I have my radiator laid at a 45 degree angle.
And yes, this will slightly hinder air flow through the core as the air is now hitting the core at an angle.
But it does allow for more core height due to the mounting angle.
You may improve the flow through the core by ensuring the radiator is shrouded around its perimeter, so all air that flows to the core must flow through the core & not escape around the radiator.
The air exiting the core I found to be an issue as the air wants to flow more upwards due to the radiator angle, than out the bottom of the car as the original design intended.
And the flow upwards is hindered by the fact that if you do have the aftermarket hood vents installed; they simply are not large enough to cater for the flow rate.
Look at the radiator core area, then the vent area, there’s a big difference.
So it means hot air pressure will build up at the back of the radiator as it try’s to exit the hood vents & has no choice but to spill out from under the car.
One would assume there must be a certain venturi effect at speed under the car as well as over the hood helping suck the hot air out.
I had an issue with the hood getting excessively hot due to the air not exiting the vents fast enough & becoming trapped.
This is in hot Australian conditions though which tends to exacerbate the issue.
Regards,
Tony.
