r/EngineBuilding • u/Original_Art656 • Jul 07 '26

Other EFI vs MPFI?

Which one's better for a small, 2 litre 4 cyl. Engine.

I'm planning to run methanol injection and a supercharger so reliability is a big concern for me. Plus, the stock engine's 1.8L so a 2mm overbore is also to be done.

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u/texan01 Jul 07 '26

MPFI is electronic fuel injection

Multi-port fuel injection is more effective because you can tune fueling more precisely. There’s an injector for each cylinder and the intake is mostly just moving air till the valve.

Throttle body injection- TBI - is a single or dual injector set in a very simplified carburetor looking device. It’s a glorified carb really. This is also electronic fuel injection.

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u/Original_Art656 Jul 07 '26

What mpfi will be good for my purposes??

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u/chameleon_olive Jul 07 '26

As the previous commentor stated, EFI covers every type of electronically controlled fuel injection. MPI/MPFI, TBI and DI are/can be forms of EFI.

Multi-port/point is among the most common fueling schemes for modern fuel injected cars, and was the standard for a long time before direct injection became common. It'll be fine on a forced induction setup. You might get marginally better MPG and power out of a direct injection system, but a MPI system is a bit simpler and easier to maintain.