Closer Look: Trick Flow GenX 215 Cylinder Heads
Slide Show
Technology sure is grand. From thumb-size cell phones to music players that hold 9 million songs and cars that parallel park themselves, the bounty of science and modern manufacturing seems virtually limitless.
That bounty also allows us to enjoy V8-powered musclecars that can easily make over 400 horsepower and knock down 20-plus miles per gallon right from the factory. We can buy powerful, fuel injected crate engines for our classic muscle and street rods that make silly horsepower—then buy bolt-on parts to make even sillier power.
GM’s LS engines are a case in point. The ultimate extension of the small block V8, the LS motors are the new darlings of the hot rod set; they’re compact, make good power in factory form, and take to modifications like grease to T-shirts.
If there is one thing LS engines love, it’s airflow, especially at the upper end of the rpm range. And if there’s one thing Trick Flow Specialties knows, it’s airflow. So it should come as no surprise that the company’s GenX 215 (LS1) and 225 (LS2) cylinder heads flow lots of the invisible stuff—up to 338 cfm on the intake side of the GenX 225.
More Airflow By Design
Acknowledging the GM factory heads are more than adequate for stock and mild performance use, Trick Flow tailored its LS heads for engines with upgrades like increased cubic inches, hotter camshafts, nitrous, and turbo/supercharging. The heads have several key features that promote better mid- and high-rpm airflow:
• CNC Porting: The combustion chambers, intake ports, and exhaust ports are all fully CNC ported to maximize airflow The only thing factory about the ports themselves is the shape of the opening.
• Valve Angle: Trick Flow decreased the valve angle from 15 to 13.5 degrees. This decreases valve shrouding, significantly improving mid-lift airflow. It also improved rocker arm to valve cover clearance, which allows the use of higher-lift cams and/or higher ratio roller rockers.
• Spark Plug Relocation: Extensive dyno testing revealed that the factory spark plug boss between the intake and exhaust seats hindered airflow. Trick Flow engineers literally rotated plug away from the factory location to remove the boss, and slightly recessed the plug as well. This markedly improves mid-valve lift airflow, and also helps keep the air and fuel off the plug more efficient combustion.
Trick Flow made the GenX heads heck for stout, too. Material was added to the rocker arm pedestals, and the entire casting was reinforced in critical areas to improve rigidity. These improvements yield rock-solid valvetrain operation at high rpm.
What About Horsepower?
So what is a pair of Trick Flow GenX heads worth in the power department? Trick Flow tested the GenX 215 heads (215cc intake ports, 64cc chambers, 2.040/1.575 inch valves) on a 5.7 liter LS engine with 10.5:1 compression, a stock bottom end, factory LS6 intake, factory throttle body, Harland Sharp roller rockers and 1 ¾ inch Hooker F-body headers. The engine was dynoed with three different Trick Flow roller cam profiles.
Need a taste of the horsepower? With the .585 inch lift cam installed, the 5.7 made 515 peak horsepower and 460 foot-pounds of torque. The dyno charts in the accompanying slide show tell the whole story.
Taking a look at the airflow charts below, you can see that the LS heads can support a pretty healthy powerplant. Customers with stock 5.7L LS short blocks and the GenX 215 heads routinely make 500 rear wheel horsepower; similar factory short blocks with the GenX 225 heads can produce 515 horsepower or more.
Airflow: Trick Flow GenX 215 Heads
Lift Value Intake Flow (CFM) Exhaust Flow (CFM)
.100 inch 68 55
.200 inch 142 115
.300 inch 215 185
.400 inch 269 230
.500 inch 305 251
.600 inch 320 259
Airflow: Trick Flow GenX 225 Heads
Lift Value Intake Flow (CFM) Exhaust Flow (CFM)
.100 inch 68 55
.200 inch 142 115
.300 inch 220 185
.400 inch 279 230
.500 inch 316 251
.600 inch 338 259
The Trick Flow GenX heads are available as bare castings or fully assembled. The bare castings are ideal for engine builders who want to spec their own valvetrain setup or do additional port work. The castings are fitted with ductile iron valve seats and bronze alloy valve guides, and have a 1.480 inch valve spring pocket that accepts popular dual style LS1 springs. The assembled heads feature 1.300 inch dual valve springs, stainless steel valves, Viton valve seals, machined valve locks, and titanium retainers. The assembled heads can handle hydraulic roller cams up to .650 inches of valve lift.
When the time comes to turn up the wick on your LS-powered ride, make sure to give Trick Flow’s LS1 or LS2 cylinder heads a good, long look. Chances are they can provide all of the power-building airflow you’re gonna need. Like we said, technology sure is grand.
Specifications for Trick Flow GenX 215 and 225 Cylinder Heads, Assembled
Material: A356-T61 aluminum
Combustion Chamber Volume: 64cc (LS1) or 65cc (LS2)
Intake Port: 215cc (LS1) or 225cc (LS2), 3.25” x 1.07” cathedral—port in stock location
Exhaust Port: 80cc, 1.46” x 1.67” oval—port in stock location
Valves: Stainless steel, 2.040” (LS1) or 2.055” (LS2) intake, 1.575” exhaust
Valve Angle: 13.5 degrees
Valve Seats: Ductile Iron
Valve Guides: Bronze alloy
Valve Springs: 1.300“ double (140 lbs. 1.800” installed height, 385 lbs. @1.150” open),
.650” max valve lift
Valve Spring Retainers: 7 degree titanium
Valve Locks: 7 degree machined steel
Valve Seals: Viton
Recommended Components
Head Gaskets, MLS: GM Performance Parts NAL-12498544 (LS1), NAL-12589227 (LS2)
Head Gaskets, Graphite: GM Performance Parts NAL-12498543 (LS1), NAL-12558936 (6.0L, special order)
Head Bolts: ARP-134-3609 (LS1), ARP-134-3610 (LS2)
Head Studs: ARP-234-4316 (LS1), ARP-234-4317 (LS2)
Spark Plugs: NGK-4177
Valve Cover Spacers: TFS-3060800 (provides additional 1/2” of clearance for shaft rocker arms)
Pushrod Recommendations
Longer than stock pushrods required—must measure on engine with desired rocker arms in place
