I was just lookin at fmu's and they had different ratios ie. 6:1, 10:1, and 12:1 what does that mean?

http://store.summitracing.com/defaul...=egnsearch.asp

 

Increase in fuel pressure : Increase in manifold pressure

 

I'm sorry, what does that mean? haha

 

Example:

6 to 1 ratio For every 1psi of boost the fuel pressure raises 6psi

8 to 1 ratio For every 1psi of boost the fuel pressure raises 8psi

Etc.

Hope this helps.

 

It does, thanks

 

Any ideas which one i'll need? I'm planning on running around 7 psi on a 5.7L Stock TPI

 

we need to know this pretty quick so that we can get the car back together before June 18th... or at least get the parts ordered as soon as we can......

 

Who knows?

Get an adjustable FMU, a wideband o2, and reserve a few hours on the dyno.

-- Joe

 

Cartech FMU's work beautifully in my experience. Just don't crank up the base fuel pressure over 50psi (it can damage the stainless steel shim protecting the diaphragm). Lots of adjustability for a fair price.

I also use a Vortech SFMU in my IROC, which is very adjustable, but expensive if purchased new (mine was from eBay).

 

what do you mean by base fuel pressure, cause i'm planning on putting a inline booster pump in that will put the fuel pressure well over 50psi, just wondering if this is base. Cause that vortech one is pretty pricey, as you mentioned.

 

nevermind, just got onto cartech's website and noticed that they are just a bit cheaper than the vortech, i'd rather pay a LITTLE more for something better.

 

Walbro 255lph high-pressure version in tank, no booster = better route.

If you wanna REALLY do it right, use a 2-bar EFI setup, rather than an FMU and dial in the AFR you want under boost. What a motor needs at 5psi and 4,500rpm, might not be what it needs at 12psi and 6,000 rpm as I have found over the years.


-- Joe

 

I dont wanna argue, but i'm curious as to why it is better than having a booster, cause i would really rather not have to get into my fuel tank, don't sound like much fun from what i've heard, also if i do use the inline booster pump do you have any suggestions?

 

Well eventually you'll need to get into the tank anyway. Its just how it is.

I used to run the booster pump FMU setup.

With a 2-bar setup, you have electronic control over your fuel and timing curve. To me thats priceless.

-- Joe

 

will i need it with only 7 psi of boost ever, because i dont plan on ever running more than that with this engine, i'm being so stingy because i'm 16 with limited money

 

How did you afford the blower or turbo or whatever your putting on it?

-- Joe

 

I had enough saved up from work to buy the supercharger plus 600 bucks. so i'm looking for one of the cheaper routes to go.

 

is a 15 psi booster pump enough to run with the fmu setup? Thanks for your time

Trey

 

ttt

 

I'm not sure I ever seen a booster pump rated in that manner. Doesn't sound like much to me. You are running TPI , and not a carb, correct?

FWIW, here is my fuel system on my '89 TT IROC-Z, which is recieving 6psi from two Garrett T3/T4 hybrid trubos (TO4E 57 compressors, T3 stage III. .63 A/R turbines). I have run it up to 9-10psi for some test runs, but have not done enough testing at that boost pressure to insure it's safety (though it did run well and the narrow band O2 readings were good; with no detonation).

*Vortech SFMU
*Stock 90k mile in-tank fuel pump
*Vortech T-Rex booster pump
*Ford SVO 24# injectors
*I always use premium pump gas (and will probably run race gas for boost pressures over 6psi at the track)

Timing Controls:
*MSD 6AL
*MSD BTM pulling out ~1/2° of timing per pound of boost
* 6° base distributor timing
*Stock ECM and PROM

It all works well for me, but I am planning to go to custom ECM tuning in the future. I would like to build my engine to take 15+ PSI of boost, and my band-aid of a fuel/spark control system will not be up to the task (as other have eluded to, you need total control of fuel and spark once you decide to get serious).

**For an FMU, I feel a booster pump is a better idea than a 255lph Walboro in-tank unit. I don't believe the 255lph Walboro would provide enough volume of fuel flow at the extremely high pressures demanded by the FMU (80+psi fuel press). As fuel pressure rises, the volume capability of the pump quickly deminishes. If two pumps can split the pressure ratio, they will have much greater flow capabilty. For instance, a single in-tank pump would need to make 80psi AND 50gph flow for a given HP potential. If you use a booster pump, each pump would still need to flow the 50gph, but at only 40psi each (its no harder for a pump to take the pressure from 40 to 80psi than it is to go from 0 to 40psi). But, the in-tank pump must be healthy enough to support your flow volume!

 

First off thanks for the info. So you think 80 psi total, from both the in-tank pump and the booster pump combined is enough pressure? i'm trying to decide how big of a booster pump i will need to purchase. The particular pump that i'm asking about that flows at a max of 15 psi, pumps 43 gph. So i'm not sure how that ties in. I'm new to all this stuff so please excuse my ignorance. Thanks

Trey

 

As for the TPI or carb question, i'm running tpi. I'm also curious as to how many gph the stock tank flows and if you know at what psi that would also be extremely helpful. BTW that twin turbo set up sounds badass, its pretty unique to hear about a third gen with turbos.

 

Sounds like the pump you are refering to is for carb applications. You have to test your AFR to insure that it is correct. I cannot tell you what fuel pressure you will need under boost to provide the correct AFR (many, many variables). You have a lot of research to do yet, and nobody is going to be able to spoon feed all of it to you, you need to learn some stuff on your own (I gave the specs on my system just for a reference point- never assume that because it works on my car it will work exactly the same on yours- I had to do tuning to the fuel pressure curve to get it right for my application). Start by reading some supercharger/turbocharger books.

 

the fmu shims can be oredered for the injector you run. when you hit boost you should be aroud 80 psi. look at the holley inline pump (pn 12-920). that is the pump i ran when i had full exhaust and was running 8#. now i run that pump with a walbro that are feeding 48# injectors. the holley pump is $159.88 at summit.

 

Thanks, your old set up sounds very similar to the one im trying to do. I'll look into that holley fuel pump, thanks

Trey