jwork101

I'm a little bit confused. I am about to embark on my homemade turbo project finally, and searching for some info on the Cartech FMU I am buying I found a few domestic sites as well. One guy was saying that the FMU is plumbed in on the return line to the tank? Is this true? I was under the impression that the it went on the feed line before the stock FPR. Can someone better explain this to me? And is there anything else I should know about the FMU? I assumed it was on the Feed Line, hook up a intake manifold vaccum line so that it sees boost, and then it would raise the fuel rate accordingly at 10 to 1 ratio.
Please help me out bc the UPS man is gonna be here soon next week.
Thanks guys
Jim

tonydatyga

-he's right, return line
-yes it is true
-you're wrong
-probably but noone wants to
-you should know a lot more
-you're assuming too many things
-UPS men are gods, they bring my happy boxes everyday

Cramerox

that guys is right. it fits on the return side of the line with the FPR. what is does is like pinch the return flow to the tank. This pinch causes the increase in fuel pressure. Its like tying a nott or stepping on your garden hose while running.

if your using stock injectors- use a 12:1 ratio.
if your going to upgrade you injectors then u can step down because you dont need as much fuel pressure. like 10:1 or 8:1

Sorry i dont have diagram, maybe someone else does?

HTH

Cramerox

stressing day man?

jwork101

Thanks for the reply cramerox. Much more helpful than the first reply. I've been wandering this board for almost a half a year now trying to pick up what I can and unfortunately misunderstood where the FMU went. Your explanation was great.
Thanks man.
The FMU supplies stock fuel pressure + (boost pressure x 10) on say a 10 to 1 FMU correct? Does anyone have numbers on what kind of pressure is really needed for around 6 pounds of boost on a D16? Is there really gonna be a huge difference from the 10:1 to 12:1?
Thanks
jim

Cramerox

well basically your fuel presure regulator pinches your line already. now what the FMU does is pinch it even more to raise the fuel presure. It pinches it according to boost presure. hense 12:1= for ever psi of boost it will give you 12 lbs or fuel presure.

On my car (Integra) if i want to run stock injectors- i have to use a 12:1
Im not sure how it is on your car but its a good chance that you also run 12:1. its better to be rich than lean.

for 6lbs of boost= that means 6x12=72lbs of fuel presure PLUS about 50 lbs of fuel presure from your FUEL PRESURE REGULATOR. so that gives u 122 LBS OF FUEL PRESURE!!!!!!!

now thats alot of presure- meaning your stock fuel pump wont be able to provide that much, so you have to run an inline fuel pump. Most people look down FMU beacuse they cause more of a problem for something going wrong.

what Sonny told me is just boost low and see how the systems goes. when all the bugs are worked out-invest in a good fuel management. 122 lbs if just way to much fuel presure for you lines to handle. getting bigger injectors will help lower that. you just gotta get them tuned out.

Good luck