Had a 1.6 race engine rebuilt. Makes great power but runs about 5* hotter measured at the back of the head than the previous engine. Heater core is bypassed.
I also changed the thermostat twice now to see if there was some imprecision between them. Both resulted in the same operating temps.
Any ideas on why I'm seeing the higher operating temps?
I'm getting the injectors cleaned soon in case there's an issue there.
More power means more heat.
That's my guess.
More power = more heat, and if the cylinder walls were bored, there's less cylinder liner mass to absorb the heat, so it gets passed to the coolant.
Same water pump impeller design?
Did you bypass the heater core at the same time as the new engine? My wild guess is that is your cause. The heater core acts as a mini-radiator.
The heater core accidentally acting as a micro-radiator even when off is one possibility...another could be an issue with how you bypassed the radiator, depending on how the coolant flow is laid out there can be a big difference between looping the lines vs. blocking them. Rubber blocking caps tend to be troublesome in my experience though.
You don't want to block them, that's where the bulk of the coolant flow goes before the thermostat opens. But once it's open, having the lines looped might encourage more coolant to bypass the radiator due to the decrease in restriction, and that will increase the temp. A well-chosen restrictor would probably work best. A bit of empirical testing might work.
If the bores were honed, they will have a lot more friction than broken in bores, and this will create more heat.
Is 5 degrees really changing anything during an outing? If it's still rejecting heat... I wouldn't worry unless your already on a ragged edge.
Sounds like you need a coolant re-route
5 degrees?
Different sending unit maybe?
Did you test with a mechanical gage to verify?
Is it overheating? No?
Then it is probably the new engine has a different normal than the old engine.
Noddaz said:Then it is probably the new engine has a different normal than the old engine.
So it seems.
Thanks fellas
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