rb26 overheating at idle/traffic

[gtrjon]

So guys my gtr started overheating today while i was sitting in a drive thu for 10 minutes then stuck in traffic for a while. Im pretty sure its not my thermostat since it never overheats unless its stuck in traffic on a hot day. Im thinking my n1 water pump could be flowing too fast? I am running twin 12" electric fans that are hard wired to ignition and are always on and have always done the trick? any ideas?

[nimblestix]

Hey Jon,

Where are you taking your reading from? I had this issue too, until I swapped back to the OEM fan.
My defi gauge temperature would rise in stop and go traffic, and level out on the freeway, although the laptop/ecu showed it was running at operation temp.

Sent from a galaxy far, far, away.

[Skym]

Use stock Subaru radiator fans, shroud to suit, as have a wider blade design -



With road spec engine you are meant to run a stock waterpump. N1 waterpump is for racetrack only, as reduces cavitation (creation of bubbles) at higher rpm. Usually engines with N1 waterpump have overheating problems in stop and start traffic.

Nismo run stock waterpump on S tune engines -

http://www.nismo.co.jp/omori_factory/original_menu/engine_m/s2/index.html

[frankiman]

i've never had problems with overheating in my GTR except for 1 time, when the car was parked at idle with the wind to its back, air just couldn't enter the rad, maybe thats what happened to you too

[Dragon Humper]

And....electric fans pull FAR more air through the rad at idle than the stock one would. Could be the N1 water pump isn't flowing enough coolant at idle, hense why they wouldn't cavitate at 7000rpm. My car has a standard pump, Infini must have left it that way for a reason.



Jon.

[MarusGTR]

Yeah its your N1 pump. Use parts for your application; the N1 raises its flow rate for high RPM, leaving idle starved where N1 use was not considered for.

[Dragon Humper]

Actually I think the N1 lowers the flow rate everywhere, to much flow is just as bad if not worse than to little flow. The coolant needs to spend enough time in the rad to actually cool it off. Like soldering, the iron needs to make contact long enough to melt the solder. If you assume that the flow rate is linear, enough flow at idle to keep the car cool on a hot day with the AC running would be way too much at 7000. Because the system can only flow so much due to restriction the pump cavitates (its not positive displacement) and literally stops flowing coolant. The N1 flows less at 7000 and has a backing plate behind the impeller to prevent cavitation. I bet the stock pump flows more than the N1 up to the point of cavitation.

Is your temp sample being taken from the upper rad hose? Get one of those cheap temp guns from Princess Auto, when your temps are really high, measure the temp at the top and then the bottom of the rad. If there is a huge difference in temps the flow is really slow, almost the same, too fast. If its too slow, simply revving the engine to 2500 while standing should drop the temp pretty quickly.






Jon.

[NismoS-tune]

Could either go back to a factory water pump (for your daily driver) or undersize the pump Pulley a little to gain some flow

[Skym]

Blade design is different on N1 waterpump vs stock waterpump (top is N1) -



Can see why N1 water pump wouldn't create alot of bubbles. But they still run a header tank on racecars to remove the bubbles from cooling system.

[MarusGTR]

Actually I think the N1 lowers the flow rate everywhere, to much flow is just as bad if not worse than to little flow. The coolant needs to spend enough time in the rad to actually cool it off. Like soldering, the iron needs to make contact long enough to melt the solder. If you assume that the flow rate is linear, enough flow at idle to keep the car cool on a hot day with the AC running would be way too much at 7000. Because the system can only flow so much due to restriction the pump cavitates (its not positive displacement) and literally stops flowing coolant. The N1 flows less at 7000 and has a backing plate behind the impeller to prevent cavitation. I bet the stock pump flows more than the N1 up to the point of cavitation.

Jon.

I meant the flow rate distribution, i.e. flow vs RPM is translated towards higher RPM for a higher efficiency under a track environment.

I just wrote my last comment like a potato because I'm fed up with writing, my last article to a prominent scientific journal got refused by someone who couldn't even spell their concerns right, let alone follow some grammar.

Skym; I assume less blades, less wake, less low pressure zones, less cavitation. Edit: ...and it seems from your pictures that the N1 blades have a reduced attack angle and have actual curvature. It should cause nice even flow and not just shearing fluid around.

[Fred-R]

Have recently read some info about the pros & cons about electric vs oem fan: Many rb26 drivers said that oem is better and many have experienced overheating with electric's... Can't remember why tho. Read on other forums about it (you prolly already did it...)

[steveo1502]

I just installed a big rad, dual electric fans, shroud, it gets Warmer than with the stock, I think because te stock fan keeps spinning and drawing air where the electric stops until it reaches temp, then it kinda has to catch up, especially with the ac on it heats up more too

[Skym]

Most that do encounter it with electric fans switch to stock Subaru fans which solves the problem. It's something to do with the blade design (I'm no expert on blade design). Subaru wouldn't run fans on radiator, have engine overheat. They have done alot of testing to workout what works and have control module, temp sensor on block to control speed of fans. There is a aftermarket version of these control modules which can be programmed to control the fans (can't remember the brand name, but know they exist).

[nimblestix]

I found with my twin electric fan's the engine would overheat often in the city. After installing the oem clutch style, even without a shroud i saw an immediate improvement. To add, the oem fan seem to draw much more air than my electric fans were.

Having said that! If you were to invest in a set of high flow fans (2000-3000 CFM combined), i believe they will move enough air to keep her cool'.
I had explored this route before making my decision on the oem setup, at the time i found the electric options either too expensive or I couldn't fit the sizes required due to my power steering lines and oversize radiator.

[xcye]

Please also check your radiator cap or leakage, If your coolant system does not hold pressure very well, then you will have overheating issue.