Hot days! A cooling system that works

[BrandonsZ]

I don't have any pans, and no sealing between rad and core. My fan fuse blew a couple months ago, it was a hot day 80's and my gage never got above 1/2 on the freeway (stock gage) and in neighborhoods it only climbed to about 5/8 at slow speeds. Over 25 it went down again. I normally drive to work 19 miles or so without the fan turning on in the morning.

[jgkurz]

I've been having problems keeping mine cool as well..

 

demidian, I'm surprised you are having cooling problems with your setup. Your fan has decent CFM so assuming it's shrouded properly that shouldn't be your problem. Let us know how the new radiator works out. I'll bet that cures the problem.

 

As for us turbo guys we simply have too many heat exchangers on the front of the car.

[MikeJTR]

An extremely powerful and thin fan that fits between the JTR radiator and the 6-cylinder engine, is the fan used in the Volvo S60, S70. These can be purchased on ebay. Normally, the fans on ebay have broken controllers, but these are normally removed, and power can be wired directly to the fan motor.

The shroud is about 17" x 24",and the overall thickness is slightly less than 4".

The fan is 16" diameter, and the thickness of the fan/motor is less than 3-1/4".

The fan draws about 30-35 amps, and is being used in 1993-1995 LS1 powered RX-7 with good success.

We are looking at making a universal mounting bracket for this fan, so that it can be used with our 6-cylinder radiator kit.

[jgkurz]

An extremely powerful and thin fan that fits between the JTR radiator and the 6-cylinder engine, is the fan used in the Volvo S60, S70. These can be purchased on ebay.

 

I've actually installed one these fan's on a friends V8Z. Your right about the amperage draw. They pull some serious AMPS! I know it will cool my friends car but I wasn't sure about how it compares to the 3850 CFM Zirgo fan I mentioned above. I guess there's no real way to verify without installing and testing.

[jgkurz]

I used to think my cooling system was good until the three digit temps hit this summer. I have an Arizona Z aluminum radiator with dual 10" fans behind a full face custom shroud. The temp gauge will stay in the middle or slightly past middle when it's 100 degrees or more. Unfortunatley it's game over when I turn my A/C on. Temps start climbing ever so slowly until I turn the A/C off. My problem is I have an intercooler that covers 3/4 of my radiator. My fans don't pull enough CFM through the intercooler and condensor to cool the fluid before it goes back into the engine.

 

Space is tight but I'm thinking about trying a 3895 CFM fan from Zirgo.

 

http://tinyurl.com/rbc6l

 

I'm just not sure I have room for the fan motor let alone a decent shroud. The jury is out whether a single high CFM unshrouded fan is better than two lower CFM fully shrouded fans.

 

Honestly' date=' I'm a little annoyed that I went through the trouble of keeping my A/C and can't even use it. Grrrrrrrr [/quote']

 

 

 

Well, I made some changes that seem to have made a difference. I can run my A/C and the temp stays in the middle of the gauge. I can even tell when the thermostat opens because the temp will go down slightly. I'm not sure which one's helped or hurt but this is the list.

 

1) Installed the OEM belly pan

2) Changed to coolant ratio to 90% water/10% antifreeze

3) Added an air diffuser lip just rear of the radiator to create a vacuum in the engine compartment

4) Removed my front license plate that was directly blocking the radiator

[BrandonsZ]

You might want to go back to at least 40-50% AF or you may get rust especially if you have alum heads and iron block. Also the iron impellor on the waterpump will turn to dust, that'll cause a slight change to the performance of your cooling system.

[LS2 V8 Miata]

Ultimate answer, which is our "proven" solution here in "Smoking Hot Arizona"; Ron Davis Racing Radiators.

 

Talk to Bill Williamson, Manager 800-842-5166 he's one of my best friends and he drives a 400 HP V8 Miata himself.

 

Hope it helps

 

- Lee

[jgkurz]

You might want to go back to at least 40-50% AF or you may get rust especially if you have alum heads and iron block. Also the iron impellor on the waterpump will turn to dust, that'll cause a slight change to the performance of your cooling system.

 

I don't plan to run the 90/10 mixture permanently, it was just for troubleshooting. The proper fix is to get a better fan and more effective shroud.

[LS2 V8 Miata]

Reason I mention our radiator set-ups is because we (V8 Miatas) run 400+ HP, headers, accessories in a tiny engine bay a fraction the size of a Z-car's (Miata to Z-car= Car to Truck) in Arizona (routinely see 110 degree days through summer). We run our cars HARD on track days, on roadracing courses (125 degree track temps) all without any overheating problems.

 

Also your discussion while addressing the corrosion possibilities is lacking the most important points of AF / Water mixtures to cooling.

 

Water is THE most efficient cooling medium with a specific heat value of 1.0 Anti-freeze has a specific heat value of .75. That means for every gallon of Antifreeze in your system you are only getting 75% the cooling capability compared to a gallon of straight water. More Anti-freeze in mixture means LESS cooling.

 

And if you're considering higher Anti-freeze concetrations just to prevent rust possibilities you can get just as good corrosion resistance running 100% water with a water-pump lube / corrosion inhibiter available at any auto supply.

 

My Miata's radiator is 27 X 16 with shrouded, dual Spal 13" fans. I don't know how that compares with what you run in Z-cars now.

 

My Ford 289 V8 in my 73 240Z overheated constantly, until I got a new radiator fan combo sized correctly.

 

Just thoughts.

[John Scott]

Reason I mention our radiator set-ups is because we (V8 Miatas) run 400+ HP' date=' headers, accessories in a tiny engine bay a fraction the size of a Z-car's (Miata to Z-car= Car to Truck) in Arizona (routinely see 110 degree days through summer). We run our cars HARD on track days, on roadracing courses (125 degree track temps) all without any overheating problems.

 

Also your discussion while addressing the corrosion possibilities is lacking the most important points of AF / Water mixtures to cooling.

 

Water is [u']THE[/u] most efficient cooling medium with a specific heat value of 1.0 Anti-freeze has a specific heat value of .75. That means for every gallon of Antifreeze in your system you are only getting 75% the cooling capability compared to a gallon of straight water. More Anti-freeze in mixture means LESS cooling.

 

And if you're considering higher Anti-freeze concetrations just to prevent rust possibilities you can get just as good corrosion resistance running 100% water with a water-pump lube / corrosion inhibiter available at any auto supply.

 

My Miata's radiator is 27 X 16 with shrouded, dual Spal 13" fans. I don't know how that compares with what you run in Z-cars now.

 

My Ford 289 V8 in my 73 240Z overheated constantly, until I got a new radiator fan combo sized correctly.

 

Just thoughts.

Your temps sound brutal. The Griffin radiator is 19 x 24 x 3....Its going to be hard making side by side comparisons with all the engine variables, water pumps, power ratings, displacement, etc but if it works in your conditions it should about anywhere.

[Mike Mileski]

I still think the real telling factor on how well a system cools is when you're sitting in traffic at idle. The lack of forced air flow, combined with no easy escape route for the hot underhood air, may even be worse than flat out track driving. Even though I haven't had any cooling issues, before I add my AC, I plan to louver the hood or install some functional hood vents for hot air to escape.

 

Mike Mileski

Tucson, AZ

[jgkurz]

I still think the real telling factor on how well a system cools is when you're sitting in traffic at idle. The lack of forced air flow, combined with no easy escape route for the hot underhood air, may even be worse than flat out track driving. Even though I haven't had any cooling issues, before I add my AC, I plan to louver the hood or install some functional hood vents for hot air to escape.

 

I agree with Mike. Idling in stop and go traffic with A/C on is a real test of a cooling system. Additionally I think the way a fan and shroud are setup have a great deal of affect on the way air flows through the radiator. I have recently learned that my dual 10" fan and custom shroud setup is far less than ideal. I built a flat aluminum shroud that basically covers the whole backside of my Arizona Z radiator. I then cut two 10" holes for my fans. The flaw in this approach is that my so called shroud is flat and roughly 1/2" from the core. This does not allow the air to funnel air into my fans. Basically I only have two ten inch holes that are being cooled with the rest of the radiator having no air flow. With the flat shroud removed and a large single caged fan installed I think the air coming in through the grill will pass through the radiator properly and out through the hood vents. For the hood vents to work properly I think the OEM belly pan should be installed.

[Oldestzguy]

After shroud and underpan and maybe wrapping the headers, the next best thing might be to put two small six inch fans in the bottom of the engine bay on each side to "pull" the hot air out. that's what I did with my old Limo and no more blown rear a/c hoses while sitting in traffic.

[COZY Z COLE]

After shroud and underpan and maybe wrapping the headers, the next best thing might be to put two small six inch fans in the bottom of the engine bay on each side to "pull" the hot air out. that's what I did with my old Limo and no more blown rear a/c hoses while sitting in traffic.

 

 

Here's a write up on that method...

 

http://www.georgiazclub.com/tips/ztech/v8cooling.htm

 

 

LARRY

[JMortensen]

The fan might work better in traffic, but I still like the idea of a couple of large hood vents. Not only will they let the air out, they also reduce lift from the pressure under the hood at speed and sending that air back out the top instead of around the side or down below the car.

[LS2 V8 Miata]

Your thinking Jon, is borne out in my Miata's application.

 

I fabbed & installed these hood louvers and they work great. The area of the openings is equal to the frontal area of the car's mouth. 0 under-hood pressure. Not only do visible, intense heat waves pour out (natural convection) of them while I'm sitting at a stoplight on hot days, my top-end, straight-away speeds have increased by about 3-4 MPH. I also have additional air-inlets integrated with my parking lights

 

The nasty vibrations at high speed and hood bulging are no longer problems. The Miata also has an under-body tray that encloses underneath, starting from below the air dam to aft of the steering rack. I've never run with mine off before so I don't really know the true effectiveness.

 

I should mention after "chasing" a number of small, individual solutions in trying to cope with our "extreme" hot environment (Arizona) that an "over-all" approach with a great radiator, fans & shroud, air inlets, louvers is sure the way to go.

 

Different subject, I once had an "experience" when the metal Z medallion flew off of my V8 240Z's hood (noticed your picture) and shattered my windsheild at around 160 MPH! (Pucker factor 10 as we used to say in the Navy) just a thought.

 

- Lee

[MikeJTR]

.

 

Space is tight but I'm thinking about trying a 3895 CFM fan from Zirgo.

 

http://tinyurl.com/rbc6l

 

I'm just not sure I have room for the fan motor let alone a decent shroud. The jury is out whether a single high CFM unshrouded fan is better than two lower CFM fully shrouded fans.

 

I doubt the Zirgo fan would help you. It only draws 10 amps.

The thin blades (compared to the Ford Taurus or Volvo fan blades) don't move air as well as the thicker blades.

I believe the CFM ratings of the Zirgo fan are both exaggerated and meaningless.

On another note, I do like your car, the pictures and video are quite impressive.

[jgkurz]

I doubt the Zirgo fan would help you. It only draws 10 amps.

The thin blades (compared to the Ford Taurus or Volvo fan blades) don't move air as well as the thicker blades.

I believe the CFM ratings of the Zirgo fan are both exaggerated and meaningless.

On another note, I do like your car, the pictures and video are quite impressive.

 

My understanding is the S blade fans are quieter but move a little less air. The straight blade fans are suppose to move more air (CFM) but are noisier. Whether I use the Zirgo or a Flexalite fan, I think (hope) a large high CFM fan plus a removing my faulty shroud with be a big improvement. With the intercooler tubing I don't have room for the Volvo or Taurus fans...

 

Thank you for the comments.

[MikeJTR]

With the intercooler tubing I don't have room for the Volvo or Taurus fans...

 

Thank you for the comments.

 

 

I just measured a JTR radiator with the Volvo/Taurus fan, and custom (prototype) fan brackets. There is about 4" from the front of the radiator (where it bolts to the Datsun) to the back of the fan blade (in the area of the upper intercooler pipe).

Would this fit in your application?

[LS2 V8 Miata]

Nobody really likes paying anything extra, but there are a lot of custom sized radiators available with fans & shroud assembled that are absolutely worth the extra dollars to protect the big investment in a serious engine.

 

I have a small budget just like a lot of guys but I reasoned since it took so long to save for my LS V8 I damn sure wasn't going to scrimp on keeping it cool and protecting it.

 

Pix of my radiator and also (space utilization comparison) early RX7 with a Turbo Buick Grand National V6 GNX installed (Thanks, Scotty's project, not mine).

 

Have a great week-end guys

 

- Lee