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Alloytec block compatibility

Discussion in 'V6 Development And Modification' started by xauterus, Jun 16, 2019.

  1. xauterus

    xauterus Member

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    I'm looking for some advice on alloytec blocks. Are they the same block for LFX to LY7 etc? In the 3.6 litre engine.
     
  2. rtmpgt

    rtmpgt Member

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    Blocks are completely different between LLT, LY7 and LFX. They only share a common thermostat housing, oil filter housing, heater core routing and accessory pulleys as far as I know. Even things like the timing covers are slightly different between the models. Correct me if i'm wrong, fellow armchair mechanics.

    LLTs and LFXs have an extra cam lobe for the high pressure fuel pump. They pressurise fuel twice, once electronically at the tank and another at the engine, for the DI injectors. Therefore their heads cannot bolt onto LY7 blocks.

    LLTs and LFXs have under-piston cooling jets, whereas LY7s don't.

    Cranks are different, rods are similar but not quite, pistons are similar but also not quite. Same bores and strokes but different designs and arrangements.

    LFXs don't have exhaust headers, and instead have an integrated manifold. LLTs and LY7s share the same manifolds, but LLTs require a tune due to stricter emissions controls and the DI. You can bolt Paceys to LLTs and get the same power as an LFX after a tune as that's theoretically what the single exit manifold does on the LFX. This is also why LFX heads won't bolt to an LLT as extra clearance is needed for the Exhaust manifolds, and different looms are needed.

    So to be fair, not much is cross-compatible between the Alloytecs. All I know is that LLTs and LFXs face next to no stretching issues with the timing chains, but you should still be wary of things like oil quality, pressure, etc. All alloytecs are oil sensitive.
     
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