The SRT4 engine had many improvements, including: stronger crank case webbing, a thicker deck with 11 mm head bolts (vs 10 mm), an oil drain back for the turbo, a cast aluminum structural oil pan, a higher capacity oil pump, a crankshaft of higher hardness steel, improved machining of bearing journals, oil squirters (to cool underside of pistons), eutectic aluminum alloy pistons made specially by Mahle, and forged connecting rods with cracked caps and 9 mm bolts.
Mahle GmbH, a large German industrial company automotive supplier
Mahle GmbH | Ernst Mahle | Mahle |