I have rebuilt my engine, got it back in and running today. Next job on the list is revise the cooling system a bit. In the summer it was getting warmer than I would like in traffic. my car has what I believe to be a mk1/2 escort rad, I am going to fit a polo rad. During the rebuild I have fitted an 82 degree stat and an 88 deg fan switch.

Are the alloy rads worth the extra expense over a standard item? £35 vs £100+.

Or are there other options better suited? I'm all ears.

It's for an MK Indy by the way.

I would not fit a Polo rad to a quality road based kit.

Spend some money on a bit a quality.

quote:

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Originally posted by JacksAvon
I would not fit a Polo rad to a quality road based kit.

Spend some money on a bit a quality.

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Polo rads ate pretty much the default for road going kits, will be interesting to hear the reasons behind that statement.

1700 x/flow 2yrs - 2.0 Blacktop 1yr - all good ...

Originally took the sides off a GTi Rad & fan (£5 scrap yard) fitted them to a very cheap eBay polo core - chopped Gti fan down and have used rad & sensor since - works a treat.. 4th year coming up..


VW Gti Rad Fans & new core

polo rad vw gti fittings

Many cars overheat from more than one problem. Often we assume a bigger radiator or a similar big gun solution will fix the problem. Maybe it will, but often by so doing you are addressing the symptom and not the cause. Look at the whole car when addressing overheating problems.

Before you do anything else, tune up the car. Be dead sure you are not running lean or with retarded timing.
A lean fuel mixture will overheat your car. If your engine runs lean you can chase your tail looking for problems in the cooling system and never figure it out. Be sure you are not running lean. The easy way to do this is richen your jetting a couple of steps. If the overheating is better, you're on the right track.

There is a lot of misinformation about ignition timing and cooling. Retarded timing contributes to overheating.

Advanced timing helps cooling. Bump up your initial timing a few degrees and see if it helps the car run cooler. It's an easy and practical fix.

Of course, if you advance enough to enter pre-ignition or detonation you will start to overheat. Detonation contributes to overheating. If you start to detonate back off the timing. Overheating cars should always run vacuum advance. Vacuum advance helps cooling.

Cars can overheat from coolant circulation that is either too slow or too fast. Your car may not have the right circulation speed for the water pump. Remember cars can overheat from circulation that is either too fast or too slow.

Look at your airflow. Be sure your shroud fits properly and is sealed to the radiator. What'd ya mean you don't have a fan shroud??!!?? If not, obtain a shroud before you do anything else. You can adapt a shroud from the junkyard or many after market suppliers can provide you one. Seal the shroud to the radiator with weather stripping.

Reduce the antifreeze in your coolant. A 50/50 mixture does not help cooling. Either run 100% distilled water with water pump lubricant or distilled water with about 15-20 % antifreeze. Either mixture will cool better than 50/50 and still lubricate the water pump and provide corrosion protection for your system.

Use a better grade of petrol. If you are not running premium and you are overheating, step up to the top grade. If there is no improvement, try advancing your timing a few degrees. The extra octane will allow you a little extra timing without getting into detonation.

[Edited on 15/2/16 by johnemms]

I fitted a Polo plastic ended rad to my 2.0 Pinto MK Indy and had no problems with it at all - always kept the engine at the right temperature whether moving or stationary, even for long periods of time. IMHO it was more then capable of the job and spending more money would have been a waste.

ETA...I fitted a pulling fan to the inside of the radiator which also worked just fine. IIRC, the Pinto's built in fan didn't clear the Indy chassis and would have caused issues.

[Edited on 15/2/16 by nick205]

I also have a polo "plastic ended" rad in my locost as do hundreds of other kit cars

as for the ludicrous comment "I would not fit a Polo rad to a quality road based kit. Spend some money on a bit a quality."

please explain why ?

as I am sure VW spent an awful lot of money on perfecting it, over some "tuning company " selling a couple of home made blingy items, and sell two a month, and at a very inflated price

steve

water wetter linky

Water wetter bottle, a 50/50 mix of antifreeze runs 12 degrees hotter than a 50/50 mix with water wetter.
100% distilled water with water wetter runs another 20 degrees cooler.

Never use in a computerized car. The cold engine temp will keep the vehicle in open loop which will make the engine run rich. Resulting in poor gas mileage and destroy your catalytic converters and oxygen sensors.

[Edited on 15/2/16 by johnemms]

quote:

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Originally posted by steve m
I also have a polo "plastic ended" rad in my locost as do hundreds of other kit cars

as for the ludicrous comment "I would not fit a Polo rad to a quality road based kit. Spend some money on a bit a quality."

please explain why ?

as I am sure VW spent an awful lot of money on perfecting it, over some "tuning company " selling a couple of home made blingy items, and sell two a month, and at a very inflated price

steve

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I'll get me coat.....

quote:

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Originally posted by JacksAvon
I'll get me coat.....

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After my first supplier provided a rad' that absolutely would not squeeze under the nosecone and the second supplier quoted something like 400 euro... I was advised to spend a tenth of that on a new Polo rad'.

It has plastic tanks instead of aluminum ones (potentially said to be a weak point, but it's not like VWs are fragile) and is merely a single core, but it's light as anything and multiple cores start restricting flow if you don't keep your speed up. So, it's really one of those wonderful no-brainers!!!

From an MK Indy-driver even:

"only about 40 euros ! new and it functioned very well even at full racing conditions in my race MK indy with 210bhp toyota 3sge beams engine."
And they're stupid cheap!
"Now even for 27 euro new incl btw.!!!! http://www.onderdelenshop24.com/2519786-ava-cooling-systems"

So cheap that you could easily get a new spare. And they'll always be available.

My rad' situation went from very sad to very glad with this discovery!

Steve, in the NLs
MNR Vortx

I fitted a Ali one from the company that's trades on e bay I spoke to them at stoneleigh last year got the 70mm one has made a massive difference to my temps on my striker on trackdays it was always marginal now it runs at 90 degs well worth the extra money over a std polo rad .

Excellent, thanks for all the replies. Good and bad, they have all been taken on board.

Ian, funnily enough I very nearly bought an Ali rad from the same company at stoneleigh last year. After buying wheels and some other stuff I forgot all about it but was kicking myself when I got home.

I think I'll buy an Ali one as it can't do any harm over a std one.

Just to mention that my car never once overheated. It would normally run around 70 deg but sat in traffic would go up to around 90. Though putting a proper spal fan on helped a bit. I will also try and make a shroud for it too.

Is there any particular year of polo rad to buy? I know the newer ones are way too big for a kit. From what I can tell I need a rad from a mk2?

90 degs is ok as long as it doesn't go much above 95degs and comes down to 90 or below once the fan kicks in ideally you want your car running at 85 to 88 degs if your cars running at 70 normally it's running to cool already boxing in the rad in the nosecone and a good electric fan is the way to go first I would say .

For what it's worth, I fitted my plastic ended Polo rad to the front of my MK Indy chassis using homemade ally top brackets and a welded on lower support bar. The MK supplied GRP nose cone fitted over fine and as above the cooling was top notch.

Image here...



[Edited on 16/2/16 by nick205]

From experience with plastic Polo rad in MK running Zetec...10,000 miles over 11 years, never overheated or leaked once. Ran small electric fan that would cut in/off after a few mins at idle just as you would expect.


Looks like I had a lucky escape then.

I'll add my experiences here...
Originally had a polo sized rad in my zetec powered spitfire, it was a (very) old well used rad, and was marginal. I happened to get a slightly wider version (golf I think) and fitted that, all is well.
On my other old Triumph, fitted with a TR7 engine, I bought a £16 Polo rad. This was hopeless in that the temp just kept rising if driven at 70mph on the motorway. Found a bigger passat version, and that works.

On the spitfire, airflow not ideal but I reckon a std new polo rad would be fine. The larger one gives me a safety margin.
On my other car the airflow is dreadful, so despite a mere 100bhp the polo rad struggled.
In a kit a polo rad should be fine, and even if it is marginal, they are not expensive if you have to change it later (doubtful)

I can understand some peoples reasoning, the Polo rad is designed for a 60-80bhp car, which produces far less heat than a kit. But airflow is probably seriously down on a kit.

Now, water wetter? Not sure you would get a 32degree drop using distilled water and wetter.
Redline (respected manufacturer) reckon about an 8degree F (5degree C) drop, but testers struggle to see even that. (bit more if water only, but who would be daft enough to run that? except a race car or similar, but even then the benefits are minimal compared to the downsides)

quote:

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Originally posted by cliftyhanger
Now, water wetter? Not sure you would get a 32degree drop using distilled water and wetter.

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quote:

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Originally posted by ian locostzx9rc2
90 degs is ok as long as it doesn't go much above 95degs and comes down to 90 or below once the fan kicks in ideally you want your car running at 85 to 88 degs if your cars running at 70 normally it's running to cool already boxing in the rad in the nosecone and a good electric fan is the way to go first I would say .

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quote:

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Originally posted by nick205
For what it's worth, I fitted my plastic ended Polo rad to the front of my MK Indy chassis using homemade ally top brackets and a welded on lower support bar. The MK supplied GRP nose cone fitted over fine and as above the cooling was top notch.

Image here...



[Edited on 16/2/16 by nick205]

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Regarding that pic', everything I've read is that you really should mount your rad' in/on rubber. That's what those un-threaded nubs on the bottom are for. But there are also 4, M6 threaded holes on both faces, which those nifty rubber bobbin thingies screw into nicely.

Here's the details of my polo rad if it helps, model, year, supplier etc

http://www.locostbuilders.co.uk/viewthread.php?tid=171366

quote:

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Originally posted by Andybarbet
Here's the details of my polo rad if it helps, model, year, supplier etc

http://www.locostbuilders.co.uk/viewthread.php?tid=171366

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Can't go wrong at that price :-)

The Polo rad if a very efficient bit of kit back that punches well above its' weight in the late 1970s early 1980s the many F2 and Formula Atlantic cars used VW Golf Mk1 rads. The key is getting enough airflow through to dump the heat to atmosphere.

Modern engines are designed to run on 50 perecent ethylene glycol antifreeze mix, using ethylene antifreeze is a double edged sword as the mixture has a lower specific heat capacity by weight but raises the boiling point and is more dense. When compared to pure water the disadvantages and advantages largely cancel each out. However the standard 50 percent solution is more viscous than water so takes more effort to pump and gives lower flow rates in the same system.
At atmospheric pressure a 50 percent ethylene glycol coolant boils at 107c .
A 30 percent solution would give more than adequate freeze protection for normal west european winters manufacturers specify a 50 percent solution as it gives the best combination of properties for cooling as well corrosion protection.


The main viable alternative antifreeze to ethylene glycol is propylene glycol. A 50 perecent Propylene Glycol mixture is generally similar but it has a higher specific heat capacity is more dense and is more viscous. The boiling point at normal atmospheric pressure for 50% solution is about 105c.

[Edited on 17/2/16 by britishtrident]