Some cylinder heads are advertised as "race only" or "strip only", whereas others are "street/strip" and other are street.

Is there any reason why a racing only head cannot be used on an engine which is driven on the street?

 

You could use them,just wouldnt be fun.They are made for high revving,air loving,HP monsters.You want to use the smallest ports possible for the application.Otherwise you lose the velocity through the ports which hurts throttle response,low end.

 

Generally, the more material removed the better the flow potential. Once you get to a certain point with a perticular head, removing more material would increase flow at higher rpms but you start hurting you flow at lower lifts....were you drive most of the time. This causes poorer throttle response and loss in torque and hp. The extra 10 or so hp at redline isn't worth the 20+ you may lose lower in the rpm range. Run the motor were it makes the most power. On the street it normally not redline.

Jeff D

 

"Once you get to a certain point with a perticular head, removing more material would increase flow at higher rpms but you start hurting you flow at lower lifts....were you drive most of the time. This causes poorer throttle response and loss in torque and hp."

with bigger ports of race heads, you loss velocity at low rpms, where you drive the most, which causes poor low rpm performance. your cam sees low and high lift every rpm, not just at high rpm.

jesse