School me in the ways of intaking fuel and air...

Cool deal..The mighty Justy lives! Better not brag too much CARS Tech Genies might put back the min weight rule and you'll go broke just buying the 1200 lbs of lead.

---

John Vanlandingham
Sleezattle, WA, USA

Vive le Prole-le-ralliat

www.rallyrace.net/jvab
CALL +1 206 431-9696
Remember! Pacific Standard Time
is 3 hours behind Eastern Standard Time.

Exhale, take a shot of your favorite vodka, inhale, bite a pickle.

So next question...

"back in the day" we ran junk yard motors till they blew... which was generally after 1-2 rallies. They started with low oil pressure and ended with none... I always ran 20w50.

Now I have a motor that makes 50lbs at start up idle and drops to just around 40 on 10w40 (factory spec'd weight). I haven't had time or the place to flog it much yet.

Should I start out with 10w40 or move straight to 20w50 off the bat?

Thoughts?

Also I have two thoughts on where to mount the oil cooler...

One is probably typical, in front of the rad, but it is a long run for hoses, and I'm worried about pumping loss over that long run with the tiny pump. Seen here:



The other (where I'm leaning) is in the engine bay, with added louvers in the hood to vent and force air through. Shorter run, and more out of the way of damage should we do something stupid... and wouldn't hood louvers just scream "real rally car" Seen here:



I would put it in the open spot in front of the header, but there really isn't much clearance there, plus the heat from the header...

Thoughts?



Edited 1 time(s). Last edit at 11/18/2013 12:13AM by Mad Matt F.

it wouldn't be a subaru without some sort of hood scoop....

Thoughts...

Forget the oil cooler for now. You won't need it for Tall Pines, and it looks like you've got lots of other stuff to do in the next 10 days. Figure out the oil cooler for the summer rallies...

10w40.

-Martin.

Martin,

I've kinda been leaning that way... and now seeing the high is -1C. Finding some snows seems more the issue.

the car is further along then those pics! Could be on stage tomorrow if needed!

Quote
Mad Matt F
So next question...

"back in the day" we ran junk yard motors till they blew... which was generally after 1-2 rallies. They started with low oil pressure and ended with none... I always ran 20w50.

Now I have a motor that makes 50lbs at start up idle and drops to just around 40 on 10w40 (factory spec'd weight). I haven't had time or the place to flog it much yet.

Should I start out with 10w40 or move straight to 20w50 off the bat?

Why do you want to run 20/50 oil on a stock motor? Its not going to do much aside from showing higher oil pressures on the gauge. I don't know what the bearing clearance is on those motors but it might not be an adequate oil to flow fast enough through the bearings to remove heat efficiently.

I'm sure John will have a good word or two to add to this but I would stick to the factory recommendations unless the engine was rebuilt with looser tolerances.

If you put in a quality 10w40 oil it will be fine. You probably would run thicker oils back in the day because of shearing. By the end of the race, due to loads the oil would be much thinner than 50 weight. However, modern synthetics hold their weight very well, just look at the reports by Bob is the oil guy people, after thousands of miles with track days oils are still close to specs. With thicker oil you get more parasitic losses and potentially more foaming which are not good.

Klim

Quote
mulik52
If you put in a quality 10w40 oil it will be fine. You probably would run thicker oils back in the day because of shearing. By the end of the race, due to loads the oil would be much thinner than 50 weight. However, modern synthetics hold their weight very well, just look at the reports by Bob is the oil guy people, after thousands of miles with track days oils are still close to specs. With thicker oil you get more parasitic losses and potentially more foaming which are not good.

Klim

"Bobtheoilguy" is the epitome of intra-net assertion over fact.
99.9% is just people saying "I haven't see a problem with......."

the thickness thing doesn't hold if you understand what the first number means. It means it pours like a 20W or a 15W at low temps---then thickens UP as temp rises---little microscopic polymers swell up and maintain the viscosity at higher temps.

Internal clearances haven't changed---an obvious fact for those who build engines... What has driven this thinner and thinner first number is/was the gas guzzler tax and the "Corporate Average Fuel Economy" standards which means the average of what all the cars a company sells get for MPG.
Lower the CAFE number by thinner oil or giving away thousands of little shit-box econo cars and they can sell more big high profit pig-cars.

Some added on systems like variable cam systems ARE designed for thin oils, but rod and main and cam journals, cylinder wall to piston clearances are as they have been since the 1960s.

Like everything else, horses for courses.
Was Matt puttering down to Tim Hortons for another Family Pack of Tim's best, then sure whatever for oil...

I think with a tiny little motor he will be driving with a huge size 14 shoe smashing the pedal thru thin tin-foil of the floor---constant max rpm...
That means more heat. That means maybe he should think about elevated temps the oil will need to cope with..

Rally on gravel is slightly different than ordinary street driving (for most people).

---

John Vanlandingham
Sleezattle, WA, USA

Vive le Prole-le-ralliat

www.rallyrace.net/jvab
CALL +1 206 431-9696
Remember! Pacific Standard Time
is 3 hours behind Eastern Standard Time.

My thinking was based on the 50 vs 40 as the high temp viscosity number, as that is the number which would be of concern for racing. You are right that the first number is of no concerns here. My understanding is that the multigrade oils are made out hydrocarbons which attain a compact structure at low temps. At high temps this structure unfolds, yielding a bulkier hydrocarbon chain, which in essence means thicker oil. The point I was making is that at high temps/loads over time you will actually shear the hydrocarbons, breaking them into shorter chains. This will reduce your hot weight number, making for example a 50 weight oil a 25 weight in actuality. But from the reports (not opinions), as can be seen here for example: http://www.bobistheoilguy.com/forums/ubbthreads.php?ubb=showflat&Number=2774647

Modern good oils don't shear that bad, as can be seen in the above example, where the lad claims a number of track days on the oil and the viscosity is still within spec. Therefore I think one should be fine with a good 40 weight oil, and there is no need to change to a thicker oil unless that's what is called for by the manufacturer. But again, that's just my opinion.

Klim

The oil doesn't get thicker, it just loses viscosity less.

20W50 - 20 means the oil flows at (0c?) the same as a 20 straight weight at that temp. 50 means the oil flows at (100c?) the same as 50 straight weight at that temp.

Different scales.

0W60 is very close to not losing any viscosity at all with heat. Probably why BMW likes it so much.

---

Pete Remner
Cleveland, Ohio

1984 RX-7 (rallycross thing)
1978
Silence is golden, but duct tape is silver.

Quote
Pete
The oil doesn't get thicker, it just loses viscosity less.

20W50 - 20 means the oil flows at (0c?) the same as a 20 straight weight at that temp. 50 means the oil flows at (100c?) the same as 50 straight weight at that temp.

Different scales.

0W60 is very close to not losing any viscosity at all with heat. Probably why BMW likes it so much.

So solly round eye, Rallyanarchista "Seattle Scott" Koch and Nude Hampsteroid Graham "Graminal Cullen and his dear diddie Barry cullen are all smart chemical Injur-nears and took the time to splain to me'es about the polymers 9fricking plastic shavings!) that are the Viscosity Index Improvers..

Here read dis:

Quote

Thickeners & Viscosity Index Improvers

Thickeners and viscosity index improvers are polymeric, (nice word for plastics) and are added to lubricants to reduce the degree of change in viscosity seen at high and low temperatures.

Mineral oil lubricants become less effective at high temperatures because heat reduces their viscosity and film-forming ability. The traditional solution to this problem was to make seasonal oil changes in some applications. With the advent of viscosity improvers, that’s no longer necessary or desirable.

When viscosity improvers are added to low viscosity oils, they effectively thicken the oil as temperature increases. This means that the lubricating effect of mineral oils can be extended across a wider temperature range.

When creating a viscosity improver, a balance between the thickening efficiency and shear stability of the polymer is important. Higher molecular weight polymers make better thickeners, but tend to have less resistance to mechanical shear. Lower molecular weight polymers are more shear resistant, but do not improve viscosity as effectively at higher temperatures and have to be used in larger quantities.

Polymer additives can also undergo thermal and oxidative degradation, unzipping back to smaller monomers, which reduces their effect. The highest possible degree of thermal and oxidative stability is desirable in addition to the features above.

Afton’s family of viscosity improvers is primarily used in multigrade engine oils, gear oils, automatic transmission fluids, power steering fluids, greases, and some hydraulic fluids.

---

John Vanlandingham
Sleezattle, WA, USA

Vive le Prole-le-ralliat

www.rallyrace.net/jvab
CALL +1 206 431-9696
Remember! Pacific Standard Time
is 3 hours behind Eastern Standard Time.

Does "effectively thicken" mean the same thing as "thicken"?

Is this specific to mineral oils? And does the same hold true for synthetic?

-Martin.

This is true for synthetic and mineral oils. That's why some argue that getting the oil where the numbers are close to each other is better (like 15w-40 rotella), because 15w40 is 15 weight oil with additive added to make it 40 weight at high temp, and 0w60 is 0 weight oil with additive added to make it 60 at high temp.

Klim