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Originally Posted by TheLizardKing Thank you for taking the time to type out that long post. I really appreciate it. So I get your point that a turbocharged engine is not simply a NA engine with a turbo thrown in. But here is my counterpoint. Consider two engines, one NA and the other TC, designed for exactly the same reliability. What about reliability in use? - A TC engine is more complex with a greater number of parts.
- It needs special care while driving (e.g. the idling rule) that a NA engine does not.
- It needs special maintenance that a NA engine does not. (I have never owned a turbo so I am making an intuitive guess here.)
So as a result of the above points, wouldn't a TC engine tend to fail more often than a NA one on the road?
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See my earlier post. I do believe that in general reliability has improved and so has the complexity of engines. To your earlier point, adding components/increasing complexity tend to decrease reliability, at least in theory. The only way to increase reliability whilst also increasing complexity, is that the reliability of the various components has improved as well. And that has been happening. A practical example, an electronic fuel injection system is infinitely more complex than a carburetor. However, most electronic fuel systems are much more reliable than carburetor systems.
I own a 1986 Alfa Romeo Spider, which is equipped with a Bosch L-tronic injection system. It was one of the earlier Bosch electronic system. This very same Spider was also built with a carburetor. I'm intimately familiar with both system, having been on the Dutch Alfa Romeo Spider Technical Committee for many years and 10's of thousands of miles of rallying all over Europe. The electronic systems hardly ever give any problems. We were endlessly poking screwdrivers into the carburators and adjusting them, cleaning them etc.
I don't think a TC engine needs much special care. There is a whole thread on this forum about the idling rule and I've added my 2 cents there as well. In general modern TC don't require it at all. If the owner's manual doesn't state it, don't bother. Very few people actually read the manual, so there are very few people out there that have ever heard of the idle rule other than us nerds on this forum. Still, as I pointed out, the roads in India are not exactly littered with cars with blown up TCs. These days its largely a myth kept alive by well intended but not well informed car nerds.
So TC engines are really reliable and really need very little care, with the few exceptions, see your owners manual. Of course, for a NA or a TC engine goes you need to adhere to the standard operating procedures. If not, you could damage or break the thing, but that is not really a reliability issues I think.
TCs require very little to no maintenance.
So, from my point of view; all this extra complexity is a good thing. It makes engines more reliable, allows us to pack more punch into the same volume/weight, gives us less emissions etc. However, there is one downside. People that don't understand this new complexity tend to have issues with it. They call it less reliable, difficult to troubleshoot and so on. This forum is absolutely awash with threads on problems with modern engines and most of the advise offered is complete rubbish. Because people don't understand how to deal with this sort of stuff. It needs a different skill set/competence, a different set of tools, notably an OBD analyzer and very different diagnostic skills and insights.
So I don't think a TC engine fails more often then a NA engine. I think people perception is wrong, based on bias towards old technology and a lack of understanding new technology. What is not understood is often disliked and discredited.
There is probably one aspect of older engine technology that is better then modern engines. There is a general sense that old engines last longer then modern ones. That's totally different from reliability as such. Although I can't really say anything based on facts, I do believe there might be some element of truth in that. What remains to be seen is how relevant it is for the average car owner who trades his/her car for a new one after a couple of years or when it reaches 100 - 150K. Any car with any engine will get there. For me it is relevant because I tend to buy all my cars with at least 100K on them.
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Originally Posted by blacksport Probability addition:
P(EF or TF) = P(EF) + P(TF)
If you think I am wrong, you may want to explain the math. I would like to learn. |
Have a look at this link which illustrates perfectly my point on how two reliable systems/components on their own function as a complete system.
http://www.eventhelix.com/realtimema...m#.U613LRZ-FFc
So first you need to understand how these two system affect each other, then you need to define how you measure the reliability. In the above case it is expressed as percentages.
The engine and TC are a serial system. If we take you figures it means both engine and TC have a reliability each of 99.999%. So according to this formula the reliability of the two is 99,998%. Hence my earlier statement that it is only a very small effect.
As a rule of thumb, reliability and or accuracy calculations depend heavily on the system configuration. The math is never a simple add/divide, but actually tends to involve "power to 2", 1/x and square roots in its most basic form. Or in case of a very simply model. Modeling these sort of systems, or rather much more complex system, say a nuclear power plant, and doing these sort of calculations is pretty much a science in itself. I'm not an expert by any means, but I find it very fascinating and if I can draw one conclusion is that very few people even understand the very basics. Its really down to statistics and generally people suck at that. That's how Casino's make a killing!
Jeroen
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Originally Posted by suhaas307 Great point.
I too mentioned that keeping it simple is the key. Yes, DSG is the way forward, but not the way VW are going about it here. They should either give us a sorted DSG or just a manual gearbox. Not something that has a *ahem* reputation.
If not anything, issue official recalls and fix the problem. |
Just to bring my previous post a little more back to the original topic.
To my earlier points and previous posts. I don't think keeping it simple is the key perse. Keeping it reliable is the key and I hope I made it clear that those are different things and they don't necessarily conflict at all. Plenty of proof for that.
The DSG saga is probably one of the exceptions, or dud, as I mentioned in my earlier posts. I have had several VWs and Audi's with DSG, but those were the earlier models. Last one I drove was a 2008 Audi and that was the 3rd DSG company car I drove. Never gave me any problems, in fact I absolutely loved it, great auto box and for somebody like me who did close to 100.000 km a year an absolute God sent.
On a slightly more lighter note: The current DSG might be a bit of a wonky box. The DSG commercial is one of the best I've ever seen:
Jeroen