Turbo'ing costs

[Max]

Sorry to meander off topic but is the K03 still best for under 200bhp given that the manifolds and downpipes are relatively easy to get hold of?

[dub-disaster]

Rad fan- stock item isn't really up to the job with the extra heat from the turbo into the
cooling circuit.

is this the case i thought that the stock fan and cowling was pretty good as the clowing helps guide the air around it i wen out of my way to refit the stock on in a new position when i did mine is a slimline aftermarket one realy much better then ??

[vwmk3jon]

Be interested to know this

[dub-disaster]

Sorry to meander off topic but is the K03 still best for under 200bhp given that the manifolds and downpipes are relatively easy to get hold of?

pretty much, unless your good at fabricating own a scrap yard or have acess to equipment parts that may make other options cheaper but even still you'd be hard pushed to get a setup as cheap as you can now do k03 for especialy with the large amount of knowledge avalible for this setup now.

[Andy]

Rad fan- stock item isn't really up to the job with the extra heat from the turbo into the cooling circuit.

is this the case i thought that the stock fan and cowling was pretty good as the clowing helps guide the air around it i wen out of my way to refit the stock on in a new position when i did mine is a slimline aftermarket one realy much better then ??

The plastic cowling in front of the radiator is always beneficial, as it ducts moving air onto the cooling pack when the vehicle's moving - but it's difficult to retain the stock plastic cowling once you've whacked a front-mount on there.

The stock fan and metal rear cowling are effective at keeping the car cool in stationary traffic and that's the point of them.

However, once on the move the effect of the radiator fan is much less significant than the natural ram air effect. It's at this point that the stock fan and metal cowling start hampering cooling. The metal cowling covers a large portion of the radiator, but presents quite a bluff surface to oncoming air which slows the air speed down massively. Remove the fan and the metal cowling, and your cooling at 50mph is significantly improved.

When you're stationary in traffic, your boosted Polo engine is pretty much no different to a 55bhp AAV in terms of heat rejection, and in UK ambient temperatures overheating in traffic is just not an issue. So go for a slimline fan (more effective/efficient than a stock one) to deal with stationary traffic situations, and remove the metal cowling to get optimal cooling on the move (i.e. when you're ragging it and the engine's producing lots of waste heat).

Mine, Robin's, Hayesey's and Yoof's turbo'd G40s are all fine in traffic. But mine gets very hot when ragging - and I'm the only one with a stock fan and metal cowling, the others have slimline fans and no cowling.

An old trick was to cut holes in the metal cowling and rivet flaps of stiff rubber over the holes. That way at stationary/low speeds the flaps are closed and the rad fan can draw air through the cowling effectively cooling the whole radiator, but at higher speeds the flaps are forced open and you benefit from the forced air cooling without the restriction of the fan/cowling.

[hayesey]

Mine still has the standard fan and cowling too andy.  But I do want to get rid of it for a slim line one for the reasons you say there.  Just gives a bit more under bonnet space too

[dub-disaster]

Intresting never even thought of the metal cowling hampering flow at higher speeds just always thought about it in traffic realy. Makes good sense though, does your andy and hayesey golet warmer than usual when on the move then ?
    

[Yoof]

Yeah they do- it's also worth noting that we all run water cooling on the turbos too, certain companies never bothered, which is utterly pikey in my opinion. Hence more demand on the cooling circuit, but less on the oil.

I have an ally rad on mine, which keeps everything super cool, no matter what ambinet 

[Andy]

Mine still has the standard fan and cowling too andy.  But I do want to get rid of it for a slim line one for the reasons you say there.  Just gives a bit more under bonnet space too

I stand corrected! For some reason I thought you had a slimline fan. Even when Yoof's car was on the stock rad with the slimline fan it never got as hot as mine on full ragging.

[hayesey]

I don't really seem to have any issues with temps on mine though, even on track days. Although it will get a bit warm doing 90 for ages on the motorway

[Yoof]

I don't really seem to have any issues with temps on mine though, even on track days. Although it will get a bit warm doing 90 for ages on the motorway

Does your gauge work 

[hayesey]

Yes!

[cheys03]

After reading the experiences above I've given the rad fan & cowling a bit of attention lately, as I've noticed that mine too gets quite warm at motorway speeds on sunny days. I'm running the standard cowling and 2-stage fan and temps could get to 105*C relatively easily doing 70-80mph on the motorway. Are these temperatures similar for you Andy?

To check if the coolant system and rad itself was man enough for the task, I removed the cowling and fan completely and went for a blast on a warm day.  I gave it a little stick and sustained 90-95 mph for about 15miles, but couldn't get the temp above about 93-94*C (as indicated on the clocks, not terribly accurate). Further runs at 70 and 80mph were similar, never more than ~97*C. Bizarrely about 75-80mph was hottest, I can only think that the increased airflow at greater speeds more than offsets the increased heat produced by the engine..?

I then torched the original cowling, adding Airflow Apertures^TM where possible and refitted.






The results were quite positive, good enough to still keep the temperature down at idle, and a noticable difference at motorway speeds with a max. of about 100*C under similar testing. However, although a good improvement I don't personally see it as being good enough? and will be looking for a slimline fan in the near future.
Just wanted to share this testing really.

Please, if anyone has any recommended fan models, that would be much appreciated

[Yoof]

Chris, did you get a plasma cutter for Christmas? 

Plenty of fans like this:

http://cgi.ebay.co.uk/12-inch-Genuine-SPAL-engine-cooling-fan-not-copy-/280678067654?pt=UK_CarsParts_Vehicles_CarParts_SM&hash=item4159b76dc6

Available at cheap prices, from memory mine's 9" (my nob's much smaller), that does a fine job (the fan), but I've got an ally rad, so not really fair.

[Yoof]

Also bear in mind you'll have to get to 130'C+ before you start boiling the water