[hotboat]

I own a Fourwinns boat 245 Sundowner with a 8.1 hp1 375 hp . What is done to the engine to make it a 8.1 hp 2 420 HP ? As far as I can see from info available from Volvo Penta the RPM range is up from 4400 to 5000 . Do you have any insight to this topic?
Hotboat

 

[04yukonxl]

Do a search on HP3 on this site. You can also go to the GM vortec site and get the specs. They don't give the details on cam specs but both the HP2 and HP3 have more duration and lift which is why they make more HP and higher RPMs. The HP2 has a forged crank and stuff but the HP3, which makes more horsepower than the HP2 (525 to 420) uses the stock 8.1L bottom end. The mods are detailed on the vortec site.