getting hot

[vettestr]

This is long winded but a story of chasing an overheating problem that I went too far on right at the end. The engineer and help from C & R rad was incredible, thanks Mark. All the listed steps are the standard point by point checks but I then got frustrated and went bigger is best with a radiator choice. I was so close then created my own next set of problems masking all others, ones I already solved.

Being based in sunny Arizona and tasked with making cars reliable and enjoyable the bane of overheating has been a long nightmare. Although self proclaimed I do consider my abilities at least fair. I was just taught a new lesson from an engineer at C & R Aluminum Racing Radiator http://www.crracing.com/ . We spent 1/2 an hour going over testing and theory. In the end I had TOO MUCH radiator and this caused the overheating. I was close before the rad. change masking the end result.
1. We went over the basics of engine performance (meaning was it running close to proper settings). 2. Was the coolant flow system at full performance potential. Did I have water pump overdriven or running faster than the crank by 15 to 20 %. The W.P. pulley should be 20 % smaller than the crank pulley and the pump should be in good condition. 3. Did I have a T-stat and at a realistic open point. If you want the engine to run at 180 why install a 160 T-stat. Do not remove T-stat as you remove the ability for stem to cycle and therefore must live with the average of all conditions. 4. Did I have system pressurized to proper level to increase heat transfer and decrease boiling point to operating levels. A system pressure of 12 to 14 works but if you run hotter it will puke coolant and game over, run a higher cap to have a little safety net I like 18 PSI. It is not high enough to damage other items but keeps coolant in the engine.
Now we can get to the radiator and is it enough surface area to cover the heat generated? More is better when talking frontal area but it must have air flow to be usefully. 5. Frontal surface area and ducting of air intake is a key. 360 degree front ducting means no open bottom to dump air pressure at speed. 6. A shroud and GOOD pull fans on the back side to force airflow at lower speeds is needed. Fans are a biggie here and many are advertised as having a much higher flow than the real world when you restrict the inlet to them... like a radiator !!!! Next is proper amperage supply to these fans, if supplied with low voltage or low amperage then their performance drops like a rock. Use a relay to supply full system voltage and amperage in the 30 to 40 amp potential range. Do not tie into a 18 gauge wire found under the hood someplace that may be feeding your ignition ,fuel pump or whatever.
Now here is where I screwed the pooch!! Bigger has to be better and I did all the above but had a heating problem. It was now right on the verge of OK but would creep up and traffic was a killer. I could not get a larger frontal area so I went to a higher fin per inch and more tubes. I bought a C & R Cup radiator. If it worked in a Winston Cup car at 900 HP then this should be a piece of cake even at 120 degree Phoenix day... Right! Well I went to far and the high fin count and 4 rows of tubes made a 4 inch core. The electric fans could not move enough air through the restriction I installed. A 180 miles per hour would force air through but the twin 14 inch puller fans did not stand a chance. Even highway speed with the fans pulling away were marginal.
I went to a lower fin per inch count and 3 tube instead of 4 lowering the thickness and restriction so the fans could now move enough air to allow the radiator to work. This engine now runs on the T-stat regardless of what is happening. You can get to point of too much!!

[rblong]

Well, my pulleys are about the same size - 5.75 crank and just under 6 on water pump. Radiator is a Griffin 3 inches thick-Radiator Griffin GRI-1-55182-X 22 x 19 - 2 row. Fan is Cooling Fan SPAL Advanced Tec VA18-AP6-41MA. Water pump is an Edelbrock. Look in my gallery for pics of shrouds/fan.

[vettestr]

Hey RB,
I went back to see if you were original poster and names changed if not same par are you having heating issues too? I did go through your gallery and it looks great. I will hold my 2 cents to hear specific issues not that I am any great expert but I do try and learn a bunch from conversations like this as too what is working and what is not. I did see rear bottom corners of shroud are open, put good old duck tape on them for test reasons. The pulley ratios are off for ideal performance and reinforced by Kirkhams (I trust them as a grat source above many.
For general info I found these links make me think or see from another view and hope they do that for those checking in. There are a ton of other repeated same old links but check these. I am fully disclosing the absolute plagiarism of these and other links!!!!!!!! http://www.teae.org/cooling/cooling_article.html and http://www.arrowheadradiator.com/14_...utomobiles.htm and from griffin a bit of a repeat but who was first??? http://www.carolinarodshop.com/Store...0_commands.htm

[tmareina]

Mine did not have a problem overheating at normal driving speeds...runs at 165-185 degrees with the fan running in city traffic 90-100 degree days. However...get in a cruise (eg. Hot August Nights) where you idle for about 30-40 minutes and go about a mile and the temp soars to 230-240 degrees for the last few blocks...leaking fluid from the overflow tube. Get to normal driving speed and the temp comes back down to 165-185 in about 5-6 blocks. After a few minutes checked the fluid level and I lost about 16oz. of coolant. I use Red Line water wetter and water. I have since changed the fan to one that was bench tested at 3900+ cfm. The old one was about 2100 cfm. Hope this makes the difference...time and another cruise will tell.

Tom

[rblong]

vettestr,

I has heating issues till I do all the mods, now I have none.

[bulletbrown]

I agree with VETTESTR point #6 we found that the fan power was going threw the dash then back to the fan . Jerry Clayton changed that and installed two relays up front and now has the power to them direct from the alt. There is a low speed relay and a high speed relay with an override switch on the dash. The 2002 Viper fan I,m using is a two speed . I also had the alt. stepped up .

[David Kirkham]

Anthony,

Edelbrock, I haven't used a stock pump in 10 years...if not more.

vettestr,

I agree with your fin count problem. Years ago we used a higher fin count in our radiator (I don't remember what that count was but it is definitely lower now) and we did indeed find the higher fin count actually blocked air flow and made the cars overheat.

We were buying our radiators from a guy who built extremely high quality radiators for many prominent race teams. They had to have high fin counts to suck the heat out of the motor--but, they run at high speed! Idling a car in traffic is not something an Indy car is expected to do.

We actually don't run shrouds on our fans--for a reason. There are two times you need maximum cooling. One is idle and the other is full throttle on the track. We found fan shrouding to block air flow through the radiator at high speed on the track when you are really leaning on the motor.

Now, not shrouding the fan is NOT the same thing as not shrouding the radiator! The radiator MUST be sealed up to make sure all the intake air goes through it. Bypassing air does nothing to cool the radiator.

As a final note, we have found the aluminum motors to run far cooler than the iron motors. Our cars that have aluminum small blocks in them have a HARD time getting oil temperature so they have to block off the oil cooler for street driving.

David

[vettestr]

David,
Have you found any trade off or down side to shrouding the cooling fans only and not the core? Did you need to increase the fans CFM from the full shroud design fan? You mentioned the aluminum small blocks were slow to reach oil temp with uncovered oil coolers on street cars. Do you run oil T-stats as standard configuration or is that more on the owners side of the coin?
Thanks for the input and lessons learned.
Jeff C

[David Kirkham]

Jeff,

If you shroud the cooling fans and not the radiator, you will effectively force air around the radiator--which is not good. The increased resistance to air flow (by the shroud around the fans) will allow to follow the path of least resistance, or around the radiator.

We do not use shrouded fans, as I mentioned above, because the actually block air flow at high speeds (like on a race track). Many, many of our customers take their cars both on the street and the track. Tracking our cars is becoming more and more common. It is just too much fun.

We do not run thermostats on our oil coolers for the big block cars. On small blocks, we simply block off the oil cooler until we are fortunate enough to get some rubber on the track.

David

[David Kirkham]

Oops,

We do not run oil cooler thermostats as a standard configuration on any of our cars.

David

[David Kirkham]

That said, there is nothing preventing a customer from doing what ever they want! We are happy to help in any way we can.

David

[Mysticle31]

Hello dragon 462:

I have a 1966 Galaxie with a 428 motor. I had the engine rebuilt and modified slightly with a Edlebrock RPM manifold and a Holly 650 double pumper and guess what, it also got hot. I put in a 5 blade fan, fan shroud and even got a new 4core radiator but guess what. It also got hot especially standing at stop lights. So I took the next step; a bigger radiator. I took the 18 X 19 radiator out and put in a Be Cool 33 X 18 radiator with a 180 degree thermostat and guess what all my cooling problems went away. Now even setting a a red light in 100 degree weather the temp. gage goes to 195 degree the fans turn on and then the temp. goes back down to 180 degrees when the fans shut off. This was my cure! I hope this helps.

[vettestr]

Thanks for the reply David,
I am glad I asked specifically about the fans' shroud. I did read your statement that no shroud was used but made the often fatal mistake of reading it from my point of view. That view was the fan itself had a shroud or rim (like Spal or other manufacturers) but was then not placed in a larger radiator shroud.
I know you are busy and do not wish to beat this horse to death but please indulge 1 more quick ?. What is your coolant temperature target for a street car? Take care Jeff C

[David Kirkham]

Jeff,

Happy to beat dead horses. That is much easier than trying to push dead Cobras!

We try for the following:

All measurements are in Celsius (because that is how the original cars were)

85 degrees really sweet
95 degrees, no big deal, pretty normal for summer driving
100 degrees, no big deal, but I tend to look at the gauge more often
105 degrees, start to get worried and look more at the gauge than I do at the road
110 degrees, time to start looking for an open stretch of road to open it up and get the air going over the radiator to cool things back down
115 degrees, better find that open stretch of road
120 degrees, find the road NOW or PULL OVER
125 degrees, PULL OVER AND SHUT DOWN OR YOU WILL MELT DOWN!
130 degrees, time to look up Keith Craft's phone number.

Luckily, I haven't seen temps above 105 for a long, long time on the street.

Now, if you are leaning on the motor on the track, 110-115 is pretty normal for a hot day. But, then again, a track is very controlled, you aren't going to get caught in traffic or at a stop light and you can always pit if the crap hits the fan.

David

[bkozlow]

Most common problem with Cobras are ones relating to heating in traffic etc.
Well, I guess I am going to be really sacriligist and suggest this. I see people trying to decide if they should connect their oil coolers. Well, here in Florida and other parts of the South and Southwest you need every degree of cooling you can get when you get into traffic. One over looked area is the oil cooler. Since a heater is not a common addition to the Cobra, most people block off the heater ports on their block. I suggest, tapping them and running AN lines to the oil cooler. The oil cooler, then functions as additional radiator fin area, helping cooling. A valve can be put in line, manual or electric to close the system when you don't want it.

If you are not taking your car to the track or are wondering, if you really need a oil cooler on the street, this is an alternative. With the Daytona Coupes, it is a little different situation. The oil cooler is after the radiator and it too can work as additional water cooling. But at the same time it functions very well as an oil cooler as the hot air stream from the radiator heats the oil up to temperature that will boil off the water in it.

Just a thought.

Bill K

[vettestr]

David,
You are a hoot! Cathy came in to check on me and see why I kept laughing out loud, she knew I was alone in the office. I find myself writing and rewriting remarks for each peg on the gauge. Most of them start at about 115C and involve folks driving 15 MPH below the posted limit, their skills at rolling road blocks, entering my lane while hanging out the window and when did that become a 1 way street etc..

Thanks for a good laugh to start the day!!
Jeff C

[David Kirkham]

Jeff,

Glad you liked it.

David

[ksmiff]

Does anyone have pictures of the Viper fan?

[bulletbrown]

KSMIFF , send me your E-mail and I will forward them to you
bobb@bobjass.com

[dragon462]

pictures and part number.... the motor is out going back to look at it .. does any one sell stock pulleys.