Harrymonk

For the past 3 years of running the car, the temp gauge will read consistently at 78°, irrespective of engine speed. This was with no shroud and a slimline fan tied directly to a skunk2 rad. This year has been different. It will run upto 85° at 80mph and in slow moving traffic this will increase to 90° which is understandable in slow moving traffic but once I get going again it takes a long time to cool down. The only thing I have changed is fitting a aluminium fan shroud. Could the shroud be preventing air from flowing through the radiator and also preventing heat from dissipating as quickly through the back of it? B18c4 civic ej6

Edit: something that occurred to me is before I had the fan fixed directly to the rad, I had the factory shroud and fan, back then the temperature was consistently 82°
So factory fan and shroud=82° consistent
Slimline fan no shroud=78° consistent
Slimline fan and alloy shroud=82° and rising
I have taking air temperature into consideration here also

oneheadlight

Do you mean 82 degrees fahrenheit? Or do you mean celsius.. Celsius would make more sense as 82c equals around 180 Fahrenheit.. With that said, think about an aluminum material fan shroud, that will absorb the heat so of course the temps would be rising. The factory is a plastic type (plastic composite) shroud which is slow in absorbing heat. So yes that's why your temps are increasing, try and put a plastic shroud back on there, that's why the honda engineers picked plastic for that situations.

Maxcapacity

lol, pretty sure they used a heat resistant, durable plastic because it was Cheaper, easy to mold and wouldn't damage the rad core being mounted on the face.
The aluminum shrouds work great if it was made right and sealed to the core. You need at least a half inch clearance from the core, use a appropriate size fan (cfm's equal or greater than stock) depending on your motors needs if stock or not. And make sure the shroud is sealed all around to the rad core or it will be inefficient causing not as much heat to not be drawn through the rad.
Maybe your slimfan and shroud is just not sealed tight enough to the rad and is leaking too much or it's too close to the core? What "alloy" did you use....I hope aluminum..


Here's mine I made, half inch clearance, had to offset the fan to clear the my turbo 3" down pipe but zero cooling issues. Also I used some heat resistant aluminum tape to seal the fine gap around the shroud to rad to make it air tight.

spAdam

iTrader: (1)

Well that shroud is blocking airflow over ~1/3 of your rad. In race car terms, you're running a backside shutter.

The factory style shrouds work because they act as a duct that forces the fan to pull air across the full rad surface and they don't block flow across any of the rad surface while the car is moving. Your space constraints won't allow for that.

I'm not a big fan of those style of shrouds (punnyness really unintended). Everywhere it's flat against the rad, you are getting zero airflow. I'd try cutting it out something like so:

NukeNinja

As long as you are moving in traffic, the fan is not part of the equation. In fact, most fans do not operate while the vehicle is going very fast. So yes, a fan shroud does inhibit airflow by blocking some of the frontal area. But cooling at speed is not usually an issue. I would be surprised to see a change in temperature.

The purpose of a fan and its shroud is to cool the engine when you are not moving at all, or moving very very slowly. As you slow down, at some point there will not be enough air movement to transfer the engine heat. And as your temp rises, your fan will turn on to recreate the air movement. At that point, cooling will be more effective with a shroud because the fan will move more air through the radiator.

Maxcapacity

My fan draws air across the entire surface of the core. The flat surface of the shrouds sits just over a half inch away from the core (as far away as I could get it) allowing the air to go only through the fan with the space limitation. Cutting it would only allow heat soak going straight directly to the core rather than onto the surface of the shroud and dissipate its heat from the exhaust piping being so close. Any who.. it works very well..
OP should just try sealing the shroud tight or run it whatever worked better.

spAdam

iTrader: (1)

Sorry, I got your post mixed up with OP's post. I was wondering why I was looking at (what I think is) an EF core support while we're in the 92-00 forum. Your installation is complicated by all of the hot side turbo parts near your rad. There's no clear answer there - maybe a formed duct to the fan would help. Shuttering off the backside of the rad is not ideal, and as mentioned above you really only care about fan flow while the car is stopped/moving slowly. But if it's not giving you problems then there's nothing you need to do at all.

Without seeing OP's new shroud, my lunch money is still on his new shroud shuttering the back side of his rad.

Harrymonk

Sorry for the late reply I didn't get any notifications from this thread.
Yes you are correct, the new shroud is acting like a shutter like you said. I thought about getting it cut out around the fan to allow more through flow but I think I'll remove it and go back to just a fan with no shroud - whilst it reduced fan efficiency marginally, it definately helped cooling at speed.
This is the shroud I have and its more obvious from the inside view how much it block through-draft of the radiator

tony_2018

I thought about bendin/making my own shroud to have better flow. these slim shrouds aren't helping

jdblock

I saw a youtube vid where they cut holes around the fan and then installed sheets of rubber over them to act like flaps. When the car was moving they would open, and at lower speeds they shut to allow the fan to work a little better.

Harrymonk

I think in warmer climates, the fan needs to be working as efficiently as possible but where I live, the fan without the shroud worked absolutely fine. I know this because I watch my gauges all the time, sometimes too much

jdblock

Depends how much you're moving. Had a track car with no fan and it cooled just fine in the heat.

tony_2018

Well...why is it not working now?

nd4sped

Cut air holes into that shroud. Check fan amperage draw. Perhaps its not flowing 100% anymore causing higher idle and low speed temperature.
On another note replace the thermostat.

Harrymonk

Im not sure what you mean. I'll go back to running the fan with no shroud as it worked fine when it did kick in at 92°, and I expect the temperature of the engine to go back down to what it was previously(78°). The thermostat opens at 72° and there are no air locks in the system

Harrymonk

Removed the shroud and refitted the fan using one of those plastic fan tie kits. Temperatures reduced by at least 5° at cruising speed, and over 100mph the gauge didn't go above 80° whereas with the aluminium shroud it was hitting 85° and in turn making the oil run hotter.

oneheadlight

wow so my first post that was being made fun of and discounted was correct all along.. imagine that! So the discovery that plastic absorbs less heat than metal, exactly what I was saying which is basic physics of elements.. It's why they use aluminum in engines (besides the weight savings) is because they have a better heat absorption rate.. Something you want in a radiator but not in the surrounding shroud, to those who made fun of the Honda engineers, guess you'll have to apologize that they did know what they were doing in designing the radiator shroud.. told ya so, feels so good!

Harrymonk

I think it was more likely due to the shutter effect of the shroud not allowing air to pass through and out the back of the radiator