Are The 19lb's Good Or Should I Go Next Size (24)

This spring when the weather warms up, I'm going to finally be putting my motor back in and test rest of car back together (been 4 long years).. I pulled the motor to fix strut tower/frame rail rot.. and ending up removing pretty much everything else, which all new parts going back on...

Anyway.. .I had the 165k stock motor rebuilt while out... bored .030 over... I had the Ford racing forge mahle pistons put it (was on clearance at LMR... good price)..
I installed the Ford racing E303 cam, and GT40P heads (I install the Trick flow spring kit)with the Explorer intake (the good one with the internal EGR), I also installed Scorpion 1.6 roller rockers, and new ford racing lifters, and trick flow push rods.
I'm going to install Ford Racing P shortty headers, UPR 2 cat X-pipe, and I 86'ed the smog pump.

So, I'm planning to used the stock air box and put a K&N filter in it.. I don't see any benefit over this with a cold air kit, tube.. since there still sucking air from the fender well...(am I correct here?)

Anyway, I have a set of the Explorer 19lb injectors.... I was planning to get the ACUFAb 65mm TB with EGR plate... and the MAF from a 94-95 mustang (guess that's a 70mm right?) from what I read that maf will be good... but of course now I believe that company that makes the adapter is closed up?? so how can I mount that to the stock air box??

also should I stick with buying the 65mm TB or go to the 70mm TB????

and should I use the 19lb injectors or go to the next size 24lb,?(not sure if I'll be running to the end of the duty cycle with the 19's) and if I do need the 24, what ones should I get? (If I understand right, with the 24's I will still be flowing the same as the 19's since that's what the computer is telling it to do, but the 19's would be running close to the full duty cycle and bad for the injectors....., or with this mods is that even a concern?)

I am going to install a Walbro 155 LPH fuel pump in the new gas tank as well., also, have 3.73 gears installed in the rear, just have to put it back in car.

Mustang5L5 said:

Explorer intake opening is 69-70mm. Just measured one not even 20 mins ago.

Question for the OP is what size EGR spacer are you using with it?

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When I buy the ACUFAB TB I'm ordering the one with the EGR plate..so there matched set, so if I get the 65 it will have the 65 plate, same if I get the 70.

haven't order anything yet, wanted to wait until I get ready to put the motor in... which will be when the weather warms back up... hopefully March/april...

if the 65mm is all I need I'll order that.... I just wanted to make sure... for some reason LMR sells the ACUFAb 70 but not the 65, so I would have to order the 65 right from ACUFAB.

I plan on doing nothing else performance wise to the motor then what I listed.... so once it's done, I'm done... I don't want to touch it... just enjoy driving it (on nice weather days of course..will never see rain, salt, ect..)

FoxMustangLvr said:

I believe the Explorer intake only has a 65mm opening so unless you port the opening there is no need to run a larger TB unless you have one already or the deal is too good to pass up. Personally I’d go with the 24# injectors because you should be around 300 hp at the flywheel once you get dialed in. You will be at the upper limit of their duty cycle for 19# injectors.

Fuel flow requirement = (brake horsepower) x (BSFC)

Example: A 300 hp naturally aspirated gasoline-powered V8 requires what size fuel injector?

First, assume a BSFC of 0.50 lb/hr and injection pressure of 39.15 psi across the injector.

300 hp x 0.50 lb/hp-hr = 150 lb/hr maximum total fuel flow requirement

Since this is the total fuel flow requirement to the engine, we must now divide this by the number of injectors being used to determine the flow rate necessary for each injector so that you can select the correct size injector from this catalog. In this example, we have an 8-cylinder engine using 1 injector per cylinder, which gives: 150 lb/hr/8 injectors = 18.8 lb/hr per cylinder.

So, technically, the engine only needs a 19 lb/hr fuel injector to support 300 hp, but this will require that the injector is at nearly a 100% duty cycle in order to achieve this horsepower level. You want to be at or below 80% duty cycle.

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Ok, so 24lb injectors it is then... so what ones should I order? is the Type III EV1 the ones I want that will plug into the factory injector plugs? this kit here? - https://lmr.com/item/LRS-37263/mustang-24-pound-fuel-injectors-bosch-type-3-8604-ev1

so then is the MAF from a 94-95 mustang out then? what MAF would I want to buy then... and my understanding I wouldn't need any special tune right?

This Pro-m one is a 75mm calibrate for 24lb injectors, and for use with stock air box. https://lmr.com/item/PMA-12579AE/1989-93-Mustang-50L-75Mm-Black-Pro-M-Mass-Air-Meter-For-24Lb

Mustang5L5 said:

MAF's work have in hand with an ECU for a specific injector size. The values that the MAF outputs are read by the ECU and translated for the injector size the ECU thinks it has. So in that case, the 94-95 MAF will work with a fox ECU, but only with 19# injectors. You probably could get away with 19's if this is the route you want to go.

Do you intend to getting a tune? In that case you could use the SN95 maf (or a larger oem maf ) and tune for the injector size you intend to use.

No tune? Pick up an aftermarket calibrated MAF and injector size of choice and go with that. For the same of cost, I'd probably try the 19's and Sn95 MAF and see how it runs. You can always upgrade later

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I wasn't planning on getting it tuned (was hoping not too, but who knows that could change in the futere, but for now, no.)... so I'm thinking getting the Pro-M 75mm Maf for the stock air box and 24lb injectors would be the way to go then.... we don't have any good junk yards around here to even look for a used 94-95maf....(so I was going to order new one, plus it looks like that place that made the adapter is gone now...so not much more money to buy the pro-m) which won't work for the 24lb injectors anyway... so I'll just do the new pro-m maf then...and 24lb injectors and the ACUFAB 70MM TB and EGR plate.

so, are the type 3 EV1 type injectors the correct ones for the factory injector plugs?

again, thanks for the help, trying to get my list nailed down on what I need to order to finish this...

btw, I am now going to get it tune, once the motor is broke in.... the place I had to the rear, does tuning... so I will get that done...
I've been doing some more reading... and the way I understand... the 24's with the 24 calibrate maf will work fine, but at mid throttle it will cause the computer to advance the timing a little to much (not a issue at WOT)... but having it tuned will get it correct....

Mustang5L5 said:

The correct way to do it is to always tune.

Calibrated MAF's are just a round-about way to get it done without having a tune done. You are basically fooling the ecu into thinking you have more air than you really do so it adds more fuel

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right, but I still need the calibrated 24lb MAF... either way right?