Oil viscosity vs HP

Status
Not open for further replies.
Joined
Oct 4, 2005
Messages
785
Location
Western Washington
I think that the major advantage with lower viscosity oil is a reduction in loses due to windage. The amount of power wasted slinging oil on the around the crank and cam can be quite substantial with a high viscosity oil. Although windage can be mostly corrected, some losses associated with high viscosity oil cannot be corrected such as oil pump drive HP.

As far a heat loss, I think a steam hybrid is the way to go, something along the lines of BMW’s concept. Use the exhaust to heat water and drive a steam turbine inside a fairly standard automatic transmission. You basically have no losses other than in transport.
cheers.gif
 
quote:

Originally posted by 1040 WreckerMan:
I think that the major advantage with lower viscosity oil is a reduction in loses due to windage. The amount of power wasted slinging oil on the around the crank and cam can be quite substantial with a high viscosity oil. Although windage can be mostly corrected, some losses associated with high viscosity oil cannot be corrected such as oil pump drive HP.

This might change your perspective:

http://iantaylor.org.uk/papers/IMechEFE2000.pdf
 
I would agree that most of what is in that link is relevant. However, in my own experience I've seen larger improvements by keeping oil in the pan where is belongs and directing oil carefully rather than splashing it all over. I own or operate a variety of different vehicles, and very few of them are affected by oil viscosity in any way that I can say is something other than normal variables such as tire pressure or temperature changes. My 4.0 SOHC Ranger gets around 14 mpg on my normal commute running anything from 0w30 to 10w50. SBC 327 in the Impala gets 11.2 on my normal commute regardless of oil. The SBC 350 in the Jeep gets 10.5 on my normal commute with anything from 0w20 to 20w50. In the Impala I gained about .8 mpg when I installed a windage tray. I don’t own anything smaller than a 3.0 Vulcan (gets 18 around town 0w30-0w40), and I imagine that it’s smaller engines that are more susceptible to HP/MPG losses due to oil viscosity. It seems that the original posters figures would bear that it out and are in agreement with the text that 427Z06 linked to (I have to admit I have only read the first page so far, I’ll finish it when I have more time).

I also think that the compression rings have more frictional losses than the skirts due to oil viscosity. Again, a smaller engine I think would see more of an impact from thick oil. Thanks for the link.
 
quote:

Originally posted by 1040 WreckerMan:
However, in my own experience I've seen larger improvements by keeping oil in the pan where is belongs and directing oil carefully rather than splashing it all over.

It may be prudent to distinguish between high RPM/full power and more normal driving conditions when we talk about frictional losses. I believe properly designed windage trays show they stuff in the former case, whereas under normal driving conditions, other factors, such as viscosity and ring tension will be the dominant variables.

Even windage is probably engine design specific. SBC's crank assemblies have to deal with spillage from the cam bearings and the top end. Modern OHC designs usually channel oil back to the pan through separate oil return passages.

I don't believe the size of the engine has anything to do with it other than it being proportional.
 
This from a car forum - FYI

Motorcars are bought for all sorts of reasons, but enthusiasts like lots of power. To get more power, a lot of fuel must be burnt, and more than half of it, sadly, gets thrown away as waste heat. For every litre of fuel burnt, 60% of the energy goes as waste heat into the exhaust and cooling system. A turbocharger can extract a few percent as useful energy and convert it into pressure on the intake side, but only 40-45% is left, and only 25% actually shows up as BHP at the flywheel.

6% goes in pumping air into the engine, 6% as oil drag losses and 2-3% as engine friction.

The oil deals with 97% of the friction; so reducing the remaining few percent is not easy.

If you doubt that even ordinary oil has a massive effect, take a clean, dry 200 bhp engine, connect it to a dyno and start it up. It will only make 1 bhp for a few seconds. Now that’s real friction for you!

Oddly enough, people get starry-eyed about reducing friction, especially those half-wits who peddle silly “magic additives”, which have not the smallest effect on friction but rapidly corrode bearings and wallet contents. In fact, even a virtually impossible 50% reduction in the remaining engine friction would be no big deal, perhaps one or two bhp or a couple of extra miles per gallon.

Even More Power!

The place to look for extra power is in that 6% lost as oil drag. In a well-designed modern motor, the oil doesn’t have to cover up for wide clearances, poor oil pump capacity or flexy crankshafts, so it can be quite thin. How thin? Well take a look at these dyno results.

A while ago now, we ran three Silkolene performance oils in a Honda Blackbird motorcycle. this fearsome device is fitted with a light, compact, naturally aspirated 1100cc engine which turns out 120+ bhp at the back wheel. The normal fill for this one-year-old engine was 15w-50, so the first reading was taken using a fresh sump-fill of this grade. (The dyno was set up for EEC horsepower, i.e. Pessimistic)

15w-50
Max Power 127.9 bhp @ 9750 rpm
Torque 75.8 ft-lbs @ 7300 rpm

After a flush-out and fill up with 5w-40 the readings were;

5w-40
Max Power 131.6 bhp @ 9750 rpm
Torque 77.7 ft-lbs @ 7400 rpm

Then we tried an experimental grade, 0w-20 yes, 0w-20! This wasn’t as risky as you may think, because this grade had already done a season’s racing with the Kawasaki World Superbike Team, giving them some useful extra power with no reliability problems. (But it must be said, they were only interested in 200 frantic miles before the engines went back to Japan)

0w-20
Max Power 134.4 bhp @ 9750 rpm
Torque 78.9 ft-lbs @ 7400 rpm

In other words, 3.7 bhp / 2.9% increase from 15w-50 to 5w-40, a 2.8 bhp / 2.1% increase from 5w-40 to 0w-20 or a 6.5 bhp / 5% overall. Not bad, just for changing the oil! More to the point, a keen bike owner would have paid at least £1000 to see less improvement than this using the conventional approach of exhaust/intake mods, ignition re-mapping etc.

Cheers
Simon
 
I had a dragbike that I ran 5/10W30 in and it really made the bike rev up faster. I was able to 60 foot better with the thinner oil than with the 20W50 I was using before.
 
Should I bother to point out that the absolute reproducible accuracy of these kinds of dynoes are in the +/-3% range. No probably not....
 
quote:

Originally posted by Mitch Alsup:
Should I bother to point out that the absolute reproducible accuracy of these kinds of dynoes are in the +/-3% range. No probably not....

Excellent point...for a sample size of one.
 
In a large engine I think the proportional amount of loss due to oil related frictional losses is not enough to create an effect that will change performance much. If you wanted to run an ISO 460 oil in a big HP engine, then you would see a noticeable difference. If you have a 3000 cubic inch engine in a boat I don't think the conclusions in the paper you posted are relevant any longer, however we don't typically deal with engines of that size. I suppose I should have said something along the lines of, in normal conditions with typical oil grades frictional losses due to oil viscosity are minimal.

I certainly agree that there is going to be more hp loss using 15w50 rather than 0w20. In the engines I deal with I generally see about a .5-mpg variance due to operating conditions. On these engines, which are "large" displacement, I have not seen an improvement in mpg that was consistently greater than my operational error.

I think we will need more technology before we can really move forward in a meaningful way in regards to using oils as a means to better fuel economy. For this to make a real impact on fuel consumption we will have to have 0w10/0w20 oils that are able to provide the same engine longevity that 15w40 does currently (or whatever thicker grade you chose as an example). In some engines 5w20 works very well, such as Ford's modular engine lineup. 5w20 can't, in its current form, adequately perform in a light/medium duty diesel where xW40 would normally be used. In the future, as better base stocks and additives become available I don’t doubt that a 5w20 will have the capability to perform in more applications that it doesn’t now. I wonder at what point the additives will not correct for the oil being physically thinner? In a given application a certain thickness of oil, film strength, etc. is require for a particular part such as main and rod bearings. In a HD application 30wt seems to be the thinnest (at operating temp) oil that gives good service, and in most cases a 40wt is preferred. With better technology thinner oil will do the same job as current oils. Certainly at some point the additives will not compensate any farther and a minimum film thickness is required. It’s interesting to see what will happen in the next few years with technology to increase the applications low viscosity oil can be used in with as good as results as in the Hondas and Ford modulars.
 
1040 WreckerMan, you might know a thing or two about diesels and running a maintenance operation, but you're at least a decade behind the power curve when it comes to modern engine technology. Improved engine designs combined with modern manufacturing technology to include advanced machining, surface finishes/coatings and advancements in Tribology are already ushering in a whole new paradigm of low viscosity lubricants. We already see this in gasoline engines with efforts from Ford (to include some subsidiaries), Honda, Toyota, Chrysler, with others soon to join in. Diesels engine manufacturers won't be far behind. It's simply old school folklore to think that the only way to properly lubricate an engine is with SAE grade 30 or 40 oil. When you get to really large engines, like ocean going vessels, well of course you run into problems of manufacturing them with tight clearances cost effectively, so yes there are limitations there, at least in the intermediate future.
 
427Z06, We've got several "modern" engines from both Ford, GM and Chrysler that do not respond well to 5w20. The Ford V10's we have do not do as well on 5w30 as they do on a thicker oil, mostly we've started running 30wts in them. My Ford 4.0 does very poorly on even thin 30wts. I had to 2.3L Rangers that I used as tests, one ran 5w20 and the other the control oil. The 5w20 engine failed considerably sooner than the others in the fleet. I have quite a few I fully agree that there are advancements that are ushering in a new paradigm, but it's not fully ushered yet, IMO. I'm slow to jump on any bandwagon. I don't care what the research says, I care what happens in service. I base my comments on knowledge I gained in the field. These research papers are interesting to read, and they are helpful but what happens in the lab is not always a direct corollary to what happens in the field. You are right, I deal mostly with HD diesels and marine applications which have different requirements and are produced with different goals in mind that passenger car power packages. I have started using low viscosity oils when they test well in a given application, not just because “it's better because they tell me it is.” I'm probably a little too conservative adopting some types of new technology. As I have stated before, I still do not think that oil viscosity has as large an impact on real world fuel usage as is being portrayed. When we switched our gas fleet from 20w50 and 10w40 to 5w30 we saw about a .2mpg improvement in economy which certainly can be contributed to the thinner oil in some measure.

Yes, I agree that lower viscosity oil is in the cards for a wide array of applications. I do not agree that the oil has reached the point where it can be almost universally adopted as seems to be indicated many times. I'm not going to do the oil company's R&D on my fleet on my dime. I guess my biggest problem is what I see as a trend toward thinner is always better, and I don't think that is the case and I will continue to evaluate what oil to use by application and by the actual performance of the oil.

I always have a few vehicles of various types that I try new stuff on. Typically I'll take 2 (or some larger number depending on the circumstances and total number of units) components and put them to work with the same duty cycle and use. One with the test oil and one with the control oil and I run the units until they fail and compare the test oil to the control oil to what are normal service records indicate. I have two Allisons that I'm testing a new fluid in right now. Both have right around 66,000 miles the last time I checked. With normal servicing we generally get around 175K miles on these units before they have a failure that requires the transmission to be pulled. The new fluid I'm testing is a light weight ATF which the manufacturer claimed no reduction in LTO and significant decreases in fuel usage. Not sure what they consider significant decrease though.
cheers.gif


BTW, which 0w20 or 5w20 are you using in the Vette?
grin.gif
 
1040 - You actually have "failures"
confused.gif


(visions of that guy again)

I think you need to define "failure" before I could comment.
grin.gif
 
In terms of a lubricant test (at least the ones conducted in house - wish I had full lab too) a failure is when the component the lube is being tested in doesn't go anymore. In the case of the transmissions I mentioned in my last post, when the units get towed in they have failed - and that is how long I'll run them. There are some items in the test I would like to isolate further, but I can't take the units out of service for these tests so I'm somewhat limited there. I would really like to expand our research, but it's hard enough to get the suites to fund the simple tests that we do now. Really what it all comes down to is, my truck runs at the end of the day and gets me home and - I can't see it from my house
grin.gif
 
I know the Formula 1 and Nascar guys have gotten into this big time. I first found out about oil viscosity and power when a competitor told me to stop using 20-50W in Formula V. Believe me, the Formula V crowd has got thin oils and oil control down to NASA like science. I learned that you can afford some engine damage just to get the power benefits of thinner oil or lower oil volume.You really don't want to push any extra oil through the motor if you don't have to.The difference between a "club race" and national race motor is partly using less oil in the national motor. If you start to overheat, you can try slightly more oil volume or a thinner oil. If parts start to destroy themselves you try to see if you can direct more oil just to that part and then get it to drain out quickly. In pursuit of minimal oil volume you risk getting oil aeration which will quickly destroy the motor.
 
quote:

Originally posted by 1040 WreckerMan:
...We've got several "modern" engines from both Ford, GM and Chrysler that do not respond well to 5w20. The Ford V10's we have do not do as well on 5w30 as they do on a thicker oil, mostly we've started running 30wts in them. My Ford 4.0 does very poorly on even thin 30wts. I had to 2.3L Rangers that I used as tests, one ran 5w20 and the other the control oil. The 5w20 engine failed considerably sooner than the others in the fleet...

I see a lot of "do not do as well's", and "does very poorly on's", and "failed considerably sooner's". Can you quantify and qualify those? Teardown, inspection, measurement? UOAs? Anything? Did you call the manufacturer, give them your data and ask for their recommendation?

Do you think manufacturers don't do any field testing whatsoever? Not to mention extended dyno tests to failure. Ever been to Milford, Mesa and the like?

I'm not saying that we'll see less viscous oils in everything built tomorrow or the next day, but there coming. And I very, very, rarely if ever recommend to anyone to run anything less viscous than what the manufacturer recommends. (I believe Gary will vouch for me on this.) I've seen some of the testing the manufacturers have done, and they do have a clue.

We may be just misunderstanding each other on a few points, but one thing I dislike is when someone drops a bomb here and scares the bejesus out of people with an undocumented failure. One guy here was almost talked into returning 80 qts of M1 because he had a few more ppm of Fe in his UOA. That's irresponsible in my book.
 
Yes, 427Z06 doesn't stray too far from the OEM spec party line. It can appear otherwise since he's often compelled to discount the shear numbers of "heavier is better" theoryists. This is often misread. He's also, as he stated, quick to define fact from conjecture and opinion. He has this disposition whether it's oil filters, oil, ..or whatever. I've been called to task to prove something that I've asserted several times. He places no hammer before its time. (feeling the need to recite some line like, "You kin run ..but you kenna hide."
grin.gif
)

If you've got a notion/impression/intuition/opinion ..just state it as so. There are thousands of people relying on this site for information. It should be as "unvarnished" as possible.
 
Status
Not open for further replies.
Back
Top