Engine temperature

[BigBen]

What is the ideal coolant temperature for a petrol engine ?

The K-series in my Atom from the factory (and in all Rover K-engines with this ECU) runs to 102deg before the fan comes on. I have modified the fan to come on at 90deg which seems to keep the temperature at around this point, will this cause any harm / performance detriment ?

TIA

Ben

[Trooper2]

Most modern gasoline engines have a thermostat opening at somewhere between 180° and 210° Fahrenheit, so it sounds like you are right in the Ballpark for happy running.

[GavinPearson]

This is going to sound like a wishy washy answer, but it really depends on the engine.

The reason for this is that you are measuring the bulk temperature of the coolant, but what really counts is what temperature the exhaust seats stabilise at before you start to get detonation.

On a standard engine you can assume that whatever the factory plumbed in is good enough, on something you tune yourself you would need to find it out on a rolling road.

My recommendation if you are going to tune an engine is to put the coldest thermostat available in, fully open by 90C and do exactly what you've done with the fan.

[BigBen]

I think the thermostat is open at mid 80s so may set the fan to come on at a slightly higher temperature of say 90 to give it more of a chance

Ben

[stevieturbo]

LS's do run quite warm.

But in general, most engines run around 90 degC

[350Matt]

We found at Cosworth that once the coolant was over 85-90°C you start to lose power.

Below 70°C also costs power as the bores are tighter

Now obviously this is hugely dependent on the coolant flow layout / jacket design block material, thickness of castings tolerance on parts etc etc

But as an indication its a start

Matt