In the search for more power on a supercharged vehicle, one way to improve performance is by increasing the capabilities of the heads and cams. Though the Three-Valve cylinder heads flow much better than the Two-Valve, there's still some power potential left on the table to be remedied by porting and/or installing larger valves.
Our test subject, an '07 GT with a six-speed, has been the street/strip daily driver for Lakeland, Florida-native Matt McDonald. McDonald has done most of the work on the car himself, from the GT500 body kit, to the BMR and Steeda chassis and suspension components. Powering the GT is an Aluminator short-block (with 8.5:1 pistons), stock Three-Valve heads, Comp Stage 2 NSR (no spring required) cams, and a Saleen blower.
This month we had the opportunity to test Ford Racing Performance Parts' (FRPP) new high-flow CNC-ported Three-Valve cylinder heads. We also got our hands on some prototype camshafts from FRPP, designed specifically for supercharged Three-Valves.
After making 488 rwhp and 487 lb-ft of torque on the Dynojet at Ramsey's Performance in Lutz, Florida, McDonald's GT500 clone con- sistently ran a best of 11.82 in the quarter-mile at 118 mph. Though that may be quick for a daily driver, McDonald wanted more.
Last summer, FRPP released its high-flow CNC-ported Three-Valve cylinder heads (PN M-6050-463VP3; $1,849.95/M-6049-463VP3; $1,849.95). The 214cc intake runners were sure to improve performance over the stock 174cc runners on McDonald's GT. These OEM-produced castings have gone through a series of upgrades including 5-axis CNC porting, 35mm stainless steel intake valves, 38.5mm stainless steel exhaust valves, bronze guides, light-weight steel retainers, and upgraded valvesprings. The combustion chamber is also reduced from 51cc to 48cc.
After Ramsey's Performance technician Robert Bugg removed McDonald's stock heads, we contacted Fulco Racing Engines of Lutz, Florida. There we had cylinder head flow tests performed on the stock heads and the high-flow CNC-ported FRPP heads. On the intake side, the stock heads flowed 200 cfm at 0.300-inch lift and 232 cfm at 0.600-inch lift. The FRPP heads flowed 215 cfm at 0.300-inch lift and 288 cfm at 0.600-inch lift. Though only a 15-cfm increase at 0.300-inch lift, it's a whopping 56 cfm difference at 0.600-inch lift.
On the exhaust side, the stock heads flowed 124 cfm at 0.300-inch lift and 180 cfm at 0.600-inch lift (with 17?8-inch pipe). The ported heads shined yet again with a flow rate of 130 cfm at 0.300-inch lift and a whopping 207 cfm at 0.600-inch lift (with 17?8-inch pipe).
Back at Ramsey's Performance, Bugg got busy installing the new heads using Cometic MLS head gaskets and ARP head bolts. Then he turned his attention to the camshafts that we swindled from Jesse Kershaw at Ford Racing. The camshafts are almost identical to FRPP's Hot Rod Three-Valve camshafts, though Kershaw wouldn't give us the exact specs.
"These cams have less overlap, more like an 'RV' cam, which is good for torque and keeping the boost from blowing through the combustion chamber," says Kershaw.
He did tell us that lift was the same as the Hod Rod cams, but duration and the exact difference in overlap will remain a mystery. If you've heard rumors about a new set of Hot Rod cams specifically for supercharged engines, then you can rest knowing that these are, in fact, the mysterious alleged camshafts.
Unfortunately, though, Ford Racing put the brakes on production of the camshafts because of their lack of power at high RPM and negligible gains through the midrange. "For max power, the Hot Rod cams are the way to go, because while they will lose some low- and mid-range torque and power on blown cars, the engine really needs the overlap at high rpm," said Kershaw. "We like the Hot Rod cams even in blown cars."
Once the new cams were installed, Bugg finished assembling the engine using OEM gaskets from Sarasota Ford. It provided us with timing cover gaskets, water pump gasket, cam cover gaskets, and intake manifold gaskets. He swapped in a set of longer ('08-'10) spark plugs that Chris Jones at Blow-by Racing was nice enough to overnight to us after we overlooked the spark plug/coil pack upgrade necessary with these CNC-ported heads.
1 The valves are 1mm larger...
1 The valves are 1mm larger than stock, and the combustion chambers are 48cc (compared to 51cc stock).
2a Our contact at Ford Racing,...
2a Our contact at Ford Racing, Jesse Kershaw, got his hands on a pair of experimental Three-Valve camshafts for our test. Rumors have been flying for over a year about FRPP working on Hod Rod camshafts for supercharged Three-Valves. Well, here they are...
2b ...Well, here they are....
2b ...Well, here they are. Other than a slight change in overlap, these are almost identical to the naturally aspirated Hot Rod camshafts.