never leave your engine cover off or you might lost 5hp from it here's some useful info that has been discussed:

https://www.rx8club.com/showthread.p...t=engine+cover
https://www.rx8club.com/showthread.p...t=engine+cover

 

Thanks for the links.

I agree that it's mainly opinion and guesswork. My own is that it doesn't seem to hurt with it on and looks better, so I leave it on.

 

I think it purely cosmetic. the modern rotary is such a ugly engine, with all the vacuum lines and pipes. I have had mine off for 3 years without a worry. most air in the engine bay exits under the car doesn't it?

as for a heat shield? the bonnet has got insulation attached which would be more effective than the cover.