How well is the ENTIRE radiator (or intercooler) used?

[ShaggyZ]

I don't know anything about fluid dynamics or whatever one would need to know about how the coolant (or air) would flow in a radiator (or intercooler). In my head, I don't see how the fluid can move down the end tank (thinking side tanks, not top/bottom) uniformly in such a way that the entire radiator would be used. Seems like there'd be a lot of comparatively slow-flowing (or stagnant) areas. Am I wrong?

 

I'd love to see test results using a thermometer gun on 6 sections of the radiator to see which tubes are getting the most heat and which are radiating the most by the end. Obviously, it would be great to see someone post results from one them fancy fluid software programs. I've seen one here for a few intercooler designs.

 

 

 

I've thought about running two smaller radiators or a single radiator with custom end tanks so it acts like two and then running Y-splitters to and from the engine.

[johnc]

I don't know anything about fluid dynamics or whatever one would need to know about how the coolant (or air) would flow in a radiator (or intercooler). In my head, I don't see how the fluid can move down the end tank (thinking side tanks, not top/bottom) uniformly in such a way that the entire radiator would be used. Seems like there'd be a lot of comparatively slow-flowing (or stagnant) areas. Am I wrong?

 

I'd love to see test results using a thermometer gun on 6 sections of the radiator to see which tubes are getting the most heat and which are radiating the most by the end. Obviously, it would be great to see someone post results from one them fancy fluid software programs. I've seen one here for a few intercooler designs.

 

 

 

I've thought about running two smaller radiators or a single radiator with custom end tanks so it acts like two and then running Y-splitters to and from the engine.

 

If your focus in your car build is heat exchanger efficiency then two smaller units will improve the efficiency of the heat exchangers - at the expense of greater weight, system complexity, and cost. If your focus is the temperature of the coolant exiting the heat exchanger, then one heat exchanger has proven to by a very effective and simple design.

[ShaggyZ]

If your focus in your car build is heat exchanger efficiency then two smaller units will improve the efficiency of the heat exchangers - at the expense of greater weight, system complexity, and cost. If your focus is the temperature of the coolant exiting the heat exchanger, then one heat exchanger has proven to by a very effective and simple design.

 

Thanks, John. That is helpful to hear from you, but I'm looking for something specific. I guess no one here has pointed an infrared thermometer or otherwise measured temps around on a radiator. The Z radiator is so easy to get to compared to my other two cars (near impossible to get everywhere) but it's not together so I can't test it myself.

Edited December 1, 2010 by ShaggyZ

[bjhines]

If you look at high-performance, high-budget equipment you will see a whole new level of heat exchanger efficiency and complexity. Automotive radiators were meant to be stamped out cheaply. We actually get great performance for the money. You can verify with a fast responding thermometer in several areas. I am sure the water flow will vary with engine speed, thermostat opening, etc. You really want to know how the radiator performs at road speed and stopped with the fan running.

 

The real deal would be for someone to rent an IR camera and run the car on the road while recording. You would need to spec a wide angle lense to facilitate mounting the camera close to the front clip. I say go for it!!!

 

We have already found that excess airflow into the engine bay will adversely affect radiator performance. You have the whole aero thing to consider there.

[bodie]

Thanks, John. That is helpful to hear from you, but I'm looking for something specific. I guess no one here has pointed an infrared thermometer or otherwise measured temps around on a radiator. The Z radiator is so easy to get to compared to my other two cars (near impossible to get everywhere) but it's not together so I can't test it myself.

 

actually i have run a ir thermometer across a radiator, i do it one a regular basis to check for a stopped up radiator. you should see a uniform temp at the inlet tank across the fins and as you travel down the core to the outlet tank youll see the temp drop uniformly. if you got cold spots then you got a stopped up radiator. usually see a temp drop from 50-80 degrees depending on veh, amb temp and fan speed.

[Tony D]

I guess no one here has pointed an infrared thermometer or otherwise measured temps around on a radiator.

 

Oh, I've done that EXTENSIVELY but I'm swamped at work now doing some temperature profiles on compressor gearcases exhibiting an oil whip phenomenon... My head is so full of those figures now I can't remember specifics from my surveys.

 

Driving to Albequerque for the convention, and then again to Kingston Ontario I did extensive measurements, including using thermocouples under hood, in the coolant flow, and at various other places.

 

It's how I realized Atmospheric Aerosols and decrease in UV results in a lower temperature thermal layer at radiator level (which explains why a car in SoCal or Arizona overheats on an 85 degree day, and the same car runs cooler on a 100 degree day in Iowa---thermal layer in SoCal is 120+ while in Iowa it's only 103!!!)

 

There is a reason there is a tank on the other end---it mixes good cooled fluid with 'poorly' cooled fluid. You can use that IR gun to find plugged tubes from calicum plugging, etc... It DOES show exactly where it's working for exchange and where it's not.

 

You should know better than to make a statement like that!

 

<EDIT> Oh, and to BJ's comment: somewhere around here I got a thermalgraph taken in 1992 by BEST (Bivens Energy Scanning & Testing Service) when they came to my plant to shoot our switchgear and MCC Buckets. He had JUST gotten the new camera (no more filling it with LN2!) and was up to take photos of anything and print them out (New kid with a multiple-thousand dollar toy!) I got him to shoot our building, most of the operators (an myself) as well as my cars headers, radiator, and engine!

Edited December 11, 2010 by Tony D

[getoffmyinternet]

Wouldn't a multipass radiator be the most conventional fix, rather than trying to use two smaller radiators etc.? It essentially multiplies the aspect ratio and the fluid stirs as it changes direction.

[bjhines]

One problem I see with a multipass is that(for an equally split multipass) there is 4x the restriction for a given area. There are half as many tubes in parallel, and twice the distance to travel through the tubes.

 

Another issue might be that the second pass is too cool to transfer much heat.

Edited December 11, 2010 by bjhines

[bjhines]

This is truly a tough problem to deal with. I have given some thoughts to this but nothing has come of it yet. Improved radiator design could use fancy header tanks, mixer tanks, etc for better consistency, but there are bigger fish to fry. Do you really want a $1000 radiator in your car?

 

1. Coolant flow through the engine could be improved on the Nissan L6 and the Chevy V8. What I notice in modern engines is that they maintain very high temps internally. They also spend some effort to keep intake passages COOL(er) and the cylinders HOT.

 

2. Outlet designs have changed. Some engines use a thermostat heater to add electronic control to the thermostat opening(BMW E46).

 

3. Temperature is monitored in more places on modern cars. Cylinder head temp. Block temp. Thermostat outlet temp. Radiator outlet temp. Ambient air temp. Intake air temp. The computer can use all of those values to control the fan and thermostat heater.

 

4. The engine inlet might benefit from mixing hot and cold coolant more effectively.

 

5. Modern engines have recuirculating expansion tanks to get rid of steam bubbles with a constant bleed from the hot spots to the expansion tank. The bottom of the tank is plumbed to the water pump inlet. You need a high pressure expansion tank to do that though.

 

6. A complete redesign of the waterpump system might include 1 or 2 electronically controlled pumps to maintain perfectly consistent flow through the engine regardless of how much water is passing through the radiator.

Edited December 11, 2010 by bjhines

[bodie]

Modern engine run hotter due to the engine burns cleaner and more efficient at a hotter temp. electric thermostat were included in some vehicles to keep the temp at a constant temp. To keep the coolant from boiling over the oems have increased the pressure. for ever psi of pressure increased the boiling point like 3 degrees.

you shouldn't have any problems keeping and engine cool with the proper radiator and thermostat. With a 2jz you might also add and oil cooler due to it being a turbo motor.

[hoov100]

Modern engine run hotter due to the engine burns cleaner and more efficient at a hotter temp. electric thermostat were included in some vehicles to keep the temp at a constant temp. To keep the coolant from boiling over the oems have increased the pressure. for ever psi of pressure increased the boiling point like 3 degrees.

you shouldn't have any problems keeping and engine cool with the proper radiator and thermostat. With a 2jz you might also add and oil cooler due to it being a turbo motor.

 

I don't know where you got that info, but most newer cars run about the same, the difference is that newer cars don't have as many hot spots where there is poor circulation or flow.

[bodie]

no your wrong, most newer motor run at least 20 degrees hotter than motors 20 years ago. most motors runs around 210-220 range where the old motor ran 190-200 range.

[johnc]

Do you really want a $1000 radiator in your car?

 

 

The one I ran in the ROD was about $1,200 but it had a Niagra water/oil heat exchanger built in and was a very custom two pass from Visteon.

 

 

Except for a bypass sizing problem which took a couple events to solves, I never had any water or oil cooling issues even at WSIR on a 110 degree day.

[bjhines]

There is a 2-pass design that solves the issues I mentioned. It has much larger tubes for good flow. It also uses the second pass to get rid of heat picked up from the oil cooler.

 

and it's rediculously expensive.

[Snailed]

The one I ran in the ROD was about $1,200 but it had a Niagra water/oil heat exchanger built in and was a very custom two pass from Visteon.

 

Except for a bypass sizing problem which took a couple events to solves, I never had any water or oil cooling issues even at WSIR on a 110 degree day.

All that radiator and you strap the fan right to the core? The car never runs at slow speeds I take it?

[johnc]

All that radiator and you strap the fan right to the core? The car never runs at slow speeds I take it?

 

No, the fan is bolted to the the two vertical aluminum "L"s. I later removed the fan completely because it wasn't needed on a pure track car.

[Snailed]

No, the fan is bolted to the the two vertical aluminum "L"s. I later removed the fan completely because it wasn't needed on a pure track car.

Oh, that's neat. Is it common to run no fan at all on a track car?

[johnc]

Oh, that's neat. Is it common to run no fan at all on a track car?

 

A lot of dedicated road race cars do not run a fan unless the rules require it.

[getoffmyinternet]

To paraphrase the way many have put it, a proper cooling system is a whole package, not just a really efficient radiator. And yes, a high tech system could be very expensive and only worth doing if you're actually having heat problems already. I guess you could just run 11 different radiators throughout the vehicle like the geniuses at volkswagen...

 

 

Another issue might be that the second pass is too cool to transfer much heat.

 

If the second pass being too cool to give off much heat is the problem then I'd say we're in pretty great shape. I've never really considered the restrictions to be a possible issue though. It seems that a clean radiator of that size would be pretty free flowing. Do any manufacturers offer a core to outlet size ratio? I wouldn't be surprised if sum of the area of all the vanes is actually greater than the inlet itself even on a multipass.

 

 

The one I ran in the ROD was about $1,200 but it had a Niagra water/oil heat exchanger built in and was a very custom two pass from Visteon.

 

 

Except for a bypass sizing problem which took a couple events to solves, I never had any water or oil cooling issues even at WSIR on a 110 degree day.

 

A combination of two heat exchangers in one?? The core has to be twice as thick just to be as efficient as the alternative (which it looks like it is). But how well does it cool the water if the hotter oil is going through the same core? It seems that relatively the oil would run cooler at the expense of the coolant running hotter, not that it's a bad trade.

 

 

Has no one mentioned a fuel/oil exchanger yet?

Edited December 17, 2010 by getoffmyinternet

[bjhines]

Tony D. drug out the fuel/oil example a few years back. I don't see that as a good alternative when you only hold 10-15 gals of fuel.