718 Positive Vibes Thread...
Discussion
JD power survey suggests a large increase in engine problems with 4 cylinder turbo fitted engines. This is becoming a major problem within the motor industry.
Over the last 15 years with a clamber for better fuel economy from the public, manufacturing has moved away from 6 cylinder NA engines, and taken a backword step in creating smaller turbo charged engines.
The turbo 4 cylinder engine has not been the great advancement that people thought it would be. A modern 6 cylinder engine NA can nearly match the figures of the smaller turbo, but will be better for longevity as the turbo engine will obviously be more stressed throughout its life.
Vehicle engine failures with 4 cylinder turbos have gone up by 10% and this may suggest problems in the future....JD power survey.....
Lets just hope this doesn't happen in Porsche world then.
Gadgit.
Over the last 15 years with a clamber for better fuel economy from the public, manufacturing has moved away from 6 cylinder NA engines, and taken a backword step in creating smaller turbo charged engines.
The turbo 4 cylinder engine has not been the great advancement that people thought it would be. A modern 6 cylinder engine NA can nearly match the figures of the smaller turbo, but will be better for longevity as the turbo engine will obviously be more stressed throughout its life.
Vehicle engine failures with 4 cylinder turbos have gone up by 10% and this may suggest problems in the future....JD power survey.....
Lets just hope this doesn't happen in Porsche world then.
Gadgit.
Fourpot.
Agreed, hopefully all the gen 2s will be fine.
Seems that there has been no problems with 981 engines, so far?
Hears hoping that perhaps the 4 pots have been properly made, and not just knocked out for the punters as a fuel and tax saver.
I would hope that at this stage Porsche have gone the whole hog with the 4 pots so as to banish the disgraceful engine problems from the past.
After all this should be the positive 4 pot posts
Gadgit
Agreed, hopefully all the gen 2s will be fine.
Seems that there has been no problems with 981 engines, so far?
Hears hoping that perhaps the 4 pots have been properly made, and not just knocked out for the punters as a fuel and tax saver.
I would hope that at this stage Porsche have gone the whole hog with the 4 pots so as to banish the disgraceful engine problems from the past.
After all this should be the positive 4 pot posts
Gadgit
bcr5784 said:
The anti-lag system as used on race and rally cars is not (as far as I am aware) used on any road cars, but the 718 does have an anti lag system as used on the 911 turbo to keep the turbo spinning after lift off. (It is suppressed in sport mode so you get the pops and bangs that many seem to like).
Doesn't sound (or for that matter feel) terribly different to the systems used in motorsport. There are only so may ways of skinning a cat after all. It wasn't rocket science back in the late 90s (but was often a little bit Heath Robinson), and with electronic throttle actuation being commonplace now I'd have the motorsport methods as just about the most sensible way of doing it in a road car. If Porsche are doing something entirely different, I'll be more than a little surprised.Liam
FourPotPorsche said:
It may be a positive vibes thread but i am not naïve enough to think the F4T will be without its own issues but hopefully they will materialise during the 3 year warranty period, if at all. By the way, the first tunes have come to market so it will be interesting to see how robust the engine really is under enhanced duress.
Shouldn't be too much to go wrong (and hopefully those aren't famous last words). 4 cylinders is easier than 6, and if Porsche can't build a good flat 4 after something like 60 years at it, what hope is there for anyone? Ditto for the turbo technology - they really shouldn't be short of experience. VVT on a petrol engine is probably the bravest move - the last time I was seriously considering it was talked out of it by Garrett as they had them working well on diesels, but thought a high performance petrol turbo would generate temperatures the mechanism couldn't reliably deal with.Spot on about aftermarket tuning - they'll help find the weak points!
Liam
Edited by LiamH66 on Friday 23 September 22:51
n4aat said:
bcr*numbers*, you are comparing 981s against a standard 718. Why? If you haven't driven the, vastly different, 718s then can I suggest you get off the pot.
Simply because I drove the 718 as a genuine replacement for my 981S - it's as fast, and handles better and is great value. I only entered the debate because one (and as far as I know there is ONLY one) who said there was NO lag. And then those who are pro the 718 accepted this as gospel. It's bulls
t - and I've demonstrated this in a number of ways.It's all very well accentuating the positives of the 718 (and there are quite a lot) but going off into lala land and accepting that sort of rubbish, is silly.
Edited by bcr5784 on Saturday 24th September 08:29
LiamH66 said:
Doesn't sound (or for that matter feel) terribly different to the systems used in motorsport. There are only so may ways of skinning a cat after all. It wasn't rocket science back in the late 90s (but was often a little bit Heath Robinson), and with electronic throttle actuation being commonplace now I'd have the motorsport methods as just about the most sensible way of doing it in a road car. If Porsche are doing something entirely different, I'll be more than a little surprised.
Liam
It's fundamentally different - read https://en.wikipedia.org/wiki/Antilag_system - it was often referred to as bang bang and relies on burning fuel in the turbocharger to keep it spinning. Unfortunately that was to the detriment of the turbocharger life. That, as you will read has been refined to the point it could be used on road cars (that is very recent update to the wiki entry), but it's not the mechanism which is used on Porsche turbo which keeps air recirculating through the turbo by keeping the throttle open on lift off (but cutting ignition and fuel) see http://www.autoevolution.com/news/2017-porsche-911... On the 718 this is used except in Sport where, in order to get the pops and bangs in the exhaust, you have to close the throttle and keep fueling so that unburnt fuel gets through to the hot exhaust manifold and explodes.Liam
Of course the anti-lag system only works on lift off in Porsches, so it doesn't spool the turbo up at small throttle openings. So a 718/718s 991.2 and Porsche turbo will all suffer a degree of lag - it's just a matter of how much. 3 seconds - which is what Porsche quote - is a significant amount of lag in my book.
LiamH66 said:
Shouldn't be too much to go wrong (and hopefully those aren't famous last words). 4 cylinders is easier than 6, and if Porsche can't build a good flat 4 after something like 60 years at it, what hope is there for anyone? Ditto for the turbo technology - they really shouldn't be short of experience. VVT on a petrol engine is probably the bravest move - the last time I was seriously considering it was talked out of it by Garrett as they had them working well on diesels, but thought a high performance petrol turbo would generate temperatures the mechanism couldn't reliably deal with.
Spot on about aftermarket tuning - they'll help find the weak points!
Liam
The chances are a highly stressed four cylinder engine will be less reliable than a lower stressed six cylinder engine. Quart out of a pint pot. Thermal stresses alone from the 600 deg C exhaust gas temp going through the turbo, for a kick off. I think if I was in the market for a 718 - or any other car with a brand new engine - I'd wait a year for any issues to be resolved!Spot on about aftermarket tuning - they'll help find the weak points!
Liam
Edited by LiamH66 on Friday 23 September 22:51
As for after market tuning - expensive Russian roulette especially on an expensive to fix car such as a Porsche!
Edited by dreamcar on Saturday 24th September 09:33
dreamcar said:
The chances are a highly stressed four cylinder engine will be less reliable than a lower stressed six cylinder engine. Quart out of a pint pot.
I suggest you check how the output per litre of N/A engines has evolved before getting your knickers in a twist over turbochargers.Anyway, Porsche has successfully been turbocharging cars for more than 30 years.
So that everyone knows, or mist my previous post.
There is evidence that 4 pot engines that are turbocharged are causing the car construction industry to think twice about where they are going.
I'm hoping that Porsche will not suffer this problem.
But industry specialist have accepted that the failure rates have risen over the last 10 years. The rise is a percentage rise in failures and not just because they are making more.
The figures don't lie, this is just a fact.
And this does not mean that porsche will be necessarily affected, and I'm just hoping that they won't.......possitive vibes please.
Gadgit
There is evidence that 4 pot engines that are turbocharged are causing the car construction industry to think twice about where they are going.
I'm hoping that Porsche will not suffer this problem.
But industry specialist have accepted that the failure rates have risen over the last 10 years. The rise is a percentage rise in failures and not just because they are making more.
The figures don't lie, this is just a fact.
And this does not mean that porsche will be necessarily affected, and I'm just hoping that they won't.......possitive vibes please.
Gadgit
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