Project LSX: Trick Flow Specialties Builds a 440 with a Bowtie (Part 2 of 2)

The cathedral-shape intake ports for the GenX 235s are 235cc—10ccs larger than ports on Trick Flow’s GenX Street/Strip LS2 heads, and 20cc larger than GenX LS1 intake ports. The exhaust ports are the same across the board at 80ccs. At peak valve lift (.600”), the GenX 235s flow 340 cfm on the intake side, and 270cc on the exhaust. At mid-lift (.400”), the heads flow a quite-healthy 287/242 cfm.

You can’t tell from the photo, but the valve angle has been reduced from the factory 15° to 13.5°. Combined with the CNC-profiled 70cc combustion chambers, this significantly improves both airflow volume and swirl (velocity). Trick Flow also moved the spark plug location away from the chamber wall and closer to the center. This helps mid-lift airflow and also improves the overall rigidity of the head casting by adding material around the intake and exhaust seat bores. This helps alleviate the cracking stock castings are prone to in the spark plug area.

Top End Assembly Something we forgot to show you in the first installment of our 440 build is how the lifter retainers differ between product LS blocks and the LSX block. The large retainer in the background is the standard factory retainer, which cannot be used in the LSX block—they block the access window to the sixth cylinder head bolt. GM Performance Parts does include LSX-specific lifter retainers, like the one in the foreground, if you decide to use factory-style roller lifters. The retainers still allow you to raise the lifters up off the cam without removing the valley cover, making cam swaps a bunch easier.

Trick Flow Engine Room associate Todd Hodges lays down a GM head gasket. The gaskets are an MLS (Multi-Layer Steel) type, which is composed of several layers of thin steel. MLS gaskets hold torque values better, do not distort, and don’t take a set like composition gaskets do—that means a better seal, a huge plus for high compression and power adder engines. The cylinder heads studs are from ARP.

Todd lays the Trick Flow GenX heads on the block and spins the nuts onto the studs. The nuts get torqued to 70 ft.-lbs. when using ARP assembly lube.

Up next is checking valvetrain geometry. Todd dropped in the 7.450” long Trick Flow chromemoly pushrods, marked the valve stems with a Sharpie marker, and bolted on a pair of 1.7 ratio Jesel roller rockers over Number 6 cylinder. (it doesn't matter which cylinder is used). After rotating the engine through one complete revolution, he unbolted the rockers and checked the marks the rocker tips made on the valve stem tips. Ideally, the mark made by the rocker tip should be centered on the valve stem. Ours were, which meant pushrod length was spot-on.

After bolting in the remaining rocker arms, the lifter valley cover is lowered onto the block. It is held in place by 12 button-head bolts. Note the nice O-ringed gasket. One of the cool things about an LS engine is that it is assembled “dry”—no gasket sealers or goopy RTV is needed. That black thing hanging down from the front of the cover is the PCV valve baffle.

A Nick Williams 90mm throttle body gets bolted to the Comp Cams’ F.A.S.T. intake manifold. This combination is popular with the LS F-body and Corvette crowd. The throttle body is CNC-machined from billet aluminum and is a true 90mm though the entire length of the bore—no tapered openings here.

The throttle body/intake assembly is lowered onto the engine. The F.A.S.T LSX intake is made from a composite material like the factory LS intakes are, but that’s where the resemblance ends. The composite Comp uses is 30% stronger than the OEM stuff, so it can handle the abuse of superchargers, turbos, and nitrous without exploding into little projectiles. In fact, the F.A.S.T. intake has cast-in bosses just for nitrous nozzles. The intake is a three-piece affair, which makes it lots easier to access the runners if you want to do some port work. And you know you will.

The fuel injectors and fuel rails are from Trick Flow’s TFX line of fuel system products. The 44 lb.-hr. injectors feature disc-type fuel control valves and updated nozzles to improve fuel atomization. The injectors also have stainless steel bodies that won’t let in moisture or corrode like aluminum bodies. The black anodized fuel rails are made from extruded aluminum and are machined for -8 AN fuel fittings.

Oiling System While it’s not strictly speaking a top-end part, the Melling oil pump needs to be installed sometime—and this point in the buildup is as good as any. LS engines use an external pump driven off the crank; it moves the oil through the crankcase via a long-tube internal pickup. The mounting bolts get torqued to 18 ft.-lbs.

The Moroso Street/Strip oil pan comes with this full-length windage tray to help keep oil off of the crank. Moroso also includes an oil pump pickup with an extended tube that runs the length of the engine.

Todd squirts some assembly lube into the oil pump passages to prelube the oil pump. That little bit of oil will help prevent metal-on-metal chaos between the pump gears on startup, vastly extending the oil pump’s life.

The Moroso Street/Strip pan is a rear-sump configuration, designed to fit late model (1998-2002) Camaros and Firebirds. The Moroso pan holds six quarts of your favorite lube, and is fully fabricated—not stamped—from aluminum. It features a 6” deep sump, trap door-type baffling, and a billet block rail for better gasket sealing (no warping here). Moroso even welded on two -10 AN bungs for use with a remote-mount oil filter.

Buttoning Up LSX-based engines have a few items specific to these blocks. One is the rear crankshaft oil seal housing, also known as the rear cover. Like virtually everything else on an LS-style engine, the rear cover uses O-rings instead of traditional gaskets and sealant. The O-rings can be pretty fussy to install; a little bit of grease or lube will help seat the rings in their grooves.

The LSX block will accept both LS2 and LS7 front covers—this 440 got an LS2 cover. It too uses an O-ring for sealing. The black plug is for the cam position sensor wiring.

Here is a piece you don’t want to forget. This plastic shaft is an oil gallery restrictor. Known as the barbell restrictor, it goes into the main oil gallery. The restrictor is pushed into the gallery until just a bit of it (.08 to 1.4mm per GM) sticks out of the block. It will be set to the proper depth when the rear cover is bolted on.

There are two screw-in coolant drain plugs in the back of the LSX block. A little Teflon tape on the threads will keep 'em from leaking.

And here’s what a 440 cubic inch LS engine looks like when it’s all buttoned up and ready for the dyno. Accessories like the water pump, valve covers, and ignition will go on when the engine is bolted to the pump.

The 440 on the Superflow dyno, ready to make some horsepower. The water pump is a Mezeire electric unit that flows 35 gpm; the balancer is from ATI. The headers are Kooks LS headers with 2” primary tubes, connected to 3 1/2” dual pipes with Flowmaster mufflers. The ignition coils are factory LS1 units. Fuel and ignition curves can be modified through the ACCEL DFI engine management system.

So what did Trick Flow get for all its hard work and effort? A kick-butt LS, that’s what. Peak horsepower came in at 680 at 6,500 rpm; peak torque of 597 ft.-lbs. occurred at 5,500 rpm. But look at the midrange power values—the 440 makes some serious grunt from 3,600 on up. That is the benefit of combining cubic inches with high-flow cylinder heads—and you get that big block-style power in a modern small block package. Ain’t technology grand?