1999-2006 big twin 2007-2013 big twin 1984-1999 big ... - S&S Cycle

INTRO-18S&S ® Step 4: CNC Ported HeadsCNC Ported Cylinder Head sERVICESStep 4 of the S&S 4-Step Performance Program is to have S&S CNC port your stock cylinder heads. Once thedisplacement is increased in Step 3, the stock heads become a limiting factor in performance because the portscan’t supply enough air to fill the larger cylinders efficiently. S&S CNC porting service is available for 1999-’13Harley-Davidson® big twins and will soon be available for 2004-’13 Sportster® models.Just send us your stock heads and we’ll make ‘em flow!Digitized port shapes are faithfully reproduced in any stock Harley-Davidson® cylinder head onour 5-axis CNC machining center. Intake port, exhaust port and combustion chamber areall modified. This head will be assembled with new forged stainless steel valves andhigh lift valve springs to complete the package.Shown is the S&S CNC machined intake port before the valve guideis installed. Notice the raised vane ahead of the valve guide hole. Thepurpose of this vane is to split the air stream ahead of the valve guideto reduce turbulence and increase flow.The CNC Difference. The dyno chart compares a stock 2009 FLHT (blackcurves) with the same bike after an S&S 106" Big Bore Kit, 585 cams and S&Sslip on mufflers, and an S&S teardrop AC were installed (blue curves). The top(red curves) show the same engine after the heads were CNC ported and a 58mmthrottle body was installed. Both 106" engines perform much better than stock,and are pretty comparable to each other until about 3500 rpm. At that point theengine with CNC heads continues to increase in torque and horsepower because itcan still get enough air.CNC PORTED HEADS & LARGER THROTTLE BODIESStep 4Dyno ComparisonStock 2009 FLHT vs S&S 106” Kit, Slip-On’s, Intake, CNC Porting. With 551 & 585 CamsS&S 106”, Slip-On’s, 585 Cams, CNC, & SE 58 S&S 106”, Slip-On’s,551 Cams CNC, S&S AC Stock 2009 FLHTPeak Rear Wheel HP Peak Rear Wheel HP 115.2 Peak Rear Wheel HP 96.968.6Peak Rear Wheel Torque 84.7Peak Rear Wheel Torque 112.0 Peak Rear Wheel Torque 113.413012011010090807060504030201001000 2000 30004000 5000 60007000EngSpd RPMChoose The Right Cam For You. This dyno chart compares a stock 96" 2009 FLHT onthe same bike with an S&S 106" Big Bore Kit with CNC ported heads, S&S slip-on mufflers,performance intake, and two different cams. The blue curves represent the 106 with S&S551 touring cams and S&S teardrop air cleaner on the stock 50mm throttle body. Greattorque for performance touring applications. The red curves show the S&S 585 cams with a58mm throttle body. The increased duration of the 585 reduces low and midrange torque,but the combination of more aggressive valve timing, higher lift and a larger throttle bodysignificantly increases usable rpm and top end horsepower. A good choice for lighter bikesand racing applications. Both engines were tuned with Screamin' Eagle® Race Tuner.