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Inprovements to the combustion chamber of both the PBS 8P and the standard A112 cylinder head have been using up every spare minute of time that I have available.
Initial work showed improvement in air flow 5mm of valve lift, but additional gains had to be made, particularly in the area from 1-5mm lift. The fourth generation of chamber design has finally provided the result that I wanted.
The numbers along the lower axis of the graph represent the increase in Cubic Feet Per Minute (CFM), The average CFM increase from .5-5mm lift is 14.78%, while the overall average for valve lifts from .5-12.7mm was 12.8%
All tests were performed on Scuderia Topolino's computerized, "Flow Performance" flow bench. Prior to each series of CFM test measurements the bench was calibrated using a known sharp edge test orifice. A series of six test runs were made with the same calibration, with an average deviation between test runs at any lift value of less than 1.6%. Valve lift amounts were measured using specialized valve lift fixture, incorporating a Starrett dial micrometer, accurate to .001 inch (0.025mm).
Taking these developments and modeling them on a Standardized Test Engine (Autobianchi A112A2 motor with PBS 8P cylinder head and dual Weber carburetors) an average increase in torque of 4.5 lbs was observed. As well an increase in HP was observed ranging from 3HP at peak torque to over 7 HP at 8500 RPM.
SPECIAL ANNOUNCEMENT - PBS "GEN4" Cylinder Head with FlowCone technology.
For a number of months I have been working on revising the PBS head, with a view to increasing the flow and optimizing the combustion chamber for better flame propagation.
This is the result of the work. This head flows an average of 14% more air than the previous version, up to 12.5mm valve lift. The head itself incorporates the new "FlowCone" technology, and with a flat top piston it will produce 12.5:1 compression. For road going applications you would have to order "dished" pistons to get the compression closer to 10:1.
This is a special "Pre-Order" offer. I will be having new heads cast in the next 30 days. These will then be machined and finished. Production time is planned for 8-10 weeks, with deliveries beginning around December 25, 2011. (A good Christmas present) Order must be received and paid for by Oct 30, 2011 to be eligible for this special offer.
These heads will be completely CNC machined, and therefore will ONLY be available in completely finished versions ready for installation:
Part # 01-05-04 Complete head with 7mm stem valves, titanium retainers, 6 deg. collets, springs, spring seats, bronze guides, valve seats, 4 angle valve job and FlowCone chambers. Also included is intake manifold and valve cover. Work includes full port preparation and intake manifold port matching. Normal Price $ 2950 USD (2235 Euro) Special Pre-Order Price $2537 USD (1922 Euro)
Part # 01-05-05 Complete head with 5mm stem valves, titanium retainers, 6 deg. collets, lash wear pads, springs, spring seats, bronze guides, valve seats, 4 angle valve job and FlowCone chambers. Also included is intake manifold and valve cover. Work includes full port preparation and intake manifold port matching. Note: This reducess the reciprocating mass of the valve train by 34%. Normal Price $2999 USD ( 2275 Euro). Special Pre-Order Price $2580 USD (1955 Euro)
Note: These prices are actually less than a fully prepared Gen 3 head because the preparation is much more automated.
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