In the past, you’ve had to rev an engine pretty high to make serious power. But the latest cylinder heads and cam designs have allowed us to bring the RPM levels down, increasing engine longevity, and still make really good street power. We built a 540 cubic inch big block Chevy to take advantage of the new technologies.
The 540 Big Block Chevy Build
We started our build using a rather common approach—a 4.500 inch bore Dart Big M Sportsman GEN VI iron block, 4.250 inch stroke Eagle 4340 forged steel crank, and 6.385 inch, 4340 forged steel Eagle H-beam rods with ARP 7/16 inch cap screws. We topped the rods with a trick set of Mahle 4032 forged aluminum pistons with a 13cc dome profile, giving this engine a 91/93 octane pump gas- friendly 10.25:1 compression ratio. (There’s a full parts list at the bottom of this story.)
Oiling a solid roller-cammed street motor should not be left up to a cheap pan and pump combo. Our crankcase was sealed with a six-quart Summit Racing fabricated steel oil pan that features built-in windage controls, but no kickouts so it will clear just about any set of headers. An anti-cavitation Melling Select oil pump and a 3/4 inch welded steel pickup fills the Dart block’s priority main oil passages with Driven DT40 Synthetic Street Performance Oil.
For the top end we drove three hours south to our buddies at ProMaxx Performance in Rainbow City, Alabama to pick up a bare set of their Shocker CNC-ported aluminum heads and one-piece stainless 2.300 inch intake and 1.880 inch exhaust valves. We created a custom spring package in-house using 1.625 inch diameter valve springs (273 lb. installed pressure, 685 lb. open pressure), titanium retainers, and 10-degree steel locks. The springs can easily handle 0.750 inch lift solid roller cams and 7,000 rpm. We backed up the springs with stiffer .135 inch wall, 3/8 inch diameter hardened steel pushrods.
While we only share our custom cam specs with the paying customer, we will tell you that we like to run our springs close to coil bind and had Lunati grind us a billet solid roller stick rated at 0.750 inch-plus valve lift on a 112° lobe separation angle (LSA) to stay EFI friendly on the street. Solid roller lifters and Comp Cams Ultra Pro Magnum XD 1.7:1 ratio roller rockers do a fine job of moving the valves. A stud girdle was added to stiffen the valvetrain and keep the rockers in order.
Induction was handled by Holley’s Sniper EFI Stealth 4500 system. Although Holley doesn’t recommend using a system this big on engines making less than 800 horsepower, we felt it would do OK since we designed this engine with this exact scenario in mind—and it worked flawlessly. The warning is mostly for people who just want the big Dominator carb look or already have a mismatched Dominator carburetor on a poor-running or smaller engine and think EFI will fix everything. That’s not how it works. If you don’t design your engine properly from the start, a big EFI system will hurt more than it will help.
The right intake manifold is also critical to making this EFI package work. We choose a Brodix HV intake for its smaller “cloverleaf” style plenum that reduces overall volume to improve throttle response and mid-range performance on smaller cubic inch engines. Believe it or not, 540 cubes is considered small in today’s world. The manifold’s single plane design helps the built-in MAP sensor in the Holley Sniper throttle body see a more homogenized manifold signal for better bank-to-bank fueling. We’ve tried Sniper EFI on dual plane intakes with full dividers and have seen large variances in left and right bank air-fuel ratios. Since the Sniper EFI uses a single A/F sensor on one side of the engine, we want to give it the best mixture signal we can.
Ignition timing and spark were controlled and delivered by Holley Sniper/Hyperspark ignition components. While we could have run just about any ignition system with the Sniper EFI, using matched components from Holley makes for much easier, plug-n-play connections. The Hyperspark distributor drops right in since we had Lunati fit our cam with an “Everwear” press-on distributor gear. A bronze gear will eventually wear out, causing timing retard and potential destruction of the engine if not caught early enough.
Spark is generated by a Hyperspark coil and amplified with a Hyperspark ignition box, all controlled by the Sniper ECU. NGK resistor plugs and Accel suppression core plug wires were used because EFI does not play well with RFI noise.
Our 540 Chevy Big Block Goes to the Dyno!
Some people fear testing with EFI. Actually, it’s not challenging at all when you know how to properly configure the parameters and can carefully monitor the engine’s vitals during the critical break-in and tuning process. Our in-house Dynomite Dynamometer gives us that ability. We employ dual wide-band air/fuel ratio sensors from Daytona Sensors in addition to the single Bosch sensor included with the Sniper EFI kit. This gives us the ability to “see” both sides of the engine, which often have A/F ratio disparities.
While there’s no easy way to correct bank-to-bank A/F ratio differences with the Sniper system, we feel it’s a small issue compared to the big power it makes. We’ve mostly seen large variances at idle. When you start to get into the throttle, things begin to even out; by the time we’re at WOT the engine’s average A/F ratio is pretty even bank-to-bank.
Our best dyno run of the day netted an impressive 781.6 horsepower at 6,400 RPM and 721.7 lbs.-ft. of torque at 4,900 RPM. Earlier low-RPM tuning showed over 500 lbs.-ft. of torque at 2,500 RPM and 671 lbs.-ft. at 3,000 RPM.
This thing is gonna love the street!
Short Block Parts
- King XP Series Main Bearings
- King XP Series Rod Bearings
- Dart Big M Sportsman Engine Block
- Eagle Specialties H-Beam Connecting Rods
- Eagle Specialties Forged Crankshaft
- Mahle PowerPak Piston and Ring Kit
Oiling System Parts
- Summit Racing Oil Pan
- ARP Oil Pan Bolt Kit
- Fel-Pro Oil Pan Gasket
- Melling High Volume Oil Pump
- Summit Racing Oil Pan Pickup
- ARP Oil Pump Stud
- ARP Cylinder Head Bolt Kit
- Cometic MLS Head Gasket, 2 required
- COMP Cams Ultra-Pro Magnum XD Rocker Arms
- Air Flow Research Rocker Arm Studs, Intake
- Air Flow Research Rocker Arms Studs, Exhaust
EFI and Ignition Parts
- Holley Sniper Hyperspark Distributor
- Holley Sniper Stealth 4500 EFI System
- Brodix Single Plane Intake Manifold
- Mr. Gasket Intake Gaskets