Questions regarding fuel injection, the TB.

[MyMopar]

After searching the board I have come up with the following questions concerning fuel injection.

From one of Rob's replies, he stated that the Edelbrock Pro FLo was a very good system.  He then said if you didn't want to lay out $2800 then you can build your own.

I've researched the Megasquirt (www.megasquirt.com) and FAST (www.fuelairspark.com ?) and figured I'd used that as the "brains" of the system.  I'll follow along and drill out the sending unit for 3/8" line, add 3/8 inch line next to the 5/16 line and use the 5/16 line as the fuel return line.  Where I mount the fuel pump is still uncertain, it really depends on the type I get. 

SO I have most of the stuff figured out but still have a few questions.

A mention of a Ford van fuel pump can be used.  Perhaps I'll go that route, but what would you use for a fuel pressure regulator?

Also I'm having trouble figuring out what type of throttle body to use.  I can try to find a 4 barrel type throttle body, but haven't found one yet.  Then I got to thinking about a 58mm throttle body used on the Corvette or Mustang.  I can get an intake elbow made that would adapt those style TB's to the 4150 style intake.  Would their be any benefit using one style over the other besides looks?  Also if anyone has links to TB's that would be great.  I'm just unsure of what exactly to look for.  I even considered using an old Dominator carb, blocking off the metering plates and figuring out how to get a TPS to work with it.

So there you have it, I'm trying to FI, but want to build it myself (for the most part) and do it at half the cost of the Edelbrock unit.  If I can't do that, then I might as well save the other half and buy the Eddie unit in another year.

[Chryco Psycho]

the 4 bbl throttle bodys are easy to get from a # of different companies ranging from 800-2000 cfm ,generally the regulator is a limited return line type where there is a vacuum control limiting the amount of fuel returning to the tank 

[MyMopar]

So the regulator is not like a carb type that you preset to a certain psi or are you saying I'm better off gettting a regulator that is based off of vacuum and not a preset psi?

[Chryco Psycho]

Efi needs 40-60 Psi so a carb type will not work
the bypass type will close as the throttle is opened to maintain pressure as more fuel is pushed through the injectors ,you will need a different type of system for this

[MyMopar]

SO now if I am reading you right, their are two types of FI regulators.  A bypass type that runs off of vac. and will close the return portion when it senses a drop in vac. and their is a regular type that is preset to say 50 psi and will always allow a return?

Also you stated many companies sell a throttle body, are their any characteristics that I should be looking for to lean towards or stay away.   

[HemiDog]

The engine builder I am using was going to use MSD throttle boddies originally.  He still uses them, but since I placed the order and waiting for the block and heads for so long, FAST released a new one.  I am getting them.

http://www.msdignition.com/fuel_8.htm

http://www.fuelairspark.com/Information/WhatsNew/Default.asp?offset=5
There are some PDF documents there with the new TB.

Just a couple I know of.

[MyMopar]

Ok so now I heard some conflicting info that maybe someone can clear up w/an explanation.
Rob uses a 5/16 line as a return and 3/8 as a feed.

Some other people stated you'd want your return line the same size or larger than the feed line.

NOw can someone explain to me why I'd want to run a larger return line?  I figure the smaller the return line (to a point) it will help keep the pressure in the lines while still returning fuel.  If I abide by their theroy I'd want to run a 1/2 return line and then I'd need a monster pump to keep up the motor demand and the return line demand.   

[HemiDog]

In my app (572CI EFI Hemi), I am using AN-10 feed and AN-8 return.  The guys that built my tank (Rick's Hot Rod Shop) told me this should be pleanty to feed my motor.  The engine builder (MEW) agreed also.

I would think that your 3/8 feed and 5/16 return would be fine.

[MyMopar]

Thanks for the reply. I feel better moving forward now and acquiring components I need.