FMU stock 440's?

[mk3-4-me]

So I have this 12:1 blox FMU. I read that it is used with stock fuel systems and raises fuel pressure and is controlled with vacuum/boost. Has anyone used one?

If so, would it raise pressure enough to use a Lexus afm with stock 440's and the FMU?

Thanks

 

[Another MkIII]

I usually see people go with the Aeromotive AFPR, and 550's. You would need to get around 60 PSI to flow as much as 550's. Personally I would not recommend it. The stock injectors are designed to see 33-40 PSI according to the TSRM. When you start raising the pressure significantly, a lot of issues start to creep up that I'm not about to go into.
-AM3

 

[mk3-4-me]

Ok I was just wondering cause I have one sitting around...

What about a afpr on stock 440's with Lexus afm? Cause I have one of those to... But it's an eBay one so idk if I want to use it...

Cause I see alot of ppl using stock injectors with a afpr.

 

[OfnaRcR4]

People have done it but you need careful tuning. Just get some 550's.

 

[mk3-4-me]

ya ill just wait for 550's... im in no hurry anyways.. i got untill spring to get it ready... lol

i was JW

thanks

 

[Nick M]

FMU's were used heavily on the 5.0 Mustang when it had speed density. It is a very rough tune. It was 86'd with the advent of mass air.

 

[SideWinderGX]

Supracentral had a long post on FMU's, do a search and you'll find it. From what I gathered a 12:1 unit will raise fuel pressure 12 lbs for every lb of boost. At 40 psi base pressure running even 10 psi boost you'll be telling the fuel pump to put out 40 + (10*12) = 160 psi. Don't do it.

Get 550cc injectors and the lexus afm TOGETHER or go another route which doesn't include fuel modulation units.