I've used a polo radiator and cheap electric cooling fan - and now with engine running and car nearing completion I can see its not up to the job.

VW POLO 86C 1.3 G40 1.0 82-94 HIGH FLOW ALUMINIUM ALLOY RACE TRACK RADIATOR RAD

Looking at one of these for radiator - is 45mm core going to be thick enough? I'm likely going to have an intercooler in front of it.

And a 12" spal or kenlowe fan - they have their standard models for around £100 and high performance ones around £150 is it worth it/necessary to get the performance one.

I also thought I could make a shroud from a suitable sized oven tray if it makes much difference.

[Edited on 29/12/14 by luke2152]

45mm should be good enough
Depends on how many cores but aluminium is much more efficient than steel/brass
Ducting or at least boxing the radiator in, forcing all the air to go through the radiator and not round it makes a massive difference as does the car moving compared with static in the garage.
A bigger better fan will always draw more air through than a cheap job and pull through is considered better than push

Cooling will be a permanent fixture unfortunately.

Accurate anti freeze to water ratio essential.

A good oil will also keep things cool as it doesn't breakdown under the higher temperatures you reach.

Spend the money on a real efficient fan as its the only thing between you and a rebuild when you come to a junction with a learner waiting to turn left in heavy traffic !

Think about bonnet vents for the hot air to leave from around the block and the radiator area. I've let in some BMW kidney grills into the nose cone which helps to expel air.

After that you should be merely paranoid about standing in traffic.