420a Build Suggestions

[rstare]

What type of fmu and fcd would you suggest?

Symtechlabs FCD, and Vortech 12:1 fmu. Or you could go better and get a Vortech Sfmu. (Super fuel managment unit, it allows you to control idle/static fuel pressure, so you can get bigger injectors, and allows you to ditch your stock fpr, its a better but more expensive alternative)

Can I clean my injectors or should I buy new ones?

If you get a 12:1 fmu you have to use stock injectors. Use fuel injectors cleaner, dumps in your gas tank. They should be fine though.

Do you guys run a seperate inline fuel filter?

I replaced my fuel filter, with another OEM one. But you dont need a additional filter.

Will my stock fuel pump hold up to the demand of the fmu or will I need a different one?

No you will need a Walbro 255lph hp pump.

So the ecu controls fuel trim but does it also control pressure? Is there still a mechanical fuel pressure regulator?

There is a fpr, if your a late 96' or up then its back by the fuel filter/gas tank. If your a late 96' or earlier then its on the fuel rail.

The fpr keeps the 53psi fuel pressure and the ecu controls the injector pulses, so there is no need to add pressure. Now there is more air that the ecu isnt accounting for so you need to rise the pressure accordingly.

12:1 wouldn't that equate to 149psi at the full 8psi of boost. Sounds like alot will my fuel lines take this?

Ahhh, the question. , I had the same question. I have SS braided line so I was more concerned about the fuel pump.

You must be logged in to view this image or video.

The pump simply doesnt support that much pressure, and it wont supply the needed fuel. I have only seen one afr sheet and it agrees 100% with my previous statment. But so many people run this setup everyday and it works just fine.....thats the other argument.

I went with a sfmu, one word saftey. Lean = no good, and knock = no good, I dont care how well my engine handles it I just dont want it, because sooner or later it will go out.
Its up to you which one to go with and many people have run a 12:1 fmu forever and they are still running strong. I dont understand it, and Im just not willing to take that risk.

 

[Locke]

Vortech 12:1 FMU.

Symtech FCD.

Most people don't clean or replace their injectors, but it can only help to have them cleaned.

No separate fuel filter needed.

The stock fuel pump will NOT work - you will have to purchase a 255hp, or something of the like.

The factory ECU doesn't care about fuel pressure, it assumes you are running stock 50psi. The FMU will take care of all of that.

The math says 149psi, but the pump won't actually be able to support that. It's safe though -barely. The fuel lines can handle the pressure.



All of these questions have been answered before, and while we generally don't mind giving out answers, a little deeper research on your own will not only show good faith, but will likely answer your questions faster than waiting for one of us to respond.

edit: Ryan beat me to it.

 

[fornstar13]

Hmm I didn't even think the stock fuel filter was in line. i thought it was in the tank. that sfmu is $400, do u think its worth the money. Yea by the chart it wouldn't seem like the pump should take it. Well thanks again and props for the charts.

 

[rstare]

Sorry Locke im good like that, sometimes, except with my car it seems.... dang. Well I have explained turbo build ups more times then I even know... and I dont mind giving a few minutes of my day to people, guys like Locke, Paul, Slippi, along with others do it for me, so I do what I can for others.
Anyways...
I got my sfmu used from a dsmer for $175. So it made a easy decision for me. Honestly, its totally your decision. Lots of people do it and it works, I just dont understand how, and I NEED to know how stuff works in order for me to put it on my car...

 

[fornstar13]

Well thanks again. I think everything theoretical is ironed out. Probably will need helpl when it comes to the install though. Until then thanks again and good luck with your guy's projects.
FornStar