Radiator hoses so big ID Why?

[TIB3300]

So am trying to cool the old girl down in traffic, I posted a question about bypass hose ect! Thanks for the input

Anyhow got me to thinking?

Why do the top and bottom radiator hoses have such a large ID? As the thermostat hole is so much smaller in relation to them.

Radiator hose ID 38mm
Thermostat hole size 25mm

[Blue]

I don’t have the answer but the lower hose is bigger than the top, 1-3/4” as opposed to 1-1/2” I prefer to use Mr Gasket high flow thermostats which have a larger than normal orifice.

[Dave999]

flow is better in a fat pipe, less pipe wall contact per unit of coolant middle of fat pipe is bigger than middle of a thin one etc flow is better

stat needs to be smaller to provide load for the pump
otherwise the pump can thrash the water so much it splits molecules away from each other making bubble of pure empty SPACE
which when they pop (inwards rather than outwards) can errode the pump, impellor and block face.

the restriction provided by the stat dictates the pressure the pump see's and coolant under pressure is harder to thrash into vacuum filled bubbles than coolant that isn't

Dave

[Blue]

Good answer Dave other than pressure and flow I wasn't sure of what else was going on.

[Stu]

Every day’s an education.

[Kev]

Cavitation

[Dave999]

Indeed

Dave

[TIB3300]

flow is better in a fat pipe, less pipe wall contact per unit of coolant middle of fat pipe is bigger than middle of a thin one etc flow is better

stat needs to be smaller to provide load for the pump
otherwise the pump can thrash the water so much it splits molecules away from each other making bubble of pure empty SPACE
which when they pop (inwards rather than outwards) can errode the pump, impellor and block face.

the restriction provided by the stat dictates the pressure the pump see's and coolant under pressure is harder to thrash into vacuum filled bubbles than coolant that isn't
Dave

Thanks Dave
My apologies for the slow reply, been in wales with the van and limited internet and mobile devices , I cant get my head around properly

Again thanks