RPM Range

[foreverfaster]

whats a good rpm range for a 390.
Full Race and or mild build. Small blocks go to 8000 all the time with dependable parts and properly built. is the same apply to a honda 390??

 

[CarlsonMotorsports]

Depends on the build.
Our typical 30-32 CHP open build with bigger valves, 310 lift cam and 1.3:1 ratio roller rockers, with a 33mm carb likes to turn 6800-7200. If we go with a more aggressive cam, it'll turn 8800, but how long do you want it to live?
These engines are torque monsters, they don't need to rev high in my opinion, but they certainly can if that's your intention.


-----
Thanks and God bless,
Brian Carlson
Carlson Racing Engines
Vector Cutz
www.CarlsonMotorsports.com
Carlson Motorsports on Facebook
31 years of service to the karting industry
Linden, IN
765-339-4407
bcarlson@CarlsonMotorsports.com

 

[alvin l nunley]

whats a good rpm range for a 390.
Full Race and or mild build. Small blocks go to 8000 all the time with dependable parts and properly built. is the same apply to a honda 390??

Self evident truth #1; "nothing beats cubic inches". All else being equal!
Believing that, I would look at the rod to stroke ratio, cam lift and duration, rocker ratio, balance and others. What about the intake track? What about exhaust track? Is the carburetor proportionately bigger? Is the compression ratio the same? Lots of things.
I'm pretty sure the engineers just want more horsepower at the same RPM, solution, make it bigger! Using the engine for racing karts, I would imagine, was not in their "we need more horsepower calculations"

 

[foreverfaster]

Depends on the build.
Our typical 30-32 CHP open build with bigger valves, 310 lift cam and 1.3:1 ratio roller rockers, with a 33mm carb likes to turn 6800-7200. If we go with a more aggressive cam, it'll turn 8800, but how long do you want it to live?
These engines are torque monsters, they don't need to rev high in my opinion, but they certainly can if that's your intention.


-----
Thanks and God bless,
Brian Carlson
Carlson Racing Engines
Vector Cutz
www.CarlsonMotorsports.com
Carlson Motorsports on Facebook
31 years of service to the karting industry
Linden, IN
765-339-4407
bcarlson@CarlsonMotorsports.com

that's what we are really looking for.. pulling force along with good speed. i think in this project having the torque to pull is more important than overall speed although we do have a speed in mind. 100+ mph, 400# +/- ride.