Midlife Crisis C5/LS3

This is my first build: a 1999 Corvette. I'm in Utah, but I built and tuned this car about 3 years ago in Oklahoma. I wanted to transform this older Corvette into a modern, naturally aspirated sports car. After building the engine, I tuned it myself (stock ECU) because I could not find any tuners in the area that could provide good torque and power while still retaining OBD II emissions compliance as well as a stable idle and a smooth ride at low rpm cruise.

This is the Corvette before I started the disassembly:

· Naturally Aspirated GM LS3 Engine:

o ARP Fasteners (bolts, studs, and nuts)

o Felpro Gasket/Seal Kit

o Callies Billet 24 Tooth GM Reluctor Wheel

o Timing Sprocket Gear

o Valvetrain:

§ Cam Motion Custom LS3 Camshaft

· 226°/240° | 0.605"/0.588" | LSA 112°+4°

§ Hardened rocker trunnions with C932 bushings

§ PAC Racing .660” lift dual valve springs

§ Morel link bar hydraulic roller lifters

§ SAE 4130 pushrods case hardened to 60 HRC

o C6 Engine Mounts

o Wiring & Emissions:

§ Caspers Wire Harnesses for LS3 Conversion

§ Re-pin fuel injector connectors — EV1 to EV6

§ C6 EVAP Purge Solenoid & Bracket

§ C6 PCV Tube

§ C6 Intake Fitting

§ C6 Fuel Vaper Line

§ Elite Engineering E2 PCV Oil Catch Can

o Air Intake:

§ 90mm LS2 Throttle Body

§ Halltech C5 Killer Bee™ II Induction Package

§ LS7 MAF/IAT Sensor

· Exhaust:

o Kooks 1-7/8” Headers and catted 3” X-Pipe

· C6 Z51 (RPO J55) Brake Package:

o Caliper brackets, pads, and rotors

§ 13.4” front rotors | 12.9” rear rotors

· Drivetrain:

o LS7 Clutch & Hydraulic Package

o C6 Shifter

o HPI Differential Brace

o Texas Drivetrain Performance:

§ 300 Maraging Steel Output Shafts

§ T56 Rebuild — 3/4 steel shift fork, triple cone synchronizers, 30-spline mainshaft

§ Differential — 3.90:1 Motive Performance ring & pinion, seal kit, 30-spline pinion, bearings

· Steering & Suspension:

o Turn One Steering Pump and Pulley

o Bilstein B6 Performance Shocks

o Hotchkis Sport Suspension Anti-Sway Bars

o Lexani L-CC7 Wheels

§ 18x9.5 front | 19x11 rear

o Continental ExtremeContact Tires

§ 255/40ZR18 front | 295/35/19 rear

· Kenwood DNX697S Double Din Radio:

o Rear View Camera, Bluetooth, and Garmin GPS

· EFI Tuning — self tuned with HP Tuners

o TAC Module — improve throttle response

o Fuel Flow:

§ Set injector control to match the LS3 injectors

§ Set power enrichment for safe WOT

o Idle — establish smooth idle without stall

o Establish Stoichiometric AFR:

§ Volumetric Efficiency and MAF sensor calibration

o Closed Loop Fuel Trims — O2 sensor calibration

Spark Advance — optimize for 91 octane pump gas

This is Corvette after I completed my build and moved to Utah:

The following images show my hard work in my garage.

RADIO SWAP

· Replace center bezel, solder wiring, install double DIN receiver.

· Add backup camera and run wiring behind body panels and through existing gromet in the firewall.

ENGINE SWAP — replace stock LS1 with the modified LS3

· Remove hood, bumper cover, condenser, radiator, intake, exhaust, ABS module, PCM, shocks, etc.

· Separate fuel and EVAP lines, wire harness connectors, etc.

· Separate drivetrain from chassis and support on tires.

· Separate LS1 engine from drivetrain and remove from front cradle (engine sold & shipped)

· Disassemble drivetrain to send out transmission and differential for upgrades (30-spline & 3.90:1 ratio)

LS3 UPGRADE — camshaft, valvesprings, pushrods, and rocker arm trunnion

· Disassemble engine and swap cam sprocket (4-probe to single-probe)

· Send crankshaft out for reluctor wheel swap (58-tooth to 24-tooth)

· Valvetrain Upgrade — install guides, springs, locks, and retainers

· Engine Reassembly — crankshaft, main bearing caps, rod caps (stretched rod bolts)

· Replace stock camshaft — more duration, lift, and overlap; advance to maintain dynamic compression

· Install front/rear covers and seals, windage tray, oil pan, lifters, and pushrods

· Replace rocker roller bearings with bushings, trunnions, and snap rings

· Complete engine assembly and prime with oil

DRIVETRAIN REASSEMBLY

· Replace engine mount brackets with C6 brackets to accommodate LS3 block boss with hole

· Modify C6 engine mount brackets — drill ¼” diameter blind hole for engine mount dowel

· Install LS3 engine onto front cradle

· Mount new LS7 clutch kit — flywheel, clutch disc, pressure plate, slave cylinder, and throw-out bearing

· Modify clutch pedal assembly to accommodate master cylinder upgrade

· Replace stock shifter with C6 shifter

· Attach aftermarket brace to differential — reduce powertrain shake

· Mount differential and transmission to rear cradle

· Insert rear axles into differential

· Assemble drivetrain — torque tube to engine and transmission/differential to torque tube

WIRING

· Install and connect wire harnesses to sensors and actuators

· Re-pin fuel injector connectors — replace stock Minitimer (Bosch EV1) with USCAR (Bosch EV6)

INSTALL NEW ENGINE ACCESSORIES AND SENSORS

· Replace steering components — pump, pulley, hoses, and cooler lines

· Replace belt tensioners, idler pulleys, and belts — both drive and A/C belts

· Relocate and/or replace solenoids and sensors — EVAP purge, EOP, CKP

· Add wire harness adapters — CMP, MAP, EVAP purge, TP, TAC, and knock sensors

FINAL ASSEMBLY

· Complete main assembly — drivetrain to chassis, brake lines, fuel lines, emissions, wiring, cooling, etc.

· Upgrade induction with LS7 MAF/IAT sensor and larger duct to accommodate 90mm LS2 throttle body

· Add PCV oil catch can system (emissions compliant closed system)

SUSPENSION & BRAKE UPGRADE

· Replace shocks with aftermarket performance shocks

· Replace anti-sway bars with 1-1/4” front and 1” rear bars (1/4” increase over stock)

· Swap front and rear caliper brackets with C6 Z51 brackets to accommodate Z51 brake package

· Add Z51 brake pads and larger Z51 rotors

· Replace rear wheel bearing and hub assemblies

· Adjust parking brake star wheel to spread brake shoes appropriately

· Add new wheels and tires (255/40R18 front, 295/35R19 rear) with rear wheel spacers

EXHAUST UPGRADE

· Remove stock manifold and mid-pipe

· Add stock O2 sensors to collectors and wideband O2 sensor to passenger side collector

· Install new 1-7/8” headers and 3” catted X-pipe — sent out for coating after verifying install/fitment

WHEEL/TIRE ALIGNMENT

· Adjust front and rear camber, thrust angle, rear toe, and front toe

PREPARE FOR THE ROAD

· Add fluids — engine coolant and oil, brake and clutch fluid

· Bleed brakes and clutch

· Charge A/C system

· Speedometer calibration — calculate and change the VSS calibration for final ratio and tire size

· Engine Break-In — follow GM guidelines for rpm and engine load limits as well as piston ring seating procedures

EFI ENGINE CALIBRATION

I developed mathematical formulas to establish smooth 2D curves and 3D maps and used Excel VBA to generate tables from my formulas where I copied the values into the HP Tuners VCM Editor, thereby allowing me to transform the stock LS1 tune into my custom tune for the modified LS3.

Ø I calibrated ("tuned") my engine for 91-octane E10 pump gasoline

TAC MODULE — improve throttle response

· Increase throttle area by 20% in the mid and upper range accelerator pedal position

· Smooth out the “Desired Pedal Area vs. Pedal Position” curve

FUEL FLOW — tune injector control to match the LS3 injectors

· Injector Offset — interpolate offset/voltage/vacuum from stock 2013 (C6) Corvette

· Increase flow rate vs. vacuum to accurately control the EV6/USCAR 42 lb/hr @ 58 psi injectors

· Modify EQ (equivalence ratio) table to target 12.05:1 AFR (air to fuel ratio) during power enrichment

IDLE — establish smooth idle without stall

· Set ETC Area Scalar appropriately to the 90mm throttle body

· Add 25 rpm and 60% more airflow to accommodate Stage 2 camshaft

· Adaptive Idle — adjust PID controls and overspeed/underspeed idle spark advance

VOLUMETRIC EFFICIENCY — establish Stoichiometric AFR (air to fuel ratio)

· Install and set-up wideband O2 sensor

· Disable MAF (mass airflow) sensor and closed loop operations

· Conduct open loop test drives at part throttle and low rpm, followed by WOT (wide open throttle)

· Use wideband data to modify VE (volumetric efficiency) values — establish ≤ ±5% AFR variance

MASS AIRFLOW CURVE — establish Stoichiometric AFR

· Enable MAF sensor to entire rpm range

· Use wideband data to modify part throttle frequency values — establish ≤ ±5% AFR variance

· Conduct aggressive drives up to 7000 rpm and 95 kPa MAP — establish ≤ ±5% AFR variance

CLOSED LOOP FUEL TRIMS — O2 sensor calibration

· Conduct part-throttle test drives — analyze narrowband O2 sensor voltage readings

· Calibrate O2 sensor voltages to appropriate air flow mode settings

· Enable closed loop operations and STFT and LTFT (short and long-term fuel trims)

· Verify ≤ ±5% long term and short-term fuel trim variance

SPARK ADVANCE

· Compare and analyze “Main Spark Advance” tables from stock 1999 Corvette (LS1), 2013 Corvette (LS3), and 2010 Corvette Z06 (LS7)

· Consider variables affecting flame speed including ignition lag, bore diameter, piston speed, dynamic compression ratio, airflow turbulence (i.e., air/fuel mixing), engine load, etc.

· Develop custom formulas associated with flame speed variables to create spark advance maps

· Conduct test drives and adjust values for Stage 2 camshaft — remove low rpm “bucking” and improve street drivability

CHASSIS DYNAMOMETER RENTAL

· Adjust power enrichment to maximize torque without compromising combustion chamber temps

· Adjust spark advance to maximize torque while avoiding pre-ignition and detonation

· Adjustment results @ WOT — 10 ft-lb increase and 15 hp increase

· Ensure engine protection after dyno runs — retard spark advance by 3° – 4° (depending on engine load) and increase power enrichment by 3%

· Measure and record values after final adjustments

TORQUE/POWER CURVES — STOCK LS1 VS. STOCK LS3 VS. MODIFIED LS3

· Peak wheel torque increased — 12% over stock C6 LS3 | 36% over stock C5 LS1

· Average wheel power increased — 15% over stock C6 LS3 | 43% over stock C5 LS1

That's pretty comprehensive. Nice!