Advice - Economical fuel delivery for Turbo

[Schmieder]

Little thing to remember about the FMU. What ever ratio you go with make sure you have a wideband on your car and a Fuel PSI gauge. Here is what happened to me. I was running 42.5# injectors, Walbro pump and 7psi with a 12.1 FMU. Whats 7 x12?....84PSI!!!!!!!!! plus the normal psi. I was hitting 100+ psi on my rail with the FMU. It was giving me terrible wash down on the cylinder walls.

Some have had better luck with the FMU, but now me lol. Thank god for Shane and his DHP tuner.

Mark

I currently have in budget an electric Fuel Pressure gauge for the cabin. I found a GM adjustable FPR, good quality. link
Nice thing about that AFPR is the shop sells an -6 AN adapter for the out line from the AFPR, making hosing attachment easy.

Plus a Vortech 12:1 FMU with bleeder valve to gently reduce ratio if needed.

I also have wideband, oil temp, trans temp and boost/vacuum. Those will be my gauges.

High Pressure Walbro 255.

I am going to run Braided Steel lines rated at well above 500 psi.

I am considering the Vortech Super FMU as it has ways to prevent mid RPM richening and can alter the psi curve. But me thinks I'll be fine with what I have planned.

[Weatheralls Auto]

www.wot-tech.com has AFPR and Adapters as well for your fuel rail, and I think they are cheaper.

[Schmieder]

Tell me if I got this right or not.

Lets say the stock injectors are 19#'s at 199.69 cc/min

If I switch to 21# injectors the flow would increase. But if I reduce the pressure to bring the 21# back to a 19# rating, I would have a reduced top end psi from the 12:1 fmu ratio.

To make a 21# inj flow like a 19# I would need to drop the psi to 35.5.

Then, when I hit 5 lbs boost and the FMU pushes an extra 60 psi, it would only be 95.5 psi instead of 103.5 psi.

Would there be any noticable negative effect from running 21# injectors on 35.5 psi in the fuel rail? If not, I think this would be a great idea to reduce top end pressures.

What is, in theory, the lowest fuel rail psi that will run 'normal'? Cause if I can run 25 psi w/o a problem, then 25# injectors would flow equal to 19#'ers. Thus reducing the top end fuel psi to 85 psi.

For a turbocharged v6 displacing about 191cc's at 5 psi boost, I would need about 328 cc/min fuel flow. 21# injectors (idling at 35.5 psi) will flow 326 cc/min at 95psi in the fuel rail.


This all seem accurate enough?

[Schmieder]

www.wot-tech.com has AFPR and Adapters as well for your fuel rail, and I think they are cheaper.

Yeah, I saw them listed but WOT is out of stock atm. If they don't stock up or are unable to fill such an order I will have to go with the Automotive Brand. Planning for the more expensive of the two just in case. I would prefer the WOT AFPR.