The G-spot

[GoCougs]

150,000 was the mileage at which a statistically significant number of turbo failures are expected, not a hard number at which all turbos will require replacement or a firm expiration point for a turbo.  I'll bet the average will last 200,000, maybe more.

So what's the difference then?

[hotrodalex]

Yeah my engine runs until the turbo cools down after I shut it off.

They should just use an electric oil pump.

[12,000 RPM]

This makes zero sense.  If people are putting turbos on their VQs and getting better mileage it's because they are driving them very differently post-turbo, not because it will actually improve fuel efficiency.  At any amount of boost, you're putting more air into the engine than if naturally aspirated.  More air requires more fuel.  So at any RPM, that motor will be burning more fuel than it was before forced induction.

Yes, you are pumping more air/fuel into the engine under boost, but you are also running the engine slower to make the same power if the turbo is sized properly, and you are using the free energy of the exhaust to eliminate the induction pumping losses. I.e. a stock 350Z makes ~240WHP at ~6000 RPM; a turbo one making a measly 6 lb of boost makes that same power at ~3700 RPM. In order to stay within the confines of the law you would have to change your driving style; i.e. I don't drive my Civic like I drive my Z just like you don't drive your Mustang like you drive your Jetta.

So I don't know what I'm talking about, kinda like how adding a turbo to a VQ improves mileage? (C'mon, man.)

Your attempt at equivalency are not successful. First, big rigs are designed for more mileage, big rigs operate much more often at constant speed, and big rigs do untold higher mileage between starts/stops.

Ive seen multiple examples of it, and from an engineering standpoint it makes sense. Less pumping losses and less friction thanks to lower engine speeds to make the same power.

And I wasnt talking about big rigs. A Hino 195 is not a long distance hauler, it's a short distance delivery truck which probably has similar or worse driving cycles than a regular car. Engine is much higher loaded and boosted etc etc. Turbo engines work fine if they are designed right; problem is Germans still have problems with designing basic components like camshafts and fuel pumps, which under the added stress of turbocharging lead to problems. All the Japanese companies have extensive turbo experience.... when they throw their hats in the fray it will be fine. Only Mazda has faltered but despite claims otherwise Mazda has always had below average reliability.

[MrH]

When a turbo goes kaput, it's pretty obvious.  Bearings seize or the compressor blows pieces of itself into the intake or the turbine throws pieces out the exhaust and the car suffers a major drop in power.

Turbos can last a long time if they are designed properly and one pays attention to lubrication and cooling.  Change the oil frequently and use high-quality oil and allow the turbo some cool-down time before shutting the engine off (or get a turbo-timer, I think many new turbocharged cars have them from the factory now) so that oil doesn't carbonize in the bearings and they hold up much longer.

Woah really? I had no idea stock cars are starting to get turbo timers. That's pretty awesome actually.

Any idea which ones have that now?

[hotrodalex]

Yes, you are pumping more air/fuel into the engine under boost, but you are also running the engine slower to make the same power if the turbo is sized properly, and you are using the free energy of the exhaust to eliminate the induction pumping losses. I.e. a stock 350Z makes ~240WHP at ~6000 RPM; a turbo one making a measly 6 lb of boost makes that same power at ~3700 RPM. In order to stay within the confines of the law you would have to change your driving style; i.e. I don't drive my Civic like I drive my Z just like you don't drive your Mustang like you drive your Jetta.
Ive seen multiple examples of it, and from an engineering standpoint it makes sense. Less pumping losses and less friction thanks to lower engine speeds to make the same power.

And I wasnt talking about big rigs. A Hino 195 is not a long distance hauler, it's a short distance delivery truck which probably has similar or worse driving cycles than a regular car. Engine is much higher loaded and boosted etc etc. Turbo engines work fine if they are designed right; problem is Germans still have problems with designing basic components like camshafts and fuel pumps, which under the added stress of turbocharging lead to problems. All the Japanese companies have extensive turbo experience.... when they throw their hats in the fray it will be fine. Only Mazda has faltered but despite claims otherwise Mazda has always had below average reliability.

Would have to change the gearing in order to see any potential mileage benefits from more power.

[12,000 RPM]

Would have to change the gearing in order to see any potential mileage benefits from more power.

Why? Just short shift or skip gears. W/small enough turbos u could prob do 2-4-6.

[MX793]

Would have to change the gearing in order to see any potential mileage benefits from more power.

Or drive in a taller gear than you normally would, i.e. cruise in 4th at 30 mph instead of 3rd.

[MX793]

Yes, you are pumping more air/fuel into the engine under boost, but you are also running the engine slower to make the same power if the turbo is sized properly, and you are using the free energy of the exhaust to eliminate the induction pumping losses. I.e. a stock 350Z makes ~240WHP at ~6000 RPM; a turbo one making a measly 6 lb of boost makes that same power at ~3700 RPM. In order to stay within the confines of the law you would have to change your driving style; i.e. I don't drive my Civic like I drive my Z just like you don't drive your Mustang like you drive your Jetta.

If you're making the same power, you're burning the same fuel (unless you've somehow improved efficiency with the turbo as well).

And for the most part, I drive the Jetta about the same as I drive the Mustang.  The Mustang, sadly, gets better mileage.

[hotrodalex]

Why? Just short shift or skip gears. W/small enough turbos u could prob do 2-4-6.

Real world examples don't back up the turbo MPG hypothesis.

[12,000 RPM]

If you're making the same power, you're burning the same fuel (unless you've somehow improved efficiency with the turbo as well).

You do. I just explained it. Less pumping losses as the intake tract isn't under vacuum, less frictional losses as the engine isn't spinning as fast. We can argue that the turbo introduces a huge flow impediment in the exhaust, but you're still recapturing energy you would have been tossing out the tailpipe. Fuel input minus operating losses = usable horsepower; turbocharging works to help eliminate those losses.

Real world examples don't back up the turbo MPG hypothesis.

Depends which ones you look at. BMW's turbo engines are more fuel efficient than NA motors making the same power.

And within a brand turbo engines are more efficient than the ones they replace. I.e. Hyundai's 2.0T might not be more efficient than Honda's 3.5 V6, but it's more fuel efficient than its own old V6s.

[hotrodalex]

Depends which ones you look at. BMW's turbo engines are more fuel efficient than NA motors making the same power.

And within a brand turbo engines are more efficient than the ones they replace. I.e. Hyundai's 2.0T might not be more efficient than Honda's 3.5 V6, but it's more fuel efficient than its own old V6s.

But are those N/A engines utilizing the same technology (other than turbocharging)?

[FoMoJo]

You do. I just explained it. Less pumping losses as the intake tract isn't under vacuum, less frictional losses as the engine isn't spinning as fast. We can argue that the turbo introduces a huge flow impediment in the exhaust, but you're still recapturing energy you would have been tossing out the tailpipe. Fuel input minus operating losses = usable horsepower; turbocharging works to help eliminate those losses.
Depends which ones you look at. BMW's turbo engines are more fuel efficient than NA motors making the same power.

And within a brand turbo engines are more efficient than the ones they replace. I.e. Hyundai's 2.0T might not be more efficient than Honda's 3.5 V6, but it's more fuel efficient than its own old V6s.

I think turbo engines, that are tune for efficiency, can provide better fuel efficiency than NA of equivalent power.  If the boost doesn't kick in until about 2500 rpm, most of the driving is done with a non-boosted engine...but when you want to go, just rev up.  Turbo engines, largely for trucks, that need a low-end torque, have the boost kick in at a much lower rpm...around 1500.  Certainly more difficult to get good fuel efficiency but still possible.

[ifcar]

Real world examples don't back up the turbo MPG hypothesis.

The way they work is better mileage when you drive gently and worse mileage when you drive hard, but the ability to choose one or the other. A lot of critics only drove hard.

[MexicoCityM3]

Depends which ones you look at. BMW's turbo engines are more fuel efficient than NA motors making the same power.

IDK Sporty, I think most of the "gains" are mostly tuned to game the european test cycle and, to a lesser extent, the EPA tests.

Real world I see minimal if any gains comparing mpg s between the E46 and the 1M. The 1M is a bit lighter but also more like a brick in aerodynamics.

And the S54 is a 15 year old design!

[GoCougs]

Ive seen multiple examples of it, and from an engineering standpoint it makes sense. Less pumping losses and less friction thanks to lower engine speeds to make the same power.

And I wasnt talking about big rigs. A Hino 195 is not a long distance hauler, it's a short distance delivery truck which probably has similar or worse driving cycles than a regular car. Engine is much higher loaded and boosted etc etc. Turbo engines work fine if they are designed right; problem is Germans still have problems with designing basic components like camshafts and fuel pumps, which under the added stress of turbocharging lead to problems. All the Japanese companies have extensive turbo experience.... when they throw their hats in the fray it will be fine. Only Mazda has faltered but despite claims otherwise Mazda has always had below average reliability.

You're forgetting lower CR (= lower efficiency = lower mpg) when not on boost relative to its N/A counterpart, and the cornerstone of why turbo motors in general do not get better (and plenty of times worse) mpg than their N/A counterparts in the same application.

Big rig = commercial = vastly more miles per year. Drive a big rig like a retail vehicle (~15k miles/year) and see how long the turbo lasts.

[12,000 RPM]

But are those N/A engines utilizing the same technology (other than turbocharging)?

Yes for the most part

IDK Sporty, I think most of the "gains" are mostly tuned to game the european test cycle and, to a lesser extent, the EPA tests.

Real world I see minimal if any gains comparing mpg s between the E46 and the 1M. The 1M is a bit lighter but also more like a brick in aerodynamics.

And the S54 is a 15 year old design!

U are a mile up, S54 prob never comes close to making full power whereas the 1M does. That prob helps fuel efficiency

You're forgetting lower CR (= lower efficiency = lower mpg) when not on boost relative to its N/A counterpart, and the cornerstone of why turbo motors in general do not get better (and plenty of times worse) mpg than their N/A counterparts in the same application.

Big rig = commercial = vastly more miles per year. Drive a big rig like a retail vehicle (~15k miles/year) and see how long the turbo lasts.

For the 10th time a Hino 195 is not a big long haul rig



This prob gets started and turned off more per mile driven than a regular car, and yet the powertrain is warrantied for damn near twice as long. The diffs between trucks like these and passenger cars speak to a harder life for the trucks by your chosen metrics, and again those turbo motors do fine. Design it right and it works, its not rocket science.

[SVT666]

You cannot compare a commercial diesel engine that operates at low RPM to a car that cruises on the freeway at what would be close to redline for one of those trucks.

[12,000 RPM]

You cannot compare a commercial diesel engine that operates at low RPM to a car that cruises on the freeway at what would be close to redline for one of those trucks.

Turbocharger speeds != RPMs, and Cougs point was that turbochargers = point of early failure. Hino/Toyota seem to disagree and have put a lengthy warranty up to back that bet.

[hotrodalex]

Turbocharger speeds != RPMs, and Cougs point was that turbochargers = point of early failure. Hino/Toyota seem to disagree and have put a lengthy warranty up to back that bet.

Being a different type of vehicle, I'd be more inclined to go with Ford's statement. Much more relevant.

[SVT666]

Turbocharger speeds != RPMs, and Cougs point was that turbochargers = point of early failure. Hino/Toyota seem to disagree and have put a lengthy warranty up to back that bet.

Again, you can't compare a small commercial turbo diesel to a passenger car turbo gas engine.  Completely different operating parameters, both in application and in the mechanical operation of both powerplants. 

Turbochargers are in many ways more suited to operation in diesel engines. The smaller speed range that Diesel engines work in (between 1000 and 5000 rpm for a passenger car, and as little as 1000-3500 rpm for a larger unit in a commercial vehicle) mean that the turbocharger has to change speed less, reducing turbo lag and improving efficiency. Diesel engines do not require dump valves (see the turbocharger article for more information). Perhaps most significantly, the diesel engine is immune to detonation because the fuel is not injected until the moment of combustion. Therefore, the compression ratio does not have to be reduced, or other anti-detonation measures taken, as would be necessary for a turbocharged spark-ignition engine.

[GoCougs]

So I've 90% decided my next car is going to be the Golf R (10% B9 Audi S4). There is quite simply nothing else interesting save for MAYBE a 335i x-Drive (S4 is better and more reliable anyway). Reviews are off the charts, which includes excellent ride and low road noise. Road tests are also showing 0-60 under 5 sec and low 13s in the 1/4 mile. The only hitch is looks like M/T and Apple Car Play won't be available till MY 2017.

[CALL_911]

Get an STI

[Laconian]

So I've 90% decided my next car is going to be the Golf R (10% B9 Audi S4). There is quite simply nothing else interesting save for MAYBE a 335i x-Drive (S4 is better and more reliable anyway). Reviews are off the charts, which includes excellent ride and low road noise. Road tests are also showing 0-60 under 5 sec and low 13s in the 1/4 mile. The only hitch is looks like M/T and Apple Car Play won't be available till MY 2017.

Yeah all the MQB car reviews are amazing. $40k is a lot to spend on a lil' hatchback, though.

[GoCougs]

True but gonna be a lot cheaper than the next closest hi-po AWD DSG/MT 4-door sorta luxury cars (S4, 335i Xdrive).

[Xer0]

So I've 90% decided my next car is going to be the Golf R (10% B9 Audi S4). There is quite simply nothing else interesting save for MAYBE a 335i x-Drive (S4 is better and more reliable anyway). Reviews are off the charts, which includes excellent ride and low road noise. Road tests are also showing 0-60 under 5 sec and low 13s in the 1/4 mile. The only hitch is looks like M/T and Apple Car Play won't be available till MY 2017.

Werent you originally down to either a G or GTI/R the first time?  Kind of sad that some 3 years later, nothing has changed in terms of what's out in the market.


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[Cookie Monster]

What about the Focus RS?

[SVT666]

What about the Focus RS?

He would never buy a Ford.

[GoCougs]

Werent you originally down to either a G or GTI/R the first time?  Kind of sad that some 3 years later, nothing has changed in terms of what's out in the market.


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I did really like the Mark 6 GTI. Felt I needed AWD though (and really I did).

Mark 7 Golf R is a huge advancement but yeah, if anything all the rest of the poser class has backtracked. Pretty lame.

[GoCougs]

What about the Focus RS?

The GTI is a vastly better car than the ST and I expect the same advantage for the Golf R. Also, far too ricey looking and I'm not even sure if it will have 4 doors (which is a requirement).

[CJ]

The Focus RS will absolutely have 4-doors.