leonpiper69

iTrader: (3)

i bought a turbo off a friend and he gave me all the stuff he used with it. basically the wastegate and fmu and i think a blow off valve and some pipeing (all thrown in a box that i havent really gone thourgh yet).

anyhow he was asking to buy the fmu back off of me because since im going to run bigger injectors on my ls motor he said i dont need the fmu.

so here's where im confused. does an fmu just replace the presure regulater so that you have a boost referenced regulator? i thought that even with the correct size injectors and the proper tune you still needed to increase fuel presure with boost?

Lonnies Performance

iTrader: (16)

The FMU installs in the return line after the regulator to boost fuel pressure under boost. It is not required if you run large enough injectors & ther proper tune. These were typically used in earlier cars with engine mounted regulators.

Boost referencing the fuel pressure regulator is another (& better) way to control pressure. This increases fuel pressure equal to the boost level. This maintains fuel flow under boost, whereas a FMU drastically increases pressure to make up for an injector that is too small for the application.

JoshuaGrooms83

iTrader: (2)

i know this is old but wanted to say thanks for putting that out there as well. was having trouble understanding the difference between the two. they almost sound like they do the same thing but i guess not.