to be or not to be? a thermostat question
The coolant can go too fast.
It isn't in the engine long enough to pick up much heat from the block and heads.
If you run without a stat , a restrictor is pretty much a must have.
I went with a stat still restricted the flow to try and focus the cooling around the center cylinders.
Plugs in the passages in the deck drilled down to 3/16ths " and used smaller lines from the ends of the head vs. the center. ( W-9's )
I use a remote electric pump and coolant enters the block through the center core plugs via -12 line , exits through the heads , aluminum radiator and HHR fan and shroud.
It stays cool on the street and I will probably have to work to get it to temp on the track.