View Single Post
Old 09-24-2007   #31 (permalink)
RallyBob
Project 1450 supporter...
 
RallyBob's Avatar
 
Join Date: Mar 2002
Location: Pleasant Valley, CT
Posts: 7,452
Real Name: Bob Legere
RallyBob has a spectacular aura aboutRallyBob has a spectacular aura about
Garage
Originally Posted by Hiro View Post
this will happen with my 50mm valve head,
the inlets are so recessed I'm afraid I will lose the benefit of the bigger valve...
Hiro
Certainly you will lose some of the benefit, but not all of it. You can compensate somewhat by increasing the valve lift but retaining the same duration. This way you'll have more lift area under the curve where it counts the most for racing....at peak airflow. Normally the peak flow is only momentary...when you hit maximum lift for a microsecond you have peak flow, but as soon as the valve starts to close again the flow drops. With higher valve lift you can his this peak flow while the valve is still opening, retain it for numerous degrees of rotation as it passes peak lift, and then retain the same peak flow until the valve has closed below the head's peak airflow numbers. So you will have more cam duration at the maximum airflow level.
RallyBob is offline   Reply With Quote Top home