Question on radiators

[earlbrown]

During the summer months I always remove the rear hood gasket that lets more air exit the engine compartment.

That's a high pressure area, not a low pressure area. If it does anything, it pressurizes the engine compartment and lowers airflow across the radiator the faster you go.

 

[ShaunKris]

To answer your question I have an old ATR radiator boxing kit. I would have to confirm but it seals up very well. I don't have the horizontal plastic piece though that goes from grille to radiator and I feel the air goes to the intercooler scoop right below it once it hits the radiator.
IIRC taking off the rear hood weather stripping doesn't really help. Something about it being a high pressure area at speed. Plus half of it protects the AC from sucking up hot engine air.
If your temps are skyrocketing from having some openings in the box kit I think you have another issue or you have a very crappy box kit. All the air should go into the engine compartment after it goes through the radiator, and then under the car.

I agree, radiator, water pump, thermostat, relay, fan clutch could be any one of those things. Is it an old rad original? Mine was original and the fins were litterally crumbling out of it. As In-efficient as could possibly be.. my car is a Hot, hot-air. Now I have no problems, before the new W/P, and Radiator overheating would happen very quickly.
This was my process of elimination,
1-top up fluid
2-make sure your w/p is pumping.
3-check your thermostat is functioning or just replace it. 160°
4-check the fins on your rad for corrosion, and make sure there are no blockages.
5-make sure your fan clutch is working, it should feel smooth resistance when turning cold by hand.
5a-if your electric, then check your grounds, connections, relays.
I hope that helps.

 

[Boostrules]

That's a high pressure area, not a low pressure area. If it does anything, it pressurizes the engine compartment and lowers airflow across the radiator the faster you go.

So the gasket that goes along the back of the hood by the windshield won't allow more air to exit the engine compartment if it's not in place? I totally got it wrong in my lay mans way of thinking that if you had less restriction for the hot under hood air to escape it would improve/lower engine compartment temperatures.

 

[captndave737]

If you want to know for sure tape some pieces of yarn along the bottom of the windshield and see what they do with the gasket in place and off.

 

[TurboSmart]

That area will actually suck air INTO the engine compartment.
Only at low speed (less that 25mph) the air will got out.

Check this video.

 

[No disintegrations]

The tricky thing about this whole discussion. During cool weather if the car has 180 tstat. The coolant will be right about 180*. Go figure! A well cared for system that's not clogged up as Earl said, may really shine on a 105 degree day but its hard to quantify how much heat is rejected by these systems. We end up either overheating or not. If I'm in car and it's hot out and it stays under 210 and no creeping up I 'm happy. Some want it to stay 180 on a 105* day and may not be realistic. Here's to NOT overheating !

 

[Boostrules]

If you want to know for sure tape some pieces of yarn along the bottom of the windshield and see what they do with the gasket in place and off.

That's actually a good idea, see if there is any difference at speed one way or the other. Looking at the video from Turbosmart I'm guessing it'll be counter productive like Earl said in which case most of the hot air must be exhausted thru the bottom of the engine compartment.

 

[Boostrules]

Now that I think back, in 1981 my girlfriend at the time had a brand new Citation X-11 with a 4 speed, H.O. V6 engine with functional cowl induction air intake. It really did work as evidenced by the dirt on the air filter. I seem to remember it had about 140 HP. I should have realized that removing that rear gasket would not exhaust heat but suck in more air and not help with getting more hot air out but restrict air coming in thru the front of the car. Thank you Earl for setting me straight.

 

[ShaunKris]

If you want to know for sure tape some pieces of yarn along the bottom of the windshield and see what they do with the gasket in place and off.

Pressure rises when airflow volume is restricted. If air flow is un-restricted then pressure decreases until it reaches a volume of flow where it starts to restrict again. There is math for that but it would be extremely difficult to measure.

 

[ShaunKris]

Pressure rises when airflow volume is restricted. If air flow is un-restricted then pressure decreases until it reaches a volume of flow where it starts to restrict again. There is math for that but it would be extremely difficult to measure.

There is also other math for maximum heat absorption on the existing pressure and heat and what not. But you’re getting very technical for the amount of Gains you’ll get out of it.

 

[ShaunKris]

Difference Between Pressure and Flow | Compare the Difference Between Similar Terms

Pressure vs Flow Pressure and flow are two terms often used when dealing with fluid; that is liquids or gasses. These two properties are characterist

www.differencebetween.com

 

[GNRick]

Boxed radiator and these. I think the fans turn off at 35 mph with the stock ECM and chip. Not sure about after market.

Fans turn off at 35 mph? Never heard this before!

 

[No disintegrations]

It makes sense because those speeds are stuffing air through the radiator faster than the fan can do it. So save some wear on the fan motor and ditch the electrical draw on the alternator.

 

[captndave737]

I'm pretty sure it's in the factory shop manuals somewhere. I'll see igf I can find it when i get a chance.

 

[captndave737]

I knew I had read about the fans shutting off somewhere in the shop manual. Turns off at 45mph. NA engines it shuts off at 35.

 

[earlbrown]

That would be with the stock chip on low speed. No idea if Eric or Bob leaves it alone on their chips.

 

[captndave737]

I have no idea what the other chips do but it would be wasted energy if they kept the fans running when the airflow was high.

The high speed fan only turns on when the temp. is over 248 deg., the AC pressure is over 300 psi or the delay relay is draining your battery while you’re asleep. Stock chip anyway.

I’ve rewired my system so the dual ram chargers fans are hot wired, and the 2 hot wired relays are controlled by the low speed relay. They run high only. The high speed relay, the delay relay along with associated wiring have been 86’d. When I had a chip they were turned on at 185 and off at 180. I have my Sportsman so they come on at 188 and off at 180

Stock wiring vs what I have done

 

[earlbrown]

It's defiantly a waste if it's running while the car is going fast enough to supply the raditator with the airflow it needs.


Much like it's a net negative to draw 10,000 watts of energy from the crank pulley running the alternator so you can have fans from a wind tunnel to cool an idling engine (that's making about 12hp at idle).

 

[salvageV6]

With Bob's extender extreme chip the fan will run above the lowered setpoint (175 ON 170 OFF for my car), without the A/C on of course, at highway speeds.

With the A/C on that pressure switch can keep the fan running at any speed including Key ON car not running.

Even at 70 mph you will still see a few degrees drop with the high speed fan on.

High Speed Fan is 226 degree turn on point, idiot light is 250 degrees.

 

[captndave737]

I never see temps above 190. Look at the schematic in post 55 from the factory service manual. It shows the high speed relay coming on at 248 deg.

The HS fan will come on with the AC on and the pressure above 300 psi regardless of speed is true but the pressure should be cycling above and below that so the and at WOT the AC cuts out. The low speed fan comes on at pressures above 260 PSI.