Scat H-beam steel rods complement...
Scat H-beam steel rods complement the Scat stroker crankshaft. The rods check into this affair with a length of 6.385 inches. A coated set of Mahle pistons was also tapped for this bullet.
We don't doubt the toughness of the short-block; Musi told us of several 555s in service that inhale nitrous on a regular basis. Musi tested an earlier version of this engine with an Edelbrock Performer RPM nitrous plate (110 jet) and blasted the 555 to 1,018 hp and a max torque output of 1,140 lb-ft. He was happy to report that the customer still runs the engine after two years of abuse. Musi was also working on a prototype Edelbrock throttle body during our visit. He started with Edelbrock's four-barrel-style universal throttle body and is adding a nitrous port in the center. The nozzle will spray down into the manifold and will be run as a dry-shot of nitrous. That means only nitrous will be sprayed through the system, and the EFI will add the additional fuel required. It will offer a clean look while packing a massive punch-up to 400 hp Musi says.
A closer look at the Mahle...
A closer look at the Mahle pistons shows each slug has a dual coating. The initial coating is on the piston for protection, while the secondary coating is on the piston skirt. The coating on the skirt reduces wear and friction. Earlier Edelbrock big-block crate engines didn't have this upgrade.
"We went with a triple nickel because the bigger bore helps the head breathe better. That bore also allows a guy to go with a bigger one if he wears out the engine. The 555 is a really nice combo," Musi says. There is nothing like a joint venture to bring two powerhouses together to deliver a powerful and reliable product.
| BY THE NUMBERS |
| EDELBROCK/PAT MUSI PERFORMANCE |
| 555CI RPM XT CRATE ENGINE |
| Engine type: |
big-block Chevy |
| Displacement: |
555 ci |
| Bore: |
4.560 inches |
| Stroke: |
4.250 inches |
| Block: |
Dart Big M 9.8-inch deck iron |
| Crankshaft: |
Scat 4340 steel |
| Connecting rods: |
Scat 4340 steel |
| Pistons: |
Mahle forged |
| Camshaft type: |
Edelbrock Rolling Thunder |
|
Performer RPM hydraulic roller |
| Valve lift: |
.632-inch intake, .648-inch exhaust |
| Camshaft duration: |
248 intake/256 exhaust, |
|
at .050-inch lift |
| Cylinder heads: |
Edelbrock Performer RPM XT |
|
(PN 51559), CNC-ported |
| Intake valve diameter: |
2.300 inches |
| Exhaust valve diameter: |
1.880 inches |
| Compression ratio: |
10:1 |
| Rocker arm ratio: |
1.7:1 |
| Intake manifold: |
Edelbrock Victor Jr. |
|
454-R (PN 2902) |
| Recommended fuel: |
pump gas |
|
with minimum of 91 octane |
| Max horsepower: |
677 at 5,800 rpm |
| Max torque: |
649 lb-ft at 4,800 rpm |
| Total cost, as-tested: |
$12,800 (carb) |
|
$16,500 (EFI) |