Car engines. Turbo vs no turbo

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jharkin
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Location: Boston suburbs

Re: Car engines. Turbo vs no turbo

Post by jharkin » Fri Mar 10, 2017 12:28 pm

marcwd wrote:
What about the need for contaminants to be flushed from the lubrication system on a regular interval regardless of the type of oil used? Maybe this is Honda's position.
If you want to dig into the science of this, the definitive website is BITOG:

https://bobistheoilguy.com/

There is a lot of technical reading there about how oil is made, the difference between conventional and synthetic, why it needs to be changed, and a lively discussion forum. The popular thing over there is users get their used oil analyzed by a lab to monitor engine wear and figure out ideal change intervals.

If you read though threads and look at the lab analysis results and commentary usually oil gets to a point where it needs to be changed because the additives get used up (anti-wear chemicals, detergents, and in the case of conventional oil friction modifiers) before the point that it builds up too much contaminants... Unless of course the engine has a major mechanical issue that needs fixing - in which case frequent changes wont help.

I think the bigger issue with Honda's guideline (and its in every manual I have ever read also) is that there is so much variation in what constitutes a "synthetic" that it would be very hard for them to come up with a recommendation that fit all oils. They would need a rule for MobilOne, a rule for Pennzoil Platium, a rule for Castrol Syntec, a rule for Amsoil, and so on...

Much easier and lower liability to just have one basic recommendation for everything.

Swansea
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Re: Car engines. Turbo vs no turbo

Post by Swansea » Fri Mar 10, 2017 12:33 pm

The oils listed below are highly recommended:

Castrol Syntec European Formula SAE 5W-30
- Mobil 1 SAE 0W-40
- Pennzoil Platinum European Formula Ultra SAE 5W-30
- Valvoline SynPower SAE 5W-30

marcwd
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Re: Car engines. Turbo vs no turbo

Post by marcwd » Fri Mar 10, 2017 2:08 pm

jharkin wrote:
marcwd wrote:
What about the need for contaminants to be flushed from the lubrication system on a regular interval regardless of the type of oil used? Maybe this is Honda's position.
If you want to dig into the science of this, the definitive website is BITOG:

https://bobistheoilguy.com/

There is a lot of technical reading there about how oil is made, the difference between conventional and synthetic, why it needs to be changed, and a lively discussion forum. The popular thing over there is users get their used oil analyzed by a lab to monitor engine wear and figure out ideal change intervals.

If you read though threads and look at the lab analysis results and commentary usually oil gets to a point where it needs to be changed because the additives get used up (anti-wear chemicals, detergents, and in the case of conventional oil friction modifiers) before the point that it builds up too much contaminants... Unless of course the engine has a major mechanical issue that needs fixing - in which case frequent changes wont help.

I think the bigger issue with Honda's guideline (and its in every manual I have ever read also) is that there is so much variation in what constitutes a "synthetic" that it would be very hard for them to come up with a recommendation that fit all oils. They would need a rule for MobilOne, a rule for Pennzoil Platium, a rule for Castrol Syntec, a rule for Amsoil, and so on...

Much easier and lower liability to just have one basic recommendation for everything.
Thanks for your informative reply. (And a tip of the hat to fellow Boston-area BH.)

I know of the site you reference, but I haven't waded through it. My ten-year-old Accord (165,000 miles) has been increasingly requiring me to top off the oil level between changes and I've been thinking to soon replace it with a new one (or similar) and at that point possibly switch over to synthetic.

From what you write, it seems reasonable to extend the interval between oil changes if I use synthetic - the question being how much. So I could have the oil tested and/or just get a general consensus from BITOG for a particular synthetic. But what I might end up doing is to simply continue to more or less follow the conventional oil change schedule and not worry about the cost difference.

NHRATA01
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Re: Car engines. Turbo vs no turbo

Post by NHRATA01 » Fri Mar 10, 2017 3:00 pm

tetractys wrote:Blowers provide direct high volume air, so why settle for a puny lagging turbocharger? -- Tet
Because a properly sized and engineered modern turbo will have minimal lag, and because by nature a supercharger is robbing horsepower to turn it and thereby is less efficient.

NHRATA01
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Re: Car engines. Turbo vs no turbo

Post by NHRATA01 » Fri Mar 10, 2017 3:02 pm

Atilla wrote:My wife's car is a 2007 G35X. 300+ horsepower V6 with no turbo. My friend has an Impreza WRX of similar vintage - or probably a few years newer - 4 cyl. motor with turbo. Definitely not 300 horsepower.

On a long road trip in the Impreza, he was keeping an eye on his cruising speed to keep it below the point the turbo would start to spool up and turn his mileage to crap.

Claimed city/highway mileage in both vehicles is similar. All things being equal I'll take a non turbo engine of larger displacement. The Infiniti has more power and no lag.
A turbo won't just spool because of engine speed, it is also a function of load. Even at higher rpms, in low load situations the turbo won't be making much boost. OTOH at higher speeds load goes up, so even at lower rpms the turbo will start to spool.

alfaspider
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Re: Car engines. Turbo vs no turbo

Post by alfaspider » Mon Mar 13, 2017 8:18 am

marcwd wrote:
alfaspider wrote:
marcwd wrote:
alfaspider wrote:
Frisco Kid wrote:. By that I mean let it reach normal operating temperature before leaning on it, let the turbo cool down before shutting it off, etc.

As an aside on oil, I think synthetic oil should be pretty much standard on every engine by now.* Mobil 1 is only about $15 more expensive per oil change than cheapo non-synthetic, but it will last at least a few thousand miles longer. If you aren't changing your own oil, any savings will be eaten up by additional labor costs.** In the end, it's not really much more expensive, allows for fewer changes, and is better for your engine.


My Honda Accord owner's manual states that synthetic oil may be substituted for conventional oil but that the change interval should not be increased.
Two reasons:

1) Honda doesn't want to deprive the dealers of revenue by recommending a longer interval.
2) If the engine is consuming oil and the owner does not regularly check levels, the motor could be run low from a long service interval.
What about the need for contaminants to be flushed from the lubrication system on a regular interval regardless of the type of oil used? Maybe this is Honda's position.
That is one of the reasons for oil changes to be done at all, but I would point out that other manufacturers, such as BMW are fine with 10,000+ intervals. There's nothing special about BMW engines that allow them to go longer between changes. The main difference is that BMW provides free maintenance with new cars, so their financial incentive is to do fewer changes.

alfaspider
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Re: Car engines. Turbo vs no turbo

Post by alfaspider » Mon Mar 13, 2017 8:22 am

tetractys wrote:Blowers provide direct high volume air, so why settle for a puny lagging turbocharger? -- Tet
Why puny? A turbo can be big or small, just like a supercharger. However, turbochargers tend to be favored for being more efficient and more flexible. Boost can be adjusted with just software and a solenoid on a turbo. For a supercharger, boost changes generally require pulley changes. Superchargers also have more parasitic loss and tend to be less effective at higher boost levels. Some manufacturers, such as Volvo, are starting to look at twin charged designs (both supercharger and turbo).

TOJ
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Re: Car engines. Turbo vs no turbo

Post by TOJ » Mon Mar 13, 2017 8:29 am

Do all these new turbo cars require premium gasoline?

lazydavid
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Re: Car engines. Turbo vs no turbo

Post by lazydavid » Mon Mar 13, 2017 9:30 am

alfaspider wrote:That is one of the reasons for oil changes to be done at all, but I would point out that other manufacturers, such as BMW are fine with 10,000+ intervals. There's nothing special about BMW engines that allow them to go longer between changes. The main difference is that BMW provides free maintenance with new cars, so their financial incentive is to do fewer changes.
There's nothing special about the internals, but there is something special about the fully-assembled engines: BMWs have MUCH larger oil sumps than many other brands. So oil gets less use for the same mileage, and therefore lasts longer.

For example, my wife's Lexus RX350 is a 3.5L V6 that takes 6.5 quarts of oil. My previous E46 323i was a 2.5L straight six, which took 7 Liters (7.5 quarts). 30% smaller engine, 15% more oil. Combine this with a strict requirement for full synthetic, and you have a recipe for a long OCI. My 323i did just fine for the 130k miles i put on it with 17.5-18k oil change intervals, as indicated by the computer. When I had the head open at around 85k, the valvetrain was impeccably clean, with just a thin coat of light amber-colored oil on everything. At that point, the oil had been changed just five times (I did the sixth change at the same time as this other work) in 7 years and 85k miles, including a break-in change at 7500 miles.

My current E90 335d is a 3.0L straight six with a 7.5L (8 quart) sump. I have no concerns about the 13k OCI. Currently just over 70k, and expect it to go quite a long time.

stoptothink
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Re: Car engines. Turbo vs no turbo

Post by stoptothink » Mon Mar 13, 2017 9:44 am

TOJ wrote:Do all these new turbo cars require premium gasoline?
Pretty sure this has been answer already in the thread, but no. In fact, the huge majority of them will run fine on regular, you just might be giving up a miniscule amount of power. Our new jetta with the 1.4t is tuned for regular.

alfaspider
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Re: Car engines. Turbo vs no turbo

Post by alfaspider » Mon Mar 13, 2017 9:45 am

lazydavid wrote:
alfaspider wrote:That is one of the reasons for oil changes to be done at all, but I would point out that other manufacturers, such as BMW are fine with 10,000+ intervals. There's nothing special about BMW engines that allow them to go longer between changes. The main difference is that BMW provides free maintenance with new cars, so their financial incentive is to do fewer changes.
There's nothing special about the internals, but there is something special about the fully-assembled engines: BMWs have MUCH larger oil sumps than many other brands. So oil gets less use for the same mileage, and therefore lasts longer.

For example, my wife's Lexus RX350 is a 3.5L V6 that takes 6.5 quarts of oil. My previous E46 323i was a 2.5L straight six, which took 7 Liters (7.5 quarts). 30% smaller engine, 15% more oil. Combine this with a strict requirement for full synthetic, and you have a recipe for a long OCI. My 323i did just fine for the 130k miles i put on it with 17.5-18k oil change intervals, as indicated by the computer. When I had the head open at around 85k, the valvetrain was impeccably clean, with just a thin coat of light amber-colored oil on everything. At that point, the oil had been changed just five times (I did the sixth change at the same time as this other work) in 7 years and 85k miles, including a break-in change at 7500 miles.

My current E90 335d is a 3.0L straight six with a 7.5L (8 quart) sump. I have no concerns about the 13k OCI. Currently just over 70k, and expect it to go quite a long time.
Valid point, but many newer BMWs aren't quite so generous with their oil capacity. The n20 (in the 320/8) only takes 5 liters, which is on-par with many other 2 liter engines out there with shorter manufacturer-recommended intervals.

lazydavid
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Re: Car engines. Turbo vs no turbo

Post by lazydavid » Mon Mar 13, 2017 10:03 am

alfaspider wrote:Valid point, but many newer BMWs aren't quite so generous with their oil capacity. The n20 (in the 320/8) only takes 5 liters, which is on-par with many other 2 liter engines out there with shorter manufacturer-recommended intervals.
5 liters is 5.3 quarts. I spot-checked a couple of other engines, from the Civic and Mazda 3. Both require 4 quarts. This is a significant difference. The Volvo S60 2.0T also takes 5.3 quarts, and its recommended interval is 10-12k miles (depending on year) on full synthetic, which is the same as the F30 320i/328i.

I'm not saying there aren't other 2L 4-cylinders with a 5 quart capacity and a shorter interval, I didn't want to dig through all of them. But I would be surprised to find one that has both of those AND a strict requirement for synthetic oil.

alfaspider
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Re: Car engines. Turbo vs no turbo

Post by alfaspider » Mon Mar 13, 2017 10:09 am

lazydavid wrote:
alfaspider wrote:Valid point, but many newer BMWs aren't quite so generous with their oil capacity. The n20 (in the 320/8) only takes 5 liters, which is on-par with many other 2 liter engines out there with shorter manufacturer-recommended intervals.
5 liters is 5.3 quarts. I spot-checked a couple of other engines, from the Civic and Mazda 3. Both require 4 quarts. This is a significant difference. The Volvo S60 2.0T also takes 5.3 quarts, and its recommended interval is 10-12k miles (depending on year) on full synthetic, which is the same as the F30 320i/328i.

I'm not saying there aren't other 2L 4-cylinders with a 5 quart capacity and a shorter interval, I didn't want to dig through all of them. But I would be surprised to find one that has both of those AND a strict requirement for synthetic oil.
Perhaps my perception is skewed since my 2 liter Alfa engine takes 7 quarts.

lazydavid
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Re: Car engines. Turbo vs no turbo

Post by lazydavid » Mon Mar 13, 2017 10:15 am

alfaspider wrote: Perhaps my perception is skewed since my 2 liter Alfa engine takes 7 quarts.
:mrgreen:

FandangoDave5010
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Re: Car engines. Turbo vs no turbo

Post by FandangoDave5010 » Mon Mar 13, 2017 11:47 am

I trade my 2014 Subaru Forester XT (Turbo, CVT) for a 2017 Acura RDX (V6). Reason: The Turbo and CVT lacked the power and traction to confidently make it up my 17% grade if there was snow or ice on the gravel surface. Maybe snow tire would have helped but chains, according to Subaru, are a no-no. My daughter is happy with her Forester 2.5, for $10,000 less.

Conclusion: For now, no turbo.

TN_Boy
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Re: Car engines. Turbo vs no turbo

Post by TN_Boy » Tue Mar 14, 2017 2:58 pm

FandangoDave5010 wrote:I trade my 2014 Subaru Forester XT (Turbo, CVT) for a 2017 Acura RDX (V6). Reason: The Turbo and CVT lacked the power and traction to confidently make it up my 17% grade if there was snow or ice on the gravel surface. Maybe snow tire would have helped but chains, according to Subaru, are a no-no. My daughter is happy with her Forester 2.5, for $10,000 less.

Conclusion: For now, no turbo.
I confess, I found this post surprising. For one thing, Subarus have a reputation for being a little more capable in off-road/difficult situations than most of the SUVs out there -- good AWD system, decent ground clearance, etc.

While the 2017 RDX does have more horsepower than the 2014 XT Forester (279 versus 250) it has about the same torque (252 versus 258, a bit less actually). Plus the RDX weighs about 300 pounds more. Road tests do show the RDX as being a touch quicker to 60 and through the 1/4 mile.

But anyway, while I haven't driven either car (I have driven later model Foresters) I find it, well, odd that the extra 29 ponies in the 300 pound heavier RDX gave it that much better hill climbing ability. If there was a *traction* problem well, that's a tire issue I think. But you were there and know what tires were on the cars. For a 17% grade with snow or ice, I think tires are going to be critical.

I guess it also doesn't follow (in my head) that even if the Subaru wasn't as good as the RDX (given equivalent tires) that the problem had anything to do with turbo/non-turbo. How does that follow?

NHRATA01
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Re: Car engines. Turbo vs no turbo

Post by NHRATA01 » Wed Mar 15, 2017 10:09 am

TOJ wrote:Do all these new turbo cars require premium gasoline?
A lot of the non-luxury makes use the wording "recommended not required" (the luxury makes tend to expect you to pony up anyway). Which means it takes premium to make the advertised horsepower but the car can run on regular.

In my opinion, and others will disagree, I would not run a turbo engine on 87 unless the manufacturer specifically recommends 87. Turbos produce more heat, which leads to more chance of detonation under harsh conditions (think climbing a mountain with the A/C on in the middle of summer). If the engine is tuned for 89 or 91, it will back off timing and richen the mixture but only after the knock sensors have detected knock. That's a reactive response, not a proactive one (vs say, if the car was capable of detecting the octane rating of the gas and adjusting the tune in advance). Theoretically thousands of miles driven with knock events could conceivably shorten the engine life; practically it's more difficult to say.

Consider mileage will certainly be improved at the higher octane to, so that offsets some of the 30-40c price per gallon premium.

JMHO...

NHRATA01
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Re: Car engines. Turbo vs no turbo

Post by NHRATA01 » Wed Mar 15, 2017 10:21 am

lazydavid wrote:
alfaspider wrote:That is one of the reasons for oil changes to be done at all, but I would point out that other manufacturers, such as BMW are fine with 10,000+ intervals. There's nothing special about BMW engines that allow them to go longer between changes. The main difference is that BMW provides free maintenance with new cars, so their financial incentive is to do fewer changes.
There's nothing special about the internals, but there is something special about the fully-assembled engines: BMWs have MUCH larger oil sumps than many other brands. So oil gets less use for the same mileage, and therefore lasts longer.

For example, my wife's Lexus RX350 is a 3.5L V6 that takes 6.5 quarts of oil. My previous E46 323i was a 2.5L straight six, which took 7 Liters (7.5 quarts). 30% smaller engine, 15% more oil. Combine this with a strict requirement for full synthetic, and you have a recipe for a long OCI. My 323i did just fine for the 130k miles i put on it with 17.5-18k oil change intervals, as indicated by the computer. When I had the head open at around 85k, the valvetrain was impeccably clean, with just a thin coat of light amber-colored oil on everything. At that point, the oil had been changed just five times (I did the sixth change at the same time as this other work) in 7 years and 85k miles, including a break-in change at 7500 miles.

My current E90 335d is a 3.0L straight six with a 7.5L (8 quart) sump. I have no concerns about the 13k OCI. Currently just over 70k, and expect it to go quite a long time.
There's not anything special about the BMW in this case. The large sump capacity is a function of the straight 6 design vs the V6. A straight 6 has a much longer crankshaft (roughly twice as long really). Therefor the oil pan must also be longer to account for oil drainage off the main bearings. That's going to lead to a larger volume pan and thus more oil capacity in the sump. The displacement of the engine is less relevant than the cylinder layout and head design in regards to oil capacity. I have a 5.7L LS1 V8 that only spec'd 5.5qt capacity (but squeezed in the full 6 easily).

Also your E46 was a port injected naturally aspirated motor. The newer BMW I4/I6's are direct injection/turbocharge which is harsher on the oil (335d being a diesel is obviously a different story altogether). BMW has officially dropped to a 10K recommended interval on the newer engines.

Frisco Kid
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Re: Car engines. Turbo vs no turbo

Post by Frisco Kid » Wed Mar 15, 2017 10:36 am

Atilla, mileage with a turbo is more a result of throttle position than cruising speed as boost is only created under load. Now high speed cruising under load will definitely reduce mileage whether the car has a turbo or not so your mileage would have been reduced as well. Heavy engine load (especially on hot days) is also where detonation, both audible and inaudible comes into play. Modern engine management will back out the timing to avoid detonation while also reducing engine power, grade of fuel matters here as to how much timing the computer will back out. When/if this happens it makes sense to ease up on the throttle.

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