My car runs awsome when its cold and runs good up to about 170-180 degrees but after that it starts to lose power, the fan keeps the temp around 190-200 degrees on a cold day, i know i should expect it to run a little hot because i am running 10-1 compression pistons .030 over. The cam i am running is a 535 lift with 310 duration. Im running 10-40 penzoil. Why would i lose power when it gets into the higher temperatures? Is this even a temperature problem or does anyone think it might be something else? The other thing is that at lower temps it runs good from low rpm to mid rpm and when it gets hot it only runs decent mid to high rpm. anyone have any ideas?

 

Sounds like you are suffering from good ol' heat soak. As your engine heats up everything in your engine bay it also heats up the incoming air into your intake. I assume you have a open air element? Hot air has less oxygen per intake stroke than cold air does. Both my RS and LT1 (which does have a cold air intake) suffer from these problems.

 

i thought about that after i posted...i am going to be putting a 2nd gen shaker scoop into my 3rd gen hood and i am going to open up the scoop so it draws fresh cool air...im thinking that will help a lot. it does get pretty hot under the hood so your right it seems like a heat soak.