overheating, bigger radiator?

[Paynts]

Hi guys I have trouble with my track car overheating it used not to have a fan on it and was fine round the track but i had problems coming into the pits off a hot lap and idling in the pitlane so i put an electric fan on, this now sorts the idling temps but the car tends to get too hot during prolonged hard running on the track -say 6-10 laps flat out ( i think the fan is actually detrimental to the airflow at the higher speeds onb track) is there a bigger radiator which has the hose outlets and inlets in the right place that anyone else has used - engine is M20B25
thanks for your help

[Jhonno]

How old is the current rad?

[kimbo]

Normal 1st upgrade is to use a 'tropical' rad i.e. off of a car with air conditioning. I'm not sure if they're physically larger, or have a thicker matrix. Our 325 racer has one of these.
Next up the ladder of performance / expense would be a performance alloy rad.I've seen these on the 'bay and I think alloyproducts on here do them? It's certainly something thats going to get done on ours.
Btw check if your right about the fan thing first, (i.e if it was alright before and it isn't now, something has gone wrong) - no amount of raddage will cure an overheating motor if you've got a head gasket on the way out.

You're using the car though - that's good. Dan has got a 'proper job' now, so should have some money to spend on the racecar now, so we'll see you out there soon!!
Kim

[Theo]

The tropical rad is a couple of inches deeper top to bottom, the core is the same thickness though.

[Paynts]

Hi Kim

yeah its getting used - and abused haha! I'm reasonably confident the head gasket hasnt gone ( although i had thought of that as the problem!) I had it running just before the cold snap at Xmas and I got it up to heat let it cool dropped the water out and re filled with antifreeze then i ran it up again bled the air out and as long as the fan cuts in properly you can rev it hard and it will stay cool and not boil etc . You can run it hard on the track but not for lap after lap at full chat if you do come in at 95 deg it will peak at 110 and then the fan will pull it down ok
Before you say - I know!! you should do a warm down lap etc and bring her in cool but that just doesnt happen when the track has been wet all morning and has dried after lunch and 2 or 3 drivers all want a go!!! LOL

PS tropical rad where do i get one!! or could i just use a bigger rad out of say a 5 series or another car completely ie running a 200+ hp engine??

[Paynts]

PS Kim hope to see you and Dan out and about this season good luck with getting thr car sorted!

Simon

[AlpineCab]

My 320 cab came with an australian spec rad which is a good bit bigger (wider) than the normal rad. Not sure if its any deeper or not.

Needs different part number hoses as well to accommodate the extra rad width.

Can dig out the part number if you want.

[Theo]

Come to think of it, there are two types of larger rad - one is for A/C equipped cars and the other is the 'tropical' version.

The radiator I described in my earlier post is the one for A/C equipped cars.

Link to show different rads:

http://bmwfans.info/parts/catalog/E30/T ... tor_frame/

[DanThe]

I have an aircon spec rad I wont be using anymore if you want to buy it, £40 + post
Its done about 2000 miles in the 2 years ive owned it, its a Nissens rad and I bought it to use on my M50 converted car with aircon and it helped keep it a lot cooler than the standard 325i rad.

It would be a good idea to fit a lower temp thermostat if you mainly use the car on track, 80° is best IMO

[Paynts]

thanks Dan I've Pm'd you

BTW taking the stat out good idea or not ? or where do I get a lower tewmp stat from?

[DanThe]

You should be able to get a stat from ECP or GSF, just ask them for an 80° one

[Mikey_Boy]

Folks - just as an aside here - it's doubtful that the electric fan is stopping enough air getting through the radiator. Air speeds through the radiator are very low (which is why they cause so much drag) and have to be for the air to pick up enough heat from the water to be effective. Radiators of the E30 era were typically oversized for the application as engine and oil cooling (and warm up!) were not as well optimised as in more modern applications

I have an electric fan on my 325 (admittedly in the UK) and this doesn't overheat on trackdays at all. Might just be that the original rad is a bit cabbaged from age or whatever and given up the ghost. Another good upgrade for an electric fan is a temp switch which kicks in at a lower temp - BMW I believe list 2 - one at 98 degrees and one at 91... 91 is best!

All the tropical / aircon upgrades are all senisble!! I am assuming that the M20 engine is standard - more power = more heat to the water into the rad! (Apologies for stating the obvious!)

Cheers,
Mikey_Boy

[DanThe]

Rad is still available BTW, noticed you havent seen the PM I sent you back last week

There are about 3 different rated temp switches, the one you want is an 80°/88°
The next one is 91°/99° and the other is over 100°

[AlpineAde]

In terms of custom alloy radiators I can recommend those made by PWR and Zionsville. Both are excellent. I run a PWR one myself:

http://www.pwr.com.au/#/view=products/s=rs/

Some of our track days hit the mid 30s (approx 90-100 degrees fahrenheit) so they're bloody hot!

[rix313]

You can get tropical rads from ECP for around £100.