Actually there will always be flow through the two loops that flow through the turbo and the oil cooler, plus a little flow through the heater core thermostat as well due to the hole I drilled in it. That is important, since both thermostats need to see flow across the paraffin actuators so that they will 'know' when the engine is warm and open up.

In the diagram I show those lines connected to the 'upstream' side of the thermostat, probably not clear though.

On that freeze plug, dang it I wish I could remember. It is metric, I want to say 34mm. I do remember I had to go to O'Reilly to find one. Auto Zone and Advance did not have it. Cannot remember if NAPA does.

30mm, usually labeled as 30.05 or so. Autozone had 'em down where I live.

Thanks Joe.

You know, back to my question about determining if there is enough flow through the engine while the thermostats are closed... The first time I start up the engine with this hooked up, I could log/watch the coolant temperature closely; the temperature sending units (stock and aftermarket gauge) are right at the back of the head, before the t-stat.

If the temperature suddenly jumped (or oscillated) at or near the thermostat opening temperature, this could be an indication that there were some pockets of hot coolant in the engine that were not circulating well with the rest of the constant-flow circulation (while the thermostat was closed).

Alright, ill ask for a 30 (30.05), thanks.

Do you really trust two 3/8" lines and a little coolant going through some (1/8" or so I'm assuming) holes to supply enough coolant to your head for warm up? That doesn't seem like much.

Yeah that is what I am not sure about. How much is really needed?

You're thinking of using the wrong pair of ports. You can choose a pair of ports that have near zero leakage when hot.

Why don't you run the Turbo and Oil Cooler outlets to the radiator inlet?

Chris

Good question. I think they will flow more if they are connected at the pump inlet since the pressure should be a little lower there. Plus, though I doubt they will flow enough to significantly effect the engine warm up time, they will be circulating warm flow like the heater core does in the stock configuration.

So, how do we solve this? I am about to route the heater return to the radiator inlet, but understand that the car may take ages to warm up on the street...

What do you consider too cool for the street? My reroute is kinda similar, just without the t-stat in the heater hose but I'm getting 195-200° temps in normal driving. Have you tried turning the heater on full blast when on track?

The car would take 15 minutes or more to get above 160-170F. And, the temperature would fluctuate greatly from 160-200 depending on if I was sitting at a light or on the highway. It is just not very stable.

I run the hard top so I really do not want a setup that relies on running the heater to keep the engine cooled off. Even with the windows down it would heat up the cockpit too much for me on a hot day.

I'm in the process of installing this reroute so I'll report back on how well it does once the car is running again. I am making several other cooling related changes as well so it will be hard to look at it as a back-to-back comparison. But, I think the logs of the coolant temps will still be useful data. I fabricated a thermostat housing for the heater core circuit using a spare thermostat cover and the thermostat housing I removed from the front of the engine. It looks to me like it will work well.

I just put a valve in the heater core return that goes to the mixing manifold. Put it at 'almost closed'.

That, and I remolded the hood vent. Flushed all coolant with pure water.

Thursday's track day will tell if my temps stay lower now.

Spookyfish, is this somehow switching between returning the heater outlet to the mixing manifold and to the radiator inlet? Or are you just choking off the return to the radiator to speed up the warm up process, wouldn't that limit flow?

I think what he is doing is restricting flow through the heater core (and into the water pump via a stock mixing manifold type configuration) to a bare minimum. This will force most of the flow through the radiator return hose (and through the radiator) once the t-stat opens.

Do you have a coolant reroute with the thermostat at the back of the head? Seems like this would be a must for this setup, otherwise there will not be much flow through the back cylinders.

Correct. Just enough flow for warmup. After that, maximum flow through the radiator.

In fact, I have a front AND rear exit. I want to cap off the front still, but haven't done that yet. Both exits mix at the top radiator inlet.

None of that. Just limiting flow through the heater core return that goes to the water pump/mixing manifold.

Freeze plug that bitch already! :)

Nah, too much trouble. My turbo sees coolant from that spot. I will use a block off plate. Someone needs to make me one.

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I know, just haven't found thick enough Al plate around here that isn't an acre in size.