Performance Upgrades

The Problem

The Vortec 4200 (and all Atlas engines) were designed to supply the valvetrain with oil direct out of the oil filter, with the front main and rod bearings tee'd off the same output. This was due to perceived (but unfounded) engineering concerns on GM's first ever VVT engines, which require high oil pressure and flow to move the cam phaser. However, due to complicated internal oil passages and the long length of the Atlas engines, what started out as good oil pressure to the number 1 main and rod bearings, drops off significantly as it works it's way through the oil galley to the back of the block. Because of this, the rear main and rod bearings see less oil, which is made worse if poor oil changes caused sludge to build up in the passages.

The Solution

Dual Feed: Redirect filtered oil into the rear main oil gallery, balancing oil flow

Benefits: Protects rear bearings, critical for turbo/high RPM builds

Bonus: Provides excellent turbo oil feed location

Recommended (Easy Checkout): Atlas Industries Oil Feed Mod

Alternative: Emtech Oil Feed Mod

Includes: Complete kit with -8AN Teflon hose, fittings, heat sleeve

Optional: Kit available with built-in 1/8" NPT tap for turbo oil feed

Installation

Step 1: Tap rear of block for -8AN fitting

Step 2: Install fitting at oil filter location

Step 3: Run -8AN line from filter to rear block

Step 4: Use heat-resistant sleeve to protect hose from exhaust

Difficulty: Moderate - can be done with engine in vehicle

Upgrade Options

Factory Coils: Adequate for stock builds, prone to failure at high RPM

2006+ Coils: Updated design, more reliable than 2002-2005

LS2/LS7 Coils: Higher energy output, bolt-on upgrade

MSD: Aftermarket high-performance coils available

Recommendation: Upgrade to 2006+ GM coils minimum for turbo builds

Factory Injectors

Flow: 26 lb/hr @ 43.5 PSI from factory

Decapped: 75 lb/hr @ 43.5 PSI

Height: Rather tall, unique to LL8

Good for: ~300-350 hp maximum

Recommended: Snake Eater Performance (Deka Height)

Link: Snake Eater Injectors

Advantage: Drop-in replacement, no spacers needed

Available: Up to 1100cc (110 lb/hr) in Deka height

Options: 62 lb/hr (620cc) and 110 lb/hr (1100cc)

Note: 1500cc Deka injectors discontinued, use 1100cc or Bosch 210s

Proven: Running successfully in Fairmont Futura build

Other Injectors (Require Spacers)

Bosch EV6: Available 36-80 lb/hr, need spacers

Bosch 210s: For 600+ hp builds, need spacers

Installation: Install spacer onto bottom of injector

Reason: Connector boss will foul on head without spacer

Sizing Guide

300-400 HP: Stock or 62 lb/hr Snake Eater

400-500 HP: 110 lb/hr (1100cc) Snake Eater

500-620 HP: 110 lb/hr Snake Eater (on E85)

620+ HP: Bosch 210s with spacers

E85 Note: Need 30% larger injectors vs gasoline

High RPM Reliability

Stock Beehive (2006+): Good to 7000 RPM

Aftermarket: PAC Racing springs available for 7500+ RPM

Critical: Must use 2006+ beehive springs for performance - earlier straight springs surge at 6500+ RPM

Retainers: Titanium available for reduced mass

Camshaft Options

Stock VVT Cam: Excellent low-end torque, good to 400 hp

Competition Eliminator: Custom grinds available for drag racing

Note: Very few aftermarket options available

VVT: Stock VVT system works well, difficult to delete

Recommendation: Stock cam sufficient for most turbo builds