[Dragncar]

Its Pro Stock where every single bit of power can make a difference. You will make more power with super thin oil.

[Tim Corcoran]

Originally Posted by Dragncar

Its Pro Stock where every single bit of power can make a difference. You will make more power with super thin oil.

Like mentioned above, Pro Stock is grabbing every bit of power they can and will
even sacrifice durability of the engine to win races.

[Dragncar]

Originally Posted by Tim Corcoran

Like mentioned above, Pro Stock is grabbing every bit of power they can and will
even sacrifice durability of the engine to win races.

I think its also a reason why new cars all get super thin oil. To bring CAFE numbers up on a whole fleet.
My Tundra says 0-30 05 5-30 WT oil under the hood.
It has always gotten 10-30 from me.
I want protection first.

[Elarson]

I haven't found exact current data but apparently NHRA PS mains are about 2.300. That means they create less heat and parasitic drag than a Pontiac 3.00 or 3.25 but have less load carrying capacity and therefore are more difficult to maintain the hydrodynamic wedge. And they survive with 0W-5 oil.

We ran the Grocery Getter for 17 years with 3.00 mains and 10w-30 oil at 1500 hp and never failed or wore out a main or rod bearing. No traces of a failed hydrodynamic wedge.

So that's (2) pieces of actual data.

Eric

[Dragncar]

The 461 is getting 10-30. Going to have to, its 90lbs with a drill and 30 WT with a qt of Lucas. So I will be watching oil pressure closely.
We will see when the oil pressure settles in at hot.

[PunchT37]

How much pressure are we running in these high rpm/ hp engine examples?

[Elarson]

Originally Posted by PunchT37

How much pressure are we running in these high rpm/ hp engine examples?

Grocery Getter used a standard Melling 80 psi pump. Cold start-up and fast idle would be around 90 psi but as soon as it got a little heat in the oil, it would drop down below 80. No clue about NHRA PS but I'm sure it's as low as they can get away with. But with the super-thin oil, it doesn't take as much pressure to move a lot of oil flow. Which gets me back to the original point. High pressure isn't necessarily a good thing....it's a measure of resistance to flow.

But to be clear, if a guy is running 20w-50 oil and the bearings are happy, I'm not advocating a change.

Eric

[PunchT37]

Originally Posted by Elarson

Grocery Getter used a standard Melling 80 psi pump. Cold start-up and fast idle would be around 90 psi but as soon as it got a little heat in the oil, it would drop down below 80. No clue about NHRA PS but I'm sure it's as low as they can get away with. But with the super-thin oil, it doesn't take as much pressure to move a lot of oil flow. Which gets me back to the original point. High pressure isn't necessarily a good thing....it's a measure of resistance to flow.

But to be clear, if a guy is running 20w-50 oil and the bearings are happy, I'm not advocating a change.

Eric

Hot damn. At least you`re not forcing an opinion.

I`m out of the mechanic business now. I operate 2 water plants down here. We have pumps coming in, pumps in the middle, and high service pumps going out. And you`re right. Pressure is a measurement of head. Or, resistance to flow. These pumps use more power with 0 head vs 100 psi as they flow more water. Opposite to what most folks think.

[Elarson]

I make it a point to never force an opinion. I like to lay out the physics that are happening and then people can make their own judgment how that applies to what they're doing.

Interesting data from the water plant.

Eric

[P@blo]

Originally Posted by PunchT37

Hot damn. At least you`re not forcing an opinion.

I`m out of the mechanic business now. I operate 2 water plants down here. We have pumps coming in, pumps in the middle, and high service pumps going out. And you`re right. Pressure is a measurement of head. Or, resistance to flow. These pumps use more power with 0 head vs 100 psi as they flow more water. Opposite to what most folks think.

Vertical turbine pumps? I also operate water plants

[Jay S]

We built a 455 (was in the stock car in my Avatar photo) with .0025” rod clearance and .0035” mains clearance, mechanical cam with restricted lifter bores, it had a 80psi pump, remote oil filter with large lines, larger remote pickup welded to the bottom of a custom pan, with a 3 quart accumulator it had 12 quarts total system capacity (took awhile to warm the oil up). When it was started cold with 20w50 VR1, it would get to 115 psi and shear the key off the top timing gear. We dropped to a 15w40 and it made a couple hundred RPMs higher and did it again. But made it enough RPMs more that when it happened the next time it bent a bunch of valves. We pulled the engine and put in a 60 lbs spring from a used oil pump we had sitting in the shop. Then it worked perfectly with 60psi hot at idle, and about 80 psi hot with 20w50. That was with a new key in the same timing set that sheared the key twice and never had an issue after that. After having that happen, past 110 psi cold, I get nervous.

We will not run restricted lifter bores with the 80 psi spring anymore after that. Restricted pushrods would probably be ok. We have never had any issue with less than 110 lbs oil pressure no matter what the oil weight was, even straight 60 wt. I know of Pontiacs that have broke timing chains running big cams and a lot of RPMs and didn’t shear the key we sheared. Usually at the top end of the RPMs. But the oil pump made the key shear at about 2000 to 3000 rpm, apparently a much different stress than pulling the valve terrain at high rpms, basically the same RPM range as most peoples cruising RPMs on the street.

Oil pressure in the first post sounded good to me, I would run that for sure. 20w50 is probably overkill though. You should drop to 15w40 or 10w30 before you go clear down to a 5w30.

Modern stuff that runs 5W oil has a lot tighter clearances and the bearing journals are smaller also. If you had your engine designed for 5 w oil or your racing and going for it, that it totally different.

[PunchT37]

Originally Posted by P@blo

Vertical turbine pumps? I also operate water plants

Yep. Mostly. Few positive displace for chemical.

[Kenth]

Originally Posted by Jay S

We built a 455 (was in the stock car in my Avatar photo) with .0025” rod clearance and .0035” mains clearance, mechanical cam with restricted lifter bores, it had a 80psi pump, remote oil filter with large lines, larger remote pickup welded to the bottom of a custom pan, with a 3 quart accumulator it had 12 quarts total system capacity (took awhile to warm the oil up). When it was started cold with 20w50 VR1, it would get to 115 psi and shear the key off the top timing gear. We dropped to a 15w40 and it made a couple hundred RPMs higher and did it again. But made it enough RPMs more that when it happened the next time it bent a bunch of valves. We pulled the engine and put in a 60 lbs spring from a used oil pump we had sitting in the shop. Then it worked perfectly with 60psi hot at idle, and about 80 psi hot with 20w50. That was with a new key in the same timing set that sheared the key twice and never had an issue after that. After having that happen, past 110 psi cold, I get nervous.

We will not run restricted lifter bores with the 80 psi spring anymore after that. Restricted pushrods would probably be ok. We have never had any issue with less than 110 lbs oil pressure no matter what the oil weight was, even straight 60 wt. I know of Pontiacs that have broke timing chains running big cams and a lot of RPMs and didn’t shear the key we sheared. Usually at the top end of the RPMs. But the oil pump made the key shear at about 2000 to 3000 rpm, apparently a much different stress than pulling the valve terrain at high rpms, basically the same RPM range as most peoples cruising RPMs on the street.

Oil pressure in the first post sounded good to me, I would run that for sure. 20w50 is probably overkill though. You should drop to 15w40 or 10w30 before you go clear down to a 5w30.

Modern stuff that runs 5W oil has a lot tighter clearances and the bearing journals are smaller also. If you had your engine designed for 5 w oil or your racing and going for it, that it totally different.

5W means the cold engine viscosity (Winter) and 30 is the hot engine viscosity.
NO difference in viscosity using 5W30 or 10W30 while driving the engine at normal running temperature. 5W will flow to the lubrication points faster than 10W at cold starts though.

FWIW

[Tim Corcoran]

The oli system is an important part of the cooling system. If you run too high viscosity your pressure might be great but you might not be getting enough flow to cool the rod bearings and the back side of the pistons. Thicker oil does improve the protection of the rods and mains but there is a point of diminishing returns if they are getting too hot from a lack of flow. One of the reasons for larger bearing tolerance and thicker oil for a race engine. Many people build a street engine with factory bearing tolerance then run 15/40 or 10/40 oil and this is a mistake.

[Jay S]

Originally Posted by Kenth

5W means the cold engine viscosity (Winter) and 30 is the hot engine viscosity.
NO difference in viscosity using 5W30 or 10W30 while driving the engine at normal running temperature. 5W will flow to the lubrication points faster than 10W at cold starts though.

FWIW

5w is a really big step from the 20w cold it has been running. That was why I mentioned the 10w oils. If it isn’t ran in sub zero temps, no reason I can think of to run 5w30, 10w30 plenty thin.

[PunchT37]

Originally Posted by Tim Corcoran

The oli system is an important part of the cooling system. If you run too high viscosity your pressure might be great but you might not be getting enough flow to cool the rod bearings and the back side of the pistons. Thicker oil does improve the protection of the rods and mains but there is a point of diminishing returns if they are getting too hot from a lack of flow. One of the reasons for larger bearing tolerance and thicker oil for a race engine. Many people build a street engine with factory bearing tolerance then run 15/40 or 10/40 oil and this is a mistake.

Yep. Even too tight of a rod side clearance. The oil can`t get out fast enough to cool the bearings.

[Dragncar]

Originally Posted by Tim Corcoran

The oli system is an important part of the cooling system. If you run too high viscosity your pressure might be great but you might not be getting enough flow to cool the rod bearings and the back side of the pistons. Thicker oil does improve the protection of the rods and mains but there is a point of diminishing returns if they are getting too hot from a lack of flow. One of the reasons for larger bearing tolerance and thicker oil for a race engine. Many people build a street engine with factory bearing tolerance then run 15/40 or 10/40 oil and this is a mistake.

Way back in High School Auto Shop I had a great teacher. When we had test there was a question about the purpose of engine oil.
If you answered "lubrication" you got it wrong. "cooling" and you got it right.
Its obvious lubrication is a major part of what oil does. But he wanted it put into our young minds how important cooling was.

[Sirrotica]

Originally Posted by Dragncar

Way back in High School Auto Shop I had a great teacher. When we had test there was a question about the purpose of engine oil.
If you answered "lubrication" you got it wrong. "cooling" and you got it right.
Its obvious lubrication is a major part of what oil does. But he wanted it put into our young minds how important cooling was.

To add to your teachers obsession of using oil to cool, one of the best things you can do on Pontiacs in general, and especially large journal Pontiacs is an oil cooler if your running it more than 1/4 mile at a time. I've seen how much better reliability a large journal engine has when the oil isn't at it's upper temperature limits a good portion of the time. The other alternative is more frequent oil changes to get the oil exchanged for fresh oil.

The same oil in a SBC is no where near as stressed in upper RPM ranges as it is in a Pontiac, due the extra friction area of the cranks bearings. If you notice that almost all BBC engines in their trucks have oil coolers, they also have similar bearing area of a small journal Pontiac. Same goes for diesels in chevy trucks, most have oil coolers. Whenever your stressing the engine with large journals, an oil cooler is always going to help reliability with a near stock oil capacity. While some SBCs do have oil coolers when pressed into truck duty, many do not. HD usage, more than just pushing an automobile down the road at 60-70 MPH is going to generate more heat, and it has to go somewhere.

Someone said "engineers do stuff for a reason"............

[Dragncar]

My engine is filled and I bet a oil cooler would not be a bad idea.
I did not do the remote filter deal.
But I did run a K&P and they do double as a oil cooler of sorts.
Flow way more than a paper filter and they are compact.
Thats a good thing because with my new headers and mid plate the WIX 1049 I ran for years was not going to work. I would have to run the shorter filter.

[Tim Corcoran]

Originally Posted by Dragncar

My engine is filled and I bet a oil cooler would not be a bad idea.
I did not do the remote filter deal.
But I did run a K&P and they do double as a oil cooler of sorts.
Flow way more than a paper filter and they are compact.
Thats a good thing because with my new headers and mid plate the WIX 1049 I ran for years was not going to work. I would have to run the shorter filter.

This is very interesting, anyone else using one of these K&P filters?