MSefi.com read only forum (Jan.15,2018)

I'm working on a system for an AMC six using a GM TBI unit. However, I have been keeping in mind a desire to eventually convert to a multi-point set-up, using the TBI unit just as a throttle body. However, I've come accross an '84 Ford 5.0 with Ford's version of throttle body injection which they called Central Feul Injection, or CFI. Anybody have a source for specs on this unit? Throttle bore diameter? CFM? Injector size? Anything? There's oodles of info on GM TBI's, but where do I find info on Ford CFI's?
Thanks!
Bruce

I can't give you any real specs or hard info but 85 Mustang GT's with the AOD transmission got CFI. Ford has used 500 cfm 2bbl carburetors for years on 302 engines and I would have to guess that the throttle body on the CFI would have to be very close to that. (measured at 3" HG for 2bbl's)
The engine was rated at 180 hp so if you figure a bsfc of .5 then the injectors were probably in the 50-55# hr range.

Check this out..

http://home.earthlink.net/~jopeterson/CFI-EFI.html

Ford 5.0L CFI injectors came in two different types both are 46lb low impedence injectors though. People who have flow tested them have gotten varied results on their flow rate though.

http://www.juscuzmotorsports.com/faqindex.html

AFAIK, there are two types of Motorcraft two barrel CFI units. A standard 155HP model, and the HO 185HP model. the HO has bigger bores and injectors. I have them both at home, I can measure all that stuff if you really want.

The injectors on the Regular 155HP are 46lb, and the 185HP HO has injectors rated at 52lb.

They made a single barrel CFI too, this has a different injector though.

None of the Ford TBI stuff has nearly the size throttle blades as the GM TBI, but they are cheap in the salvage yards, and they work good on small low horsepower engines. One nice feature is that they fit the same bolt pattern as the standard Autolite/Motorcraft two barrel carb, and they use an adjustable throttle stop style Fidle solenoid.

OK, so far I know this-
The CFI injectors are rated at 46# at 39 psi, right? And most sources I have come accross in the past couple of days say that they are very inconsistant, as well. So a TBI injector rated at 44# @ 13 psi will flow better at the same pressure. Some TBI gurus I have come accross say that the TBI injectors are more accurate at higher pressures, anyway.
So, the only reason I would want to mess with the CFI is for its closer throats and more universal bolt pattern. So what are the throat diameters of the two cfi bodies? I guess that's the only question I have left.
Thanks!
Bruce

The inconsistency is in how different people are measuring them - not the injectors themselves. They are made by, and are, regular Bosch MPFI design injectors. Rochester, Mopar and Holley TBI injectors are not more accurate at higher pressures than the Bosch and Nippondenso CFI style. There is some thick BS flowing somewhere... or something is getting lost in the translation.

I have no loyalty to any particular brand or style - I use whatever works best in a particular situation. I would suggest you consider what will physically and functionally fit your application and go from there. Hopefully Scott will get the bore info for you. I'll measure one the next trip to the 'yard if not; but it may be a while. Otherwise a simple horsepower match may be a good start.

Don't forget that in addition to the 5.0 std and HO Ford also used CFI with 32# injectors on the V6 T-Birds, Cougars and such. That may be a good fit for an AMC I6 as well as the GM TBIs for 2.9's, 3.8's and 4.3's. I won't even start on the good Mopar versions...

Hope that helps,
David

I completely forgot about the V6 version... Well anyway.

Here's some specs

Standard Motorcraft TBI

P/N E3VE-EAA-3E27
Rectangular Mounting base, 5.150"x3.5"
Throttle Bore 1.558 Measured at the bottom of the bore.
Stepped Venturi Approx 1.1"
Injector Bosch style E06E-A1A

HO LTD P.I. Motorcraft TBI unit.

P/N E4ZE-BAA-4B44
Rectangular Mounting base, 5.150"x3.5"
Throttle Bore 1.558 Measured at the bottom of the bore.
Stepped larger above throttle bore to Approx 1.75"
Injector Bosch style E4ZE-CA

Here the HO CFI is on the left, you can sort of see the difference in the Venturi bore.


Here the HO CFI. Notice virtually no restriction in the throttle bore.


And the standard CFI. Clearly there is a large restriction when compared to the HO unit. The throttle blade size is identical.


In my previous post I wrote in error that they have a solenoid style Fidle, In fact the FIDLE is an Electrically heated element that runs a cam to give larger throttle angles when cold, with a vacuum assist. Also there is an adjustable Mechanical dashpot as well.

Holy cow, I might just be blind lucky! First off, I'm looking at your pics (great pics, by the way!) and i'm seeing standard Bosch injectors, right? According to a link in this msefi site, Ford used a Bosch injector rated at 64# for the 2.5L four cylinder cfi THAT I JUST HAPPEN TO HAVE A COUPLE OF OUT IN THE GARAGE!!! BWAAA-HA-HA!!!!!
Now, if I can bore out the CFI body to take TBI throttle plates (1.69") I should have enough airflow for 200 hp, and have a much cleaner setup than the TBI I'm working on! Do you think there's enough meat to bore them out roughly an eighth of an inch?

pstrbrc wrote:Holy cow, I might just be blind lucky! First off, I'm looking at your pics (great pics, by the way!) and i'm seeing standard Bosch injectors, right? According to a link in this msefi site, Ford used a Bosch injector rated at 64# for the 2.5L four cylinder cfi THAT I JUST HAPPEN TO HAVE A COUPLE OF OUT IN THE GARAGE!!! BWAAA-HA-HA!!!!!
Now, if I can bore out the CFI body to take TBI throttle plates (1.69") I should have enough airflow for 200 hp, and have a much cleaner setup than the TBI I'm working on! Do you think there's enough meat to bore them out roughly an eighth of an inch?

I don't want to burst your bubble, but I think the Four cylinder CFI uses a different injector, but I could be wrong.

Yes, it does look like you could bore out the Throttle body more, you would need a corresponding plate to match the new bore size.

Let us know how it goes.

Oops! You're right about the injectors. The 4 cylinder's have the top harness connector, ala Rochester TBI's. But the throttle plates are no biggie. 1 11/16 is a standard Holley size. So, next question - is the fuel pressure regulator on the CFI adjustable? I've seen info that leads me to believe that this is so on some 4 cylinder cfi units of the mid-80's. Does anybody know how these units respond to higher (~50 psi) pressure?

These injectors respond to pressure changes just like any others. The injector calculator on the Megamanual can be used.

http://www.megasquirt.info/v22manual/minj.htm#size

I think the regulator is adjustable. Theres a cap in top you can remove, with a screwdriver adjustment. Unknown how much pressure you can get out of it.

This is old, but I'll add anyway. The CFI regulator is popular to swap onto an EFI engine once modified because it is fully adjustable. I'm running one of these on my 2.3T, and to make it work for me I had to drill a hole in the upper part and add a vacuum/boost reference nipple (epoxied in) and line to make fuel pressure go up with boost and down with vacuum. Once you take the plug out the adjustment is done with a metric hex head screw under the plug. The CFI regulator is atmosphere referenced in stock form as there is a hole in the center of this adjustment screw. This may be fine for you, but if you need it vacuum referenced and you add the vacuum nipple to it then the hole will have to be sealed off for it to work properly.

These regulators work great, I've had mine set between 39 psi and 45+ psi base FP and with 20 psi of boost the pressure rises just like it's supposed to so it's been tested to work at 65-70 psi of fuel pressure. In the stock atmosphere referenced form, it should adjust anywhere you want.

These regulators have a standard bolt pattern and will work on any Ford fuel rail of that era, 5.0 Mustangs, 2.3T EFI vehicles, etc.

I am using a CFI unit from the Australian Falcon 6 cylinder engine (EA or EB falcon).

http://www.fordforums.com/showthread.ph ... i+pressure

The last post in this link quotes:

"CFI uses an injector that opens in stages. The ecu controls how much the injector opens which in turn changes the amount of fuel going into the manifold."

And Im wondering if this could be true and if it will have any effect if i use the CFI injectors as you would normall do on a megasquirt.

Does the TBI option in megasquirt do anything regarding this "stepping" of injectors?

Personally im sceptical they work any differently to normal injectors.

Reason Im asking is I had it running for maybe 1 hour, had a half decent road tune. The next morning i installed the flyback board and then my car wouldnt start. The Injector circuit failed and am curious to know if the injectors caused this failure.

This failure could also be due to me running 6 low impedance injectors on my other car without flyback board for sometime, or perhaps my installation of the flyback board caused problems. So its not necessarily to do with the injectors, especially as it was running for a decent period of time.....

The CFI Unit:

http://gallery.teamshitbox.com/gallery/ ... temId=4436

http://gallery.teamshitbox.com/gallery/ ... temId=4438

http://gallery.teamshitbox.com/gallery/ ... temId=4440

juls wrote:I am using a CFI unit from the Australian Falcon 6 cylinder engine (EA or EB falcon). ...Personally im sceptical they work any differently to normal injectors. ...

I am not familiar with the AU CFI units, but the US versions use standard port-injection style injectors. No 'staging' or anything different to standard injectors, and are commonly used in port injection installations.

FWIW,
David