Does Oil Pooling in the Heads Cool the Valves?
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From: SoCal
Does Oil Pooling in the Heads Cool the Valves? Does the pooling of oil in the heads help to cool the valve springs? Is the pooling intentional, or simply a result of design constraints? I have seen head designs with external oil drain backs, but was wondering if that would put the valve springs at risk? I know NASCAR motors use spray (bars) to cool valve springs, but that is a severe duty application with a dry sump configuration.
Thanks,
Andy1
Thanks,
Andy1
Last edited by Andy1; May 22, 2012 at 06:37 PM. Reason: Misleading title
On The Tree
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From: Keller, TX
Not really... because you need a constant flow of oil to the valve springs. A couple of methods are effective at this; spring oiling via the rocker like T&D uses or independent spring oiling as you mentioned, via plumbing the rocker cover.
I use a T&D setup on my endurance engine for this very reason. Seems to increase spring life considerably.
As far as drain-back is concerned... what is "excessive pooling"? Some pooling is always evident but you want good drain-back characteristics throughout the block; head and lifter valley.
I use a T&D setup on my endurance engine for this very reason. Seems to increase spring life considerably.
As far as drain-back is concerned... what is "excessive pooling"? Some pooling is always evident but you want good drain-back characteristics throughout the block; head and lifter valley.
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From: SoCal
Melkor, you last paragraph ("but you want good drain-back characteristics" ) touched upon the underlying reason for my pooling question. There's a lot of discussion over on the Roadracing forum regarding bearing failures due to lack of oiling. The predominant opinion is that oil is getting trapped in the heads during long sweeping corners and starving the pan of oil. Some manner of improving oil drain back may perhaps be a solution (though I doubt that's the only singular one). So if one were to employ external oil drain backs, would the springs and/or vavle stems suffer as a result?
Thanks,
Andy1
Thanks,
Andy1
On The Tree
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From: Keller, TX
A few questions....
Which block are you running?
Any oil restrictors?
HV oil pump?
Any street duty?
Vacuum pump??
And thanks on the compliment. I actually considered the GT40 MkI, and went around debating "MkI or Daytona" for months before pulling the trigger. I'm glad I went with the Daytona though... it's really a quality kit and the car is an amazing drive. I'd take it any day over a new GT...
Which block are you running?
Any oil restrictors?
HV oil pump?
Any street duty?
Vacuum pump??
And thanks on the compliment. I actually considered the GT40 MkI, and went around debating "MkI or Daytona" for months before pulling the trigger. I'm glad I went with the Daytona though... it's really a quality kit and the car is an amazing drive. I'd take it any day over a new GT...
Thread Starter
TECH Resident
Joined: May 2004
Posts: 792
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From: SoCal
A few questions....
Which block are you running?
Any oil restrictors?
HV oil pump?
Any street duty?
Vacuum pump??
And thanks on the compliment. I actually considered the GT40 MkI, and went around debating "MkI or Daytona" for months before pulling the trigger. I'm glad I went with the Daytona though... it's really a quality kit and the car is an amazing drive. I'd take it any day over a new GT...
Which block are you running?
Any oil restrictors?
HV oil pump?
Any street duty?
Vacuum pump??
And thanks on the compliment. I actually considered the GT40 MkI, and went around debating "MkI or Daytona" for months before pulling the trigger. I'm glad I went with the Daytona though... it's really a quality kit and the car is an amazing drive. I'd take it any day over a new GT...
Of course a full on track car would employ the use of a dry sump system, it seems that anything short of that for HPDE's/track days puts the motor at risk. The Corvette forums are full of bearing failure/oil starvation stories; some of those guys have had engine failures within minutes on the track. At the risk of being long-winded, I thought that adding external oil drain backs might be one step towards helping to resolve the oil pooling issue without significant cost. Years ago, my buddy with a F5000 Lola added drain backs to his left side SBC valve cover due to the predominance of high speed long right hand sweepers at Willow Springs; it worked out very well, hence my thoughts.
BTW, my buddy has a 914/383 SBC/930 caged track car (with license plates) that I've been helping out to get the handling sorted. His SBC has a roadrace pan and Accusump (no dry sump). He has no oiling issues.
Andy1
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"Flooding" the valve covers does indeed provide cooling for the valve springs and is typically used in high endurance/ high rpm situations. The cylinder heads are usually modified to allow flooding and several types of "drain back" routes can be implemented. You will also have to increase oil volume in the sump to allow for the extra oil in the valve cover and modify breathers on a wet sump system. Spring spayers are used as a more user friendly setup although they have limitations for the professional racers like NASCAR.
For the LS engine racer a good set of "oiler" valve covers are a great choice. There are a couple of manufactures making these in billet covers and sheet metal covers. The billet covers allow for adjustment of how much oil you want spray on the springs by changing the individual sprayer jets.
And yes, keeping the springs cool is a major factor in durability of the springs of a race engine.
For the LS engine racer a good set of "oiler" valve covers are a great choice. There are a couple of manufactures making these in billet covers and sheet metal covers. The billet covers allow for adjustment of how much oil you want spray on the springs by changing the individual sprayer jets.
And yes, keeping the springs cool is a major factor in durability of the springs of a race engine.
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On The Tree
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From: Keller, TX
The idea behind spring oilers is heat transfer via oil flow... flow being the key word here. Pooling implies a lack of drain back, and that's not as good for cooling as a targeted spray of oil in critical areas, with good drain back characteristics.
I'm not sure, but these blocks probably have priority main oiling, so starvation at critical bearing surfaces shouldn't be an issue unless some type of restrictor is installed. I agree that the oil pan capacity should be increased, and with that, all the typical oil control items; windage screen, scraper, etc.. You restrict some oil to the valvetrain with a smaller diameter oiling hole via the pushrod. Smith Brothers and others make some, but in most cases I don't feel it's necessary, so long as there is adequate pan capacity and a HV pump isn't being used. They're simply not necessary and haven't been for some time.
There are also plenty of porting epoxies that will live fine in/on a cylinder head, and you can shape flowback areas within the rocker valley in that way too. Seen many guys do this on older sbc's. That and/or the typical opening/radiusing of flowback passages.
I'm not sure, but these blocks probably have priority main oiling, so starvation at critical bearing surfaces shouldn't be an issue unless some type of restrictor is installed. I agree that the oil pan capacity should be increased, and with that, all the typical oil control items; windage screen, scraper, etc.. You restrict some oil to the valvetrain with a smaller diameter oiling hole via the pushrod. Smith Brothers and others make some, but in most cases I don't feel it's necessary, so long as there is adequate pan capacity and a HV pump isn't being used. They're simply not necessary and haven't been for some time.
There are also plenty of porting epoxies that will live fine in/on a cylinder head, and you can shape flowback areas within the rocker valley in that way too. Seen many guys do this on older sbc's. That and/or the typical opening/radiusing of flowback passages.
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There is always oil being exchanged in the valve covers via the pushrods at all times (oil flow). That is why it is prefferable not to restrict oil to the rocker arms through the pushrods. Also, on that note, the oil going through the pushrods lubricates and cools the pushrod cup in the rocker arm and pushrod tip/end.
Spring sprayers also just spray at one general spot on the spring and do not give full coverage at maximum cooling capability like flooding the valve covers in race applications. Although most anything less then the profession top series don't need flooded valve covers and sprayers are more then adequate.
Something I forgot to mention is that the pro's that flood the covers typically have a metered source of oil flow as well in addition to the pushrods. Some just use oiler valve covers for the extra oil supply, some pipe in an external line to head somewhere as the oil only needs to get in there. There is enough valve/rocker action to fully distribute fresh oil through out the cover with no temp differential in any one location. Some engines, like the Chevy R07 have pressurized oil galleys through the block into each cylinder head. This was specifically done to eliminate the need for an external oil source.
Anyway, just thought all that should be mentioned
Spring sprayers also just spray at one general spot on the spring and do not give full coverage at maximum cooling capability like flooding the valve covers in race applications. Although most anything less then the profession top series don't need flooded valve covers and sprayers are more then adequate.
Something I forgot to mention is that the pro's that flood the covers typically have a metered source of oil flow as well in addition to the pushrods. Some just use oiler valve covers for the extra oil supply, some pipe in an external line to head somewhere as the oil only needs to get in there. There is enough valve/rocker action to fully distribute fresh oil through out the cover with no temp differential in any one location. Some engines, like the Chevy R07 have pressurized oil galleys through the block into each cylinder head. This was specifically done to eliminate the need for an external oil source.
Anyway, just thought all that should be mentioned
Thread Starter
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From: SoCal
Mell00,
The road course guys are losing engines from bearing failures that most speculate is due to oil filling up in the heads and starving the pan of oil. Drain back seems to be the culprit, and as such, I was wondering if some form of external drain back system might help resolve this problem. I am of course concerned about the downside such as draining too much of that oil and possibly compromising the springs, ergo my original question regarding pooling and cooling. See post #6 for the reason why I'm asking the question.
Thanks,
Andy1
The road course guys are losing engines from bearing failures that most speculate is due to oil filling up in the heads and starving the pan of oil. Drain back seems to be the culprit, and as such, I was wondering if some form of external drain back system might help resolve this problem. I am of course concerned about the downside such as draining too much of that oil and possibly compromising the springs, ergo my original question regarding pooling and cooling. See post #6 for the reason why I'm asking the question.
Thanks,
Andy1
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Andy, understood.
Its obvoiusly difficult to check how much oil would be in the heads while racing but adding extra oil would still be an option. Oval track racers with stock type oil pans do this regularly. Its a bit of trial and error to get the amount right but bearing issues , if caused by starvation, are solved. Of coarse external drain backs will help empty the cover but the pushrod oiling is probably still adequate for what you are doing. If draining the covers causes inadeqaute spring cooling you be at least able to monitor the springs on a regular basis before serious issue.
Its obvoiusly difficult to check how much oil would be in the heads while racing but adding extra oil would still be an option. Oval track racers with stock type oil pans do this regularly. Its a bit of trial and error to get the amount right but bearing issues , if caused by starvation, are solved. Of coarse external drain backs will help empty the cover but the pushrod oiling is probably still adequate for what you are doing. If draining the covers causes inadeqaute spring cooling you be at least able to monitor the springs on a regular basis before serious issue.
On The Tree
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From: Keller, TX
FWIW,
I ran Manton restricted (.060 orifice) pushrods in another race endurance engine with T&D shafts and spring oilers.. never a single issue. Oil flow was still good at the top end. I wouldn't run them on the street, but there's not much difference in restricting the oil galleries and running a restricted pushrod. So long as you're running oilers, I don't know anyone yet who's had a problem with them in a race engine.
I ran Manton restricted (.060 orifice) pushrods in another race endurance engine with T&D shafts and spring oilers.. never a single issue. Oil flow was still good at the top end. I wouldn't run them on the street, but there's not much difference in restricting the oil galleries and running a restricted pushrod. So long as you're running oilers, I don't know anyone yet who's had a problem with them in a race engine.
On The Tree
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From: Keller, TX
Thanks for the info Kevin. I'm certainly not as 'up' on the new blocks as I probably should be.
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From: SoCal
I just watched an episode of GEARZ where they visited a NASCAR race team showing the Chevy NASCAR motor. When describing the top end oiling, they did mention that "in some series" they do intentionally fill the head with oil so that the valve springs are completely immersed to keep them cool. This is of course using a dry sump oiling system.
Andy1
Andy1
