i dont know if this is bullsh!t or not cause i really dont know alot about eclipse engines yet but if you get a 420a over 300hp is it true that you gotta replace the heads in it or else the stock ones will lock with that much power

 

In order to get that much horsepower I believe you would need to go with a turbo... And if your looking at that much horsepower, your gonna want to beef up the motor.. I dunno about the heads locking.. But the motor isnt meant to hold that much power. slow420a would know what you would need to do...

 

There is only 1 head. And no it doesnt need to be replaced at least I have never heard of a replacement aftermarket head. You will however need to beef it up with some cams and maybe springs retainers bigger studs ect ect

 

Hey my horsepower got underlined!! You would prolly wanna go with different pistons, and rods if your looking to get 300+ hp on that motor too... I don't know if you would absolutely need to.. But to be safe so your not replacing them later..