Written by Steve Turner
Photography courtesy of Daren Poole-Adams
In the quest to hot-rod small-block V8s, swapping intake manifolds is a long-standing tradition. In the early days, the options were few, and modified stock parts were common. These days, however, the aftermarket offers myriad induction options for most eight-cylinder engines.
One of the most popular modern performance engines is Chevrolet’s vaunted LS engine. Because of its popularity, there are so many intake options, that just about every performance niche. This allows picking just the right breather for your build. However, the number of options makes the selection process a bit daunting.
To find out which intake would work best on a Stock Eliminator engine he was selling, Daren Poole-Adams set out to test Holley’s full repertoire of EFI-capable intake manifolds.
Longtime Bow Tie racer, Daren Poole-Adams logged plenty of experience with the LS platform but selling off an engine to facilitate the move to a new combo opened up the opportunity to dyno test several intakes to see how their characteristics translate to a particular engine.
“I had been wanting to do a real-world comparison for some time,” Poole-Adams said. “This was a great opportunity to learn, and the new owner agreed.”
The powerplant in question is based on an LS7 block with 4.125-inch cylinder bores. Fitted with a stock LS3 crankshaft stroked by .013-inch, it clocks in at 389 cubic inches. Riding in Clevite H-Series bearings, that crank swings Callies 6.10-inch Compstar connecting rods topped by NHRA-spec, forged, flat-top pistons by Diamond that interface with the bores via Total Seal rings. The stock heads are blueprinted by Frankenstein Engine Dynamics and fitted with PAC springs, retainers, and locks. The valves accept marching orders from a custom Bullet camshaft, BAM solid-roller lifters, and Harland Sharp Rockers.
“This motor was in my 2014 COPO Camaro that Jeff Warren has campaigned for me as an LS3 combination (flat hood) in NHRA Stock Eliminator. It ran a best of 9.815 at 134.87 in AA/SA at 3,145 pounds in NHRA competition,” Poole-Adams explained. “The air on that run was 724 DA, with a 1.006 correction factor. We are switching that car to a 396 COPO combination and sold the motor to a guy that will run it in a rear-wheel-drive conversion Grand Am in Super Stock.”
The testing included all the ram-style intakes as well as the carb-style single-plane units from Holley.
Being a fan of Holley gear, Poole-Adams set out to test the company’s full repertoire of LS intake manifolds on this stocker engine. Of course, as a baseline, he began with the factory LS intake manifold, and for the sake of consistency, he ran the same Holley Sniper 90mm throttle body on all the intakes and kept the changes to the Holley EFI system’s calibration to a minimum.
“We had the Holley HP in closed-loop,” Poole-Adams said. “The tune for the stock manifold was spot on. For each combination, we adjusted the fuel and timing a little to make the motor happy.”
The factory intake delivered peak outputs of 569.2 horsepower and 516.8 lb-ft of torque, which is certainly respectable and would suffice for many applications. Racing, however, requires extracting every last pony from a combination.
The test engine was an LS3 built for Stock Eliminator competition. Based on an LS7 block and an LS3 crankshaft, it features Callies Compstar connecting rods, Diamond flat-top pistons, a custom Bullet camshaft, and more. It clocks in at 389 cubic inches and delivers a best elapsed time of 9.72 seconds under the hood of a 2015 Camaro.
Pool-Adams then tried the Holley Ultra-Lo Ram intake. Designed for forced induction engines with tight hood clearance, this intake might not seem like a great fit on a naturally aspirated combination. While it did give up so bottom end to the stocker, this intake ramped up the horsepower, delivering 605.1 horsepower and 497.5 lb-ft of torque.
“Everyone was very surprised at how well this one did,” Poole-Adams confessed. “I am converting my COPO 350 motor to run in a Super Stocker with low hood clearance. I am personally very happy with the results.”
Moving up to the slightly taller Holley LS3 Lo-Ram intake, which also leans toward power-adder applications and allows for a top-feed, plenum-mounted air-to-water intercooler when needed, this intake delivered 604.8 horsepower and 498.1 lb-ft of torque, which is comparable with its Ultra-Lo cousin.
“This manifold performed better than expected,” Poole-Adams said. “One of my good friends at Holley had expected the power to fall off a lot more when compared to the High Ram.”
To put these intakes to the test, Poole-Adams headed to Warren Engines in Clinton, North Carolina, where Jeff Warren did the honors on the engine dyno.
Speaking of the Holley Hi-Ram intake manifold, it was created as an affordable alternative to fabricated sheetmetal intakes designed to maximize both high-winding naturally aspirated or power-adder engines up to 7.0 liters of displacement. Featuring runner lengths and tapered cross-sections that perform well on a wide spectrum of applications, it can be run in carbureted or EFI applications, but in this instance, it was run with the EFI top. It delivered impressive peaks of 611.2 horsepower and 510.3 lb-ft of torque.
“As expected, this manifold was king,” Poole-Adams stated. “If you have the hood clearance, this is the way to go in a naturally aspirated combination.”
To ensure the results were comparable, all the tests were run using a Holley Sniper 90mm throttle body.
In addition to the traditional EFI-style Holley intakes, Poole-Adams opted to test the company’s two carb-style intakes. In this case, however, he installed a forward-facing elbow on both intakes to facilitate running the aforementioned Sniper 90mm throttle body. The Holley Single-Plane is cast with a familiar 4150-style square bore. It is built for engines ranging from 5.3 to 6.2 liters and rev ranges from 6,000 to 7,000 rpm. It topped out at 590.6 horsepower and 490 lb-ft of torque.
“If you are looking for something that looks cool and runs well in your hot rod this is pretty nice,” Poole-Adams said.
Testing began with the stock LS3 intake and the Holley throttle body. All configurations were fed an ample supply of Sunoco Purple fed by an Aeromotive A1000 fuel pump and factory 42 lb/hr fuel injectors regulated at 60 psi. A Holley HP EFI running in closed-loop kept all the combinations happy. The stock intake yielded 569.2 horsepower and 516.8 lb-ft of torque.
A more aggressive version of the same-style manifold is the Holley Single-Plane Race intake. Featuring a two-piece split design inspired by far more expensive racing intakes, it operates across a wider rpm spectrum up to 7,000 rpm. Its split design is really meant to allow for easy porting, but these intakes were run in as-delivered form, even still it might have been too much intake for the test engine. It topped out at 605 horsepower and 507.3 lb-ft of torque.
“I really expected more out of this one,” Poole-Adams said. “It would be interesting to test the Hi-Ram, Lo-Ram, Ultra-Lo Ram and this on a motor with more cam.”
Given its design is optimized for minimal hood clearance, the Holley Ultra-Lo Ram impressed on the dyno. Meant for power-adder applications with peak power between 7,000 and 8,000 rpm, it produced 605.1 horsepower and 497.5 lb-ft of torque.
In the end, he sent the engine out the door with one of the carb-stye intakes but selected an EFI-style intake for his personal engine.
“The customer took the motor with the single-plane race manifold and the elbow,” Poole-Adams said. “That's what a lot of the Super Stock guys are running. My motor will get the Ultra-Lo Ram.”
Moving up in height, the Holley Lo-Ram intake is meant for forced-induction engines peaking between 7,000 and 8,000 rpm. It can even accept a plenum-mounted air-to-water intercooler when needed. On this naturally aspirated engine, it produced 604.8 horsepower and 498.1 lb-ft of torque.
Of course, testing usually begets more testing, and that is the case here as well. Another combination would certainly favor a different intake manifold, but the great news is that there are five worthy options to choose from under the Holley umbrella.
“This test was just the beginning for me. I plan to keep playing with LS-based Super Stock combinations,” Poole-Adams added. “This particular stocker motor is very limited in what you can do with the camshaft. The piston has no valve notches. Even a stock-lift cam has serious limitations. Super Stock allows head porting, valve notches, and any lift. It will be interesting to see how the intakes respond to a hotter motor.”
Built as a cost-effective option to pricy sheetmetal custom intakes, the Holley Hi-Ram Intake is designed for naturally aspirated and forced-induction engines peaking between 7,000 and 8,000 rpm. It delivered the highest peak outputs in the test at 611.2 horsepower and 510.3 lb-ft of torque.
Moving on to the carb-style manifolds, the test maintained consistency by running them in fuel-injected form via an inlet elbow and the same Holley EFI Sniper 90mm throttle body. The Holley Single-Plane is meant for LS engines peaking between 6,000 and 7,000 rpm. This intake resulted in 590.6 horsepower and 490 lb-ft of torque.
The more aggressive Holley Single-Plane Race intake’s split design allows for disassembly and porting, but all the intakes in this test were run in as-delivered form. It was also run with the elbow and 90mm throttle body. It delivered with peak outputs of 605 horsepower and 507.3 lb-ft of torque.
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