Using the LS430 water inlet housing on 1999 LS400 improves coolant flow.

The more direct coolant path of the LS430 inlet housing allows viewing the thermostat.

Observed one of the thermostat supports slightly blocks the coolant path with the "dongle" at 12:00 o'clock.

By indexxing the dongle slightly to left removes the thermostat frame out of direct coolant flow.


2000 LS400 vs 2001 LS430 water inlet housing.

Thermostat housing

Dongle indexxed 12:00

Thermostat frame shrouding the spring in coolant flow path

Dongle positioned slightly to left of 12:00.

View down the inlet housing with thermostat frame indexxed to left. Frame is out of the way of coolant flow.

 

How much can you improve the cooling capability doing this?

 

Excellent question, the thermostat frame shrouds the passage 5% -10%....but there is a spring behind it which has surface area in path of coolant flow...

So without ability to perform flow measurements and based on removing the thermostat frame from flow path, will use lower 5% figure and divide by 2 to account for unshrouded spring area = 2.5 %.

Hope all can agree this does not reduce coolant flow.