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[Kevin Wood]

looks like we said the same thing there about the block routing and the pump. I certainly wouldn't advise changing either. Swindon didn't for their 300 HP endurance-race engine

Ahh, and you've explained how the "intake in the oil cooler plate" mod helped.

Of course, the less restriction at the low pressure side of the coolant pump, and the cooler the water there, the more effective the pump will be and the greater margin you'll have over cavitation.

[2woody]

yep - you could reduce the coolant pump inlet temperature to very close to radiator outlet - that may give you an extra 15 degrees headroom.

[cem_devecioglu]

However sub-optimal the cooling setup appears to be, you can be sure that 1.it has been carefully optimised during design to give even cooling of the engine. Change one component and you have disturbed that balance and you have to start again. If trial and error is your only tool, it could be an expensive game.

2.Electric pumps are all very well, but they have nothing like the power available to them as the engine driven pump. They'll flow more coolant when the revs are low (and heat generated is also low) but don't underestimate how much coolant the standard pump will shift at high revs.

3.Also, changing the pump drive ratio can cause issues. There is probably a fine balance between enough flow at idle speed, and avoiding cavitation at high revs.

4.If there is a real issue with cooling the rear cylinders a bit of very localised attention to the flow in that area would be best, IMHO, but you run the risk of creating a hot spot elsewhere, IMHO.

1. without doubt they carefully designed the engine..  but design is towards low emissions and a daily usage engine imo..  I also  agree that trial error will be an expensive game.. My thermodynamic knowledge was good at university but that was a quarter century ago   still can work on that but
a visit to friends at mechanical engineering dept may be useful ..  besides whatever calculations you make you will rely on some assumptions  which will change the picture.. I still think that after some solution theories    it must be experimented  .. question is do I have that budget ? answer is no unfortunately..
 
2. I do think that a variable rate pump can easily be designed by Kevin Wood
 
3. that also requires a trial error in machine shop which wont be expensive..
 
4.rear cylinders really need attention .. but before changing anything in design , theoritically a 1:1 working model must be tested outside a car with some temperature sensors at some points .. and thats a hell of a lot of job..  so back to square one , trial and error

[Kevin Wood]

1. without doubt they carefully designed the engine..  but design is towards low emissions and a daily usage engine imo..  I also  agree that trial error will be an expensive game.. My thermodynamic knowledge was good at university but that was a quarter century ago   still can work on that but
a visit to friends at mechanical engineering dept may be useful ..  besides whatever calculations you make you will rely on some assumptions  which will change the picture.. I still think that after some solution theories    it must be experimented  .. question is do I have that budget ? answer is no unfortunately..

Consider the engine to be like a central heating system. If you don't balance the flow between all radiators, some rooms will get too hot and some will get too cold. Change the system somewhere and the radiators need to be re-balanced. It's the same with an engine, in that you need to avoid areas of stagnant coolant flow around heat sources. The back cylinders are furthest from the pump, so, without looking in detail at the coolant circuit, one might theorise that maintaining adequate coolant flow around them might be a challenge, hence they might well run hot when the engine is tuned. I am sure that GM would have tested an engine with all the required monitoring devices fitted and decided that their cooling system was "good enough". They may have accepted some compromises there, perhaps the rear cylinders do run slightly hotter, but "good enough" in their case was to deliver 218 BHP occasionally and spend most of its' life on a motorway or pootling around town.

As soon as you change things, though, you've thrown their work away and need to make sure what you put in place is better - without the luxury of all the tools and budget they had at their disposal!

2. I do think that a variable rate pump can easily be designed by Kevin Wood

Yes, but why bother? The engine already has a nice, simple, elegant variable rate pump by virtue of the fact that it's driven by the crankshaft. Generally, the faster the crank turns, the greater the cooling demand. An electric pump would not be able to draw on a couple of horsepower of energy like the standard pump probably does at high engine speed, and it would be much more complex, expensive and less reliable. It would have to offer a tangible benefit to bother, and I'm not yet convinced it would.

3. that also requires a trial error in machine shop which wont be expensive..

Yep. You can't easily get a feel for what's going on inside the cooling system as very little of it is accessible. All you can do is measure temperature at a few points and theorise about what's happening. All the more reason not to change too much, IMHO.

4.rear cylinders really need attention .. but before changing anything in design , theoritically a 1:1 working model must be tested outside a car with some temperature sensors at some points .. and thats a hell of a lot of job..  so back to square one , trial and error

Yep. First job IMHO would be to figure out exactly what's going on in those cylinders. What is the exact failure mode? Pistons getting too hot and melting? Pistons getting too tight in the bore and picking up on the bore? Damage due to detonation, etc? More intake air to those cylinders so they run slightly lean?

Also, is there an easier way to combat this? If you just run the engine cooler and improve the pump inlet as detailed by 2Woody does it help? Can you improve oil flow to the piston bases using some oil jets? Can you run a little looser piston/bore clearance? Can you run a slightly richer mixture? Are you actually at the limits of what a cast piston can achieve in that engine, and just seeing the rear cylinders fail marginally before the rest, so should you just go forged and forget the cooling issue?

This is the problem with stepping into the unknown with an engine that's not got a lot of tuning pedigree. The answers take some time and money to discover. Get yourself a C20LET instead and that work has all been done, and paid for, by someone else!

[Marks DTM Calib]

Its easy enough to add an oil jet to the rod sides to aid cooling of the underside of the piston crowns....every little helps!

[05omegav6]

If this is being done for outright performance purposes, then there's potentially work to be done removing plumbing for creature comforts such as heating and air conditioning, thus freeing up some space around the back of the engine for improved airflow. Could then lose the condensor and fit a bigger, more efficient radiator.

[cem_devecioglu]

Its easy enough to add an oil jet to the rod sides to aid cooling of the underside of the piston crowns....every little helps!

thats a good idea

[cem_devecioglu]

If this is being done for outright performance purposes, then there's potentially work to be done removing plumbing for creature comforts such as heating and air conditioning, thus freeing up some space around the back of the engine for improved airflow. Could then lose the condensor and fit a bigger, more efficient radiator.

agreed.. air conditioning condensor takes too much space, and more importantly decrease the air flow rate through radiator.. a better/bigger aluminium rad can be installed..  also I think air conditioning compressor takes too much space..  however, a dark colored omega without air conditioning will be "interesting" in our summer

[cem_devecioglu]

long post alert....

ok, so the 54 degree V6 usually expires because of bottom end failure, caused undoubtedly by strainer blockage and/or over-temperature oil thinning out and reducing protection. The standard thermostat is far too high a temperature for efficient cooling ( chosen probably to help emissions instead ).

Having looked at this in some detail, removing the standard oil cooler would be a great idea, BUT this would only be a good idea if the coolant can be introduced to the pump without having to go through the block from back-to-front first. This would involve either introducing the coolant through an oil cooler blanking plate or inserting a seperate tube through the block from back to front and then making sure both that it doesn't leak and is insulated from coolant. In the standard car, the "cold" coolant from the radiator outlet goes through the transfer pipe ( above the exhause manifold ) and thropugh the cylinder block ( hot ) and around the oil cooler ( hot ), so by the time its at the pump may already be at 90 degrees C.

Next, the thermostat must be exchanged for another one operating at a much cooler temperature. Land Rover Discovery-II Td5 would be my choice as its an external unit. The bypass hole could be blocked, as the main bypass is through the heater ( as long as the HBV is removed, too ). Pipework is up to you.

In my opinion, the actual routing through the block from pump to outlet needs no improvement.

Interesting/Useful info, thanks 2woody
 
now question is, can we  use different design strainer ? also the oil thinning problem again pushes me to think that cooling still insufficient..  also a different oil cooling system may be used ?
 
I can partially remember, what Omegatoy told us..  Oil was very critical when they install the turbo ..
but cant remember finally what API they used
 
 
and now please excuse my ignorance (I'm a petroleum engineer so we install pipes everywhere ) ,
 cant we drill the block and use 2 seperate water inlets and outlets ? (honestly I have no idea about the coolant flow inside the block except the things Kevin tell )
 
 

[cem_devecioglu]

1. without doubt they carefully designed the engine..  but design is towards low emissions and a daily usage engine imo..  I also  agree that trial error will be an expensive game.. My thermodynamic knowledge was good at university but that was a quarter century ago   still can work on that but
a visit to friends at mechanical engineering dept may be useful ..  besides whatever calculations you make you will rely on some assumptions  which will change the picture.. I still think that after some solution theories    it must be experimented  .. question is do I have that budget ? answer is no unfortunately..

Consider the engine to be like a central heating system. If you don't balance the flow between all radiators, some rooms will get too hot and some will get too cold. Change the system somewhere and the radiators need to be re-balanced. It's the same with an engine, in that you need to avoid areas of stagnant coolant flow around heat sources. The back cylinders are furthest from the pump, so, without looking in detail at the coolant circuit, one might theorise that maintaining adequate coolant flow around them might be a challenge, hence they might well run hot when the engine is tuned. I am sure that GM would have tested an engine with all the required monitoring devices fitted and decided that their cooling system was "good enough". They may have accepted some compromises there, perhaps the rear cylinders do run slightly hotter, but "good enough" in their case was to deliver 218 BHP occasionally and spend most of its' life on a motorway or pootling around town.

As soon as you change things, though, you've thrown their work away and need to make sure what you put in place is better - without the luxury of all the tools and budget they had at their disposal!

2. I do think that a variable rate pump can easily be designed by Kevin Wood

Yes, but why bother? The engine already has a nice, simple, elegant variable rate pump by virtue of the fact that it's driven by the crankshaft. Generally, the faster the crank turns, the greater the cooling demand. An electric pump would not be able to draw on a couple of horsepower of energy like the standard pump probably does at high engine speed, and it would be much more complex, expensive and less reliable. It would have to offer a tangible benefit to bother, and I'm not yet convinced it would.

3. that also requires a trial error in machine shop which wont be expensive..

Yep. You can't easily get a feel for what's going on inside the cooling system as very little of it is accessible. All you can do is measure temperature at a few points and theorise about what's happening. All the more reason not to change too much, IMHO.

4.rear cylinders really need attention .. but before changing anything in design , theoritically a 1:1 working model must be tested outside a car with some temperature sensors at some points .. and thats a hell of a lot of job..  so back to square one , trial and error

Yep. First job IMHO would be to figure out exactly what's going on in those cylinders. What is the exact failure mode? Pistons getting too hot and melting? Pistons getting too tight in the bore and picking up on the bore? Damage due to detonation, etc? More intake air to those cylinders so they run slightly lean?

Also, is there an easier way to combat this? If you just run the engine cooler and improve the pump inlet as detailed by 2Woody does it help? Can you improve oil flow to the piston bases using some oil jets? Can you run a little looser piston/bore clearance? Can you run a slightly richer mixture? Are you actually at the limits of what a cast piston can achieve in that engine, and just seeing the rear cylinders fail marginally before the rest, so should you just go forged and forget the cooling issue?

This is the problem with stepping into the unknown with an engine that's not got a lot of tuning pedigree. The answers take some time and money to discover. Get yourself a C20LET instead and that work has all been done, and paid for, by someone else!

Good questions Kevin.. of course I know that V6 engines modification not feasible in our budgets.. 
 
you can buy a ready turbo engine with a lower cost than modifying V6..  or even a complete smaller lighter car with a race developed engine.. where forged performance items are already in market , and people had done/worked on them several times..
 
but the reason I opened this thread is, I wanted members to share their views and do some brain exercise on building a modded v6..  also, say a 0.6, 0.7 bar application is not that hard to achieve..
and gains will be more than enough for daily usage..
 
 

[cem_devecioglu]

here is some info on oil jets    (thanks Mr DTM)
http://mngforce.typepad.com/nc450vdev/engine-modification-piston-cooling-oil-jet.html
 
http://www.turbo-mini.com/44648/23109.html
 
http://www.youtube.com/watch?v=uMnFbsy0Hgg&feature=player_embedded
 
 

[cem_devecioglu]

here is some info on oil jets    (thanks Mr DTM)
http://mngforce.typepad.com/nc450vdev/engine-modification-piston-cooling-oil-jet.html
 
http://www.turbo-mini.com/44648/23109.html **
 
http://www.youtube.com/watch?v=uMnFbsy0Hgg&feature=player_embedded

[omega3000]

If this is being done for outright performance purposes, then there's potentially work to be done removing plumbing for creature comforts such as heating and air conditioning, thus freeing up some space around the back of the engine for improved airflow. Could then lose the condensor and fit a bigger, more efficient radiator.

agreed.. air conditioning condensor takes too much space, and more importantly decrease the air flow rate through radiator.. a better/bigger aluminium rad can be installed..  also I think air conditioning compressor takes too much space..  however, a dark colored omega without air conditioning will be "interesting" in our summer

Yep , ran my car without condenser for over a year ...cooling was improved . How come your condenser never fell to bits like the rest of them 

[cem_devecioglu]

If this is being done for outright performance purposes, then there's potentially work to be done removing plumbing for creature comforts such as heating and air conditioning, thus freeing up some space around the back of the engine for improved airflow. Could then lose the condensor and fit a bigger, more efficient radiator.

agreed.. air conditioning condensor takes too much space, and more importantly decrease the air flow rate through radiator.. a better/bigger aluminium rad can be installed..  also I think air conditioning compressor takes too much space..  however, a dark colored omega without air conditioning will be "interesting" in our summer

Yep , ran my car without condenser for over a year ...cooling was improved . How come your condenser never fell to bits like the rest of them 

I still use the original radiator and condenser.. 

[omega3000]

Throw condenser and pipes and double fans in the bin  I used main engine rad and single fan no problems and with condenser and fans out the way improved cooling but not in the car in summer  Summer's will no longer be hot here anymore so air con is useless and saps power .