Type E 37x32 ported cylinder heads
When choosing cylinder heads for your engine, CFM ratings are about the 5th most important thing on the list of important considerations. The correct average port velocity, intake port volume, valve throat diameter, intake to exhaust flow ratio, valve diameter to throat diameter ratio, are all more important than a high CFM number. Two heads with equal CFM numbers but different intake port volumes will perform quite different. The head with the smaller port volume will usually have a higher average port velocity. High air speed builds more torque by aiding with a more complete cylinder filling. If an intake port has been hogged out and has a huge volume, it will make for soggy low RPM power, even if it has a high CFM number.
Each pair of Type E heads are custom built to match their intended use. A bug will need a different cylinder head than a bus will. We do not keep heads on the shelf ready to go because of this.
These start life as AA Performance 500 series heads. The valve guides are removed and discarded. The stock intake valve seats are removed, and replaced with a larger seat. They are fully ported, while keeping the port volume small, and the airspeed very high. The chambers are re-worked to un-shroud the valves. The chambers are also flycut to meet the needs of the customers engine.
New high quality silicon-bronze valve guides are installed, and then they get a Serdi style 3 angle valve job. The heads are then flow tested, and fully assembled with high quality USA made HD single valve springs, stainless valves, ground keepers, and CroMoly spring retainers. The heads are shipped ready to install.
These 37x32 size heads work great on hot 1776-1915cc engines for street bugs, and for mini stroker bus engines.
For a bus, the 92x74 1968cc, Web 218, 8.8cr, 40mm IDF's and these heads are a great combo.
For bugs, 94x69 1915cc, Web 163, 1.3 rockers, 9.0cr, 40mm IDF's, 1 1/2" header, and these heads is a really strong combo.
Intake port volume is 62cc
Average port velocity is 285 ft/sec.
Intake/exhaust ratio is 72%
Intake Flow is
All numbers are measured with a calibrated AudieTech Flow Quick controller, at 28" with a ported offset style manifold and a radius inlet.
The customer will need to supply the manifolds to be used before porting starts. The manifolds are part of the intake tract, and must be ported along with the head.