Advanced cooling design!

[Procharmo]

What denotes a radiators ability to cool and what percentage of cooling ability to the following attributes add.. The size and speed of fan(s).The air flow available. The size, material and number of cores.

My Porsche 911 has two 8"x10"x1" and a smaller 5"x20" centre radiator.
Do you think the two side radiators are connected in parallel and then the returns are fed into the centre radiator or the other way round!!!I'm not taking the Porsche apart. It's my daily driver and I can't afford the down time!


How much extra cooling is to be had by a separate engine oil cooler and transmission cooler? Could these extra coolers mean you could get away with smaller engine radiators?

I'm looking to design a cooling system for a twin Procharged 406 SBC which cannot have the radiators in the conventional location.
Much like the one below.


But I cannot cut my frame rails and have twin Prochargers hence I cannot use radiators the same size as above.



I did ask here before but It was deemed a cooling question. However I think the possible solution demands some physics and structured thinking with regard to air flow, fans, driving location etc...


I am considering adding a 3rd radiator above my blowers...

[LSx_88_Ciera]

This may sound like an off the wall suggestion.
Look into coolers made for water cooling a computer. They are using some different tube design techniques with very high fin counts which increase cooling efficiency. I think you may be served well to run a combo of series and parallel, left and right in parallel and a series of smaller coolers on each side. Does anyone offer an over/under setup for the chargers vs the side by side setup.
I must say I am intrigued by your dilemma.

[Twentyover]

....
My Porsche 911 has two 8"x10"x1" and a smaller 5"x20" centre radiator.
Do you think the two side radiators are connected in parallel and then the returns are fed into the centre radiator or the other way round!!!I'm not taking the Porsche apart. It's my daily driver and I can't afford the down time!

Parallel. This presents the greated log mean temp difference to the incoming air yielding best cooling efficiency

.... How much extra cooling is to be had by a separate engine oil cooler and transmission cooler? Could these extra coolers mean you could get away with smaller engine radiators? .............

Additional cooling is available, the amount is dependent on how much heat the TOC is adding to the mix. Usually EOC and TOC's are placed in feont of the water radiator. If you're using the Porsche to tow a trailer up a grade, it will add more heat than if you're running on a level surface

[Procharmo]

Thanks guys. Good solid technical/scientific info... I'm going to go parallel and add the extra one above the blowers in series if needed.
It does pay to look at what OEM manufacurers did to package cooling into a small space for the 911 and adapt it to my Camaro dilema......Looking at the front of the Lambo Gallardo, Murci and Ferrari 360 and 430, twins must allow some space advantage over a large single and now that I know they are parallel I feel more at ease.


When you want a deep comprehensive answer, you can do not better than come to the guru section!!!!
Cheers.

[Procharmo]

Just found a simple answer to this question buy comparing domestic hot water radiator systems to this dilemma.



However I'm limited to -12AN hoses as I cannot find -16AN Y blocks..

[Rod]

why don't you design your own blocks? and have them machined? you can even do them yourself online with different companies like eMachineshop.com

or instead of a Y use a T from RBS superchargers.com has many different sizes

or just mill out an aluminum block and thread the AN fittings you want into it?

[MonzaRacer]

One big thing to think of is the coolant you use. check out Evans Cooling NPG+ 375F deg boiling point with no pressure, no corrosion issues and simply the best you can buy.
http://www.evanscooling.com/ or call 1-888-990-2665
Trust me this stuff WORKS.
Friend of mine has a V8 Monza with a 060 over 80 model 400 sbc, this thing ran hot in his truck with hug by large 4 core, but when strapped into his Monza, even with an aluminum replacement rad he couldnt stay under 240F deg. We pulled it out, cleaned everything and double checked heads/gaskets. Flush was ran through everything, and NPG+ installed,,,, run 195 on a 192 thermostat an d never goes over 210 ever.

[tonykim]

In OEM applications the cooling system is designed to handle all the heat loads generated by the thermal management systems. The design space is obviously the width and depth but also very importantly the amount of airflow available. This airflow estimate is based on the ability of a fan to either pull or push air through the cooling system with the vehicle or ducting restriction downstream. Typically the cooling system air side restriction is much smaller than the vehicle restriction behind it.

In practice what's typically done is that radiator core(s) and other auxiliary heat exchangers are sized based on the package space available and to match the heat rejection requirements on the internal cooling medium (water for the radiator circuit, air for a charged air system). Then the airside mass flow across the engine and vehicle operation range is estimated in a combination of experience from past vehicles, 2d simulations, and cfd analysis which use manufacturer fan curves adjusted for the restriction as installed. Just using a manufacturer's fan curve to estimate air flow often get's you nowhere. Each car, truck, or engine builder defines cooling design points (typically high hp or torque, high ambient, low vehicle speed) where the system must perform below certain top tank values. With that met everything else works.

Without simulation software for most people it's a process of trial and error. The most common mistakes people do are not having a correct blend of coolant or having a very deep radiator without proper fan shrouding or fan installation, too low a coolant flow, or poor baffling. Air is like electricity and it will take a path of least resistance. If you have a very thick radiator sitting in between large open gaps the air would prefer to bypass the cooling system and exit under fender wells or into the engine compartment. Large and deep radiators also require higher coolant flows so that the the localized fluid velocities get high enough to reach optimum heat transfer. Imagine the difference between pouring water from a waterhose into a bathtub or pushing it through a straw.

[Procharmo]

why don't you design your own blocks? and have them machined? you can even do them yourself online with different companies like eMachineshop.com

or instead of a Y use a T from RBS superchargers.com has many different sizes



or just mill out an aluminum block and thread the AN fittings you want into it?

Thanks, I found -16 AN and -20 AN Y fittings at Peterson fluid systems.

[Procharmo]

One big thing to think of is the coolant you use. check out Evans Cooling NPG+ 375F deg boiling point with no pressure, no corrosion issues and simply the best you can buy.
http://www.evanscooling.com/ or call 1-888-990-2665
Trust me this stuff WORKS.
Friend of mine has a V8 Monza with a 060 over 80 model 400 sbc, this thing ran hot in his truck with hug by large 4 core, but when strapped into his Monza, even with an aluminum replacement rad he couldnt stay under 240F deg. We pulled it out, cleaned everything and double checked heads/gaskets. Flush was ran through everything, and NPG+ installed,,,, run 195 on a 192 thermostat an d never goes over 210 ever.

Thanks for the info. It does look promising. I hope he can export to the UK!!!

[Procharmo]

In OEM applications the cooling system is designed to handle all the heat loads generated by the thermal management systems. The design space is obviously the width and depth but also very importantly the amount of airflow available. This airflow estimate is based on the ability of a fan to either pull or push air through the cooling system with the vehicle or ducting restriction downstream. Typically the cooling system air side restriction is much smaller than the vehicle restriction behind it.

In practice what's typically done is that radiator core(s) and other auxiliary heat exchangers are sized based on the package space available and to match the heat rejection requirements on the internal cooling medium (water for the radiator circuit, air for a charged air system). Then the airside mass flow across the engine and vehicle operation range is estimated in a combination of experience from past vehicles, 2d simulations, and cfd analysis which use manufacturer fan curves adjusted for the restriction as installed. Just using a manufacturer's fan curve to estimate air flow often get's you know where. Each car, truck, or engine builder defines cooling design points (typically high hp or torque, high ambient, low vehicle speed) where the system must perform below certain top tank values. With that met everything else works.

Without simulation software for most people it's a process of trial and error. The most comomon mistakes people do are not having a correct blend of coolant or having a very deep radiator without proper fan shrouding or fan installation, too low a coolant flow, or poor baffling. Air is like electricity and it will take a path of least resistance. If you have a very thick radiator sitting in between large open gaps the air would prefer to bypass the cooling system and exit under fender wells or into the engine compartment. Large and deep radiators also require higher coolant flows so that the the localized fluid velocities get high enough to reach optimum heat transfer. Imagine the difference between pouring water from a waterhose into a bathtub or pushing it through a straw.

Thanks again Kim,
I'll take all the points raised into consideration. The pair of radiators I have now will go in the car and we will see what does and doesn't work from there. Ducting may be constructed as well, if needed.

[tonykim]

If it was me I would run these radiators in parallel which I think is what you've decided. only problem with this is if you're still getting hot top tank temps it could be one side cooling better than the other and you'll have trouble figuring that out. also once you have the electric fans installed you may need to figure out a way to baffle around the area of the cores that isn't inside the fan radius. just come up with ideas. sometimes this is needed and sometimes not. often you'll get more ram air cooling (just air flow from vehicle speed with fans off) with some of the core not shrouded/baffled and not in the diameter of the fan.

also if you have other coolers like for the auto trans, power steering, a/c, etc. keep this out of the main air path to the radiators and try to use air coolers as much as possible.

also consider the option of running an electric water pump. if you can get some info from the radiator manufacturer about optimum coolant flow you can try to size your pump mass flow to get close to that. standard mechanical water pumps will increase mass flow with rpm and with smaller radiator surface area, even with lots of airflow you may find you have low rpm cooling issue. with an electric pump you get constant coolant flow all the time....just another thought.

[Procharmo]

Thanks for all the input on this thread. I will install the small radiators I have in parallel. I can get the hoses to be identical in length to equalise flow. I also have plenty of room to upgrade to a pair as large as 14.5" x 18" x 2.5" overall size if needed. The fan sits above the channel in the frame..
Made a start!!!


One down one to go. (It's only the mock up!) Some bracketing, welding and tidying up is needed....



But I guess it will all be worth it when I can get these in between the rads...

[slownova73]

JEEEBUS! i cant wait to see the finished product... and hear it whistle at me!

[Procharmo]

Thanks, progress is slow but steady!

[beyonda68]

Love the pics. Great progress.

[Procharmo]

Thanks.

It idles and sits in central London traffic at 170 degs....I burnout then idle again with no great temp increase....I have the 3rd rad but have found no need to fit it yet. I'm waiting on a new carb as the old one didn't allow any significant boost before it went lean (1lbs). As soon as I get the dual needle quad inlet Carb shop beast installed I'll let you know how the cooling holds up when I take her up to 8000 rpm.................stationary!!

[beyonda68]

Wow looking at those tt the phrase that comes to my mind is that "size does matter"

[Pagani]

Love your new setup

[Procharmo]

It got to 200 degs today in rush hour traffic........ So I think it's time for the 3rd rad........



After a few measurements and a quick template I bolted it to the rad support. I may put some rubber bushings on the bolts later.
Now I've just got to plumb it in series with the two parallel radiators.



I will also have to move the power steering reservoir.