Head cooling on cylinder #5 - solutions?

[X64v]

I am feeding my turbo from the by-pass line on the lower t-stat right now. Tony and I talked about my plans and he suggested running the turbo feed line from #5 and not #6.

 

If I had (or when I get) a water-cooled turbo, that's what I'd do. Then return #6 straight to the pump inlet.

 

I'm bringing my next head back from Phoenix tomorrow, so I'll start on this and have pictures probably Monday or Tuesday.

[ktm]

If I had (or when I get) a water-cooled turbo, that's what I'd do. Then return #6 straight to the pump inlet.

 

Right now the turbo coolant is returned to the pump inlet. However, Tony and I agree that #6 can return to the lower t-stat where I am currently feeding the turbo. Remember, without the line at #6, the coolant is (actually, should be - right now it is stagnating at that point) returned to the lower t-stat housing anyway.

[X64v]

Remember, without the line at #6, the coolant is (actually, should be - right now it is stagnating at that point) returned to the lower t-stat housing anyway.

 

Ah, gotcha. Yeah, that makes sense when you think of it that way. The -AN line will have less friction and restriction than going through the rest of the head, so it will flow through that instead.

 

I think in my case, I'm still going to return both to the water pump inlet, since my single -6 line will total the same water flow as the original bypass system. In your case, you already have one -6 going back to the pump inlet, so the other needs to go through the radiator instead of being bypassed.

 

Unless I should route mine like yours? Two separate lines, #5 back to the pump inlet, and #6 to the lower T-stat housing? This would make sense if one takes into account that #6 has that giant water port from the back of the block into the head there, so perhaps a line going from there to the water pump inlet might impart too much bypassed flow?

[ktm]

Unless I should route mine like yours? Two separate lines, #5 back to the pump inlet, and #6 to the lower T-stat housing? This would make sense if one takes into account that #6 has that giant water port from the back of the block into the head there, so perhaps a line going from there to the water pump inlet might impart too much bypassed flow?

 

I am eliminating that line from the back of the head to the water pump inlet. Too much hot coolant is bypassed back into the pump. Also, this should increase the cooling system pressure slightly as I am now eliminating a lower pressure shunt.

 

My setup will be: #5 to turbo coolant inlet, #6 to lower t-stat housing, block off port in rear of head by #6, return coolant from turbo to water pump inlet. Returning the turbo coolant to the pump inlet allows the water to flow through the turbo rather than sit there if I routed it to the t-stat housing (while the t-stat is closed that is).

 

Another setup would be to return #5 and #6 directly to the radiator or pump inlet and still use the by-pass line to feed the turbo coolant.

[X64v]

I am eliminating that line from the back of the head to the water pump inlet.

 

This is not what I'm talking about. I still have my heater core, so this line is staying in place for me. I'm talking about the internal passage between the block and the head in the very back, the one big enough to fit a few fingers in when the head is off. That's close enough to where we'll be tapping #6 that I would be worried that our tapped port would just draw lots of water from there if it were returned to the pump inlet. Routing #6 to the lower T-stat housing instead would reduce the pressure differential pushing the water, thereby keeping the flow through our #6 port within reasonable limits.

 

I think your setup you just described sounds perfect, and I'm wondering if I should make mine exactly like yours (sans water-cooled turbo) instead of the way I was going to do it a few posts up (post #138).

[m4xwellmurd3r]

I've read quite a bit of what's here, so I do understand that right now my car WILL DIE no matter what big huge radiator I put in it, because the #6 output that normally goes to the heater core, has been redirected to go directly to the water inlet (just keeps pumping hot water back into the system and overheating the car)

 

But from what I read, running it to the T-stat housing or directly back into the radiator would help cool #5/6 better because it's getting that water out of there as fast as it can? It seems to make sense. right now the water flows through the block, and into the head, and then exits the T-stat due to the internal bypasses. It seems to me that if you were to allow #6 to flow back into the rad it would help get that hot water out faster since it sounds like the flow back there sort of makes the water at 5/6 sit there and sorta swirl around and become really hot before it's able to get pulled out. am I right or am I speaking total nonsense and I should quite talking before I hurt myself XD

[Tony D]

Or, maybe just increase cooling system pressure like I did. 28 to 30 psi solves most nucleate boiling problems. Or better yet, go with a non-water based cooling system.

 

John has a good point here, but his specific output was slightly lower than some of the engines being referred to here.

 

Probably increasing the cap pressure would be a quick check to see if there is an improvement immediately.

 

Only downside would be the possibility of hoses and other soft components not being up to the task long term. Nusiance leaks, etc. With a 30psi blanket pressure, in-block pressure would in essence be doubled over the stock cap pressure (or even the high-performance 16psi caps). That would keep a decent cap on the formation of the insulating steam bubbles.

 

But it may still be necessary to increase flow to take the heat out of there. The increased pressure is a functional fix of the steam formation, but not an engineered correction of a flow deficiency in the cylinder head.

 

Nissan recognised as much in their redesigned heads for FIA competition and the system on the LY head. They both have different cooling systems that evacuate the upper cylinder combustion chamber water along the whole legnth of the head into a separate off-head manifold, instead of making it all go back up front to come out a thermostat housing that is basically at the front of the head.

 

I wonder.....

 

Could you take water off the BACK of the head by spotfacing a place to make a remote thermostat housing attachment, and then simply using tubing to the radiator... That would seem to let water flow 'work properly' inside the head. As KTM mentioned, #6 has some slow velocity water, so it would evacuate out the back well, while that high-velocity water coming up the block through #1 could slow down some working it's way to the back of the head to evacuate out a rear-mounted thermostat housing. Maybe make a Corvette-Style reservoir tank at the rear of the engine bay before moving on to the radiator---giving it a 'high point' for any steam taken out of the system a point to collect before the water moves on up front to the radiator...

 

[X64v]

Could you take water off the BACK of the head by spotfacing a place to make a remote thermostat housing attachment, and then simply using tubing to the radiator... That would seem to let water flow 'work properly' inside the head. As KTM mentioned, #6 has some slow velocity water, so it would evacuate out the back well, while that high-velocity water coming up the block through #1 could slow down some working it's way to the back of the head to evacuate out a rear-mounted thermostat housing. Maybe make a Corvette-Style reservoir tank at the rear of the engine bay before moving on to the radiator---giving it a 'high point' for any steam taken out of the system a point to collect before the water moves on up front to the radiator...

 

 

There's a core plug in the back of the cylinder head. Could you just pop that out, thread the hole, and screw in a custom T-stat housing? Then, make a simple block-off plate for the original T-stat housing location.

 

My only question then would be, would the #1 chamber get enough water flow, or would we create a problem there?

[Tony D]

#1 being close to the pump with the highest pressure available should flow well with a thermostat at the back of the head...

And you always have the internal bypass there back to the inlet---likely that would have to be restricted, and 'external' bypasses be added back to the inlet of the pump from the #6 end of the head.

 

Adding flow to the #1 cylinder in this instance would be easy, since you already have a thermostat housing that is blocked off with a plate, right? LOL

[X64v]

I did my drilling and tapping tonight. Super easy with a drill press. I'm glad this head will be hot tanked at the machine shop, there are shavings everywhere. (Yes, it's a P-79, leave me alone)

 

Note: In the cut-away pictures, the top of the #5 exhaust runner casting is about where the top of the machined gasket area is around the port. Well, looking through my new water holes, the #6 exhaust runner casting comes up 1/8" - 3/16" higher; my port is just above the floor of the water passage in that area. Just beware, don't make the bottom of the hole on #6 any lower than mine is.

 

 

 

[rwdawg2]

I can't wait to see the final product with the plumbing and all. I think I am a little lost but those last pics help out with the confusion a little bit. I just don't understand how the plumbing is going to work I guess.

 

Looks good though x64v

[Tony D]

So basically, you're saying put the hole right where those chill pads are on the casting? Almost like someone was leaving a marker for people modifying the head later on, post factory? (Hint, Hint!)

 

Hindsight is 20/20, eh? If you look in the 'how to modify' book at the electromotive turbo setup, you can see their manifolding of the water above the combustion chambers...and it looks like they sunk their holes right in those chill impressions that you have photographed so well in your closeups!

[X64v]

They were tempting, but based on this photo, I thought the casting mark looked far too high to me, and I was worried about hitting the top wall of the water runner and/or hitting the casting bump in the top of the water runner in that picture.

 

What did you say they were, chill pads? My roommate and I were wondering exactly what they were.

[X64v]

I can't wait to see the final product with the plumbing and all. I think I am a little lost but those last pics help out with the confusion a little bit. I just don't understand how the plumbing is going to work I guess.

 

Looks good though x64v

 

Thanks.

 

The port above #5 will be routed back to the water pump inlet, in the same manner as the original bypass line for the SU/TB water. This will provide a great pressure difference and pull lots of water out from #5.

 

The port above #6 will be routed up to the lower thermostat housing, via a new tap, or perhaps I'll tee into my GM coolant temp sensor fitting. This will pull water out from #6, but not as much, because the pressure difference will not be as great.

 

That help?

[ktm]

Thanks.

 

The port above #5 will be routed back to the water pump inlet, in the same manner as the original bypass line for the SU/TB water. This will provide a great pressure difference and pull lots of water out from #5.

 

The port above #6 will be routed up to the lower thermostat housing, via a new tap, or perhaps I'll tee into my GM coolant temp sensor fitting. This will pull water out from #6, but not as much, because the pressure difference will not be as great.

 

That help?

 

Looks good. My head is at the machine shop getting checked for straightness, resurfaced, and the holes tapped while it's there.

 

A comment about the port above #6. When the t-stat is closed, water will probably be routed from the lower t-stat housing into #6. The pressure in the t-stat housing will most likely be higher than #6. Remember, the water in #6 is most likely stagnating due to the pressure differential between #6 and #1.

 

When the t-stat opens, water will then reverse flow, as the t-stat opening is now the lower pressure zone. The pressure through the t-stat and into the hose will most likely be lower than the pressure at #6, thereby allowing water to flow from #6 to the t-stat.

[Xnke]

Why not return both #5 and #6 to the water pump inlet?

[Tony D]

That would result in a direct shunt of the hottest water directly to the pump inleet exacerbating the cavitation issue.

 

Ideally, like Electromotive did, you would vent all cylinders above the head to the radiator, this lets the water flow directly bottom to top in each individual cylinder, and evacuates steam and air bubbles from each cylinder equally. If you look at the "How To Modify" book you will see their tapping of the cylinder head, they did all cylinders directly to the radiator.

 

You only need the two smaller bypass lines for pump circulation when the thermostat is closed. Once it cracks open the pump will flow what it can---if the vents went back to the inlet, it's the same as looping the heater core hose---too much when it's not needed. The stock external bypass lines on the 73 and 74 cars WERE CLOSED by thermostatic valves once the water in them reached 170 degrees F. After the engine is warmed, and the thermostat open, the need for bypass lines back to the inlet of the pump ceases to exist---you have an open flow loop through the radiator and no need for low-flow bypasses. If you could close them both off it would be ideal as then all water was cold into the pump, and all hot water exited to radiator with absolutely no recirculation at all of hot water to the pump inlet.

 

The routing of the turbo to the inlet of the pump is for expedience. Doing it to the radiator would entail all sorts of tubing off-engine and to the radiator, and would not work as a bypass when cold...so it's a choice of expedience more than anything else. Ideally, you would tap pressure from the output of the pump, through the turbo and into the upper t-stat housing...that way after shutdown you would have cold water from the bottom of the radiator given a direct pass through the turbo as it warmed, and up to the high point of the engine---a thermal siphon after shutdown.

But expedient that setup is....not!

[ktm]

My alternate cooling setup is complete. When Calgarty280zt comes back on Thursday, I'll have him take some pictures of the setup.

[kiwi303]

On the topic of the different coolant types mentioned in earlier pages, how does plain Glycerine byproduct from biodiesel stack up as a coolant? I believe it's similiar chemical composition to glycol, and is pretty much free if making your own Biodiesel. All it would take is a little washing and nutralising of the glycerine to ensure any of the lye and sludge from the biodiesel manufacturing is out of it.

[rxKaffee]

Has anyone worked on or desired to have reverse cooling for the L? Heads first like the LT/LS series sbc's.