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  1. #16
    Part of the furniture BasicQ's Avatar
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    Quote Originally Posted by powerabout View Post
    RLF, thanks for all that, I am still interested to know the relationship with the cooling mod and how it makes that issue go away?
    ( I would think most decks will bend as the bolts are on the outside, perhaps less bolt torque is the fix and oringed gasket?
    Lots of v8's have similar design.)
    I would pose this answer/ theory. The water pump sends the coolant from the front of the block to the rear of the block where the cross over slots are. It then enters the head and travels back to the manifold on to the thermostat. Although you would think that this is where the coolant is at it’s hottest, it would not be. As the coolant travels through the block, at 1/4, 1/2 and 3/4 along the block some of the water not yet fully heated crosses over to the head to help cool combustion chambers and then heads on back to the thermostat. The coolant that makes it to 7 and 8 cylinders is the hottest the coolant will get. When that coolant is making its way back to the thermostat it’s temperature is lowered slightly by the coolant coming through the block to head passages along the way, and it also slightly warms that same coolant resulting in a mean temp at the thermostat. The cooling of the front of the heads is also assisted by being in contact with the block below that has just received coolant at its coolest it would be from the radiator.
    This must have been more than adequate for the low power production 8-9:1 comp engines but modifying engines to produce more power means producing more heat. When producing more heat we up the capacity and cooling capabilities of our cooling system to reduce that mean temperature to a stable operating temperature. Why did I say mean? Because to reduce the engine making more power and therefore more heat operating temperature down to an acceptable temp that bigger radiator needs to supply the engine with a coolant of further reduced temperature than that of a standard radiator. Maintaining that mean coolant temperature may be through more extreme low and high coolant temperatures throughout the engine. If that were the case then the temperature of 7 and 8 cylinders difference from cylinders 1 and 2 would be greater. Overall and localized thermal expansion rates would vary to a larger degree front to back of the head and to a lesser degree the block.
    The water pump only displaces water from it, not receive. As we all know Smitty2 has used the water pump outlets that send water through the cabin heater core and on some engines through the manifold and then on to the thermostat housing. He is sending it to the back of the heads instead. The two outlets on the water pump are sending the cooler radiator coolant back to the rear of the engine to help equalize and reduce varied thermal expansion rates. I would hope this is the case because if it were traveling back to the pump then heated coolant is being sent back through the engine. This attempt at equalization of thermal expansion rates could well be what is preventing head gaskets failing in the cylinder 7/8 area in his situation and application.
    Last edited by BasicQ; 21-04-2020 at 08:59 PM.

  2. #17
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    Quote Originally Posted by BasicQ View Post
    I would pose this answer/ theory. The water pump sends the coolant from the front of the block to the rear of the block where the cross over slots are. It then enters the head and travels back to the manifold on to the thermostat. Although you would think that this is where the coolant is at it’s hottest, it would not be. As the coolant travels through the block, at 1/4, 1/2 and 3/4 along the block some of the water not yet fully heated crosses over to the head to help cool combustion chambers and then heads on back to the thermostat. The coolant that makes it to 7 and 8 cylinders is the hottest the coolant will get. When that coolant is making its way back to the thermostat it’s temperature is lowered slightly by the coolant coming through the block to head passages along the way, and it also slightly warms that same coolant resulting in a mean temp at the thermostat. The cooling of the front of the heads is also assisted by being in contact with the block below that has just received coolant at its coolest it would be from the radiator.
    This must have been more than adequate for the low power production 8-9:1 comp engines but modifying engines to produce more power means producing more heat. When producing more heat we up the capacity and cooling capabilities of our cooling system to reduce that mean temperature to a stable operating temperature. Why did I say mean? Because to reduce the engine making more power and therefore more heat operating temperature down to an acceptable temp that bigger radiator needs to supply the engine with a coolant of further reduced temperature than that of a standard radiator. Maintaining that mean coolant temperature may be through more extreme low and high coolant temperatures throughout the engine. If that were the case then the temperature of 7 and 8 cylinders difference from cylinders 1 and 2 would be greater. Overall and localized thermal expansion rates would vary to a larger degree front to back of the head and to a lesser degree the block.
    The water pump only displaces water from it, not receive. As we all know Smitty2 has used the water pump outlets that send water through the cabin heater core and on some engines through the manifold and then on to the thermostat housing. He is sending it to the back of the heads instead. The two outlets on the water pump are sending the cooler radiator coolant back to the rear of the engine to help equalize and reduce varied thermal expansion rates. I would hope this is the case because if it were traveling back to the pump then heated coolant is being sent back through the engine. This attempt at equalization of thermal expansion rates could well be what is preventing head gaskets failing in the cylinder 7/8 area in his situation and application.
    How do we know the different cylinder or head temps, I dont think we do we just measure as you say the mean once its done its weird route through the engine.
    The 304 got more holes in the deck on the exhaust side, I wonder if thats a solution for the older blocks but that would reduce the water flow to the rear.
    Race engines both rev harder and make more power, I wonder if its just the pump efficiency at high revs falling off/cavitation thats the issue?

    PS I think those 2 pipes on the pump are on the suction side of the pump not the pressure side?
    Last edited by powerabout; 22-04-2020 at 02:31 AM.

  3. #18
    Part of the furniture BasicQ's Avatar
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    Quote Originally Posted by powerabout View Post

    PS I think those 2 pipes on the pump are on the suction side of the pump not the pressure side?
    Shit you’re right, overthought it and got that important detail backwards and wrong! Back to the theory drawing board.
    Maybe it expedites the removal of some of the excessively heated coolant from that area.

  4. #19
    Do you ever leave? cava454's Avatar
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    Default .. don't think its the plug, need new engine

    Quote Originally Posted by BasicQ View Post
    I would pose this answer/ theory. The water pump sends the coolant from the front of the block to the rear of the block where the cross over slots are. It then enters the head and travels back to the manifold on to the thermostat. Although you would think that this is where the coolant is at it’s hottest, it would not be. As the coolant travels through the block, at 1/4, 1/2 and 3/4 along the block some of the water not yet fully heated crosses over to the head to help cool combustion chambers and then heads on back to the thermostat. The coolant that makes it to 7 and 8 cylinders is the hottest the coolant will get. When that coolant is making its way back to the thermostat it’s temperature is lowered slightly by the coolant coming through the block to head passages along the way, and it also slightly warms that same coolant resulting in a mean temp at the thermostat. The cooling of the front of the heads is also assisted by being in contact with the block below that has just received coolant at its coolest it would be from the radiator.
    This must have been more than adequate for the low power production 8-9:1 comp engines but modifying engines to produce more power means producing more heat. When producing more heat we up the capacity and cooling capabilities of our cooling system to reduce that mean temperature to a stable operating temperature. Why did I say mean? Because to reduce the engine making more power and therefore more heat operating temperature down to an acceptable temp that bigger radiator needs to supply the engine with a coolant of further reduced temperature than that of a standard radiator. Maintaining that mean coolant temperature may be through more extreme low and high coolant temperatures throughout the engine. If that were the case then the temperature of 7 and 8 cylinders difference from cylinders 1 and 2 would be greater. Overall and localized thermal expansion rates would vary to a larger degree front to back of the head and to a lesser degree the block.
    The water pump only displaces water from it, not receive. As we all know Smitty2 has used the water pump outlets that send water through the cabin heater core and on some engines through the manifold and then on to the thermostat housing. He is sending it to the back of the heads instead. The two outlets on the water pump are sending the cooler radiator coolant back to the rear of the engine to help equalize and reduce varied thermal expansion rates. I would hope this is the case because if it were traveling back to the pump then heated coolant is being sent back through the engine. This attempt at equalization of thermal expansion rates could well be what is preventing head gaskets failing in the cylinder 7/8 area in his situation and application.
    You got it ass about regards to flow.
    When t/stat opens the hot water exits the engine.

    Without the coolant loop. The hot water just sits in the back of the head with no where to go an begins to steam.

    With the loop, the entire engine is now circulating water. Rather then having hot spots.

    By connecting them to the water pump they are being sucked out and constantly flowing so to speak.

  5. #20
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    Quote Originally Posted by cava454 View Post
    You got it ass about regards to flow.
    When t/stat opens the hot water exits the engine.

    Without the coolant loop. The hot water just sits in the back of the head with no where to go an begins to steam.

    With the loop, the entire engine is now circulating water. Rather then having hot spots.

    By connecting them to the water pump they are being sucked out and constantly flowing so to speak.
    so where does the majority of the flow go through the engine when you look at the holes in the head gasket and the holes in the 308 block?
    I am still thinking the pump is not up to the job, how is anyone checking this?
    Last edited by powerabout; 22-04-2020 at 02:37 AM.

  6. #21
    Part of the furniture BasicQ's Avatar
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    Quote Originally Posted by cava454 View Post
    You got it ass about regards to flow.
    When t/stat opens the hot water exits the engine.

    Without the coolant loop. The hot water just sits in the back of the head with no where to go an begins to steam.

    With the loop, the entire engine is now circulating water. Rather then having hot spots.

    By connecting them to the water pump they are being sucked out and constantly flowing so to speak.
    My overactive mind was thinking of how those bypass hoses help to reduce the instances of head gasket failure and the overarching thought was that they assisted in equalizing head temps front to back. Didn’t put enough thought into flow direction and got that wrong (imagine my embarrassment, I work at a place that makes industrial radiators!). I had it that cooled radiator coolant was being sent to the back of the engine to meet with the hot pocket down the back where it would normalize and travel through the head and on to the thermostat. It seems flowing in the direction it may instead be bleeding off some of that hot pocket water and sending to the front of the engine to equalize temps. Again, just a theory to keep the mind active while sitting at home staring at the walls.
    As far as water pump capacity and capability goes I haven’t been involved with Holden v8’s for a long time, what is out there now regarding a performance water pump? If you were to need something more substantial do you need to go down the route of adapting sbc stuff?
    Last edited by BasicQ; 22-04-2020 at 10:03 AM.

  7. #22
    Do you ever leave? immortality's Avatar
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    Having the bypass hoses from the back coolant port would increase the flow past that point and prevent localized hot spots. There have been other threads on this subject over the years which had a fair bit of detail in them. I'm no expert but I'm led to believe that flow is critical to efficient cooling. Modern LS engines have steam ports from each corner of the head, surely this is not just another marketing gimmick from the engineers at GM?

    Anybody remember the Bennett cooling system? It moves the thermostat to the bottom radiator hose to control the temp at the inlet much like modern engines. Part of his system I believe is a modified stock pump to increase coolant flow.
    Last edited by immortality; 22-04-2020 at 10:55 AM.

  8. #23
    Part of the furniture BasicQ's Avatar
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    Quote Originally Posted by immortality View Post
    Having the bypass hoses from the back coolant port would increase the flow past that point and prevent localized hot spots. There have been other threads on this subject over the years which had a fair bit of detail in them. I'm no expert but I'm led to believe that flow is critical to efficient cooling. Modern LS engines have steam ports from each corner of the head, surely this is not just another marketing gimmick from the engineers at GM?

    Anybody remember the Bennett cooling system? It moves the thermostat to the bottom radiator hose to control the temp at the inlet much like modern engines. Part of his system I believe is a modified stock pump to increase coolant flow.
    Yes, agree. Apologies for covering old ground and my boredom induced rambling.

  9. #24
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    I was just checking out the coolant holes in the decks of the blocks and the early blocks have only 1 hole in the deck in the centre on the ex side, the later VN have all the holes down the ex side. So I looked at the available head gaskets and,
    STD felpro 140 has all of the holes
    O ring felpro has only the centre hole
    ACL race has all of the holes
    Cometic has all of the holes
    cheapo endurotec has all of the holes
    So should we be drilling the early blocks for the extra holes?

  10. #25
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    Best way to improve flow is to remove the thermostat all together like any race car would.

  11. #26
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    Quote Originally Posted by AED View Post
    I was just checking out the coolant holes in the decks of the blocks and the early blocks have only 1 hole in the deck in the centre on the ex side, the later VN have all the holes down the ex side. So I looked at the available head gaskets and,
    STD felpro 140 has all of the holes
    O ring felpro has only the centre hole
    ACL race has all of the holes
    Cometic has all of the holes
    cheapo endurotec has all of the holes
    So should we be drilling the early blocks for the extra holes?
    Good stuff AED, most of the development on these engines was derived from motor racing

  12. #27
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    Quote Originally Posted by RLF View Post
    Good stuff AED, most of the development on these engines was derived from motor racing
    The part I dont get is later blocks with the extra holes will reduce flow to the back so the factory didnt think it was a problem or the problem was elsewhere and the cooling pipes at the rear covered it up?
    I have seen a few photos of F5000 blocks and they had the holes like a 304 plus the rear pipes but I guess they didnt have CFD to help with design?
    Last edited by powerabout; 22-04-2020 at 12:57 PM.

  13. #28
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    Quote Originally Posted by powerabout View Post
    The part I dont get is later blocks with the extra holes will reduce flow to the back so the factory didnt think it was a problem or the problem was elsewhere and the cooling pipes at the rear covered it up?
    I have seen a few photos of F5000 blocks and they had the holes like a 304 plus the rear pipes but I guess they didnt have CFD to help with design?
    We don't actually know if adding pipes at the rear is beneficial. One race team (HDT) did it for a brief period of time during vk-vl when they were behind on engine development compared to other teams.

    The best example to copy would be the last version of the 304 in competition built by perkins. Obviously had the later block design and no rear coolant lines to the heads.

  14. #29
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    Default Holden V8 head/block/cooling/racing .. thread move

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  15. #30
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    What about feeding through middle side welsh plugs? Seem to recall that being done on a f5000 or Brabham v8?

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