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Author
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Topic: efi
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two89w
Gearhead Posts: 302
From: sydney australia
Registered: Sep 2002
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posted 06-25-2004 04:23 AM
   
I am dumping my webers and coverting to efi.
You guys running 347's, what manifold,size throttle body,size injectors,ecu,heads,cam are you running?What sort of power are you making?I am planning to run a trickflow R manifold,75mm throttle body,32lb injectors and a haltec E6X ecu....any opinions on this set up? Good bad or other wise? [This message has been edited by two89w (edited 06-25-2004).]
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SteveLaRiviere
Administrator Posts: 43791
From: Saco, Maine
Registered: May 99
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posted 06-25-2004 08:06 PM
There's a formula for figuring out injector sizing, did you use that to pick the 32s?------------------
'70 Mustang Mach 1 351C 4V/FMX/3.25 Open
'70 Mustang Convertible 250 I6/3 speed/2.79 Open
'72 Mustang Sprint Hardtop 351C 4V/FMX/4.30 Trac Loc
'94 F-150 XL 5.8L/E4OD/3.55 Limited Slip
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two89w
Gearhead Posts: 302
From: sydney australia
Registered: Sep 2002
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posted 06-26-2004 02:55 AM
No It was suggested to me by a few people.
Do you have this formula?
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SteveLaRiviere
Administrator Posts: 43791
From: Saco, Maine
Registered: May 99
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posted 06-26-2004 10:23 AM
I'm leaving on a trip in a few minutes, but if nobody else can supply it, I'll dig it up for you when I get back.Especially with EFI, I'd guess at nothing. ------------------
'70 Mustang Mach 1 351C 4V/FMX/3.25 Open
'70 Mustang Convertible 250 I6/3 speed/2.79 Open
'72 Mustang Sprint Hardtop 351C 4V/FMX/4.30 Trac Loc
'94 F-150 XL 5.8L/E4OD/3.55 Limited Slip
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Mooney
Gearhead Posts: 1691
From: Marietta, Ga
Registered: Oct 2003
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posted 06-26-2004 10:23 AM
TO CALCULATE FOR INJECTOR SIZE:
Throwing in an injector size based on assumption or simply because it's what your friend is running is an unwise way to spend your hard-earned dollars. It takes a little more knowledge than this to reach an educated determination of what is required. However, injector size requirements can be figured through some very simple mathematics. (and if I can figure them, anyone can!!)
Whatever you do, don't install larger injectors just because you want to! Without additional airflow, a larger injector will wreak havok on a stock EFI system by allowing unburned fuel to continue into the exhaust since the EEC cannot control the larger injectors to the stock engine's needs.
(Horsepower x *BSFC) / (Number of Injectors x Duty Cycle) = Injector Size
*BSFC = Brake Specific Fuel Consumption
Example:
(225 x 0.55) / (8 x 0.80) = 19.3-lb/hr Injectors
The stock 19-lb/hr injectors found in a stock 5.0 Mustang are capable of handling the stock horsepower output with everything in a well-tuned state. So, what happens if you bolt on a set of heads and install a larger cam, and power output goes from the stock 225 horsepower to 280 horsepower?
Looking at the injector equation again:
(280 x 0.55) / (8 x 0.80) = 24.06-lb/hr injectors
As you can see, you will definitely need something larger than the 19-lb/hr stockers.
However, what happens if the BFSC is changed, or leaned out to 0.50 to emulate the more effecient heads and camshaft design?
What you will have then is:
(280 x0.50) / (8 x 0.80) = 21.8lb/hr
Sometimes minor increases can be compensated for by increasing the setting on the fuel pressure regulator (aftermarket only --stock reg. not adjustable). The 5.0's stock fuel pressure regulator is set to regulate at 39 psi. What happens if this is increased to 44 psi?
To calculate the injector's new flow rating, use the following formula:
[square root of (new pressure/old pressure)] x injector flow rating = new flow rating
Example:
[square root of (44/39)] x 19 = 20.1 lb/hr
This won't be enough to meet the demands of the new horespower level. To meet the demands, the fuel pressure would have to be raised to 52 psi!
[square root of 52/39)] x 19 = 21.9 lb/hr
This tells you that for this horespower level an injector change is definitely in order! Be realistic about your horsepower levels --either use engine-dyno numbers or have your setup chassis dyno'd and drivetrain losses factored so you can get the most accurate results.
You can also determine a rough estimate of your maximum obtainable horsepower level by using this formula:
Injector flow rate x number of injectors x 0.8 / BSFC = maximum horsepower
Example:
36 x 8 x 0.8 / 0.55 = 418 hp.
VIA Ultrastang.com
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SteveLaRiviere
Administrator Posts: 43791
From: Saco, Maine
Registered: May 99
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posted 06-26-2004 10:30 AM
Excellent! Thanks Mooney!  ------------------
'70 Mustang Mach 1 351C 4V/FMX/3.25 Open
'70 Mustang Convertible 250 I6/3 speed/2.79 Open
'72 Mustang Sprint Hardtop 351C 4V/FMX/4.30 Trac Loc
'94 F-150 XL 5.8L/E4OD/3.55 Limited Slip
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Daniel Jones
Gearhead Posts: 828
From: St. Louis, MO
Registered: Aug 99
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posted 06-26-2004 01:36 PM
Why not stick with your Weber intake manifold and run TWM Weber look-a-like EFI throttle bodies? That way you get the low-to-mid range benefits of independent runner manifolding and along with EFI's benefits. Looks something like this: http://www.bacomatic.org/irefi/irefi.html Dan Jones
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Buster
Gearhead Posts: 1466
From: Hurricane alley
Registered: May 2002
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posted 06-26-2004 06:24 PM
quote:
Originally posted by Daniel Jones:
Why not stick with your Weber intake manifold and run TWM Weber look-a-like EFI throttle bodies? Dan Jones
Is that being produced yet?
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two89w
Gearhead Posts: 302
From: sydney australia
Registered: Sep 2002
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posted 06-26-2004 09:46 PM
Is there a formula to work out what size throttle body is best?
Seeing that I will be running an aftermarket
ecu,which can be programed form a lap top,will there be any problems if I am using injectors that are a little too big for my exected hp?
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Mooney
Gearhead Posts: 1691
From: Marietta, Ga
Registered: Oct 2003
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posted 06-27-2004 02:33 AM
quote:
Originally posted by SteveLaRiviere:
Excellent! Thanks Mooney!
Anything to make the day easier for our Mighty Leader!  
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Daniel Jones
Gearhead Posts: 828
From: St. Louis, MO
Registered: Aug 99
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posted 06-27-2004 07:14 PM
> Is that being produced yet? The first test pours came back last week. I've got a dimensioned drawing to send to Kelly tomorrow. After he recieves that, he'll finalize the blueprints for the machine shop so they can know where to drill all the holes. Shouldn't be long now... Dan Jones
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