Strange question - does anyone out there know of a rule of thumb for guestimating how big a radiator a car needs? Something like so much surface area per BHP or per cc of engine capacity???

I know there are lots of factors involved for an accurate calculation but I am just after a quick gut feeling sort of calculation.

Thanks

yeah fit the biggest one you can fit under the nose cone

i think the light weight has a 1.3 capri rad

Mine is a Micra mk1 rad and thats big enough for a 2.1 pinto

Early VW Polo rad is also a commonly used one. Sounds daft but will likely handle almost anything you'll fit in a 7 engine bay.

The Lightweight came with a Ford rad of some sort (I'll take your word for it that it is a capri job) However it is mounted at about 45 degrees sloping backwards and doesn't seem like a very efficient package. I have just bought a polo 1.3 item which will fit vertically in the air flow. I am just trying to check that it'll be ok for the 1.8 zetec I am going to fit.

It'll be absolutely fine for that, no sweat!!

Cheers guys!

I will stop worrying about it now!

Thanks for the speedy responses, appreciated.

Cheers

ive just orderd a polo rad 1983-90 i think. It comes tomoro! sorry today lol
its going to cool my bec indy gsxr 1000

Apart from the size of a rad, the main way to make the radiator more efficient is to duct the air into it. If you don't, then you lose some air around the sides of the rad. So a simple shroud around the front of the rad that meets the grille will all help.
My rad in the F1-2 is in a tunnel so that the air cannot go around it.

I think a bit of ducting might be a good idea then. There shouldn't be much room in the nose cone anyway but I guess every little helps!

the commonly used golf rad with the ~38mm core, enough for 280bhp?