong, as this car is the sort of thing that PH is all about - good luck
Edit - have you tried running the car with the crankcase breather disconnected? If you have blow-by, you'll get a characteristic "chuffing" noise from the breather hose.
I've seen a very similar issue on my own car (488bhp Fiat Coupe) - it was caused by the combustion process running slightly too hot and starting to melt the top edge of the piston. Sadly, mine was worse and the combustion process had got down the sides of the piston as far as the rings and caused the rings to jam into the ring lands. The result was a misfire, a loss of compression, lots of oil smoke and very oily plugs....
Is the "missing bit" under the exhaust valves?
I hope I'm wrong, as this car is the sort of thing that PH is all about - good luck
Edit - have you tried running the car with the crankcase breather disconnected? If you have blow-by, you'll get a characteristic "chuffing" noise from the breather hose.
Looks like significant pre-ignition / detonation damage and a f**ked bore to me! That amount of oil contamination on the plug means it's been running with a high ring blow by, and that means more det! (oil has a very poor octane rating, so causes det/pre ignition) I wouldn't be surprised to find the top ring has failed.
I'd get your wallet ready for a large bill, sorry!
(entirely un-surprising considering you are running the engine at something like twice it's design output......)
I'd get your wallet ready for a large bill, sorry!
(entirely un-surprising considering you are running the engine at something like twice it's design output......)
foxsasha said:
Any chance of rough pricing up the stage by stage power steps? Just the engine work, not chassis etc. Thanks.
580hp to 650hp - Stage 1 (ECU map and Air Filter only) - £1000 minimum depending any "extras" you want to add.- skips off looking for C6 RS6 Avants*
580hp to 740hp - Stage 2 (ECU/TCU map, Air Filter & main CAT bypass) - £2000 minimum depending any "extras" you want to add.
740hp to 900+hp - Stage 3 - £16k minimum. There's a full breakdown of the costs earlier in this thread, mine was £18k+ IIRC but they go upto £30k depending, again, on any extras added.
Stage 2 is the sweet-spot for these, 0-200mph in 36 seconds, very reliable and still feels like a "normal" car until you floor it and everyone else goes backwards very quickly
IanH755 said:
580hp to 650hp - Stage 1 (ECU map and Air Filter only) - £1000 minimum depending any "extras" you want to add.
580hp to 740hp - Stage 2 (ECU/TCU map, Air Filter & main CAT bypass) - £2000 minimum depending any "extras" you want to add.
740hp to 900+hp - Stage 3 - £16k minimum. There's a full breakdown of the costs earlier in this thread, mine was £18k+ IIRC but they go upto £30k depending, again, on any extras added.
Stage 2 is the sweet-spot for these, 0-200mph in 36 seconds, very reliable and still feels like a "normal" car until you floor it and everyone else goes backwards very quickly
Fantastic, thankyou. Cost of stage 2 sits extreme well with the cost of the car, mind boggling performance for the money. Is there anything else out there on a par? M5?580hp to 740hp - Stage 2 (ECU/TCU map, Air Filter & main CAT bypass) - £2000 minimum depending any "extras" you want to add.
740hp to 900+hp - Stage 3 - £16k minimum. There's a full breakdown of the costs earlier in this thread, mine was £18k+ IIRC but they go upto £30k depending, again, on any extras added.
Stage 2 is the sweet-spot for these, 0-200mph in 36 seconds, very reliable and still feels like a "normal" car until you floor it and everyone else goes backwards very quickly
IanH755 said:
So got the spring out yesterday
and got my 16mm spark plug socket today and whipped the plug out.It looks OK with no damage, it's just coated in oil stopping it firing -
And the boroscope, despite being producing an absolutely awful pic, doesn't show any obvious signs of damage, just more oil burning, so the oil doesn't look to be coming past the rings so it must be coming coming down through the heads which makes me think Valve Stem Oil Seal but the boroscope pics aren't clear enough to be absolutely sure -
As Max says, there are considerable detonation marks on the pistons and visible melting/damage of the pistons in some of the pics above.and got my 16mm spark plug socket today and whipped the plug out.It looks OK with no damage, it's just coated in oil stopping it firing -
And the boroscope, despite being producing an absolutely awful pic, doesn't show any obvious signs of damage, just more oil burning, so the oil doesn't look to be coming past the rings so it must be coming coming down through the heads which makes me think Valve Stem Oil Seal but the boroscope pics aren't clear enough to be absolutely sure -
The bores could probably clean up depending on how fussy you were, but ideally yes an overbore would be best.
But it will need new pistons at a minimum, and it will need tuned correctly and safely to prevent it happening again. Whether that involves simply having the ecu tuned correctly or requires fuel system upgrades too....whoever is tuning it should be able to advise.
But the damage itself is not a result of too much power etc, just improper tuning, unless some sort of fuel system fault had occurred which lead to running lean/detonation.
IanH755 said:
It means a destroyed engine block on the V10 RS6 as you can't hone or bore out the cylinder due to the liner fitted, so any cylinder damage means a new block if it's lost compression. I've got a spare block lined up just incase 
What is the makeup of them that they cannot be honed or bored ?Surely they can be re-finished/machined somehow ?
Or as others have suggested, install new liners ? Although that can be a specialist task too.
I imagine a new block is a hefty sum ?
Definitely looks like a bad map to me. Marks are typical of pre ignition. Running an engine at 180bhp/l requires a super safe map and also much better intercoolers / lower intake temps. Did you compression test the engine before going stage 3?
I'd also recommend getting some sort of live AFR monitoring for when you do get it back on the road; wideband lambda or other such stuff. I'm guessing your OBD can show knock sensor readings as well?
I'd also recommend getting some sort of live AFR monitoring for when you do get it back on the road; wideband lambda or other such stuff. I'm guessing your OBD can show knock sensor readings as well?
Edited by Gooly on Wednesday 4th January 12:48
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