* Engine Condition: A meticulously rebuilt and maintained engine with upgraded internals (forged pistons, rods, etc.) can handle significantly more boost than a tired, stock engine with worn components. A stock engine is much more likely to fail at lower boost levels.
* Fuel System: The stock fuel system has limitations. Running higher boost requires a capable fuel pump, injectors, and possibly fuel pressure regulator to deliver the necessary fuel. Lean conditions (not enough fuel for the increased air) are a major cause of engine damage under boost.
* Ignition System: A strong ignition system is crucial at higher boost levels to ensure complete combustion. Weaker spark can lead to incomplete burning of the fuel-air mixture, resulting in detonation (pre-ignition) and engine damage. Upgrading the ignition components might be necessary.
* Cooling System: Higher boost generates more heat. An efficient cooling system (radiator, intercooler, etc.) is critical to prevent overheating, which can quickly lead to engine failure.
* Supporting Components: Other components like the turbocharger itself, connecting rods, crankshaft, head gasket, and oil system all play a role in determining the engine's boost limit. Weak links can fail even if other parts are robust.
In short:
A *stock* 4G63 from a 1992 Eagle Talon TSi AWD is generally considered to have a relatively low safe boost limit of around 7-10 PSI. Going beyond this without significant upgrades is very risky and highly likely to result in engine failure. Even within this range, proper tuning and monitoring are crucial.
To run significantly higher boost (15 PSI or more), you'll almost certainly need substantial modifications, including:
* Internal Engine Upgrades: Forged internals (pistons, connecting rods)
* Fuel System Upgrades: Larger fuel injectors, upgraded fuel pump, and possibly a fuel pressure regulator
* Ignition System Upgrades: Upgraded ignition coil and spark plugs
* Cooling System Upgrades: Larger intercooler, upgraded radiator, possibly an oil cooler
* Exhaust System Upgrades: A free-flowing exhaust system is important to reduce back pressure.
* Professional Tuning: This is absolutely essential. A professional tuner can dial in the fuel, ignition, and boost levels to optimize performance and prevent engine damage.
Without significant upgrades and professional tuning, pushing the 4G63 much beyond 10 PSI is a gamble with potentially catastrophic consequences. You risk damaging or destroying the engine.
