Is there anything special about Porsche engines?
Discussion
Hopefully not as daft of a question as it looks.
I know sod all about how an engine works other than the very very basics. I do know that some manufacturers have "tricks" such as Honda and their V-Tec and BMW "M" engines and VANOS etc.
Do Porsche have anything similar (and if so can it be explained in terms an idiot would understand)?
I have a Boxster and whilst it goes alright and sounds alright I'm not sure if the engine (the new 245bhp unit) has any "tricks" or is just a pretty standard 2.7L lump of metal.
Hope that makes some sense!
I know sod all about how an engine works other than the very very basics. I do know that some manufacturers have "tricks" such as Honda and their V-Tec and BMW "M" engines and VANOS etc.
Do Porsche have anything similar (and if so can it be explained in terms an idiot would understand)?
I have a Boxster and whilst it goes alright and sounds alright I'm not sure if the engine (the new 245bhp unit) has any "tricks" or is just a pretty standard 2.7L lump of metal.
Hope that makes some sense!
Try VarioCam, VarioCam Plus and VarioRam. Porsche have been leading the way with alot of these technologies.
http://en.wikipedia.org/wiki/VarioCam
http://en.wikipedia.org/wiki/VarioRam
http://en.wikipedia.org/wiki/VarioCam
http://en.wikipedia.org/wiki/VarioRam
Ess_Three said:
Such a pity that for all the advanced technology, Porsche can't see their way to making their engines oil tight...
At least my garage floor will never rust...
At least my garage floor will never rust...
GT3 engine is one of the most advanced engines available in a road car, no RMS problems, and dry sump
but then i suppose it should be given the engince is 40k!
Ess_Three said:
Such a pity that for all the advanced technology, Porsche can't see their way to making their engines oil tight...
At least my garage floor will never rust...
At least my garage floor will never rust...
my 993 turbo doesn't drip oil anywhere. The undertray is alway completely dry (so far) and the car will be 10 years old in September 2007
not sure how much you know or don't know ..... but on a VERY basic level, do you realise the Boxster & 911 engine are horizontally apposed flat 6's rather than the conventional in-line or 'V' style of engines from other manufacturers ?
Only other company to currently offer a horizontally apposes motor is Subaru, with flat 4 & flat 6 engines
Only other company to currently offer a horizontally apposes motor is Subaru, with flat 4 & flat 6 engines
Perhaps the biggest advantage of the flat six is that it's perfect balance and compact design - allows a very light crankshaft and flywheel. This combined with a short power delivery route and length to the gearbox and transmission - enables more of the power developed in the cylinders to transfer to the wheels with less internal losses - so more of it pushes the car forward faster and it also enables quicker acceleration from the same individual cylinder power than many other designs.
As a car accelerates the front tends to lift the weight off the front wheels and the rear squates down so driving through the back wheels is the best place to get the most grip and the rear engine can help in this weight transfer - allowing good power delivery - while transmission electronic aids can minimise wheel spin.
With naturally aspirated engines - genrally to produce high power you need good breathing at high revs and therefore large inlet valves, long valve timing and large but short inlet tracts - but unfortunately this very design also reduces the power at low revs - that you could have got from having smaller inlet systems with longer inlet tracts and lower lift cams with shorter opening times.
The only way to get both is to vary the settings within the same engine as much as possible at different revs and Porsche have done this over the years with variable inlet lengths, cam timing and more recently inlet valve lift - but they are not alone in this and some other manufacturers provide similar systems.
Another way to spread the power band is to pump in air by a super or turbo charger. Again Porsche have been prominent in developing these areas. They are amongst the fastest in the World for placing new developments like this in the hands of their customers which adds to the pleasure of owning something with the latest technology - although sometimes there is a price to pay regarding reliability as engineers learn more about long term influences.
Overall the Porsche engine does therefore incorporate unique benefits which coupled with high quality materials and production results in an excellent sports car power source.
The only down side is that offering the public new technology tp play with can lead to initial unreliability in some confined areas - that some recent models have suffered from.
Baz Hartech
As a car accelerates the front tends to lift the weight off the front wheels and the rear squates down so driving through the back wheels is the best place to get the most grip and the rear engine can help in this weight transfer - allowing good power delivery - while transmission electronic aids can minimise wheel spin.
With naturally aspirated engines - genrally to produce high power you need good breathing at high revs and therefore large inlet valves, long valve timing and large but short inlet tracts - but unfortunately this very design also reduces the power at low revs - that you could have got from having smaller inlet systems with longer inlet tracts and lower lift cams with shorter opening times.
The only way to get both is to vary the settings within the same engine as much as possible at different revs and Porsche have done this over the years with variable inlet lengths, cam timing and more recently inlet valve lift - but they are not alone in this and some other manufacturers provide similar systems.
Another way to spread the power band is to pump in air by a super or turbo charger. Again Porsche have been prominent in developing these areas. They are amongst the fastest in the World for placing new developments like this in the hands of their customers which adds to the pleasure of owning something with the latest technology - although sometimes there is a price to pay regarding reliability as engineers learn more about long term influences.
Overall the Porsche engine does therefore incorporate unique benefits which coupled with high quality materials and production results in an excellent sports car power source.
The only down side is that offering the public new technology tp play with can lead to initial unreliability in some confined areas - that some recent models have suffered from.
Baz Hartech
This depends on what you are comparing to and the criteria of the comparison. AFAIK if you compare 996/997 engines to last generation BMW M sport motors then it appears that you get just as many costly long term reliability issues just with different parts of the engine. Comparing a 911 engine reliability to a common 16v lump like a honda vtec is hardly fair given that the end product is vastly different. However comparing said Porsche engines to perhaps ferrari or tvr is enlightening. ISTR that many say the F355 was the best recent ferrari and had bullet proof mechanicals that gasp will get past 45K before requiring serious rebuild work!
NJH said:
This depends on what you are comparing to and the criteria of the comparison. AFAIK if you compare 996/997 engines to last generation BMW M sport motors then it appears that you get just as many costly long term reliability issues just with different parts of the engine. Comparing a 911 engine reliability to a common 16v lump like a honda vtec is hardly fair given that the end product is vastly different. However comparing said Porsche engines to perhaps ferrari or tvr is enlightening. ISTR that many say the F355 was the best recent ferrari and had bullet proof mechanicals that gasp will get past 45K before requiring serious rebuild work!
you can't compare Ferrari or TVR to Porsche engines surely NJH - NA or turbo'd flat 6's (esp. dry sumped) will do 100k plus without rebuild! By 'enlightening' do you mean they are comparable on some level other than power output?
Also the Variable Turbine Geometry in the new 997 Turbo is a unique technology.
With variable vanes you can control the exhaust flow against the turbine blades.
It makes up for the need to have a Big turbo for high engines speed, and ideally a small, fast spooling one for lower engine speeds.
So that's a pretty cool technology, and not an easy one as one needs very specific materials to operate such a mechanism at very high temperatures.
As I understand this existed before but only for slow industrial diesel units, never for a fast revving production car.
With variable vanes you can control the exhaust flow against the turbine blades.
It makes up for the need to have a Big turbo for high engines speed, and ideally a small, fast spooling one for lower engine speeds.
So that's a pretty cool technology, and not an easy one as one needs very specific materials to operate such a mechanism at very high temperatures.
As I understand this existed before but only for slow industrial diesel units, never for a fast revving production car.
Gulliver911 said:
Also the Variable Turbine Geometry in the new 997 Turbo is a unique technology.
With variable vanes you can control the exhaust flow against the turbine blades.
It makes up for the need to have a Big turbo for high engines speed, and ideally a small, fast spooling one for lower engine speeds.
So that's a pretty cool technology, and not an easy one as one needs very specific materials to operate such a mechanism at very high temperatures.
As I understand this existed before but only for slow industrial diesel units, never for a fast revving production car.
With variable vanes you can control the exhaust flow against the turbine blades.
It makes up for the need to have a Big turbo for high engines speed, and ideally a small, fast spooling one for lower engine speeds.
So that's a pretty cool technology, and not an easy one as one needs very specific materials to operate such a mechanism at very high temperatures.
As I understand this existed before but only for slow industrial diesel units, never for a fast revving production car.
diesel cars have had variable vein for years but the 997tt is the first petrol engine with this technology. not sure why this has taken so long to appear on petrol engines?
kennyboy said:
NJH said:
This depends on what you are comparing to and the criteria of the comparison. AFAIK if you compare 996/997 engines to last generation BMW M sport motors then it appears that you get just as many costly long term reliability issues just with different parts of the engine. Comparing a 911 engine reliability to a common 16v lump like a honda vtec is hardly fair given that the end product is vastly different. However comparing said Porsche engines to perhaps ferrari or tvr is enlightening. ISTR that many say the F355 was the best recent ferrari and had bullet proof mechanicals that gasp will get past 45K before requiring serious rebuild work!
you can't compare Ferrari or TVR to Porsche engines surely NJH - NA or turbo'd flat 6's (esp. dry sumped) will do 100k plus without rebuild! By 'enlightening' do you mean they are comparable on some level other than power output?
I meant that what a ferrari owner refers to as bullet proof would get loads of ppl on here jumping up and down in anger and going on about how the dealer shafted them into buying such an unreliable car when in fact to date I don't remember seeing any evidence that any of the other marques have a reliability record to even compare with Porsche.
Gulliver911 said:
Also the Variable Turbine Geometry in the new 997 Turbo is a unique technology.
With variable vanes you can control the exhaust flow against the turbine blades.
It makes up for the need to have a Big turbo for high engines speed, and ideally a small, fast spooling one for lower engine speeds.
So that's a pretty cool technology, and not an easy one as one needs very specific materials to operate such a mechanism at very high temperatures.
As I understand this existed before but only for slow industrial diesel units, never for a fast revving production car.
With variable vanes you can control the exhaust flow against the turbine blades.
It makes up for the need to have a Big turbo for high engines speed, and ideally a small, fast spooling one for lower engine speeds.
So that's a pretty cool technology, and not an easy one as one needs very specific materials to operate such a mechanism at very high temperatures.
As I understand this existed before but only for slow industrial diesel units, never for a fast revving production car.
Turbotechnics put one an an elise several years ago. I asked the guys there about a similar unit in a T3 size package since at the time I had a Saab 900 that I played with no end. At the time this technology only seemed to be available in small sizes for diesel engines. They also said these turbo's are very expensive, to the point where it might be cheaper on a single turbo engine to have 2 sequential turbo's like in the mazda rx-7.
NJH said:
kennyboy said:
NJH said:
This depends on what you are comparing to and the criteria of the comparison. AFAIK if you compare 996/997 engines to last generation BMW M sport motors then it appears that you get just as many costly long term reliability issues just with different parts of the engine. Comparing a 911 engine reliability to a common 16v lump like a honda vtec is hardly fair given that the end product is vastly different. However comparing said Porsche engines to perhaps ferrari or tvr is enlightening. ISTR that many say the F355 was the best recent ferrari and had bullet proof mechanicals that gasp will get past 45K before requiring serious rebuild work!
you can't compare Ferrari or TVR to Porsche engines surely NJH - NA or turbo'd flat 6's (esp. dry sumped) will do 100k plus without rebuild! By 'enlightening' do you mean they are comparable on some level other than power output?
I meant that what a ferrari owner refers to as bullet proof would get loads of ppl on here jumping up and down in anger and going on about how the dealer shafted them into buying such an unreliable car when in fact to date I don't remember seeing any evidence that any of the other marques have a reliability record to even compare with Porsche.
ah I see, I concur.
[quote=kennyboy
diesel cars have had variable vein for years but the 997tt is the first petrol engine with this technology. not sure why this has taken so long to appear on petrol engines?
[/quote]
Potentially down to the higher EGT's experienced with petrol engines, I would have thought the increased temperatures seen would provide reliability issues with the VGT.. a diesel turbo really doesn't last very long in a medium to high boost petrol application..
slinky
diesel cars have had variable vein for years but the 997tt is the first petrol engine with this technology. not sure why this has taken so long to appear on petrol engines?
[/quote]
Potentially down to the higher EGT's experienced with petrol engines, I would have thought the increased temperatures seen would provide reliability issues with the VGT.. a diesel turbo really doesn't last very long in a medium to high boost petrol application..
slinky
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