EFI’ng Great: TPIS ZZ 450

GM’s Fast-Burn head has the highest performance potential of any factory-developed 23-degree–valve-angle small-block Chevy head. GM claims its “Cast-Ported” technology maximizes out-of-the-box flow with no need for additional custom porting.

The intake-port roofs on the Fast-Burn head (left) are 0.240-inch higher than standard (L98 port shown at right). TPIS uses special Fel-Pro intake gaskets designed to mate with the taller port.

The ZZ-409 TPIS hydraulic roller cam used in this engine has more intake duration (at 0.050-inch tappet-lift) than GM’s HOT cam and develops about the same valve lift with just 1.5:1 rocker arms. It’s spun by a Cloyes True Roller timing chain.

Comp Cams’ 1.5:1 8650 chrome-moly steel Pro Magnum roller rockers are three times stronger than typical 7075-T6 aluminum roller rockers. The company’s computer-aided Finite Element Analysis design also makes them 5 percent lighter.

Fast-Burn heads reduce high-rpm valvetrain loading with lightweight retainers, 2.00-inch hollow-stem intake valves, and high-temp 1.55-inch sodium-filled exhaust valves. Weighing under 190 grams, they’re more than 60 grams lighter than an L98 head’s 1.94/1.50-valve and retainer combo.

This prototype assembly used 0.030-over Ross forged pistons, moly rings, heavy-duty bearings, and ZZ4 powdered-metal (PM) rods. GM says the PM forging is superior to the old “pink” rods.

TPIS’s thin head gasket (PN 700-306) raises compression about 1/2 point. Thanks to EFI, computer-controlled timing, and the Fast-Burn heads’ high-efficiency 62cc chambers, running 10.5:1 compression on unleaded pump premium gas is no problem.

The high-pressure Z28/LT1 oil pump with 1.20-inch gears produces 60-70 psi oil pressure. Using a high- volume pump isn’t necessary and can even suck shallow oil pans dry. ARP’s all-steel driveshaft enhances durability.

GM is once again using a forged-steel crank (PN 12556307) in its ZZ4 crate engines. For a while, ZZ4s only had nodular iron cranks. The late one-piece rear-main-seal crank requires a corresponding flywheel or flexplate.

TPIS likes factory computers. The complete engine package comes with a GM ’90-’92 Speed Density computer, custom-burned PROM chip, and closed-loop wire harness.

The runners on the new TPIS Mini-Ram III intake (PN 500-530) match the taller Fast-Burn ports. The engine comes with an enlarged TPI-style 52mm two-barrel throttle-body (48mm was stock). Unlike later-model GM one-barrel throttle- bodies, TPI units have a conventional driver-side throttle-linkage hookup.

The TPIS 6-quart oil pan includes internal baffling and a screen that works with the factory GM windage tray to provide superior oil control under high-g acceleration and cornering loads. Keeping oil foam off the crank also adds a few horsepower.

Production TPIS ZZ 450 crate engines will be based on brand-new standard-bore GM ZZ4 partial-assemblies like this one with high-silicon pistons, four-bolt-main bearing caps, PM rods, and a forged crank. CC

Affordably priced like our ’88 Firebird, GM ’85-’92 Tuned Port Injection (TPI) cars make prime car-crafting cannon fodder. But these cars are showing their age and many of them could really use a new motor, especially if they were handicapped with a 305 or worse—a V-6. Powerful, kick-ass fuel-injected crate engines have been few and far between, but TPI Specialties (TPIS) is determined to change all that. Owner Myron Cottrell, who has been into GM electronic fuel-injected engines since their mid-’80s debut, has developed a serious TPI replacement engine that uses GM’s new high-tech Fast-Burn aluminum cylinder heads, combined with a TPIS proprietary hydraulic roller camshaft, free-flowing Mini-Ram III intake manifold, and custom computer calibration. The result is a 10.5:1 350-based motor that makes power and revs like there’s no tomorrow.

Huh? A hydraulic roller cam–equipped motor that revs? “No way,” you say. “Hydraulic rollers are too heavy and suffer from early valve float.” TPIS’s “secret” is reducing the valvetrain weight while enhancing its stability. Weight reduction is handled by the Fast-Burn heads, which use lightweight valves and retainers. Stability is enhanced by TPIS’s proprietary ZZ-409 cam profile, combined with Comp Cams Pro Magnum roller rockers.

With an engine that lives to rev, retaining a long-runner TPI-style manifold—optimized as it is for low-end performance—just won’t cut it. For years TPIS has been selling its own Mini-Ram intake as a replacement for the stock TPI manifold. The large plenum, short-runner design develops more torque from 2,000-2,700 rpm than a stock or modified TPI, yet delivers superior power from 3,500 rpm on up. The newest Mini-Ram III has raised runners that mate with the Fast-Burn heads’ taller intake ports. This is a welcome development, because previously those wanting to run EFI with Fast-Burn heads had no real choices other than GM’s marine-style Ram Jet intake.

The Mini-Ram mounts an enlarged 58mm TPI-style two-barrel throttle-body. Screwed into the intake are Bosch 24-lb/hr fuel injectors that are good through 550 hp at 60 psi fuel pressure (this engine runs them at 50 psi).

The result of all of this is a combo that makes power from 2,000 rpm all the way through 7,000 rpm, yet is compatible with GM engine management systems. Built up from component parts, TPIS’s TPI ZZ 450 prototype made 451.2 hp at 6,400 rpm, and 443.1 lb-ft of torque at 4,700 rpm. It churned out over 400 lb-ft between 2,800 and 5,700 rpm, with over 400 hp on tap from 4,800 through 7,000 rpm! Production ZZ 450s will be based on current GM ZZ4 partial assemblies rather than a hand-assembled short-block, but TPIS says the results should be the same—and will dyno-test complete assemblies before delivery to prove it.