- One of the most common problems we see when modifying a street car into a racecar,
is keeping the engine cool.
And this is a topic that I know a lot of enthusiasts struggle with, particularly
knowing what to do and how to address that problem.
To get a little bit of insight into these issues and how to address them, we're here with
Jack from C&R to find out what goes into a cooling system design.
So Jack, for a start I think it's really common that a lot of people, when they've got a
car that's overheating, think that the solution is just to fit a bigger radiator.
Is that going to solve people's problems in most instances?
- Probably not because when most people think of a bigger radiator, they think of
putting a thicker core in there and then nine times out of 10, the issue is airflow
and putting a thicker core in there is just going to restrict that airflow even more
and really provide diminishing returns.
- OK so getting airflow through the core, how can we improve the airflow?
- One way is to actually thin up the core a little bit or chance the fin design.
And another way is to improve the ducting.
The area directly in front of or behind the radiator is critical and if you don't have
a good airflow path, and aren't forcing the air through the radiator, you'll really see
a drop off in performance.
- OK so let's just come back, we'll deal with those two topics separately.
So first of all you said that going to a thinner radiator can actually improve
things and this would seem really counter intuitive to most, as you say, most people
go with a thicker radiator.
So how does that improve the airflow, is this just reducing restriction to the
airflow?
- Yeah reducing the static pressure loss between the front and back face of the
cooler, that's essentially what provides the airflow through the radiator.
So by moving to a thinner core and then maybe changing the fin design to increase
the louvre angle, or provide more active surface area for the cooling, you can
actually provide the customer with a radiator that has additional cooling capacity.
- So I think you just touched on that and I want to go a big deeper there.
The active surface area as you've just mentioned, most people would think
again going to that thinner core, you've got less core in the airflow so the heat can't
basically be passed into the airflow.
So is that where you're actually gaining that back with the fin design?
- Correct yeah so the fin design, especially the fin design that we use
has a lot of little louvres built into the fin through a forming process.
So by that, we're actually creating a lot more surface area for the air to
interact with the radiator and thus transferring more heat.
- Alright so moving onto the other topic you mentioned there which is ducting,
and I think this is an area that so many people overlook, the fact that air is
actually lazy so it doesn't really want to go through the radiator.
So how do you go about ducting it, what are you talking about specifically
there and what's important to keep in mind?
- So definitely important thing to keep in mind is that you want to create a good seal
between the radiator and the duct work.
You want to try and provide duct work that has no sharp edges or sharp corners,
you want to try and transition it to the front of the car or the roof of the car or the back
of the car, however you're doing so.
As smoothly as possible.
- Is there any rule of thumb in terms of the size of the opening at the front of the car
for that ducting versus the radiator or is that very dependant on the application?
- It is very dependent on the application.
In quite a few instances we've stuck to a 1/3 rule, 1/3 of the core face area to the
opening at the front and that's served us pretty well in the past.
It might not be optimised but it's a good starting point to try and achieve the most
efficient design that you can.
- It's one thing to get the air ducted to the radiator but of course when it goes through
the radiator it's got to get out the other side and I think this is another area
that is really easy to overlook so can you talk us through some of the considerations
there with what happens in the engine bay?
- Yeah definitely, ducting out the rear side of the radiator is important because if you
just allow the air to flow loosely into the engine bay, it's going to be lazy and it's not
going to find its way out and it's going to really block everything up and
create a high pressure point behind the radiator, not allowing any air through.
So ducting out the bonnet or the hood, trying to get my verbage right,
is the best way because there's a lot of large flat surface area there to just vent
straight out the top.
But you can also vent out through the wheel wells or through the side of the car
as well with good effect.
- Now I'm not sure if there are any options you can suggest here but for the average
enthusiast, maybe modifying their street car, attending track days and if they've got
cooling problems, if they're suspecting that they've got everything else right and
maybe there's an airflow problem out the back of the radiator, is there any way they
can actually do simple tests without getting too technical on whether that's actually the
issue restricting the airflow?
- That's probably a pretty tricky thing to do, I mean what a lot of race teams will do
at the track is actually just have different bodywork setups to test different things.
A lot of guys will just use very thin sheet metal or even core flute I've seen before used
and a hacksaw to test out different theories.
It is a tricky thing to do and it is that next level.
- Now getting the engine coolant under control is one thing but again that's
only part of the puzzle there because we've also got oil in the engine, obviously there
for lubrication but the oil is also taking a lot of heat away from the combustion
process and we need to control that as well so can you give us some considerations,
particularly if we've got a factory engine that may have no oil cooling, what can we do to
help rectify that?
- Definitely, just a simple remote mount oil cooler kit running off a oil filter adapter
will really help both with the engine oil cooling but also with the engine coolant
cooling because oil has more direct contact with the engine, sometimes putting an oil
cooler on can actually drastically help your water temps as well.
Those kits are normally pretty easy to mount, anywhere in the car, for some of the more
serious enthusiasts, we'll also do a full face oil cooler behind the radiator which plays
into as well, by moving to a slightly thinner radiator sometimes, you can open up
the rear of that package to do additional oil or transmission cooling.
- Now that's actually an interesting aspect that I want to touch on, I know that a lot
of people when they are adding an oil cooler, it can be a little bit tricky, particularly with
modern cars to find room in the front of the car to mount it and a lot of people
might get a little bit lazy rather than ducting it properly, fitting the oil cooler
this time actually in front of the radiator so can that work or is that making things
worse for yourself?
- It can work in certain applications.
Typically we recommend against it because you're essentially taking some of the cool
air that you would be using to cool your coolant, cooling the oil and then even
potentially heating up your coolant with that patch behind the engine oil cooler.
So it can be a downside.
- Understandable that if your oil temperature may be north of 120°C, then the air coming out
of that oil cooler is going to be pretty toasty.
So reducing the effectiveness of the radiator.
Now just moving back to what you said there, putting the oil cooler as a package behind
the radiator, and we see this quite often with a factory or OE style oil cooling where
they have an oil to water heat exchanger.
And this gives the benefit of actually bringing the oil up to temperature faster
because the coolant comes up to temperature quicker.
Do we see the same effect with a oil to air cooler that's fitted behind the radiator?
- Definitely, exactly the same effect, you'll have the hot air off the radiator heating
the oil at startup and then during race application or something like that,
you'll see the hot air off the back of the radiator still doing some cooling on the oil
cooler and where you might need a relatively small oil cooler in a side duct or something
like that to do that cooling, by doing a full face oil cooler you're taking full effect
of all of the air off the back of that radiator and essentially creating the most efficient
cooling package.
The most efficient cooling package is defined by the air temperature off the back
of the last cooler.
If you're using up all the energy potential in the air, you've got an efficient design.
- Alright so if people want to find out a little bit more about the C&R products,
where can they go to?
- www.crracing.com
- Perfect, thanks for your time there Jack.
- Thank you.
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