Heads up Carbon on Porky DI engines
Discussion
Andyuk911 said:
MTR,
I am afraid not.
DI is great for power and emissions, but thereafter 'pants'
A lot of other cars are going in this direction, including the Ferrari 458/ Lambo LP560/ etc..
Just google GDI carbon then you will get a picture of the problem.
It saddens me that Porsche have gone this route, especially how much info is known about the VW TFSI and Audi FSI engines.
Don't get me wrong the cars will run fine, but power will reduce as the carbon builds up on the back of the valves. Personally I don't want that to happen to my 'performance' car.
If it is just left and left, apart from the power reduction, you then end up with what you can read about the Mitsubishi GDI engine ..
If I buy another DI car, I will be doing regular oil changes(5k miles) and using DIP3 every 3k miles ...
What's DIP3 and how do you use it?I am afraid not.
DI is great for power and emissions, but thereafter 'pants'
A lot of other cars are going in this direction, including the Ferrari 458/ Lambo LP560/ etc..
Just google GDI carbon then you will get a picture of the problem.
It saddens me that Porsche have gone this route, especially how much info is known about the VW TFSI and Audi FSI engines.
Don't get me wrong the cars will run fine, but power will reduce as the carbon builds up on the back of the valves. Personally I don't want that to happen to my 'performance' car.
If it is just left and left, apart from the power reduction, you then end up with what you can read about the Mitsubishi GDI engine ..
If I buy another DI car, I will be doing regular oil changes(5k miles) and using DIP3 every 3k miles ...
i think (well 10 years ago) official emissions testing in europe is done on a new engine, where as in the USA its done on an engine that has done an unserviced 100,000 dyno miles. it seems the more 'stingent' euro regs are driving the move to dfi but will lead to worse life time performance. typical
Ian_UK1 said:
bcnrml said:
AndyUK911, thanks for a most helfpul thread (and very useful to have those links to the US). 
I'll stick my neck out and suggest that this coke problem is likely to be a cheaper and more acceptable problem than the lottery situation inherent in these scenarios:
Intermediate Shaft Bearing failure
Number six piston causing engine failure
Cracked liners
etc
It may become a service item (so every 10-20k miles, get a de-coke, especially if you run pork in a city). If it is an extra £400-500 every 20k miles, then no issue. If your driving environments and fuel choices are similar to mine, you wouldn't expect such a short cycle anyway.
I very much doubt that it will be seen as a warranty item. The attitude will be that the consumer must accept this much as we've had to accept the weaknesses (and environmental benefits) of water based paints. There's merit in that. As long as we also get reliability and no catastrophic failures as we've seen previously. So porkers with DFI may end up with better residuals than those with the IMS still within (as long as there are no catastrophic engine failures at low mileage as we've seen for porkers beyond the 993).
The problem is that it would be an extra £4000-5000, maybe even more, not £400-£500. The engine would have to be removed & stripped down. The heads would then have to be stripped down, the valves removed and cleaned, the inlet ports/exhaust ports cleaned, the valves reseated and lapped-in. The pistons would need to be removed and cleaned,the rings replaced and re-gapped the whole engine re-assembled, retimed and re-installed. To remove/replace the engine also require the aircon to be drained/recharged, the coolant to be drained/refilled and bled and the engine oil to be drained/refilled. This is a MONSTER job, not just a little service addendum.I'll stick my neck out and suggest that this coke problem is likely to be a cheaper and more acceptable problem than the lottery situation inherent in these scenarios:
Intermediate Shaft Bearing failure
Number six piston causing engine failure
Cracked liners
etc
It may become a service item (so every 10-20k miles, get a de-coke, especially if you run pork in a city). If it is an extra £400-500 every 20k miles, then no issue. If your driving environments and fuel choices are similar to mine, you wouldn't expect such a short cycle anyway.
I very much doubt that it will be seen as a warranty item. The attitude will be that the consumer must accept this much as we've had to accept the weaknesses (and environmental benefits) of water based paints. There's merit in that. As long as we also get reliability and no catastrophic failures as we've seen previously. So porkers with DFI may end up with better residuals than those with the IMS still within (as long as there are no catastrophic engine failures at low mileage as we've seen for porkers beyond the 993).
To have to do this every 20000 miles would be catastrophic. It wouldn't be dissimilar to the cost of replacing your engine every time your car went for a service. It's certainly infinitely more expensive than replacing an M97 engine once every time they blow-up (which contrary to what you might read on here is quite rare in absolute percentage terms)! All we can hope for is that they don't coke-up to quickly.
Ian
Edited by Ian_UK1 on Wednesday 14th October 09:56
Given your response, I now vary my comments and raise my concerns. One only hopes that for Porsche DFI is an interim measure to get past the emissions threat to selling cars. But I fear, given the trends elsewhere (and VW ownership), that this will not be a short term engine option.
If AndyUK911's first post and the US threads are anything to go by, I can assure you that London driving, even in the supposedly less congested C-Charge zone, will lead to coked engines at low mileage. Oh well.
Andyuk911 said:
I was hoping that Porsche had a magical way to stop this, but as the original post show this is not the case.
It would be interesting to see if the boxer DFI engines use the same oil separation method as the Cayenne DFI.
At the moment i am yet to see a posting on any Porsche forum that shows a boxer engine with this issue, but time will tell as these engines have only been around to the public for a little more than a year.
DSM2 said:
Andyuk911 said:
MTR,
I am afraid not.
DI is great for power and emissions, but thereafter 'pants'
A lot of other cars are going in this direction, including the Ferrari 458/ Lambo LP560/ etc..
Just google GDI carbon then you will get a picture of the problem.
It saddens me that Porsche have gone this route, especially how much info is known about the VW TFSI and Audi FSI engines.
Don't get me wrong the cars will run fine, but power will reduce as the carbon builds up on the back of the valves. Personally I don't want that to happen to my 'performance' car.
If it is just left and left, apart from the power reduction, you then end up with what you can read about the Mitsubishi GDI engine ..
If I buy another DI car, I will be doing regular oil changes(5k miles) and using DIP3 every 3k miles ...
What's DIP3 and how do you use it?I am afraid not.
DI is great for power and emissions, but thereafter 'pants'
A lot of other cars are going in this direction, including the Ferrari 458/ Lambo LP560/ etc..
Just google GDI carbon then you will get a picture of the problem.
It saddens me that Porsche have gone this route, especially how much info is known about the VW TFSI and Audi FSI engines.
Don't get me wrong the cars will run fine, but power will reduce as the carbon builds up on the back of the valves. Personally I don't want that to happen to my 'performance' car.
If it is just left and left, apart from the power reduction, you then end up with what you can read about the Mitsubishi GDI engine ..
If I buy another DI car, I will be doing regular oil changes(5k miles) and using DIP3 every 3k miles ...
Andyuk911 said:
Agreed not the same as Audi, but the technical principal is.
The bottom line is that Direct injection into the cylinder head is a good idea. However the problem comes from the gas recirculation from the crankcase. Audi have 3 swirl pots to try and catch the oil out of the mist,unfortunate this has proved not to be successful and carbon builds.
I was hoping that Porsche had a magical way to stop this, but as the original post show this is not the case.
It is sad, but the gases from crankcase will have oil in them and this oil is what forms as carbon on the back of the valves as there is no fuel to dilute and clean.
More manufacturers will go this route as it is an easy way to reduce emissions and that can be a headline. Watch the Ferrari 458 launch ... reduced emissions was a key part of the speech for the new car.
The new Porsche DFI engine will not be immune from carbon ...
As they say, you pay your money and take your choice.
If this is all true then we should all buy Porsche cars on 3 year rolling PCP deals, pay half the value of the car over the term and then give the problem back to bThe bottom line is that Direct injection into the cylinder head is a good idea. However the problem comes from the gas recirculation from the crankcase. Audi have 3 swirl pots to try and catch the oil out of the mist,unfortunate this has proved not to be successful and carbon builds.
I was hoping that Porsche had a magical way to stop this, but as the original post show this is not the case.
It is sad, but the gases from crankcase will have oil in them and this oil is what forms as carbon on the back of the valves as there is no fuel to dilute and clean.
More manufacturers will go this route as it is an easy way to reduce emissions and that can be a headline. Watch the Ferrari 458 launch ... reduced emissions was a key part of the speech for the new car.
The new Porsche DFI engine will not be immune from carbon ...
As they say, you pay your money and take your choice.
ds after 30,000 miles or so. Eventually this will impact on the value of their product.Another example of fuzzy thinking in response to the world's climate change challeneges. We are now faced with a generation of efficient cars that will be worthless in less than 20,000 miles. Talk about fuelling a throw away society.....
[/quote]
If this is all true then we should all buy Porsche cars on 3 year rolling PCP deals, pay half the value of the car over the term and then give the problem back to b
ds after 30,000 miles or so. Eventually this will impact on the value of their product.[/quote] Can you explain this as I've heard this before and didn't understand. If one buys a car for £100k on a PCP with a £70k balloon. Puts down a £20k deposit then pays 36 payments of £850 i.e another c.£31k.
so in total deposit + monthly payments add up to £51k one can hand the car back even though contractually bound to pay a £70k deposit?
This just doesn't make sense to me - are you sure?
IMI A said:
. said:
If this is all true then we should all buy Porsche cars on 3 year rolling PCP deals, pay half the value of the car over the term and then give the problem back to bds after 30,000 miles or so. Eventually this will impact on the value of their product.
Can you explain this as I've heard this before and didn't understand. If one buys a car for £100k on a PCP with a £70k balloon. Puts down a £20k deposit then pays 36 payments of £850 i.e another c.£31k.ds after 30,000 miles or so. Eventually this will impact on the value of their product.so in total deposit + monthly payments add up to £51k one can hand the car back even though contractually bound to pay a £70k deposit?
This just doesn't make sense to me - are you sure?
£100k car with £20k down leaves £80k to finance.
Say 36 months at £1k with balloon payment of £70k (tied to GFV).
At the end of the 36 month period, you have paid £56k and if you pay another £70k you can buy the car, otherwise you can hand it back. The balloon is usually refered to as the optional final rental as it is optional on PCP deals rather than a contractual obligation to buy.
And funnily enough when your car isnt worth £70k, its worth £40k, you walk.
Edited by emicen on Thursday 15th October 16:55
IMI A said:
theres lots of deals out there with no GVF. I understand it if it was linked to GFV but many on forum have said you can walk due to a change in the consumer credit rules
That may be something to do with being able to walk on lease purchase deals after 50% of the term has passed or similar?Edited by IMI A on Thursday 15th October 16:53
emicen said:
IMI A said:
. said:
If this is all true then we should all buy Porsche cars on 3 year rolling PCP deals, pay half the value of the car over the term and then give the problem back to bds after 30,000 miles or so. Eventually this will impact on the value of their product.
Can you explain this as I've heard this before and didn't understand. If one buys a car for £100k on a PCP with a £70k balloon. Puts down a £20k deposit then pays 36 payments of £850 i.e another c.£31k.ds after 30,000 miles or so. Eventually this will impact on the value of their product.so in total deposit + monthly payments add up to £51k one can hand the car back even though contractually bound to pay a £70k deposit?
This just doesn't make sense to me - are you sure?
£100k car with £20k down leaves £80k to finance.
Say 36 months at £1k with balloon payment of £70k (tied to GFV).
At the end of the 36 month period, you have paid £56k and if you pay another £70k you can buy the car, otherwise you can hand it back. The balloon is usually refered to as the optional final rental as it is optional on PCP deals rather than a contractual obligation to buy.
And funnily enough when your car isnt worth £70k, its worth £40k, you walk.
Edited by emicen on Thursday 15th October 16:55
This thread brought back some marvellous odd memories for me;
1]. One of the funniest films ever from Walter Matthau and Elaine May, 'A New Leaf' and Walter 'Henry Graham's' broken Ferrari being towed away many times & him shouting,"The mechanic tells me that its carbon on the valves'!
2]. Endless hours of younger days spent decarbonising Lotus Twin Cam heads and valves, and my Dad walking into the garage late into the night, and saying hmmmmmmmmmm "There's carbon on the valves!"
1]. One of the funniest films ever from Walter Matthau and Elaine May, 'A New Leaf' and Walter 'Henry Graham's' broken Ferrari being towed away many times & him shouting,"The mechanic tells me that its carbon on the valves'!
2]. Endless hours of younger days spent decarbonising Lotus Twin Cam heads and valves, and my Dad walking into the garage late into the night, and saying hmmmmmmmmmm "There's carbon on the valves!"
shoestring7 said:
FrankCayman said:
Can I just clarify, the Gen 2 Cayman S is DFI but the 2.9 isn't?
Correct.A chame IMO, the 2.9 could have been a 270bhp/35mpg car.......
SS7
But there we are, still the 2.9 is soooo much better than my old 2.7, yet still knocking out the same mpg plus lower c02, so I shouldn't moan.
I doubt 5bhp over 265bhp would really make much difference though...
What a chame (sic)
Gassing Station | Porsche General | Top of Page | What's New | My Stuff