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turbogrill

No overheat, still get oil cooler for race car?

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turbogrill    0

Hi,

 

I do 8 hour non stop racing with my 280zx. I change synthetic oil and filter after every 8 hour race session.

 

I am curious if I should get an oil cooler or not for my 280zx race car. I never have overheating problems or even close to overheating. So far the cooling system has been impeccable. I race in Texas where 100F is not unusual. 

It's a stockish 2.8 NA.

 

Does it only makes sense to add an oil cooler if the temps are getting high? Or is it always good to have one?

 

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PseudoSport    0

I've been racing 24 hours of Lemons with my 280Z. The cooling system has been great but we have noticed oil pressure dropping at higher RPMS a few hours into the race. We're running 15w40 but i'm thinking the oil is getting too hot and thinning out. Changing the oil after the first days helps with pressure but I plan on installing an oil cooler for our next race to see if that helps. Figure it can't hurt. We also have six 14 hour races on the bone stock engine and its been holding together ok. 

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turbogrill    0
Posted (edited)

We do chump and Lemons on a stockish engine. Adding an oil cooler is one more thing that can fail so would be great if it could be avoided!

We are running 10w30.

 

Our engine is finally starting to give up after 5x16 hours of racing on a junkyard engine. Haven't done anything besides oil changes.

A few races ago we run the engine without any coolant for about 45mins. Oil was squirting out of the dipstick. This caused low compression on 2 cylinders, but it survived more races after that.

 

Who runs a jeep in autocross???

Edited by turbogrill

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Leon    35

10W30 is to thin for the old L28. I've ran 10W40 and my stock L28 smoked a bit with that. I've switched to 20W50 and it stopped smoking.

These engines aren't made for that thin oil.

 

My 260Z FSM specifies anything from a 5W-30 to a 20W-40 depending on climate. I'd argue that 20W-50 is actually too thick and you can go as thin as 5W-30 which I would not hesitate to use in my motor.

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Chickenman    4

5w-30 oil 40 years ago had a lot of ZDDP in it. Modern 5w-30 contains very little. ZDDP is essential for bucket type lifters or sliding finger followers. You may or may not get away with certain low ZDDP oils on a stock Z engine. Depends on the oil. But in a Race Car or a Weekend Warrior,  with stiffer valve springs and a high lift , it can result in rapid destruction of the Cam lobes. We see it all the time on Audi VW forums and those engines have a lot less spring pressure and valve lift ( 5 valves per cylinder, 6 mm Diameter valve stems ) than an L-seriers. 

 

Anything that is Energy Star rated is low content ZDDP. Thicker oils such as 20w-50, 15w-50, 10w-40 and Diesel oils are not Energy Star rated and usually contain sufficient percentages of ZDDP . It's all buyer beware and you have to really research oils these days for use in Vintage cars, Hot Rods or modified engines. 

 

5w-30 was a recommended weight for Cold climates, but it is certainlt too thin for a southern States climate. These engines ar older designs with larger bearing clerances than a car fom the Mid 90's and up. Things change in 40 yaers. 

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Leon    35
Posted (edited)

5w-30 oil 40 years ago had a lot of ZDDP in it. Modern 5w-30 contains very little. ZDDP is essential for bucket type lifters or sliding finger followers. You may or may not get away with certain low ZDDP oils on a stock Z engine. Depends on the oil. But in a Race Car or a Weekend Warrior,  with stiffer valve springs and a high lift , it can result in rapid destruction of the Cam lobes. We see it all the time on Audi VW forums and those engines have a lot less spring pressure and valve lift ( 5 valves per cylinder, 6 mm Diameter valve stems ) than an L-seriers. 

 

Anything that is Energy Star rated is low content ZDDP. Thicker oils such as 20w-50, 15w-50, 10w-40 and Diesel oils are not Energy Star rated and usually contain sufficient percentages of ZDDP . It's all buyer beware and you have to really research oils these days for use in Vintage cars, Hot Rods or modified engines. 

 

5w-30 was a recommended weight for Cold climates, but it is certainlt too thin for a southern States climate. These engines ar older designs with larger bearing clerances than a car fom the Mid 90's and up. Things change in 40 yaers. 

 

L-series bearing clearances are really not much different from modern engines, I'm genuinely curious where you got that idea? Here's a comparison, based on some FSMs I had on hand:

 

1978 Datsun 280Z - Standard

 

Rod clearances: 0.0010"-0.0022"

Main clearances: 0.0008"-0.0028"

 

2003 Honda S2000 - Standard

 

Rod clearances: 0.0012"-0.0021"

Main clearances: 0.0007"-0.0016"

 

The 280Z actually has a tighter nominal rod bearing clearance than an S2000!

 

 

I also don't buy the ZDDP myth. I ran my last 260Z on Mobil1 10W-30 synthetic without issue and it's still running strong today under its current owner. FWIW, my first try at a hot L28 wiped its cam, using Brad Penn break-in oil...
 
Take a look at this site, it's a long read and the guy is a bit much at times but some interesting quantitative data can be gleaned from his testing (and hints at why I may have wiped that cam...): https://540ratblog.wordpress.com/2013/06/20/motor-oil-wear-test-ranking/
Edited by Leon

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Chickenman    4
Posted (edited)

Where did I get that idea? From decades of reading Race engine building articles by David Vizard, Race Car engineering, and Race Engine Tech, SAE white papers and following OEM engine design changes and understanding the trends. Engines have been running tighter and tighter tolerances for the last 20 years or more in an effort to reduce emissions and improve fuel economy by using thinner and thinner oils. 0w-20 oils are now quite common in modern engines. But don't think for an instant that you could use that thin of a weight in a 40 or 50 year old design. 

 

 

BTW, Well aware of that guys ramblings. The guy contradicts himself many times over. There is no ZDDP " myth ". It's a fact and well documented.  High performance engine builders who work with Flat Tappet engines  have known about the issue for well over 10 - 15 years. You can not compare stock valve trains to high performance valve trains. Apples to oranges. 

 

Maximum allowable main clearance of .0028" on L-series is almost double that of S2000 at .0016. How can you say that is almost the same?  Journal size and bearing width also play a big part. As does crank finish and crank stiffness. An L-6 is hardly a stiff crankshaft, even with 7 main bearing.

 

And a Honda S2000 is built a little looser compared to some other Honda engines, because it is built to run very high RPM's.  ( 9,500 )

 

Here is just one example of a more pedestrian engine built by Honda. And this was a mid-1990's Vintage. 

 

Honda D15B7 clearances:

 

main bearing clearance
No. 1,5 journals: 0.018-0.036mm (0.0007-0.0014in)
No. 2,3,4 journals: 0.024-0.042mm (0.0009-0.0017in)
service limit 0.05mm (0.002in)


connecting rod bearing clearance

0.020-0.038mm (0.0008-0.0015in)
service limit 0.05mm (0.002in)  

 

Here's some data from a real Engine Building site on bearing clearances. It's a very good read. 

 

http://www.enginebuildermag.com/2017/06/dissecting-duramax-getting-inside-six-generations-gms-6-6l-diesel-dominator/

 

And the biggest differences in modern engines is the  machining Tolerances they are built to these days. Modern Robotics, CNC machining and Laser measuring ensures that modern production tolerances are dead nuts on. Every time. Something that could not be achieved as accurately or repeatably on the assembly lines back in the 60's and 70's. The tooling just did not exist. 

Edited by Chickenman

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Leon    35

You can't deny that S2000 rod clearances are looser nominally than 280Z clearances. That puts that argument to bed. Just trying to say that things aren't as different as you're painting them to be, with regards to using a 10W-30 oil in an L-series.

 

I'd be more than happy to switch to a 5W-30 synthetic modern oil on my .540" lift cam L28 to see about the "rapid destruction of the Cam lobes".

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Chickenman    4
Posted (edited)

 

 

That puts that argument to bed. Just trying to say that things aren't as different as you're painting them to be, with regards to using a 10W-30 oil in an L-series.

 

 

Never said 10w-30 was too thin for an L-series. I was responding to your statement:

 

 

 

I'd argue that 20W-50 is actually too thick and you can go as thin as 5W-30 which I would not hesitate to use in my motor.

 

I was responding to that particular statement, which is a pretty wide generalization and could get people in trouble. Particularly given that this post started out as a discussion about Road Racing engines in Enduro's with no oil coolers.

 

You can get 5w-30 Synthetic Motor oils that are perfectly adequate for High Performance engines. Never said you couldn't And just about every one will be a special formulation with extra ZDDP and you'd be wise to choose a full Ester oil. It's just that MOST 5w-30 weight oils, especially the big store brands are all Energy Star ( SM and SN ) rated and those are the ones you have to be careful of with increased Valve pressures. . The SM and SN ratings go hand in hand with reduced ZDDP levels.

 

It's not as simple anymore as choosing between what brand you preferred back in the 70's through 90's .( I was a Pennzoil man ) I thought I made that  clear with this sentence in Post #8 .

 

 

 

It's all buyer beware and you have to really research oils these days for use in Vintage cars, Hot Rods or modified engines. 

 

Any how, interesting but we're both have our opinions and we're just flogging a dead horse. Carry on...

Edited by Chickenman

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Chickenman    4

 

I'd be more than happy to switch to a 5W-30 synthetic modern oil on my .540" lift cam L28 to see about the "rapid destruction of the Cam lobes".

 

 

And as you're a smart man, I'm willing to bet that you would put considerable thought and research into what you bought. And not just buy the first " Synthetic " you see on sale at AutoZone or Walmart beermug.gif

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Leon    35

And as you're a smart man, I'm willing to bet that you would put considerable thought and research into what you bought. And not just buy the first " Synthetic " you see on sale at AutoZone or Walmart beermug.gif

 

Correct. And I also wouldn't have any qualms of it being 5W-30 nor whether it has extra ZDDP... ;)

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