Keeping Cool: CSF Takes Your Questions

Earlier in the week we gave you a little insight into CSF Radiators’ back story – one that spans four family generations and more than 65 years. With so much experience in the design and manufacturer of automotive cooling products, CSF has an immense amount of knowledge on the subject. For that reason, and the fact that hot summer days are fast approaching in many places around the world, we thought it was the perfect time to have Ravi Dolwani – the head of CSF’s rapidly expanding Racing & High Performance Division – answer your questions on cooling in another round of Ask the Expert.

Perhaps you’d like to know what sets a real motorsports radiator apart from the countless race-style radiators available on the market today? What about the pros and cons of a rear-mount radiator set up? Or maybe you’re just interested in finding out whether upgrading to performance-grade radiator caps, thermostats and coolant is worth the money?

Whatever cooling-related question you might have, simply add it in the comments section below, and next week we’ll have Ravi will go through them and answer a bunch for an upcoming post. Don’t forget that CSF manufactures high performance intercoolers, oil coolers, transmission coolers and condensers as well, so this Q&A isn’t just limited to radiators.

As always, we look forward to seeing what you guys come up with!

Brad Lord



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Regarding intercoolers, a have a Volvo S70 (2.5 l inline 5 B5254T) , with the stock low-pressure turbo setup with max boost at 0.4 bar(5.8 psi),
and my question is; for normal driving, how does the ordinary intercoolers compare to blocktype( If that makes any sense:) Regards Johannes J


What is the coolest car you worked on? (Get it? Get it?); I'mma go hide behind the pit wall now.


have you guys done any efficiency rating comparisons against competing radiators to promote your product?  what is the optimal fin density and fin design used?  how does the fin design (ie: offset, louvered, etc) differ from that found in an intercooler or oil cooler?  with regards to placement in a tight space, what is the minimum distance that a radiator and intercooler should be from each other to avoid heat soak issues?  how effective is proper ducting from bumper to hood compared to a proper fan/shroud setup?


Hello, what is the relation between "entrance" area vs "exit" area of the radiator? what issues most be consider, if it is a street legal race car? The car involve uin the proyect is a rear engine, front radiator. Thank you!


Have you ever worked on an evo and what were your favourite points of working on it?


I have a project car, wich runs mild cams and low boost (typical daily driver ready for trackday setup) for now i run a stock radiator wich is wide and thin. My question is, can i trade it for a narrower but thicker unit? Wich characteristic is better, having more surface or a thicker core?


Performance is a very broad topic covering cooling capacity and a host of other measurable characteristics. How does weight factor into your designs? I'm sure it is measured and minimized, but do you have any sort of Q/lb requirement your designs must meet? Do you measure "performance" by any standards other than cooling capacity and reliability?


Also, where's the Takata article?



Whom do I contact about employment opportunities there?  Im a guy you used to deal with on a regular basis.  Thanks!


what is the best rule of thumb for sizing an intercooler? hp rating? engine displacement? boost level?  Also what is the main difference between a cheap intercooler and a quality unit? construction? flow? heat transfer? 
ill take my answers off the air


What is the relationship between core volume (width, height, and thickness) and cooling capacity?  Assuming a front engine car with adequate air flow through the grille, is there a rule of thumb concerning core size and the amount of horsepower that a radiator will support?  Is this relationship the same for turbo and naturally aspirated engines, or do turbo engines require more cooling per unit of horsepower than naturally aspirated engines?


Hi have you ever thought of making a radiator and a oil cooler as one unit. It would save allot of space. I owner ship of the idea so I will take a free one as payment. Seriously.


did you have any intercooler that small and good enough for top mount?
Knowing that you visit Indonesia every six weeks, what do you think about Indonesian car culture?


How important is a shroud for radiator performance?  I've had cars with factory single row rads, no shroud and a clutch fan that cool better than my dual/tri cores with e-fans (especially at idle).  I feel like no shroud e-fan vs clutch fan shouldn't make a difference but I guess I just want to know if there's a way to match your engine to radiator/fan setups?  Shroud or no shroud?  Mounting an e-fan on the "front" or engine side of the radiator for performance?


How are you different from the cheap china made cores? You guys use higher tier china made cores?


I've got three questions:
1.) Regarding radiators specifically, though I suppose it should translate to any air-to-liquid cooler; How important is shrouding, both before, in between, and after individual cooling components?
2.) How important is engine bay venting, as it relates to airflow through traditional placed front of engine radiators?
3.) What is your formula for proper intercooler sizing? Assuming I know variables such as displacement, desired power output, turbo size, etc.


Do you have a general radiator sizing rule of thumb (for cars that can use any radiator shape)? E.g. For a street car making x00hp, use a core volume of YYYin^3, perhaps with a "boosted engine multiplier"?
Also, there was an article on another site where a rep for a well respected electric water pump manufacturer was interviewed, and he clearly was of the opinion (with some numbers behind it) that the current crop of waterless-based coolants were not worth the hype. Can you share your opinion on waterless-based coolants?
(I included all of that history to hopefully open the door to your true opinion, not the corporate response...)


mbretschneider Surface area always beats thickness.


SeanStott mbretschneider Thanks for the enlightment
But why the performance cores are twice or thrice as thick, and why some applications are factory fitted with narrower thicker cores and still work properly where theres plenty of room for a thinnier wider core (like on some longitudinal VWs , for example).
Also, how much could i trade in? i could use some space around my actual radiator for supercharger piping...


mbretschneider SeanStott I feel like factory cores are usually thinner.  

I'm in the same boat as you though.  I have a front mount intercooler, and the inlet/outlet exit in the front of it.  This means I have to fit a radiator between the inlet/outlet, and severely narrowed my options.  I had to go with something around 18" square, but it's a double row aluminum unit.  Should be adequate for how I use my car. 

The first thing you want to optimize is core and tube/fin design, which usually means choosing aluminum over copper (even though copper is better heat conductor).  From there, you want to get as big of a surface area as possible for maximum efficiency.  Then, go thicker as needed.  The problem with going too thick is that you start to have too much thickness for higher speed ram-air cooling.  Figure you might have as much as an air-to-air intercooler, A/C condenser, oil cooler, and radiator all in a row.


Hi there. Just got a CSF radiator for my MKIV Supra TT and immediately saw 3-5 degrees Celsius improvement over my old aluminum radiator (also aftermarket) idling in traffic in 35-38 degrees Celsius ambient heat in traffic. Just wanted to put that out there :-) Ravi was great to deal with, really fast response considering I live halfway around the world.
My question is aside from the radiator, thermostat, ducting, fans etc where else can you find better cooling performance?I drive a street car and I often find myself blasting flat-out then suddenly hitting traffic. The temps rise up quickly but as soon as traffic goes I'm flooring it again. Can you give tips on how to manage heat-soak etc?


Whats the performance difference between a horizontal and a verticly cored raidiator? Also, can you use a small, thicker radiator instead of large thin one?


robzor We're working on it, Takata have been busy and we want to make sure the answers give the most information possible :)


I was wondering what happened to the E46 M3 radiator? I've seen pictures of it and when I contacted a CSF representative, they told me it should be out sometime in March. This looks like a great quality product and would love to put one on my m3.


I was wondering if you could provide an update on the BMW E46 M3 radiator. I've seen posts about it and I spoke with a representative who said it was going to be available in March but, still haven't seen an update on it. Just curious because I would like to put this on my M3.


SSF is our 1st distributor to have the 1st 3 pieces. If you are located in N. America, any reputable euro tuning / repair shop should have an account with them (csf# 7058)
More coming in July