craig1410
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 posted on 2/12/03 at 09:34 PM |
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Rover V8 - Which radiator will do?
Hi,
I'm sure this has been discussed before but I want to know who else out there is running a 175BHP+ vehicle and what sort of radiator/fan are you
using to keep it cool?
A friend of mine is close to completion of a Rover V8 build of a +4" wider IRS Locost and needs to rethink his radiator selection due to
nosecone clearance. I have recommended the Polo radiator as discussed on this forum but he is convinced that it won't do the job of cooling the
V8 and this has been reinforced by some folk on the Westfield forum and someone from RPi.
He has suggested the following as alternatives:
Landrover Discovery TDi 200 416mm x 418mm
Saab 9000 2.0/2.3i 418mm x 400mm
Who out there can give some good practical advice on this bearing in mind that this car will primarily be a road car so need to cool okay in traffic,
cruising and on the track.
Many thanks,
Craig.
ps. I am also building an RV8 Locost so will need to know this pretty soon too.
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Metal Hippy
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| posted on 2/12/03 at 09:46 PM |
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Young Conrod suggested to me that a Beemer 325i rad wasn't a bad size...
Cock off or cock on. You choose.
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Stu16v
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| posted on 2/12/03 at 10:10 PM |
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Craig, a Polo rad will keep a 200bhp+ VX etc cool no probs, BUT there are only four cylinders generating heat. This is where the problem lies in
trying to keep a Rover cool, that and the fact that there aint much breathing space under the bonnet...
But as for a rad suggestion-can I ask the audience?
50/50?
Ok, I'll take the money.....
Dont just build it.....make it!
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craig1410
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| posted on 2/12/03 at 10:38 PM |
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Stu16v,
Yes I am aware that some folks are running polo rads with 200BHP+ machines but just wondered how they perform in practice. Are they prone to low speed
overheating or perhaps high speed overheating? I'd expect constant speed cruising at 60MPH to be of least concern.
Of course the V8 has much more block surface area through which to dissipate heat and probably has more internal surface area to transfer heat to the
water too.
I just checked my SD1 workshop manual and the coolant capacity is 11 litres. I don't know how much of this is in the block and how much is in
the radiator but I'd expect from the physical size of the SD1 radiator it will have a high capacity.
Anyone else got anything to add?
Cheers guys,
Craig.
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stephen_gusterson
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| posted on 2/12/03 at 10:44 PM |
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I dont know too much about rads, but I have worked with them in industrial cooling applications.
The specialist I have talked to are not really concerned with flow rates or amount of coolant.
What seems to be a prime factor is temperature differential required (air in, to water temp returned), air flow volume and actual cooling capacity of
the rad itself.
How much fluid there is, and how fast it moves, doesnt seem to be a factor in equations.....
atb
steve
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craig1410
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| posted on 2/12/03 at 11:41 PM |
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Stephen,
I'd have thought that the quantity of fluid would at the very least dictate the rate at which heat gain and loss will take place. Water has a
specific heat capacity of 4200 J/Kg/degC (IIRC) and thus 11 Litres (11Kg's) will take about one minute's worth of a 10 Horsepower heat
dissipation to raise the temperature of the coolant by 10 degrees C. (4200*11*10/746/10=61.9sec)
More water effectively "damps" the rate of change of water temperature which might be important in certain cirumstances and will at least
give you time to spot an overheating problem before it cooks the head gasket. The water flow rate simply needs to be fast enough to transfer the heat
from the cylinder jackets to the water.
I do agree though that for steady state conditions, the most important factors will be airflow rate and the thermal conductivity of the water in the
radiator to the air flowing through it.
No disrespect Stephen but although I appreciate your insight, on this occasion I am particularly interested in "practical" experience of
cooling in higher powered Locost cars. The theory is all sound but I'm sure you will agree that something like cooling of a motor vehicle engine
has too many potential variables to cope with theoretically.
Any other RV8 users out there?
Cheers,
Craig.
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craig1410
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| posted on 3/12/03 at 12:06 AM |
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Check out this article on radiators and cooling. It strongly suggests that a multirow radiator is a necessity for a large capacity engine such as the
RV8. Does anyone know how many rows the Polo radiator has?
http://www.uk-hotrods.co.uk/technical/cooling/tech%20cooling.htm
Cheers,
Craig.
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stephen_gusterson
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| posted on 3/12/03 at 12:29 AM |
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no disrespect taken, but I have had several rads spec'd for industrial purposes, and have never been asked water flow rate or volume.........
they ask for air temp, temp of water in, and temp of water out required.
atb
steve
[Edited on 3/12/03 by stephen_gusterson]
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craig1410
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| posted on 3/12/03 at 12:40 AM |
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Cheers Steve, I appreciate your input.
I must admit after reading the article in my last post, that I am starting to think that maybe I need a thicker (more rows) radiator than the Polo
one. No reason why it has to be massive in terms of width and height but the number of rows seems to be equivalent to having multiple radiators in
parallel and will no doubt increase the temperature difference you are talking about.
Cheers,
Craig.
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stephen_gusterson
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| posted on 3/12/03 at 12:42 AM |
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on a less (not that I was) scientific note.....
I looked for a rad that was from a car about the same engine size as mine (2.4 litre). Thats a bit hard on a 3.5 I guess!
the more air you can get through and the bigger the surface area (ie more cores as you suggest) the better.
atb
steve
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craig1410
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| posted on 3/12/03 at 12:49 AM |
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For heaven's sake go to sleep man!!
;-))
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Metal Hippy
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| posted on 3/12/03 at 12:50 AM |
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Don't do it Steve, he's a bully... 
Cock off or cock on. You choose.
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bob
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| posted on 3/12/03 at 12:51 AM |
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What do the cobra boys use ?might be worth a search.
Since they nearly always use V8's and dont have that much room up front,like some say though the rad can be any size but if the air aint hitting
it it aint gonna work.
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craig1410
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| posted on 3/12/03 at 12:57 AM |
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Bob,
Yes the Cobra kits might use something of interest but aren't they a bit bigger than a little old Locost? Worth a search as you said.
Thanks,
Craig.
Metal Hippy,
You behave yourself and don't encourage him!! 
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stephen_gusterson
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| posted on 3/12/03 at 12:59 AM |
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i noted hippy posted at 5am a day or so back!
atb
steve
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Metal Hippy
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| posted on 3/12/03 at 01:01 AM |
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Craig... Cobblers to that
Steve... I don't know what sleep is...
Cock off or cock on. You choose.
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craig1410
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| posted on 3/12/03 at 01:04 AM |
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Okay so I'm a lightweight, I'm off to bed!!
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ed_crouch
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| posted on 3/12/03 at 08:17 AM |
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Radiator sizing
In order to keep an engine cool, (internal)energy needs to be transported away from it. Say we want a coolant temperature of 90 degs (363 kelvin), and
the engine is supplying heat power at 10kW.
every second, 10kJ are released into the coolant (and probably another couple of kJ into the atmos / engine mounts / heater matrix.
This will raise the temp of mass of water in the galleries by a few kelvins. The water pump moves this mass of hot water to the rad. then we look at
the temperature of the air going through said radiator.
Then we get into equations relating to heat transfer across an interface, and thermal conductivity of said interface, which involves surface area etc.
These equations will size the radiator.
With gas / gas intercoolers, the gas to be cooled can be pressurised very highly prior to being cooled (heats up like buggery) then cooled (the higher
the temperature gradient in an intercooler / rad, the faster energy flows), it cools very quickly, and is then depressurised and gets VERY VERY cold.
Shame we cant do this with liquid cooling, really :-)
Cant remember the maths this early in the morning, but ive got some notes from university on Aircraft environment conditioning systems (mostly inverse
Brayton cycle stuff, but theres some on heat exchangers in there somewhere): will dig it out if people want to do some calcs and finc out whether
theres a hope in hell of a polo radiator cooling a V8.
coolant flow rate and amount of coolant shouldnt make a difference, and as long as the block is full, it should be fine.
**Hangs anorak on hook, and puts "the train spotting guide for spotty losers" back on the shelf after a hard day at clapham
junction...**
Ed.
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David Jenkins
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| posted on 3/12/03 at 08:40 AM |
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When Mark Evans built his fake snake on 'A Car Is Born' his radiator was quite wide - 2 fans wide, in fact. You'd never get it in a
Locost nose!
I've got a Westfield build manual at home, covering their Locost equivalent. They use a specially-made 3-row rad in their V8, together with a
special nose that takes the air in at the front (as usual!) and vents it upwards straight after the rad.
David
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timf
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| posted on 3/12/03 at 09:02 AM |
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what size in the nose cone is there to play with
if you can find out i've got last years serck marsdon rad book that covers all rads with sizes and row info and i'll look it up.
Tim
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Simon
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| posted on 3/12/03 at 10:00 AM |
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Craig,
I've got the Polo rad, and am hoping to get the engine running this weekend
if wiring pics arrive
I'll let you know how I get on with it!
Won't be running for very long sd I haven't got any silencing
ATB
Simon
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GO
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| posted on 3/12/03 at 10:35 AM |
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Who was it who suggested the merc 190E rad, that sounded like it had a fair few cores in it, anyone got the details?
I'll also be looking for a decent rad when I get to that stage (build location permitting...)
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JoelP
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| posted on 3/12/03 at 11:18 AM |
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was mark allanson i think. i need to get some measurement on my car done as the corrolla one i got is too big...
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timf
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| posted on 3/12/03 at 11:22 AM |
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merc 190 sl H 434 w 556 rows 3
merc 190 d H 400 w 470 rows 2
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mackie
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| posted on 3/12/03 at 12:27 PM |
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What do Dax use for their Rush V8 kit? I'd imagine that would fit but I have a feeling it may be a custom job.
Good build diary here:
http://www.hoverd.org/Tim/Dax/
Obviously we need to get something suitable too so let me know how you get on Simon and Craig
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