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.

Young Conrod suggested to me that a Beemer 325i rad wasn't a bad size...

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.....

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.

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

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.

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.

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]

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.

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

For heaven's sake go to sleep man!!
;-))

Don't do it Steve, he's a bully...

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.

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!!

i noted hippy posted at 5am a day or so back!


atb

steve

Craig... Cobblers to that

Steve... I don't know what sleep is...

Okay so I'm a lightweight, I'm off to bed!!

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.

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

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

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

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...)

was mark allanson i think. i need to get some measurement on my car done as the corrolla one i got is too big...

merc 190 sl H 434 w 556 rows 3
merc 190 d H 400 w 470 rows 2

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

I'm using a Polo rad to cool my v6. hoping it will be good enough! It's about 2/3 the surface area of the Scorpio one but thicker and I imagine is has more cores.

If a polo rad will fit your car could you not put two in one behind the other?

Chris

Chris,
Yes I had thought of that but it's probably a lot of work to get all the pipes linked up and water tight. Might be easier to just get a single radiator which is the right size and thicker (ie. More rows)
Cheers,
Craig.

I thought about the old double rad trick, plumbing could be tricky trying to get the outlet of first to inlet of second. Might be worth a look but I'm not sure you'd have enough depth behind the nose??

Would be prob 3 times thicker than just one (allowing for extra plumbing).

[Edited on 3/12/2003 by GO]

i was thinking of putting the radiator inside the chassis, as i have loads of space inside the nose between the rack and the front of the engine. shorter hoses and weight further back, plus the nose can go tighter...
if i find one that fits, i will!

quote:

---

Does anyone know how many rows the Polo radiator has?

---

Guys,
Take a look at this one. The friend I was referring to earlier has decided to buy this and I must admit it looks the business. It is from a Land Rover Discovery Tdi.




Two more images to follow

Cheers,
Craig.

[Edited on 4/12/2003 by craig1410]

I should mention that this Locost chassis is +4" wider than book and as you can see has a Rover V8 3.5Litre engine with a Holley 390cfm.

[Edited on 4/12/2003 by craig1410]

Looks good. Designed to work in the Sahara no doubt. The Merc one is probably over engineered too.

Mackie,
You're probably right but given that it cost just over £100 (RRP over £200) it doesn't seem like a bad deal. RPi engineering recommend this as a suitable radiator to cool the RV8 effectively. I'm going to go around to my local scrappie at the weekend and try to find a similar sized radiator on a car which is more likely to have cheaper spare parts availability. Maybe the likes of the Golf VR6 might be worth a look not that I'm likely to find one of those at my scrapyard...
Cheers,
Craig.

ps. Just checked, the VR6 radiator is £79 from eurocarparts. I wonder what size it is...

[Edited on 4/12/2003 by craig1410]

Luego sell a radiator for their Viento V8. Maybe it'll be worth asking them for dimensions and specs?? I'm not sure if they have had any problems cooling, but a few laps round Rockingham would have put some heat into it!!!

This is a Viento V8. One built by a customer. Picture taken from Luego website! Not sure if the rad has been supplied by Luego tho.

[Edited on 4-12-2003 by Donners90]