Just wondering if an engine can be
over cooled, say with a larger radiator?

I've noticed now with the colder weather my
CA18 runs much cooler, and the heater is quite poor.
It has a bigger rad.

Can a cool engine have bad fuel economy?

Justin

Hi ogyris

Yes Poor fuel consumption will be possible unless you get minimum heat required to run the engine smoothly,and also some time when the engine is not heated to required level it might knock while driving, so definitely
you may have less fuel consumption

Thanks
Regards
Sumith

yes it can be over cooled. if u are running a thermostat is should still get up to temperature before it opens to let the cool water in anyway, so should still run normal after heating up. if theres no thermostat then thats probably the problem.i think ca's run a pretty high thermostat, like about 195 F, and if its a turbo it will definately use more fuel if running too cold. also if its taking ages to heat up, u wearing out the bearings and bore etc more. u really should get up to operating temperature asap to eliminate as much wear as possible........

buy a new thermostat there cheap
check that engine temp is actually cool
ecu uses water temp for deciding to use cold start and other things
cold running wears out engines
did you delete any water lines when you did the conversion? ca's have a really complicated water piping layout
do you have the temp sender in the standard location?
cardboard over part of the core works
dazza

My ca18 has always run hot.. darn it..

As soon as I get on boost.. I see the oil temps skyrocket above 110 degrees...at some point nearby...the Autronic starts pulling back the timing etc. due to high temp threshold. I know about this ..so I also start taking it easy.

I'm wondering if my waterpump or N13 radiator are questionable.

Maybe bugsie's thermostat theory is my problem?

Everytime I was going for dyno tunes ..we'd have to stop to let it all cool down.

As for initial problem ogyris has asked about ..I'd say stuck open thermostat.

As said, over cooling is a problem, but what your saying does not explain over cooling, if your heater isn’t working right your thermostat isn’t working right or you’ve plumbed it wrong….Over cooling would be a oil cooler with no thermostat action or a radiator that is so big that the coolant on the outlet is to cold to let the thermostat cycle correctly, IE ITS MASSIVE... also coolant speed that isn’t high enough or is to high can cause amazing problems.. remember that coolant shouldn’t see more than a 12-14c delta drop from in to out or it will break down very fast causing deposits and all kinds of nasty things (most modern cars only have a 3-4c delta drop.

Start off by checking your thermostat, never run any motor with out a thermostat and be very careful running a low temp thermo in any nissan motor, at most use the 64deg nismo unit but make 100% your ECU is not adding any enrichment from 55deg onwards and use a taper scale up as coolant temp rises to ensure fuel ratio and timing stays the same which it will when your in heavy load or boosting for longer periods of time or obviously traffic, after all a cooler thermostat does not help cooling ability, it just starts the process earlier and helps buffer thermal shock a bit easier.

And yes, and engine running to cool has bad efficiency which = bad fuel consumption and in most cases lost power, especially if its running cool due to added cooling system ability, remember IC engines are only 30% odd efficient, 60% of its energy is being lost to the exhaust heat and radiator, by going mad on radiator your actually taking away from combustion heat which robs power, you generally never want to have a engine running to cool as the cooler it is the less efficient it is

Just my 2c (sorry the engineer in me coming out )

if the motor is over cooled it can also lead to wear of the rings from my memory and bearing wear as the oil and block etc are not opperating in theoir inteanded o or optimal efficiency range.

This leads to excessive a/f ratio running rich and washing the bores with excessive fuel, leading to oil contamination and the damage mentioned above.

Remember the oil temp is directly related to coolant temperature. In most engine designs, the oil runs about 20F/10C hotter than the coolant.

Now if you fit an oil cooler this changes, but the coolant temp still affects it. The heat has to go somewhere, and it won't wait until it gets to the radiator/cooler. Heat transfers anywhere it can: through the alumi head, valve stems, cylinder walls, etc. And if the coolant is hot, heat will flow from it into the oil passages.

So if you keep your coolant temp stable, it helps keep oil temp stable too.

you really want to run an engine as hot as you can get it without it boiling
look at some late model thermostats with over 100deg C opening.
if you lose pressure they boil instantly
oil needs to get to 80 deg to boil off acidic impurities
dazza

On my 720 pick up I used to have to partialy block off the radiator.......during the chilly Vegas winter. I wouldn't get any heat till I was almost to work.

As for over cooling on our Yamaha D-Sports Racer we blew 2 engines not relaizing the motor was over cooled. A friend at one of the driving experiances gace me a huge C&R radiator, sometines the motor would run as cool as 155 F, well at 12,000 RPM's the #4 rod would weld itself to the crank. I found pieces of the rod small end inside the transmission, one curly Q noodle looking small end actuall wedged itself under the started.........a call to a racer I knew who was the engineer for Yamaha's Superbike program is how I found out the problem was overcooling.

Tom