Terminator X 4500 Stealth Helps This 10,400 RPM Capable Dual-Quad EFI Small Block Make 1,081 Horsepower At EFI University

10 min read

Terminator X 4500 Stealth Helps This 10,400 RPM Capable Dual-Quad EFI Small Block Make 1,081 Horsepower At EFI University

10 min read

At EFI University, making big horsepower is a byproduct of the real task at hand: researching and developing engines to learn what works and what doesn't when the engine is used in a competitive environment. Ben Strader and his team of instructors at EFI University don't offer an engine shop's services in the traditional sense, as they don't have several customers hitting the track every weekend that need durability and consistency. Instead, they test new products, research existing ones, and earn knowledge the hard way — by discovering the limits of these components, along with how and why an engine builder can avoid reaching the limits to prolong engine life and develop the best packages possible given build limitations. Then they share that knowledge in a classroom setting with attendees of the University.

The 424 cubic-inch small-block LS Next engine seen here was recently tested on the dyno by the EFI U team. Ben was gracious enough to share the build's details and what they learned in the testing process with us. They researched several new components, including Holley's Terminator X engine management system and twin 4500 Terminator X Stealth throttle bodies.

"This is not a customer engine. This is an EFI University-owned, 'we cannot teach if we don't learn' kind of thing. It's our own money turned into lessons we can teach in the classroom. We're always trying to find things that work and things that don't work, so we can effectively teach our Competition Engine Development course," says Strader.

This engine was originally a partnership with someone and in 2018 was slated for use in a Drag Week car, but that plan fell through, and Strader ended up buying the partner out to keep the engine for himself. After finishing it and running it, he wasn't thrilled with the current configuration's performance. He started exploring alternatives with an ultimate plan of putting it into his 19-foot Daytona Eliminator jet boat, but as it had a Pro Stock-style camshaft with 1.050-inches of lift, he wanted to see how it performed with a less aggressive design. After putting it onto the dyno using a new, endurance-style camshaft with .090-inch less lift, it didn't lose a lick of power at all.

Strader crankshaft

When building a 10,000-plus rpm-capable engine, Winberg is one of the only choices for a crankshaft.

"After I thought about it a little bit, I realized what that's telling me is that the camshaft wasn't the limiter; the problem was that I was using two 4150 1.750-inch throttle bodies, and I needed something bigger," says Strader.

This is where Holley comes into the picture with its all-new 4500-series Terminator X Stealth 4500 throttle bodies and engine management system. Strader had used these previously with Holley's Dominator engine management system on an engine package he developed for NMCA NA 10.5 racer Robbie Blankenship. He knew they would be just the ticket for this engine with the Terminator X package.

When on the dyno, engine builders will typically change only one part at a time to determine the effects of that change; in this instance, Strader committed the cardinal sin of changing the throttle bodies and the valve springs at the same time. They performed a spring change to facilitate the new camshaft, and once on the dyno, they started the engine, ran it up, and it was on a hit until it bumped into what they thought was the rev limiter at 9,200 rpm — but no limit was present in the programming. After several hours of chasing the problem, thinking it was an issue with the ECU or the wiring on the dyno cart, they went home for the night, thinking it would be best to start fresh the next day.

"After watching the video, I realized it wasn't an electrical problem; it was floating the valves so badly that it sounded like it was on a rev limiter. Once we took it apart, I had to beat the valve locks and retainers out to get them off, and I had some of the moly coating flaking off one of the valves... it was severely out of control valvetrain-wise. The good news is that at 8,800 rpm, it was up 28 horsepower from the previous combination; 200 rpm later, it was down 500. That's how bad it was on the limiter — but the limiter was floating the valves," says Strader.

The EFI U team repaired the damage and got the engine back onto the dyno, where it cranked out 1,081 at 9,300 RPM — a massive number for a naturally aspirated engine of this type with endurance-style parts inside.

Strader credits the Holley equipment with making this performance possible and its features as part of why the engine struts its stuff.

"Now you can get a standalone system like the Terminator X with the throttle body that everybody wants," he said.

For a naturally aspirated engine like this one that doesn't require a vast number of inputs to the ECU like a typical power-adder car running boost would, the Terminator X is ideal. And the choice of 4500-style throttle bodies is one borne out by EFI U's research with similar engines.

"We did a back-to-back test on the same engine [ed. note: not this engine] on the same dyno on the same day with the fuel introduced at the top of the intake runner, and the fuel at the bottom with injectors in each port. On a roughly 800-horsepower engine, it was worth 40 horsepower. When the fuel goes in at the top, because there's such low pressure in the manifold, it instantly evaporates, and evaporation is a cooling process. There was a 38-degree Fahrenheit difference in the intake air temperature from the fuel evaporating in the manifold. When you spray it into the port, and it goes directly into the cylinder, it doesn't have enough time to cool the intake charge down," says Strader.

It brings new light to the argument that carburetion makes more power than electronic fuel injection, which he stresses is not even a fair comparison when port injection is used. And Strader explains that when an engine uses throttle body injection, it can theoretically make more power than if it were equipped with a carburetor since there is no booster venturi to block airflow. With this configuration, each throttle body flows 1,440 cfm to a typical Dominator carburetor's 1,050 or 1,150 cfm — and provides the same fuel cooling effect with more effective results.

The real advantage comes in on-track tuning, as the powerful Holley Terminator X ECU can be configured to take advantage of different tune-ups for each cylinder in each gear. Strader says this is related to mixture distribution in the intake manifold as the car accelerates away from the starting line — it is much different at 2.5g in the first 100 feet than when it's pulling .9g halfway down the track. The limitless possibilities for tuning are vastly superior to those of a carbureted engine, where the tune-up is the same from end to end.

"Installation is hugely simplified. You could take a carburetor off and put the Terminator X on in 30 minutes with the exception of the fuel pump, as it needs a high-pressure pump for the EFI. The rest of it is Holley bolt patterns and linkages — everything just fits. It's killer," he says.

A racer can use this setup on any vehicle that currently uses a big carburetor — the market is full of 800-plus-horse engines topped with Dominator carburetors. Now it's simple to upgrade a dragster or door car to electronic fuel injection and gain immense tuning power, consistency, and performance. The self-tuning features also mean that the learning curve is shorter for a racer dipping his or her toe into the fuel-injection waters for the very first time.

"It is an endurance combo, so with more lift, more plenum volume, and more header size, it could make 50–70 more horsepower, but then it would be a drag race type of engine. This thing has crazy flat power — it makes 1,061 horsepower at 8,700 and still makes 1,072 at 9,700 rpm. So you can sit at peak power of 1,080 between 9,300–9,500 rpm, and just kick back and let it roll," says Strader.

All of that testing and tuning provided the desired end result based on the data they captured during the testing process. The new throttle bodies performed exactly as hoped.

“At 9,500 rpm, it is 53 horsepower better than the old 4150 throttle bodies with the same camshaft and spring combo. Even though the peak power numbers are similar, the old combo just runs out of air after about 9,000, and the Holley 4500 Terminator X Stealth just keeps on trucking!”

Although its performance is quite stout, this engine configuration is not long for the world. Strader has a set of Hammerhead hemi-chamber cylinder heads that have been worked over by Darin Morgan and flow more than 515 cfm sitting on the shelf; they will replace the current heads as he tries to achieve 3 horsepower per cubic inch with this engine.

Never one to leave well enough alone, he also had a special single-gear transmission manufactured to pair with the engine in the jet boat. In this configuration, the engine will turn somewhere around 9,300 rpm while the jet pump turns 7,000 rpm.

He closed our conversation with laughter and in typical gearhead fashion: "A hemi-headed, naturally aspirated, 10,000 rpm aluminum small-block in a jet boat with a transmission… yeah… we should make it as dumb as possible."

Strader dyno graph

Keep in mind that this dyno pull started above the engine's peak torque figure of 670 lb-ft at 7,500 rpm. Look how flat the "curves" are!

Strader boat

Once the Hammerhead cylinder heads make it onto the engine, the engine will find its way into Ben’s boat — it looks like he’s set himself (and his kids) up for one fast summer. Nobody rides for free!


Engine424 cubic inches, Dart LSNext Aluminum, 9.24" deck, 60MM babbit cam tunnel, raised .380-inch, built by Ben Strader at EFI University
CrankshaftWinberg Billet 4330V, 3.850-inch Honda rod journal, LS main journal
Connecting RodsCarrillo I-beam, Steel, 6.125-inch
CamshaftComp Cams billet Tool Steel 60mm
Cam Lift & Duration @ .050",
Lobe Separation
Rev 1: 284/313 @ 0.050", .565 lobe lift 118 LSA
Rev 2: 276/304 @ 0.050", .565 lobe lift 118 LSA
Rev 3: 273/302 @ 0.050", .517 lobe lift 118 LSA
PistonsCP Pistons, 2618 Forging, 4.185-inch Bore, Total Seal .0273-inch Steel Diamond Finished top ring, .0273-inch Napier second ring, 2mm oil ring, 15.55:1 compression ratio
Cylinder HeadsDart 10° ProStock LS Heads 368cc Runner, CNC Ported by Goodwin Competition, Wisconsin
Intake & Exhaust Peak Flow (CFM)Intake 475-ish cfm, Exhaust 300ish cfm
Valves Victory Titanium 2.325-inch Intake, 1.580-inch Exhaust 5/16-inch stem hard tip
Intake Manifold Custom billet runner, sheet metal plenum by Goodwin Competition, Wisconsin
Headers and X/H PipeDyno Headers 2-inch stepped to 2 1/8-inch, 3.5-inch collectors
GasketsCometic MLS .040-inch thick, 4.185-inch bore
EFI / Engine Management SystemHolley Terminator X Stealth 4500 Dual, 2.125-inch bore throttle bodies, 8 x 100 lb/hr Holley injectors per throttle body
Ignition System MSD LS StreetFire Coils, MSD Wires, Holley ECU


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