Atomic Barra 550 GTA Rebuild Kits
Engineering Overview
SPEC-DOCAtomic 550 Rebuild Kit
The High-Performance Stepping Stone
The Atomic 550 Rebuild Kit is engineered for the serious enthusiast looking to push well beyond standard performance. Taking the guesswork out of parts matching, this comprehensive package bundles everything you need to build a rock-solid bottom end and valvetrain capable of reliably handling up to 1000hp.
Forged doesn't have to mean noisy. The 550 kit pairs our zero-failure Superleggera Billet Rods with ICON Forged Pistons. The ICON pistons feature a unique crown and skirt geometry that allows for tighter cold clearances. This means you get the 1000hp strength of a 2618 forged alloy without the aggressive "piston slap" rattle on cold start.
A Complete System
We don't just supply rods and pistons. The 550 Kit secures your rotating assembly with a 10mm Billet Main Girdle, guarantees oil pressure with a Full Steel Oil Pump, and locks down the cylinder head with 12mm Tool Steel studs and an MLS-D head gasket. It's the ultimate street/strip package.
Kit Highlights
Rotating Assembly
ICON Forged Pistons paired with Atomic Superleggera Billet Rods (CA625 Bolts). Includes ACL Race Series bearings.
Bottom End Support
10mm Billet Main Girdle ties the main caps together to prevent cap walk and harmonic chatter under extreme load.
Oiling & Timing
Atomic Full Steel Oil Pump prevents cavitation. Supplied with our HD Timing Chain Kit featuring billet sprockets and guides.
Top End Sealing
Held down by 12mm Tool Steel Head Studs and sealed with our ultra-tough MLS-D Head Gasket. Includes Stage 3 Valve Springs.
⚠️ The Minimal Machining Advantage
This kit is explicitly engineered to save you thousands at the machine shop. By meticulously matching components, we've eliminated the need for heavy block and head modifications.
- Save ~$500 on Block Prep: Assuming a healthy starting bore, use our standard size (92.3mm) pistons to skip the expensive boring process. The block only needs to be honed and decked. (Oversize pistons require a full bore and hone).
- Plug & Play Cylinder Head: The head requires a standard service only—seat the new valves, install new seals, and vacuum test. No new valve seats or guides are required. Plus, no head stud drilling is needed; our 12mm Tool Steel studs are a direct drop-in. No block O-ring cutting required!
- No Main Tunnel Machining: With the Atomic 10mm Main Girdle, we do not require main tunnel adjustment or line honing. The girdle does not distort the standard main caps when main stud tension is kept to factory specs (90 ft-lbs / 122 Nm as per Atomic guidelines).
- Ready-to-Run Internals: The Atomic steel oil pump is supplied fully assembled, ported, and ready to install. Conrods are final sized, with pin clearances pre-set to 0.0005", and rarely require honing to suit a good condition crank with ACL standard bearings.
Choose Your Rebuild Phase
Available in three distinct configurations depending on your build requirements.
Phase 1
The core components required to forge your bottom end.
- 6x ICON Forged Pistons (Dish Top)
- Hastings Piston Rings
- Heavy Duty Wrist Pins
- 6x Superleggera Billet Steel Rods
- CA625 Conrod Bolts
- ACL Race Main Bearings
- ACL Race Big End Bearings
Phase 2
Adds essential support, oiling, timing, and head sealing.
- Includes all Phase 1 items
- 10mm High-Tensile Billet Main Girdle
- Race Spec Full Steel Oil Pump
- Powerbond Harmonic Balancer
- 12mm H13 Tool Steel Head Studs
- MLS-D Extreme Duty Head Gasket
- HD Timing Chain Kit
- Billet Crank Sprocket & HD Guides
Phase 3
The complete package, adding a full valvetrain overhaul.
- Includes all Phase 1 & Phase 2 items
- Atomic Stage 3 Valve Springs
- Anti-Pump Up High-Rev Lifters
- +0.5mm Oversize Stainless Valves
Optional Upgrades
| Upgrade Component | Benefit & Application |
|---|---|
| ATI Super Damper | Upgrade from the standard Powerbond balancer. Essential for controlling destructive crank harmonics at 800hp+. |
| Cosworth F1 Pistons | Upgrade from ICON for extreme duty. Built to withstand 1500hp+ and 9 tonnes of combustion force. |
| Billet Main Caps | Replace factory cast caps with 4140 Billet Steel to prevent main tunnel distortion under massive cylinder pressure. |
| Atomic Billet Camshafts | Add a set of Stage 3 or 4 cams to maximize flow and make more power at lower boost levels. |
