# Formula car cooling

• Automotive
brewnog
Gold Member
If your system is full, I don't see how adding volume will help by much at all. I'd be looking at increasing the size of your radiators (or getting more air flow over them).

Are you using water or glycol? Inhibited water will give you a few degrees over 50/50glycol mix.

Gold Member
i figured out why the car ran hotter on Sunday with same outside temperature. we added antifreeze to the water wetter and water coolant. as i understand it ,antifreeze will raise the boil point. i also went from 13 pound radiator cap to a 19 psi cap. the antifreeze acts as a slimy coating and cuts down on heat transfer to the aluminum radiators. everyone else is running distilled water and water wetter. also we are not running trick redline engine oil ..just synthetic Mobile 1 oil rated 5 w 30 and am told this is street car oil..all other cars running these narrow side pods are running temps of 90 to 100C which is ok with me..

brewnog
Gold Member
While antifreeze modifies the boiling point, its specific heat capacity is much lower than water. Simply put, a litre of glycol at 100deg C carries less heat from your engine than a litre of water.

Gold Member
thanks brewnog..makes sense to me...so adding some cooling fins and such may do more than upping the volume of water would...right?

You aren't going to get a significant increase with cooling fins + radiator over the radiators by themselves. Making the radiators work slightly better is a better bet.

I'd be more inclined to try different coolant, and see if any part of the radiator is getting bad airflow before adding fins.

I tend to tread lightly about adding stuff, as there tends to be scope for a little gain, but a large scope for screwing something up. eg. the fins may alter the airflow so the radiator is starved of air.

turbo
Gold Member
Hi, Ranger. I think that an aggressive coolant flush is called for, to clean the interior surfaces of your radiators, then go back to clean water and wetting agent to maximize surface-wetting and heat transfer. You've got to flush the entire coolant system, since the glycol will have glommed onto the rough-cast surfaces in the block. You need maximum heat transfer not only at the radiators but from the block to the coolant.

Did you manage to get a couple of oil-coolers installed downstream of your oil filter? That will knock down the load on your cooling system.

Gold Member
thanks turbo...am adding oil cooler before next outing and yes...i think flush is in order...wonder what i can flush to clean out all the antifreeze crap?

Gold Member
if water and water wetter boil at 250 degrees F with a 15 psi radiator cap
what temp will this boil with a 18 psi radiator cap?

turbo
Gold Member
thanks turbo...am adding oil cooler before next outing and yes...i think flush is in order...wonder what i can flush to clean out all the antifreeze crap?
You can get a flush kit from an automotive supply place. I believe that the stuff you add to your clean water after the initial flush is a caustic solution, like Drano, though it's probably buffered to prevent corrosion. You'd run that solution through the cooling system for a while, then drain and rinse several times with flushes of clean water, before filling with distilled water + wetting agent.

Ethylene glycol is very thick and slimy-feeling, and that can inhibit heat transfer both from the block to the coolant and from the coolant to the radiators.

brewnog
Gold Member
Oil coolers (unless with oil-air heat exchangers) won't help; in fact they'll make things worse. Oil coolers take heat from the oil (which would otherwise disspitate through the engine's surface area and exhaust) and put it to coolant, putting extra thermal load on your cooling system. An oil cooler can put anywhere between 2-20 degrees Celsius to coolant.

18psi vs 15psi, look up boiling point in a steam table. Mine's at work. I guess something in the region of 5-10 degrees Celsius.

Gold Member
thanks guys,,,,this forum is priceless regarding the experience and wealth of information and sage advice. i was thinking of air finned oil cooler if i can find in line model.
i think we will be safe with the water wetter and 18 psi cap...it never boiled at 240 deg F
you guys are great,,,thanks
rm

brewnog
Gold Member
Air finned oil cooler would help. Check pressure drop at your required flow rate! And be careful with the uprated pressure cap; the coolant WILL be at a higher pressure as a result.

turbo
Gold Member
Hey, RM, haunt the Harley-Davidson aftermarket dealers. They will carry compact air-finned oil coolers. You can hide them in your fairing behind the radiators, since even the warm air coming off the radiators is WAY cooler than the oil, and you'll cool the oil enough to take some load off the water coolant circuit. Remember that you'll want to send the oil through the oil filter first so you won't bottle-neck that filter flow with high-viscosity oil.

Mech_Engineer
Gold Member
For the boiling point of water vs. temperature, you can generate a chart from the NIST website.

Link to the thermophysical properties page: http://webbook.nist.gov/chemistry/fluid/

Link to a pre-made chart of what you're after, water boiling point w.r.t temp: http://webbook.nist.gov/cgi/fluid.c...nit=mph&VisUnit=uPa*s&STUnit=N/m&RefState=DEF

I attached a screenshot of the chart in case the link doesn't work. Keep in mind the pressure is absolute pressure, so you'll need to subtract 14.7 psi (1atm) to get the gauge pressure rating of a theoretical radiator cap. To put it another way, an 18psi radiator cap plus 14.7psi (atmospheric at sea level) equals 32.7psi absolute.

For a 15psi cap + 14.7psi atmospheric (29.7 absolute): Boiling point is 249.8 fahrenheit
For a 18psi cap + 14.7psi atmospheric (32.7 absolute): Boiling point is 255.4 fahrenheit

EDIT- keep in mind some antifreeze mixtures also modify the boiling point of water. The numbers above are for pure water only.

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turbo
Gold Member
BTW, RM, you can get screw-in converters for Harleys (maybe Jagg) that are threaded the same as the oil filter, and have a female thread for your standard oil filter to thread into. The converter features a nipple to allow you to route the oil after it goes through the filter to your oil coolers, and another nipple to route the cooled oil back to the engine. If you have enough outboard clearance at the filter location to allow this, it's a really slick conversion. The converter is a couple of inches thick and IIR, it costs only about $90. If you're lucky, they have a similar converter for your oil-cooler application. Science Advisor Gold Member Thanks Mech Engineer...i think if it gets to 255 weare cooked anyway...but i go some margin to play with.. thanks turbo...i sure will check it out...good idea rm RonL Gold Member Ranger Mike, Looks like we have a$180 M track (+ over run expenses of course) coming to Austin Tx. If all goes according to plan it will complete in 2012. Will you run in a class that brings you to this track ?
I know very little about this class of racing and a quick glance at the rules of formula 1 racing makes it clear the power-train is held to very tight standards. How much room in methods of cooling is there for making changes ?

If you can get wild and crazy, I might can throw something out to you that lets the side coolers be removed completely and a method of heat removal that can be variable based on a number of different things. I think water can be replaced with some kind of refrigerant which might produce a much better thermal transfer delta and a fan design that will allow all other heat exchangers to be removed.

If rules are not too restrictive and you care to look deeper into what I'm thinking, send a PM to me. I got the impression from one post, that you might have a shop and resources to carry out the research and development should the design and numbers look right.

Who knows ???

RonL

Gold Member
SCCA is sanctioning organization that we race in. about 250000 members in USA...is probably the largest part time race club in world with road course tracks all over the country. we race MID OHIO and many others in Indiana, Michigan..Kentucky is supposed to have blue grass race way but its not opened yet..my driver has won at them all .. Watkins Glen, Road America, Virginia International Raceway..and many many Mid Ohio checkers...love to trailer to Texas but will see how economy is...ref: cooling idea..heck yes..always looking for new wrinkle ..send me message and we can look over..thanks Ron L

Gold Member
think i got the cooling problem fixed. plumbed radiators in series..used water wetter and distilled water. we ran it two days in 75 degree beautiful weather..it got to 95 degrees C and no hotter. i did go with red line synthetic oil which is super trick and costs \$ 10 per quart...last resort was to add an oil cooler but this would add weight and there just is not a lot of room under the fiberglass body for it. we won one race, got second in last race...some new young kid ran 4 seconds quicker than us and the kid never been on the track before...hummmm, and my driver been track champion last 6 years??? makes you wonder...right????

hello everyone,
Im a student participating in Formula SAE event, i want a little help on Radiator connection on my teams, we are using 1.0L S-TEC II I4 petrol engine of Chevy Beat,as it consists of 1 radiator we want two radiator concept having on sidepods,how to make connections as I have seen radiators without caps on this forum and im also facing problem on height issue as in passenger cars radiator is placed slightly above or parallel to engine height as in our prototype model we used two stock radiators on side pods with parallel connection but after filling radiators water was not reaching to engine and engine started becoming hot..

Gold Member
welcome ..in my opinion , for the guy starting out, plumb the dual rad system in series to avoid air pockets. I think if you are NOT running an electric water pump. you should have bleeders at each radiator as a minimum. These can be simple petcock fittings. You need a radiator cap at the max height of the system and attached to the water expansion tank ( burp can). Finally you need an over flow can as well.

it means that i will have to use 2 radiators with perfect calculation having lateral flow,Without radiator cap arrangement on it, with only water inlet and outlet present and should be connected in series connection, And place the water expansion tank having radiator cap at max height,..

and what is bleeders at each radiator and the expansion tank is a can with radiator cap arrangement on it and hollow frm inside with one inlet & one outlet for water on it?? -explain...

First, why are you planning to run 2 radiators over running 1?
It's implied that you are going to use 2 of the current radiators.

Have you worked out how much cooling you will need?
You've got to be careful not to overcool, as an engine that doesn't get up to temperature isn't going to run as well as one that does.

First, why are you planning to run 2 radiators over running 1?
It's implied that you are going to use 2 of the current radiators.

Have you worked out how much cooling you will need?
You've got to be careful not to overcool, as an engine that doesn't get up to temperature isn't going to run as well as one that does.
Each and every calculation is done, and how much water is required,And even the optimum size of radiators has also been calculated,,we are using 2 radiators on both sidepods to balance the weight on either side..

only connection arrangement parts are left to be done.

If you run radiators in parallel, care must be taken to ensure one isn't flowing 90% of the fluid while the other does almost nothing.