351w with Efi into Foxbody with Efi Question

Rounder · Jul 29, 2018

I have a complete 94 F150 with 351w with stock EFI and putting it into my 89 LX that has all stock EFI. I have researched the fitments (hood, balancer headers end of the 351 swap) but need to know is
Is the Efi Is basically plug and play or what would need to be changed to make it work? Most of the swap threads are about going from EFI to Carb or... In this case I would have the whole system out of the F150 also so it would be efi already.. What is involved in my case?
Help appreciated

jrichker · Jul 29, 2018

See http://forums.stangnet.com/showthread.php?t=589036 for 351 swap information - lots of good information in there...

You will need 30 Lb. or 36 Lb. injectors and a aftermarket MAF to match the new injectors. Use the stock computer and you will probably be OK. AS you increase the injector size, you nee to increase the fuel pump size too. A 155LPG fuel pump will be plenty big for most Naturally Aspirated setups.

Avoid C&L and Granatelli MAFs. Pro-M seems to be the best choice see www.promracing.com.

Fuel injector sizing & injector photos

Revised 26-Dec-2014 to add statement about figures are for flywheel HP and not rear wheel HP

Injector HP ratings: this flywheel HP, not rear wheel HP.
Divide flow rating by.5 and multiply the result by the number of injectors. This uses a 100% duty cycle. These ratings are for naturally aspirated engines at the flywheel.

Example:
19/.5 = 38, 38 x 8 = 304 HP
24/.5 = 48, 48 x 8 = 384 HP
30/.5 = 60, 60 x 8 = 480 HP
36/.5 = 72, 72 x 8 = 576 HP
42/.5 = 84, 84 x 8 = 672 HP

The preferred duty cycle is about 85% maximum, so for a safety factor multiply the final figure times .85.

19/.5 = 38, 38 x 8 = 304 HP x .85 = 258 HP
24/.5 = 48, 48 x 8 = 384 HP x .85 = 326 HP
30/.5 = 60, 60 x 8 = 480 HP x .85 = 408 HP
36/.5 = 72, 72 x 8 = 576 HP x .85 = 490 HP
42/.5 = 84, 84 x 8 = 672 HP x .85 = 571 HP

Remember that the above ratings are at 39 PSI. Increasing the pressure will effectively increase the flow rating. Example: a 19 lb injector will flow 24 lbs at 63 PSI, and a 24 lb injector will flow 30 lbs at 63 PSI.

See http://users.erols.com/srweiss/calcpchg.htm to get the calculators used in these examples.

Here's the duty cycle explanation. Duty cycle is how much of the time the intake is open the injectors are turned on. The 85% figure means that for 85% of the time the intake valve is open, the injectors are spraying. The idea is that you want some percentage of the duty cycle left over so that you have some room to grow the process.

If you are at 100% and you need more fuel, all you can do is turn up the fuel pressure. That means the whole fuel curve from idle to WOT is affected. Maybe you are already too rich at idle, and turning up the fuel pressure makes it worse. If you had some injector duty cycle left to play with, a custom tune could use that where it is needed. That would not over richen the whole range from idle to WOT.

If you did turn up the fuel pressure, you might be able to change the injector duty cycle to get the air/fuel mixture ratio you want since the injectors will have extra fuel delivery capability.

With larger than stock injectors or higher that stock fuel pressure, you will need an aftermarket MAF that matches the injector size. The MAF “lies” to the computer to get a fuel delivery schedule that meets the engine’s needs and isn’t too rich or too lean. The best strategy is an aftermarket MAF and a custom tune to insure the best air/fuel ratio over all the RPM range.

Don't forget to increase the fuel pump size when you increase injector size or significantly increase the fuel pressure

Copied from the FORD RACING PERFORMANCE PARTS catalog:

PROPERLY SIZING FUEL SYSTEM COMPONENTS

Fuel Pumps
The following information is presented assuming the above information has been taken into consideration regarding BSFC, fuel pressure and specific gravity of the fuel being used. Most fuel pumps for electronic fuel injection are rated for flow at 12 volts @ 40 PSI. Most vehicle charging systems operate anywhere from 13.2v to 14.4v. The more voltage you feed a pump, the faster it spins which, obviously, will put out more fuel. Rating a fuel pump at 12 volts then, should offer a fairly conservative fuel flow rating allowing you to safely determine the pump’s ability to supply an adequate amount of fuel for a particular application.

As previously mentioned, engines actually require a certain WEIGHT of fuel, NOT a certain VOLUME of fuel per horsepower. This can offer a bit of confusion since most fuel pumps are rated by volume, and not by weight. To determine the proper fuel pump required, a few mathematical conversions will need to be performed using the following information. There are 3.785 liters in 1 US Gallon. 1 gallon of gasoline (.72 specific gravity @ 65° F) weighs 6.009 LBS.

To be certain that the fuel pump is not run to its very limit, which could potentially be dangerous to the engine, multiply the final output of the fuel pump by 0.9 to determine the capacity of the fuel pump at 90% output. This should offer plenty of ‘cushion’ as to the overall “horsepower capacity” of the fuel pump.

To determine the overall capacity of a fuel pump rated in liters, use the additional following conversions:
(Liters per Hour) / 3.785 = Gallons
Multiply by 6.009 = LBS/HR
Multiply by 0.9 = Capacity at 90%
Divide by BSFC = Horsepower Capacity
So for a 110 LPH fuel pump:
110 / 3.785 = 29.06 Gallons
29.06 x 6.009 = 174.62 LBS/HR
174.62 x 0.9 = 157 LBS/HR @ 90% Capacity
157 / 0.5 = 314 HP safe naturally aspirated “Horsepower Capacity”

Safe “Horsepower Capacity” @ 40 PSI with 12 Volts
60 Liter Pump = 95 LB/HR X .9 = 86 LB/HR, Safe for 170 naturally aspirated Horsepower
88 Liter Pump = 140 LB/HR X .9 = 126 LB/HR, Safe for 250 naturally aspirated Horsepower
110 Liter Pump = 175 LB/HR X .9 = 157 LB/HR, Safe for 315 naturally aspirated Horsepower
155 Liter Pump = 246 LB/HR X .9 = 221 LB/HR, Safe for 440 naturally aspirated Horsepower
190 Liter Pump = 302 LB/HR X .9 = 271 LB/HR, Safe for 540 naturally aspirated Horsepower
255 Liter Pump = 405 LB/HR X .9 = 364 LB/HR, Safe for 700 naturally aspirated Horsepower

Note: For forced induction engines, the above power levels will be reduced because as the pressure required by the pump increases, the flow decreases. In order to do proper fuel pump sizing, a fuel pump map is required, which shows flow rate versus delivery pressure.

That is, a 255 liter per hour pump at 40 PSI may only supply 200 liters per hour at 58 PSI (40 PSI plus 18 lbs of boost). Additionally, if you use a fuel line that is not large enough, this can result in decreased fuel volume due to the pressure drop across the fuel feed line: 255 LPH at the pump may only result in 225 LPH at the fuel rail.

My Comments:

A lot of people oversize the fuel pump by buying a 255LPH pump thinking that the fuel pump regulator will just pass the excess gas back to the tank. It does, but… Did you ever consider that circulating the fuel around as a 255 LPH pump does will cause the gas to pickup engine heat? What happens to hot gasoline? It boils off or pressurizes the fuel tank! With most of the 5.0 Mustangs having the carbon canister removed or disabled, the car stinks like gas, and the gas mileage drops since the hot fuel evaporates away into the air.

Rounder · Jul 30, 2018

Thanks for the well written reply but I cannot help but wonder if you misunderstood my situation because of my poorly worded question so Ill rephrase it.
I have a good running and currently drivable 88 F150 with a good running 351w with Efi.
Can I take that complete truck motor (intake, Plenum, Map sensor and all the EFI stuff) and transfer it all into my 89 Foxbody Will it all work or are there wiring harness problems etc? (I know Ill have to change the oil pan and put swap headers on it) but If I move the whole motor over with intake, plenum and all the EFI is that possible using all the stuff off the truck or what is the best way to make this work in my 89 Lx with Efi....
I am not that knowledgeable on Efi stuff so I am confused where you stated changing the injectors to 30 # comes into play as the truck runs fine on the stock injectors? and shouldn't The stock #19 injectors be good up to like 350 Hp? I am not adding mods just moving to another chassis
I really just want to find the easiest way to get this running EFI 351 into my 89 Lx and still use EFI without buying to much (like the TF R series swap Intake $800 or a Holley Sniper system or switching to carb).

jrichker · Jul 30, 2018

Integrating the electronics from the F150 into the Fox isn't likely to be a plug and play job. How good are your electrical skills? Can you read circuit diagrams and troubleshoot electrical problems? We are talking about some high level skills and not just swapping parts until it works.

Even if the computer connector is identical, you may have to move some connector pins around in the Fox body wiring harness. Swapping the wiring harness from the truck into the Fox Body car means that there will be some differences that you will have to fix. Using the truck wiring harness means you would need to lay the truck and Fox wiring diagrams side by side and figure out what needs to be changed. Then you get to reroute, or move computer connector pins, and lengthen or shorten the wiring as needed.

The 30 or 36 LB injectors and Calibrated MAF would be necessary if you used the stock computer from the 89 LX.

Does the truck have a Speed Density or Mass Air computer system?
Different computer systems mean different wiring layouts.

Speed Density uses Manifold vacuum (MAP), Throttle position (TPS) and RPM, & Air Temperature (ACT) to guess how much air the engine is pulling in. Then it uses all of them plus the O2 and ECT sensors to calculate the air/fuel mixture. It is dependent on steady manifold vacuum and minimal changes in airflow from the stock engine configuration to maintain the proper air/fuel ratio. Change the airflow or vacuum too much and the computer can't compensate for the changes, and does not run well. Forget about putting a supercharger, turbocharger or monster stroker crank in a Speed Density engine, because the stock computer tune won’t handle it. Every time you seriously change the airflow through the engine, you need a new custom burned chip to make the engine run at peak performance.

Mass Air uses a Mass Air Flow meter (MAF) to actually measure how much air is being pulled into the engine. The computer uses this information and inputs from the O2, TPS, ACT, ECT, RPM and Barometric Pressure (Baro) sensors to calculate the proper air/fuel ratio. It is very tolerant of changes in airflow and vacuum and tolerates wild cams, high flowing heads, and changes in displacement with minimal difficulties. Just remember that large changes in airflow require more fuel than the stock fuel system can deliver. At that point, you will need larger injectors and a larger fuel pump to make the engine run like it is supposed to. Larger injectors can be used with either an aftermarket calibrated MAF or a custom dyno tune. This makes it possible to use the stock computer with engine displacements from 302-408 cu in, and make many modifications without a custom dyno tune chip. Put a new intake manifold on your 331 stroker and the computer figures out how much more fuel to deliver without having to have a new chip burned to accommodate the extra airflow.

General karthief · Jul 30, 2018

Go through this link, read it through, it covers much of what your asking, I just skimmed it and it covers the efi aspects of a 351 swap, that figures you are starting with a V8 stang.
http://forums.stangnet.com/showthread.php?t=589036

Rounder · Jul 30, 2018

Jr Thank you for all the great info. After considering everything I think going carb might be the best option.
Right now the 351 is stock but in the future I plan to put some heads on it and a cam and a stroker kit for a 408.
This is a street car Sunday driver and will never be at the track.
Is there a good manifold and carb combination that I can put on now when its stock that I can also use when its a 408. Something that is easy to tune and can grow with the project. Id hate to buy something now and in a year have to upgrade again. This might be a crazy idea as 600 cfm and 950 are worlds apart but I thought Id ask as I don't know if there is a middle ground set up that will work on both or an expandable carb set up.
Also apply that same question to the fuel pump set up Ill have to have.

jrichker · Jul 31, 2018

Rounder said:
Jr Thank you for all the great info. After considering everything I think going carb might be the best option.
Right now the 351 is stock but in the future I plan to put some heads on it and a cam and a stroker kit for a 408.
This is a street car Sunday driver and will never be at the track.
Is there a good manifold and carb combination that I can put on now when its stock that I can also use when its a 408. Something that is easy to tune and can grow with the project. Id hate to buy something now and in a year have to upgrade again. This might be a crazy idea as 600 cfm and 950 are worlds apart but I thought Id ask as I don't know if there is a middle ground set up that will work on both or an expandable carb set up.
Also apply that same question to the fuel pump set up Ill have to have.

For EFI you need
Fuel pump 155 LPH - you need this even if you convert to carb. The EFI fuel pump is not safe to use with a carb. You risk severe engine damage if the add on regulator fails.
30 LB injectors or use the injectors already on the engine
New MAF to match the injectors.
1-1 1/2 days labor -swap fuel pump, maybe swap fuel injectors & plug in the replacement MAF.
No modification to computer or wiring, use the existing 89 LX computer and wiring

EFI to carb swaps

Revised 10 Aug 2017 to add comment about using an in tank fuel pump form an 85 5.0 Mustang

A word of warning on EFI to carb swaps: don’t expect to pass emissions in any state that does comprehensive smog inspections, because it won’t happen. Some states will not title or issue license plates to cars that have been converted from EFI to carb. Be aware that you are violating several Federal laws concerning the removal of pollution control equipment. If you operate the vehicle on public highways and get caught by state or federal law enforcement (doubtful, but possible) you could be subject to fines and imprisonment. You won't get any more power from a carb than you will from a properly maintained and tuned EFI system.

The following information is intended for informational purposes only. Operation of a motor vehicle modified in such as manner as described below should be limited to off road use only.

Doing the swap; you must know how to read electrical diagrams and wire circuits to properly do the swap. Don’t take shortcuts or cut corners in the fabrication of the electrical or mechanical assemblies. If you do NASCAR quality work, the car will look good, run good and be as reliable as a carb’d car can be. Take pride in a job done with excellence.

If you are one of those few people who do excellent work, please disregard my negative comments. They are not intended for you.

Quality, quality, quality…
Some of the motivation of my negative comments about EFI to carb has to do with the quality of electrical workmanship. A lot of the wiring “repairs” that I have seen on the road and in the junkyard looks like road kill. The other part of my negative view stems from people who can’t grasp the operation and tuning of EFI. Carbs have their own set of requirements and some learning is required to get the best performance. Every car is different and each installation needs to be tuned to get the best performance. Putting an “out of the box carb” or one from someone else’s car isn’t the way to success. There is no auto compensation for small variations in carbs like there is for EFI. Just throwing a carb on a car because you won’t bother to learn how EFI works is a poor excuse.

Now that the rant is over, here’s some practical advice…

Do not use an EFI in tank fuel pump with a carb. You will never get the pressure/flow regulated properly. If the add on pressure regulator fails, you will flood the engine with gas and wash all the oil off the cylinder walls. That will cost you big time $$$. Either go full EFI or use a tank/fuel pump/fuel lines out of an 85 or earlier Stang. The in tank electric fuel pump from an 85 5.0 Stang can be used since it is only 10 PSI and not 40PSI+ output pressure that an EFI pump delivers.. Fabricating your own setup is possible but there are some snags to overcome.
Do not attempt to leave the EFI computer in place in an attempt to control either the electric fuel pump or ignition. Doing so qualifies you for the “Road Kill Mechanics Award”.
If you try to use your current tank, you will need to pull the fuel pump out and fabricate a pickup tube & strainer sock to replace the fuel pump. Or you can have a sump fabricated and welded onto you existing tank. Many welding shops will not weld fuel tanks because of the dangers involved if the tank isn't purged properly.
You will need an external electric fuel pump unless you change the timing cover for one with the mechanical fuel pump mount on it. The external pump will have to be mounted below the bottom of the tank to get the siphon effect needed to keep the pump fed sufficiently. Rip all the EFI wiring out, and the computer controlled fuel pump won't work. You will need to add a relay & switch and wire in the existing inertia switch for an external low pressure electric fuel pump. Do not try to wire the fuel pump without the relay. The 15-20 amps the pump pulls will overload the circuit. This will take power away from other items on the same circuit or cause the fuse or fuse link to blow.
You will need to run some new fuel feed lines or braided hose. The 3/8" aluminum tubing works well, but you will need a flaring tool and bending springs to fabricate the lines. Braided hose is easy to run and route, but is much more expensive. It is about $3.50-$4.00 a foot plus the end fittings, which are $3-$4 each. Fabricating hose assembles can be difficult, but anyplace that makes hydraulic hoses can do it for you for an extra charge. See http://www.amazonhose.com for more information.
For some help fabricating your own stainless steel hose assemblies, see
http://www.turbinefun.com/Stainless_Braided_Hose_Assembly.asp
For stainless steel braided hose and fittings for automotive use:
See http://www.summitracing.com/search/?keyword=stainless steel hose&dds=1
http://www.summitracing.com/search/?keyword=stainless%20steel%20hose&dds=1
http://www.jegs.com/webapp/wcs/stores/servlet/KeywordSearchCmd?storeId=10001&catalogId=10002&langId=-1&N=0&Ntt=stainless+steel+hose&Ntk=all&Nty=1&D=stainless+steel+hose&Ntx=mode+matchall&Dx=mode+matchall&searchTerm=stainless+steel+hose&x=18&y=4
See http://www.eaton.com/Eaton/ProductsServices/ProductsbyName/Aeroquip/AeroquipPerformanceProducts/FittingsProducts/index.htm for more information on High performance automotive hose products
AN fittings require a 37 degree flaring tool. A standard automotive or household plumbing tool is 45 degrees and cannot be used with AN flare fittings. If you do, the flare is subjected to too much stress when the fitting is tightened, and is likely to fail or leak.
See http://www.mscdirect.com/ , http://www.mcmaster.com/ or for the flaring tool you will need . Prices start at $85 and go up
http://www1.mscdirect.com/CGI/N2DRVSH?PACACHE=000000013509163
http://www.mcmaster.com/#flaring-tools/=b4fxc3
Last time I was in Summit racing, they had a 37 degree flaring tool for less than $40. It may or may not be a catalog item.
While you are at the electrical part, you'll need a Duraspark or similar ignition system. The 85 Mustang GT 5 speed has a suitable Duraspark distributor with a steel gear compatible with the roller camshaft. The EFI ignition depends on the EFI sensors to advance the spark. Rip out the TPS and MAP/Baro sensors and the computer will have no idea of the proper ignition timing for best performance. Running a fixed timing setting is only for test purposes or for a race track only car. Don't try it on the street: the results will not be nearly as good as a properly setup Duraspark or equal. Crane makes a really nice distributor for non-EFI applications. . See http://www.cranecams.com/index.php?show=browseParts&lvl=4&prt=127 for more information. Cost is about $400, which makes the 85 Mustang reman units look really appealing.

Duraspark II ignition diagram:

Diagram courtesy of /www.billwrigley.com

See http://webpages.charter.net/1bad6t/duraspark.html for more help.
Note the ballast resistor shown in the diagram: you’ll need that too
If you use a coil from a 78 or later Mustang, you don't need the ballast resistor. The stock 89 Ford/Mustang ignition coil does not need a ballast resistor

A simpler HEI ignition that uses the same distributor and fewer parts can be found here. This is an excellent resource, and I suggest that you add it to your Internet Favorites
http://www.binderplanet.com/forums/showthread.php?t=48435
Tools needed:
Crimp tool for connector pins $9-$30 AutoZone, NAPA, Advance Auto Parts or other store
100-150 watt soldering gun (recommend WELLER 8200PK soldering gun kit 100/140W) $30 at Lowes or $40 at Home Depot
3/32”-1/8” rosin core electrical solder, 1/4 lb roll $6 at Ace Hardware, Home Depot or Lowes
Assorted sizes of heat shrink tubing. Buy long pieces and cut length to fit. It is cheaper that way. http://www.partsexpress.com/webpage.cfm?&WebPage_ID=346&CFID=169547&CFTOKEN=34300345
Hot air gun to shrink the tubing ($30-$40) Home Depot
Jeweler’s screwdriver kit $5 at Ace Hardware
Assorted automotive wire, 18-16 gauge 10’-20’ foot spools in different colors. $5 a roll at Advance Auto Parts.
Ford connector pins AutoZone, NAPA or other store $5-$10 for a kit of 10-12 assorted pins
You will have $110-$150 in materials and tools if you don't already have them.
The water temp and oil pressure signals feed from the sender to the main harness through the 10 pin EFI engine harness. To utilize these senders, you need to identify the wires and find a way to reconnect them to the main harness after the EFI engine harness is removed. You need a weatherproof quick connector to join the sender wiring to the main harness.
See the graphic for the 10 pin connector circuit layout.

The injector power pin is the VPWR pin in the black 10 pin connector.

You will need to construct a wiring harness from the ‘85 carb distributor to the Duraspark box if you go Duraspark, or other distributor to coil wiring.
The voltmeter picks up its signal from the switched voltage present on the instrument panel, so you don’t need to worry about that.
The fuel tank gauge is also independent of the computer wiring.
AutoZone wiring diagrams can be found if you are willing to dig through the self help repair section of their website. http://www.autozone.com/autozone/re...3835D6CFF5E3A5037BBBD332CF445FF.diyprod2-b2c3
How to solder - see
View: http://youtu.be/uaYdCRjDr4A[/i]
This is an excellent how to do it.

[*]Soldering pigtails onto existing pins is road kill quality work as far as I am concerned. Take some time to study the way the Ford connectors are assembled and you will find that a small jeweler’s screwdriver will release the pins from the connector shell. New pins and a crimping tool are available from the Standard Motor Parts or Bendix Electrical parts line that the NAPA & Bumper to Bumper Auto Parts stores carry. Ask any auto parts store about Standard Motor Products or Bendix Electrical wiring parts. Those that carry them will be able to get the parts you need. AutoZone has a cheap kit with 10 pins for about $5. Just enough pins to leave you short when assembling a connector.

[*]One of the interesting things about the Ford OEM wiring diagrams is that the connector shape on the drawing matches the connector shape in the car. That makes it easier to identify connectors and circuits. OEM Ford diagrams are available at for an 85 Mustang at http://www.helminc.com/helm/Result.asp?Style=&Mfg=FMC&Make=FCT&Model=MUST&Year=1985&Category=&Keyword=&Module=&selected_media=&mscsid=2M838NG3R5SR2MCS00A3HVE05T03C501 or can be found in the Chilton series of auto repair manuals for Mustangs.

[*]The following is an excellent idea from a fellow Stangnetter who tackled the wiring plan the right way. He obtained the wiring diagrams from an 85 carb'd V8 Mustang and laid them out side by side with the diagrams from his car. He then traced out each circuit and the wire colors and connectors associated with them. After tracing the circuit and connectors for a circuit, he laid out the changes he needed to make. One circuit at a time made a difficult big job into many smaller easy to manage jobs.

[*]Copied from pikapp33.
JR’s comments: I have heard that there have been quality problems with some of these Richporter distributors, but that may be a limited quantity of the units.

I recently changed my EFI mustang back to carb with MSD ignition, to save some money and go for a more simplistic approach. I researched, and found the best stock type distributor to use was from an 83 Bronco 5.0, which is a Duraspark (magnetic pickup, same as what MSD dists use), making it possible to use the 2 wire MSD trigger input, and also has a steel gear to work with the EFI hydraulic roller cam.

I chose to use a Richporter FD30 ($85). Then added a BWD C194A Cap Adapter ($12) to use the Fox style dist cap/wires (the Richporter comes with cap/rotor, which I didn't use; other brands come without and are cheaper, but have a core as well; no core on this one). And then a BWD D166 rotor ($6) to match the cap adapter. I also chose to buy the MSD 8869 adapter wire ($20ish) to connect the dist to the MSD harness for my 6AL. All together about $125, much cheaper than the MSD billet dists, and am very happy with the quality of the dist and the way the setup worked out.

The Richporter FD30 distributor is available at Advance Auto Parts ($90) & O’Riley’s ($81)

Rounder · Jul 31, 2018

Thanks for the information I have a few questions...
I am confused in your first post your said "You will need 30 Lb. or 36 Lb. injectors and a aftermarket MAF to match the new injectors"
But in your last post you said "30 LB injectors or use the injectors already on the engine and new MAF to match the injectors."
Id consider keeping it efi if I could just use the stock injectors in the truck (which I believe are #19 like the LX has) as it would save some expense.
Is that possible? and no changes to the computer and stock wiring harness in LX?
Also what upper intake can I use as the truck plenum wont work, will the Plenum off my 89 5.0 fit on the truck manifold to mount the new MAF on?

Chuckman · Jul 31, 2018

If it were me, id look at something like an edelbrock victor or tfs r (not the box), Both upper and lower. Both will be way overkill for the stock e7 heads, but fitment and availability are good, may even be able to sneak either under a stock hood with some tricks (and will be great once you go bigger). That being said a holley upper may work with the truck lower, but that's a long shot imo. There also the old lightning gt40s, but good luck finding one.

jrichker · Aug 1, 2018

Rounder said:
Thanks for the information I have a few questions...
I am confused in your first post your said "You will need 30 Lb. or 36 Lb. injectors and a aftermarket MAF to match the new injectors"
But in your last post you said "30 LB injectors or use the injectors already on the engine and new MAF to match the injectors."
Id consider keeping it efi if I could just use the stock injectors in the truck (which I believe are #19 like the LX has) as it would save some expense.
Is that possible? and no changes to the computer and stock wiring harness in LX?
Also what upper intake can I use as the truck plenum wont work, will the Plenum off my 89 5.0 fit on the truck manifold to mount the new MAF on?

A carb conversion done correctly will cost more than modifying the EFI to meet the HP demands of the 351 engine.
The 30 LB injectors were to allow some room to grow the HP when you go for some better heads.

The truck may not come with 19 LB injectors but if does, you will outdraw the injector flow rate very quickly when you start to add things like intake, cam or heads.

Fuel injector sizing & injector photos

Revised 26-Dec-2014 to add statement about figures are for flywheel HP and not rear wheel HP

Injector HP ratings: this flywheel HP, not rear wheel HP.

Divide flow rating by.5 and multiply the result by the number of injectors. This uses a 100% duty cycle. These ratings are for naturally aspirated engines at the flywheel.

Example:
19/.5 = 38, 38 x 8 = 304 HP
24/.5 = 48, 48 x 8 = 384 HP
30/.5 = 60, 60 x 8 = 480 HP
36/.5 = 72, 72 x 8 = 576 HP
42/.5 = 84, 84 x 8 = 672 HP

The preferred duty cycle is about 85% maximum, so for a safety factor multiply the final figure times .85.

19/.5 = 38, 38 x 8 = 304 HP x .85 = 258 HP
24/.5 = 48, 48 x 8 = 384 HP x .85 = 326 HP
30/.5 = 60, 60 x 8 = 480 HP x .85 = 408 HP
36/.5 = 72, 72 x 8 = 576 HP x .85 = 490 HP
42/.5 = 84, 84 x 8 = 672 HP x .85 = 571 HP

Remember that the above ratings are at 39 PSI. Increasing the pressure will effectively increase the flow rating. Example: a 19 lb injector will flow 24 lbs at 63 PSI, and a 24 lb injector will flow 30 lbs at 63 PSI.

See http://users.erols.com/srweiss/calcpchg.htm to get the calculators used in these examples.

Here's the duty cycle explanation. Duty cycle is how much of the time the intake is open the injectors are turned on. The 85% figure means that for 85% of the time the intake valve is open, the injectors are spraying. The idea is that you want some percentage of the duty cycle left over so that you have some room to grow the process.

If you are at 100% and you need more fuel, all you can do is turn up the fuel pressure. That means the whole fuel curve from idle to WOT is affected. Maybe you are already too rich at idle, and turning up the fuel pressure makes it worse. If you had some injector duty cycle left to play with, a custom tune could use that where it is needed. That would not over richen the whole range from idle to WOT.

If you did turn up the fuel pressure, you might be able to change the injector duty cycle to get the air/fuel mixture ratio you want since the injectors will have extra fuel delivery capability.

With larger than stock injectors or higher that stock fuel pressure, you will need an aftermarket MAF that matches the injector size. The MAF “lies” to the computer to get a fuel delivery schedule that meets the engine’s needs and isn’t too rich or too lean. The best strategy is an aftermarket MAF and a custom tune to insure the best air/fuel ratio over all the RPM range.

Don't forget to increase the fuel pump size when you increase injector size or significantly increase the fuel pressure

Injector identification chart

Diagram courtesy of Tmoss & Stang&2birds

Rounder · Aug 2, 2018

Thanks Id rather not go carbed
I am trying to only buy what I need now to get the 351 in and running in my 89 making sure they are parts that will not need to be upgraded next year when I do the 408. So I was told that if I just get a 75mm throttle body and EGR spacer $269 Item #BBK-1600 along with the Trick Flow R series 351 swap Manifold and upper for $800 MPN# 51511004
That the 88 stock 351w will run fine in my 89. and when I go up to a 408 build these parts along with bigger injectors, fuel pump and MAS will then be needed but not until I do that build.
Do you agree? If so..
If I threw on some 1.7 rockers (already have from 5.0) and a mild cam would that be taxing it that setup? If so what cams would work with that setup?

General karthief · Aug 2, 2018

Check out this build: https://www.stangnet.com/mustang-forums/threads/efi-351w-swap.900161/
The daddywagon speaks for itself, pretty cool driveway swap.

jrichker · Aug 2, 2018

Rounder said:
Thanks Id rather not go carbed
I am trying to only buy what I need now to get the 351 in and running in my 89 making sure they are parts that will not need to be upgraded next year when I do the 408. So I was told that if I just get a 75mm throttle body and EGR spacer $269 Item #BBK-1600 along with the Trick Flow R series 351 swap Manifold and upper for $800 MPN# 51511004
That the 88 stock 351w will run fine in my 89. and when I go up to a 408 build these parts along with bigger injectors, fuel pump and MAS will then be needed but not until I do that build.
Do you agree? If so..
If I threw on some 1.7 rockers (already have from 5.0) and a mild cam would that be taxing it that setup? If so what cams would work with that setup?

Look at the injector table I posted.

Take the stock horsepower the engine is rated at and add 15 HP and see where you end up in the horsepower range. You may end up in the ragged edge of having the correct size injectors . See http://www.f150hub.com/specs/351w.html for horsepower ratings.

Rounder · Aug 2, 2018

So your saying it will work stock, and you believe a cam and the 1.7's will add 15hp. Hard to tell what stock Hp to accept. But if we believe the stock injectors to be 19/.5 = 38, 38 x 8 = 304 HP x .85 = 258 HP and we used 240hp from the lightning (I don't have GT40 only stock E7 heads so I have to be lower) even with a cam and 1.7 should be right at the edge like you said.
Cost wise I wonder if the Holley Sniper Efi isn't a cheaper route to go... Anyone got opinions on that system?

General karthief · Aug 2, 2018

I believe that the holly system is basically for a carb to efi swap. You would need to change intakes and some other stuff, more money than making what you already have work

351w with Efi into Foxbody with Efi Question

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wonder how much it would cost to ship you a pair

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GTFO you fat, heavy bastard

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wonder how much it would cost to ship you a pair

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wonder how much it would cost to ship you a pair

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