What's the diff?

 

Your fuel regulator increases fuel pressure on a 1:1 ratio. ProCharger's FMU increases fuel pressure at a far greater ratio that's adjustable.

 

I should have said a boost referenced adjustable regulator. Thanks

 

Yes, that's what a boost ref. regulator does, increase 1:1

Imagine you are running 43psi fuel pressure @ atmospheric, if you are at 10 psi boost for instance, that would leave you with an effective f.pr. of 33. This is also the reason why a vac. referenced regulator pulls down the pressure, to keep the absolute effective f.pr. more consistent.

For boost enrichment the FMU increases the pressure at a ratio greater than 1:1

 

Thank you very much.

 

I thought you had to use the FMU with an fuel injected set-up and were good using a boost referenced press. reg. with a blow-thru carb set-up. Am i wrong here?

 

Yes, that is incorrect. An FMU is only used for those applications in which the engine will need more fuel and the user doesn't want to use larger fuel injectors. Basically, they are band aid fixes for applications that really need larger fuel injectors. I am not saying that they don't work, just that they are used as a lazy way to cure insufficient fueling issues.

In any boosted application (i.e. turbo or supercharger) you have to boost reference your fuel pressure regulator. As Twin-turbo pointed out, if you pressurize your intake 20 psi and you run a fixed WOT fuel pressure of 45 psi, your engine will only see an effective fuel pressure of 25psi. The whole point of boost referencing a FPR is that it maintains the same effective fuel pressure regardless of the boost you are running (assuming it is 1:1).

This applies whether you are using a carb setup or an FI setup. It's all about maintaining the same effective fuel pressure under boost/vacuum situations.