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Heat Soak And Running Temps

Gareth87

By Gareth87,
in Engines & Forced Induction

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Gareth87 Community Regular

Gareth87

Posted
Posted

Hi guys,

I just bought a big PWR radiator and twin 11" Spal fans for my FJ20 bluebird. The engine started making a lot more heat than the old radiator could handle since i built the engine. Anyway the PWR rad has certainly done it's job and is now bringing the temp back down, even at idle when the thermos are running. On the highway it runs around 75-78 deg, around town it runs between 77 and 82 and thrashing it normally sees no higher than 82 either.

Last night i was sitting in the heaviest traffic since i put the radiator in and it was stop start traffic for quite a long time. The temp sat between 83 and 84 for around 10-15 mins, but the thermos couldn't seem to bring it down any lower. Inlet air temps were coming up to 50 degrees as well, so i can only guess that the whole system became heat soaked and it couldn't move the hot air.

My question is,

1) How can i reduce some of the heat soak? - would things like a turbo beanie help?

2) Who else sees similar characteristics? (i realise 84 deg is still cool but i'm curious)

Thanks in advance,

Gareth

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R31Nismoid Grand Master

R31Nismoid

Posted
Posted

Just be a case of the fans have found their limit in terms of airflow and cooling.

Driving around you were no doubt getting aid from the actual speed of the car + fans, rather than the fans outright which in stop/start has lead to it picking up. If you had 5mins of moving (80km/h+) it would've come back down.

If you have heat shielding deflecting the heat, of course that will help - however I'd see it as almost inevitable that it will heat up to those types of temps. Ambient air temp also plays a factor, was it warmer than normal perhaps?

Also if there are larger fans/CFM, this might also help. Perhaps water spray for the I/C as well to get temps down.

Still as you said, 84 is still low and it's really not much of a drama.

Duncan Grand Master

Duncan

Posted
Posted

What temp does your thermostat open? The skyline ones are high 70s (79?), so 84 would be a perfectly normal running temp. Remember, the motor needs to be warm as per nissan's design to work efficiently (particularly fuel)

I wouldn't worry about the temps until they head past 100 under heavy use.

Gareth87 Community Regular

Gareth87

Posted
  • Author
Posted

Hey guys,

the thermostat is 77 deg, and from running it with the cap of the rad, it seems as though the thermostat is fully open and water running flat out by 82.

It was a warm evening and then i drove around an underground carpark so i think it was pretty good really, i was just interested to see the effect heat soak had and if you guys have the same sort of characteristics. As soon as i got moving, the temp came straight down again.

As for the PWR rad. Its fantastic. worth every bit. The rad is no bigger, but it runs PWRs close mesh core now and 2 top quality SPAL thermos that cover the whole radiator. Before, once the thermos came on, even on normal road cruising, they couldn't bring the temp down and going up a big hill, it would just climb, as it would with stop start traffic. Now, the hottest i've seen it was 84 the other night in traffic.

Obviously i want it to be able to pull the temp back down no matter what, even at idle, so im curious to know how other cars (especially with big cams and lots of stuff to make them hot) react in heat soak conditions.

Has anyone else had the same heat soak effects and what can help? (R31 nismoid, water spray on the cooler i know works well from having it on the dyno)

Cheers for the input,

G

AngryRB Grand Master

AngryRB

Posted
Posted

I dont have too much trouble with temperatures, but i noticed mine goes up several degrees when the a/c gets turnt on, has gone up to 87 and thats cruising on the highway,

apparently the underbody cover, is that what you call it? aids in cooling the underbonnet temps, thats what i was told and for the heat soak you can put the air filter in the front bumper down infront of the wheel, thats what im having done with mine.:thumbsup: plus some ceramic coating on the turbine housing etc

GTR_JOEY Grand Master

GTR_JOEY

Posted
Posted (edited)

well naturally the temp is goin to go up a little bit as the A/C condensor sits right in front of the radiator

the radiator is now getting hotter second hand air flowing through it

i imagine that would effect the temp a few degress

that and you are loading up the engine with an extra auxillery component

Edited by GTR_JOEY

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