A conversation I had with several drivers at last years (2014) Goodwood revival was that the FIA have started to give time penalties against cars having upgraded alloy radiators instead of the period correct copper and brass radiators.
One such driver is Barry Sidery-Smith, owner of the ex-works MGB DRX 255C who has received a number of time penalties for running an alloy radiator even though a standard copper andbrass radiator simply will not keep his car cool.
To solve his cooling problem we built Barry a massive copper and brass radiator with the thickest core we have ever put in an MGB, a 5-row at 86mm thick. To put this into context, the original copper core is 56mm thick (an inefficient gill-on-tube type core) and we regularly upgrade MGB radiators by increasing the core thickness with a very efficient 64mm 4-row (pack construction) which is usually enough.
We can upgrade any copper & brass radiator making one that is just as efficient as an alloy upgrade (but just not as light) so give us a call if you have fallen foul of the FIA due to an incorrect radiator.
(See our page on Classic Radiator Upgrades here.)