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Requesting Guidance for 306 motor swap - Fuel? - SD? MAF?

  • Thread starter Thread starter So_Flo
  • Start date Start date Jul 26, 2025
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    302 rebuild 306 foxbody foxbody 5.0 fuel injectors mass air flow mass air flow sensor motor swap speed density vortech
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So_Flo

Member
Jul 26, 2025
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Jul 26, 2025
#1
  • Jul 26, 2025
  • #1
Hello Everybody,

Introduction
I've recently picked my project car back up. A 1988 LX 5.0 Mustang that’s been in my family for over 30 years! It was also my first car back in high school (2012), and it holds a lot of sentimental value. Now, I’m aiming to finally complete the build over the next few months.

I started this project over 10 years ago and picked up various parts along the way. Unfortunately, I didn’t keep the best records at the time, but I’ll list everything I know as clearly as possible below.

Let me know if anyone wants more info or has advice on next steps. Open to all feedback. Especially around prepping a long-stored motor or if transitioning from speed density to mass air flow is recommended or needed? Especially if I want to add an entry-level Vortech system. I also have no clue what kind of fuel injectors I should get.

Background on the Car:
This ’88 LX 5.0 has been in my family since day one, bought new by my dad in 1988, and only passed between him, my uncle, and me. It was my first car in high school back in 2012. It's been sitting for over 7 years, and I’ve recently started bringing it back to life.

Last month, I changed the fuel tank and pump, topped off all fluids, and was able to get it running. To my surprise, it fires up on the first or second crank!
Thanks for reading!



Car Details
  • Year/Model: 1988 Ford Mustang LX 5.0 (Hatchback)
  • Color: Light Spiral Gray
  • Mileage: 100,000+ miles
  • Computer: Speed Density (no mass air conversion)


Current Motor Build Status
My goal is to build the motor with an eventual plan to add an entry-level Vortech supercharger. Here’s what I have so far:
**Weekend cruiser
  • Block: Used Ford 302 block
    • Sent to the machine shop years ago for cleaning and boring
    • Now a 306 (bored over)
    • Fully assembled and torqued but it’s been sitting in the garage untouched for the past 7+ years


Parts Installed (As best as I can remember)
  • Cam: Mild E303 cam (by COMP)
  • Headers: BBK equal-length shorty headers
  • Intake manifold: Edelbrock Performer RPM II upper and lower
  • Heads: Edelbrock Performer heads (Part #: 6025, CARB #: D-215-33 MAK 95)
  • Pistons: Flat top pistons (brand/specs unknown)
  • Rockers: Blue roller rockers (brand/specs unknown - The heads of the bolts are stamped with TUZ, 12.9, but I can't find them online)
  • 255 LPH Fuel Pump (Jegs)
  • Throttle Body w/ spacer 80mm (Stack Racing)
Suspension
I changed the shocks and struts years ago, but I cant recall the brand. Nothing to brag about. if anything i would love to get adjustables or go sliglhy lower. This can be done later down the road.
Gears
Rebuilt stock T5 tranny with stock gears. ( I would love to throw in 3.55 gears later down the road.)
Stock Clutch system - This will be swapped for a hydraulic clutch system. I hate the fact that the stock clutch feels like a workout for my left leg lol.
 

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Last edited: Jul 27, 2025
Reactions: gkomo

gkomo

now i can hopefully expect to receive the shaft
Aug 2, 2024
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San Diego, CA
Jul 26, 2025
#2
  • Jul 26, 2025
  • #2
Welcome!

Sounds like you have a great starting point. Does the car run after sitting for so long? Are there any specific concerns you have? What are your goals with the car?

Any suspension/brake upgrades on the car? Gears?

I have an ‘entry level’ supercharger on my stock 5.0. It definitely wakes the car up, with your H/CI it would be even better.
 
Reactions: So_Flo

AeroCoupe

lube between the nut and the face. I know my lubes
Founding Member
Oct 28, 2001
5,894
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Jul 26, 2025
#3
  • Jul 26, 2025
  • #3
Rockers appear to be Ford Racing 1.6:1 ratio pedestal mount. Basing this on the unique teardrop cutout on the top.

Ford Racing M-6564-B351 ROLLER ROCKER SET 1.6 BOLT ON

Bolt-On Style Roller Rocker Arm Set; 1.6 Ratio;
greenleesproautocare.com
 
Reactions: So_Flo
S

So_Flo

Member
Jul 26, 2025
15
7
13
Miami FL
Jul 26, 2025
#4
  • Jul 26, 2025
  • #4
gkomo said:
Welcome!

Sounds like you have a great starting point. Does the car run after sitting for so long? Are there any specific concerns you have? What are your goals with the car?

Any suspension/brake upgrades on the car? Gears?

I have an ‘entry level’ supercharger on my stock 5.0. It definitely wakes the car up, with your H/CI it would be even better.
Click to expand...
Appreciate it Gkomo

On the first crank, the fuel pump didn’t engage. Based on our past experience, we already suspected the pump had seized, and sure enough, when we dropped the tank and exposed the pump, it was completely rusted out. womp womp lol

I ended up ordering a full fuel tank kit along with a 255lph fuel pump. It took us a day to install everything, but once it was in, the car fired right up on the first spin. I took her for a quick drive around the block and then parked her back in the garage. It was definitely a nostalgic moment.

The goal
for the car is to build a weekend cruiser, not a drag car. I want to finish the project I started years ago and eventually install an entry-level Vortech supercharger running low boost. I’m not sure what kind of horsepower numbers I’d be looking at with the current motor setup without the supercharger, but if I can get into the high 300 - 400 HP range, I’d be more than happy. I don’t see the car ever going over 500+ HP, and honestly, that’s perfectly fine with me. For a street car, under 500 HP is still a blast.

Suspension
I changed the shocks and struts years ago, but I cant recall the brand. Nothing to brag about. if anything i would love to get adjustables or go sliglhy lower. This can be done later down the road.
Gears
Rebuilt stock T5 tranny with stock gears. ( I would love to throw in 3.55 gears later down the road.)
Stock Clutch system - This will be swapped for a hydraulic clutch system. I hate the fact that the stock clutch feels like a workout for my left leg lol.


That said, I do have a few concerns, and again, I'm open to all feedback.
  1. The motor was assembled by a mechanic about 7 years ago, and it’s been sitting ever since. I’m wondering if I should have someone go through it possibly even rebuild it before the motor swap take place.
  2. I’m unsure what size fuel injectors or fuel rail setup I should be considering as I build toward that low-boost setup. I already have the 255lph fuel pump installed + I know i'll need a fuel reglator if i want that perfect tune.
  3. I’m also debating whether I should keep the original Speed Density system or upgrade to a Mass Air Flow (MAF) setup. I’ve heard mixed opinions, so I’m not sure what direction to go there yet.
  4. Would a stock T5 tranny be able to handle this kind of HP / TQ in mind (400-500 HP)?
 
S

So_Flo

Member
Jul 26, 2025
15
7
13
Miami FL
Jul 26, 2025
#5
  • Jul 26, 2025
  • #5
AeroCoupe said:
Rockers appear to be Ford Racing 1.6:1 ratio pedestal mount. Basing this on the unique teardrop cutout on the top.

Ford Racing M-6564-B351 ROLLER ROCKER SET 1.6 BOLT ON

Bolt-On Style Roller Rocker Arm Set; 1.6 Ratio;
greenleesproautocare.com
Click to expand...
You're a miracle worker!
Thanks.

I hope I did well picking those rockers...
 

Sparky714

5 Year Member
Oct 16, 2015
368
208
73
North Dakota
Jul 26, 2025
#6
  • Jul 26, 2025
  • #6
Personally, I'd dump the stock ECU completely and go aftermarket. Especially if you're going to boost it eventually. I currently have a 306 on a Megasquirt ecu with the HO Vortech V3 that makes 10psi. 47lb injectors, 255lph Walbro pump and Kirban regulator. Stock rails and fuel lines. Never been dynoed, but probably low 400's to the tires. I also have a TKX transmission, but ran a T5 behind it for quite a while with no problems. I do race mine occasionally, so I did go for a heavier duty transmission. It's been a solid setup for the last seven years or so. Tons of street miles and lots of 1/8th mile passes on sticky tires.
 
Reactions: Monkeybutt2000, So_Flo and AeroCoupe

AeroCoupe

lube between the nut and the face. I know my lubes
Founding Member
Oct 28, 2001
5,894
4,018
183
Claremore, OK
Jul 26, 2025
#7
  • Jul 26, 2025
  • #7
First thoughts off the top of my head:

1) 3.55 gears are a great choice. I have 3.73's and wish I would have gone 3.55's.
2) Full length subframe connectors are a must. Maximum motorsports, Kenny Brown, or Global West and all with the optional seat brace.
3) Lowering springs, lots of choices out there but the only ones I have any experience with are the H&R Super Sports and they were awesome.
4) The stock T5 will live at those levels but no sticky tires and get a good shifter like an MGW or the like with positive stops.
5) If you do not possess the ability to tear a motor down and inspect main and rod bearings then that is a hard stop and take the motor to someone that can do a tear down and inspect all of that and then put it back together. Worst case is you are out the cost of his/her time, gaskets, and some assembly lube. Should not be any reason to pull the heads or anything like that. May be able to look down the holes in the valley of the block and see the condition of the cam lobes and get an idea on the condition of that. Hopefully they cylinder walls are not rusted but if they are a quick hone should do the job.
6) Stock fuel rails will work just fine and you may want to get an adjustable fuel pressure regulator.
7) Injector size is up to you but if you want to get a Vortech and you are looking at 500 fwhp then you will want somewhere around 42 lb/hr injectors on gasoline. Google "injector size calculator" and run your setup on several of them.
8) The 255 lph pump will be just fine on gasoline.
9) I would make the change to mass air but that is just me as speed density will work as well. I think mass air on drivers and speed density on race cars but that's just me.
10) You may want to rethink the 80mm throttle body with the Edelbrock Performer RPM II upper. The opening on the upper where the throttle body mounts is only 70mm. Can be opened up to 75mm with little issue but I think 80mm may pose some issues. Also, you just do not need 80mm (70mm NA or boosted will make 500+ fwhp) and the tip in may suffer do to how lazy the air will be coming into the intake. You do not have a "USA" lower it is an Edelbrock Performer RPM II. Look at the number above and to the right of the "Made in USA" logo and you will see 31-7120 which is the same part number on mine and the one in this eBay add:

1986-1995 Ford Mustang 5.0L Edelbrock Performer RPM 2 Intake Manifold Cobra GT40 | eBay

We use the most economical carriers for you depending on the item & your location. They are sold as is. I will try my hardest to respond quickly to your problems.
www.ebay.com

11) The heads are Edelbrock 60379's. The 6025 casting was used on several heads. These are not killer heads or anything but waaaay better the the stock piles of . Flow data is as follows (got it from Edelbrock's website):

Cylinder Head Part # .100" .200" .300" .400" .500" .600"
#60379 62/56 126/101 179/133 220/152 238/163 243/169

I probably could come up with more but its not my build.
 
Reactions: So_Flo, Mcmahst, gkomo and 1 other person

Noobz347

Stangnet Facilities Maint Tech... Er... Janitor
Admin Dude
Jan 4, 1985
43,107
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Jul 26, 2025
#8
  • Jul 26, 2025
  • #8
WhAt tHaT gUy SeD
 
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FastDriver

I was uncomfortably high & wearing a helmet
SN Certified Technician
Sep 5, 2001
6,100
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Vass, NC
Jul 26, 2025
#9
  • Jul 26, 2025
  • #9
Hard to follow Aerocoupe up. He's good. Just keep the ECU or get an A9L and get a quarterhorse to tune. Saves money. Your parts with an intercooled S-trim or better maxes out the safe limit on the stock block. When you push 500rwhp, upgrade to a T56 or TKX so you can plant the power.
 
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Noobz347

Stangnet Facilities Maint Tech... Er... Janitor
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#10
  • Jul 26, 2025
  • #10
FastDriver said:
Hard to follow Aerocoupe up. He's good. Just keep the ECU or get an A9L and get a quarterhorse to tune. Saves money. Your parts with an intercooled S-trim or better maxes out the safe limit on the stock block. When you push 500rwhp, upgrade to a T56 or TKX so you can plant the power.
Click to expand...

I would agree with that except for the 30+ year, multi-owner, unknown condition of a harness that still requires a conversion. Plus the cost of a stock EEC, plus sending it off for a health check, plus having to get the thing tuned.


Nope... We're firmly in the aftermarket ECU territory now, me thinks.
 
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FastDriver

I was uncomfortably high & wearing a helmet
SN Certified Technician
Sep 5, 2001
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#11
  • Jul 26, 2025
  • #11
I've been both directions. After all, 2 out of 3 of my foxes are stand-alone ECUs. That said, the stock EEC, with an MAF in my case, is the best driver. Granted, if you have electrical issues with your harness, that changes the calculus. If there is a computer or harness problem, then I'm open-minded. But, with these modern kits, what's the total time & $$$ investment? Seems like you can go from the $1.5k Terminator X kit to the $3.4k Holley Dominator... Then, what kind of gauges do you want? The $800 small screen or the $2k 12-13" dash screens? After all of that, I like the stock, free, gauges more. Weirdly, and just perhaps my bias, I like the UDX dash more in its own way. It's not trying to be pretty... It's all business.

Me? $300 A9L (I have one in black jack for free and another from another SN member), a $250 Quarterhorse with BE/EA licenses. And, I'm done. Got a spare wiring harness on the shelf, too. Seems like a no-brainer, to me.

I'm not afraid of tuning a stock SD, pre '89, EEC either, but I'd need to research tuning with a blower on it. A9L, though? No problem.
 
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Noobz347

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#12
  • Jul 26, 2025
  • #12
Who makes the kit that has the digital replica of the Fox Gauge cluster?\


Also...

There's a kit that integrates with the OEM gauges someplace too.
 

AeroCoupe

lube between the nut and the face. I know my lubes
Founding Member
Oct 28, 2001
5,894
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Jul 27, 2025
#13
  • Jul 27, 2025
  • #13
Autometer
https://www.autometer.com/invision-lcd-dash-kit-87-93-ford-mustang-direct-fit-digital-dash.html?srsltid=AfmBOooc51aHQbNSujGiv4eI_3Luys1PDfFRLMRX88PjeswVXhJAT3Ok

Dakota has some offerings as well but you have to configure it.

Digital Dash for Megasquirt

12.3

Introducing the Digital Dash EFI Plug-N-Play Digital Dash with Internal GPS for The Megasquirt Community. Simply plug in your ECU Tuning Cable, and have a FULLY user customizable digital dash that runs the Full Version of TunerStudio MS. NO tuning laptop needed sitting in the passenger seat anymore!
dd-efi.com

12.3″ Pro Dash 87-93 Foxbody Mustang

DD-EFI 12.3" Pro Digital Dash for 87-93 Foxbody Mustang is the 1st fully Plug-N-Play Digital Dash that can be installed using any Megasquirt equipped vehicle.
www.diyautotune.com

Holley / Anderson Motorsports

Holley 6.86" Digital Dash Kit 87-93 Mustang w/EZ Install Harness

Anderson Ford Motorsport is the ultimate source of high-quality Ford Mustang performance and racing parts. We provide parts for classic and modern engines.
www.andersonfordmotorsport.com

Holley / MF Kustoms
Utilizes the stock gauge cluster

1986-1993 Ford Mustang MFAdapter

www.mfkustoms.com
 
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General karthief

wonder how much it would cost to ship you a pair
20+ Year Stangneter
Aug 25, 2016
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#14
  • Jul 27, 2025
  • #14
Wow, the barrel on the parts cannon is melting
All good suggestions, let me say (not that anybody around here will stop me mostly 'cause it's entertaining) get the thing running and driving good in 'stock' form and repair/upgrade the brakes and body ie: subframe connectors, shock tower brace a K member brace, wheels/tires and get the 'look' you want like a little lower front to rear (not 70s jacked up but slight rake?) or lower all around.
By then you'll know about how good your engine is for a power adder.
Now the 'old timer' in me thinks this is gonna go one of two ways, you build the car for the boost and actually get it running and driving but you rarely drive it cause stuff goes wrong (part of the fun of forced induction) and after period of time want to return it to a more drivable driver.
Or..... it never gets done mostly due to too many things and not enough time/interest is lost and now you're looking at a pile of parts.
Don't let me discourage you, it can and has been done a gazillion times,
A lot of the members here have a power adder street car but the bulk of them have another mustang that's mild
Continue posting your thoughts and plans here in this thread and we can and will help you spend money....er plan your build.
Oh and check out some of the existing progress/build threads,
Post picks and ask those nagging questions you've had for years
 
S

So_Flo

Member
Jul 26, 2025
15
7
13
Miami FL
Jul 27, 2025
#15
  • Jul 27, 2025
  • #15
Sparky714 said:
Personally, I'd dump the stock ECU completely and go aftermarket. Especially if you're going to boost it eventually. I currently have a 306 on a Megasquirt ecu with the HO Vortech V3 that makes 10psi. 47lb injectors, 255lph Walbro pump and Kirban regulator. Stock rails and fuel lines. Never been dynoed, but probably low 400's to the tires. I also have a TKX transmission, but ran a T5 behind it for quite a while with no problems. I do race mine occasionally, so I did go for a heavier duty transmission. It's been a solid setup for the last seven years or so. Tons of street miles and lots of 1/8th mile passes on sticky tires.
Click to expand...
Hey Sparky,
Thanks for the advice.
Your setup sounds solid, and I’m definitely taking your suggestions into consideration.

About the 47 lb injectors are you referring to the Ford Performance 47 lb?
Also, did you need any spacers or wiring adapters for installation? I see some sources mention that if you go EV14, you'll need to order additional parts for installation.

I’m surprised you're still running stock fuel lines and rails with that combo, that’s good to know and can save $$$.
  • Did you pair it with an adjustable fuel pressure regulator? ​
One more thing, are you still running a mass air flow sensor, or does the Megasquirt ECU handle everything without one?
My '88 Fox is still speed density, and I haven’t done the MAF conversion yet.

I'll definitely keep the TKX in mind when my T5 finally gives out and yes, wide tires are a must!

Thank you,
 

Sparky714

5 Year Member
Oct 16, 2015
368
208
73
North Dakota
Jul 27, 2025
#16
  • Jul 27, 2025
  • #16
So_Flo said:
Hey Sparky,
Thanks for the advice.
Your setup sounds solid, and I’m definitely taking your suggestions into consideration.

About the 47 lb injectors are you referring to the Ford Performance 47 lb?
Also, did you need any spacers or wiring adapters for installation? I see some sources mention that if you go EV14, you'll need to order additional parts for installation.

I’m surprised you're still running stock fuel lines and rails with that combo, that’s good to know and can save $$$.
  • Did you pair it with an adjustable fuel pressure regulator? ​
One more thing, are you still running a mass air flow sensor, or does the Megasquirt ECU handle everything without one?
My '88 Fox is still speed density, and I haven’t done the MAF conversion yet.

I'll definitely keep the TKX in mind when my T5 finally gives out and yes, wide tires are a must!

Thank you,
Click to expand...
Yes those are the injectors I have. If you order them from Late Model Restoration, they are cheaper and come with the adapters you listed from Jegs. No spacers needed, they work with stock rails. https://lmr.com/item/M9593LU47-K/Mustang-47LB-Fuel-Injector-Kit-86-04. If you haven't heard of LMR, you should check them out. Excellent customer service. I have a Kirban fuel pressure regulator. Looks like LMR doesn't carry them any more, but Areomotive or any other brand of your choice should be fine for what you plan on doing. Just make sure it's boost referenced.

Megasquirt or one of the other after market ECU's are typically run speed density. No need for mass air. You can set them up as mass air, but most guys don't. The difference between your stock speed density ECU and after market is they offer much more tuning options as well as inputs and outputs for other things(Electric fan control, shift light, launch control ect.) The other thing is it's getting harder to find someone to tune the stock ECU's. Your going to need it tuned if you boost it. Much easier to find a tuner familier with Megasquirt or Holley. Not saying the stock ECU can't be done, but my preference is aftermarket.

Make sure you read the replies from all the other guys on this thread too @Noobz347 , @General karthief , @AeroCoupe @FastDriver are a wealth of info on Foxbodies.
 
Last edited: Jul 27, 2025
Reactions: So_Flo
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So_Flo

Member
Jul 26, 2025
15
7
13
Miami FL
Jul 27, 2025
#17
  • Jul 27, 2025
  • #17
AeroCoupe said:
First thoughts off the top of my head:

1) 3.55 gears are a great choice. I have 3.73's and wish I would have gone 3.55's
Click to expand...
AeroCoupe said:
2) Full length subframe connectors are a must. Maximum motorsports, Kenny Brown, or Global West and all with the optional seat brace.
3) Lowering springs, lots of choices out there but the only ones I have any experience with are the H&R Super Sports and they were awesome.
4) The stock T5 will live at those levels but no sticky tires and get a good shifter like an MGW or the like with positive stops.
5) If you do not possess the ability to tear a motor down and inspect main and rod bearings then that is a hard stop and take the motor to someone that can do a tear down and inspect all of that and then put it back together. Worst case is you are out the cost of his/her time, gaskets, and some assembly lube. Should not be any reason to pull the heads or anything like that. May be able to look down the holes in the valley of the block and see the condition of the cam lobes and get an idea on the condition of that. Hopefully they cylinder walls are not rusted but if they are a quick hone should do the job.
6) Stock fuel rails will work just fine and you may want to get an adjustable fuel pressure regulator.
7) Injector size is up to you but if you want to get a Vortech and you are looking at 500 fwhp then you will want somewhere around 42 lb/hr injectors on gasoline. Google "injector size calculator" and run your setup on several of them.
8) The 255 lph pump will be just fine on gasoline.
9) I would make the change to mass air but that is just me as speed density will work as well. I think mass air on drivers and speed density on race cars but that's just me.
10) You may want to rethink the 80mm throttle body with the Edelbrock Performer RPM II upper. The opening on the upper where the throttle body mounts is only 70mm. Can be opened up to 75mm with little issue but I think 80mm may pose some issues. Also, you just do not need 80mm (70mm NA or boosted will make 500+ fwhp) and the tip in may suffer do to how lazy the air will be coming into the intake. You do not have a "USA" lower it is an Edelbrock Performer RPM II. Look at the number above and to the right of the "Made in USA" logo and you will see 31-7120 which is the same part number on mine and the one in this eBay add:

1986-1995 Ford Mustang 5.0L Edelbrock Performer RPM 2 Intake Manifold Cobra GT40 | eBay

We use the most economical carriers for you depending on the item & your location. They are sold as is. I will try my hardest to respond quickly to your problems.
www.ebay.com

11) The heads are Edelbrock 60379's. The 6025 casting was used on several heads. These are not killer heads or anything but waaaay better the the stock piles of . Flow data is as follows (got it from Edelbrock's website):

Cylinder Head Part # .100" .200" .300" .400" .500" .600"
#60379 62/56 126/101 179/133 220/152 238/163 243/169

I probably could come up with more but its not my build.
Click to expand...

AeroCoupe said:
First thoughts off the top of my head:

1) 3.55 gears are a great choice. I have 3.73's and wish I would have gone 3.55's. Good to know!
2) Full length subframe connectors are a must. Maximum motorsports, Kenny Brown, or Global West and all with the optional seat brace. Thanks for the heads up, I wish i knew this younger.
3) Lowering springs, lots of choices out there but the only ones I have any experience with are the H&R Super Sports and they were awesome.
4) The stock T5 will live at those levels but no sticky tires and get a good shifter like an MGW or the like with positive stops.
5) If you do not possess the ability to tear a motor down and inspect main and rod bearings then that is a hard stop and take the motor to someone that can do a tear down and inspect all of that and then put it back together. Worst case is you are out the cost of his/her time, gaskets, and some assembly lube. Should not be any reason to pull the heads or anything like that. May be able to look down the holes in the valley of the block and see the condition of the cam lobes and get an idea on the condition of that. Hopefully they cylinder walls are not rusted but if they are a quick hone should do the job.
6) Stock fuel rails will work just fine and you may want to get an adjustable fuel pressure regulator.
7) Injector size is up to you but if you want to get a Vortech and you are looking at 500 fwhp then you will want somewhere around 42 lb/hr injectors on gasoline. Google "injector size calculator" and run your setup on several of them.
8) The 255 lph pump will be just fine on gasoline.
9) I would make the change to mass air but that is just me as speed density will work as well. I think mass air on drivers and speed density on race cars but that's just me.
10) You may want to rethink the 80mm throttle body with the Edelbrock Performer RPM II upper. The opening on the upper where the throttle body mounts is only 70mm. Can be opened up to 75mm with little issue but I think 80mm may pose some issues. Also, you just do not need 80mm (70mm NA or boosted will make 500+ fwhp) and the tip in may suffer do to how lazy the air will be coming into the intake. You do not have a "USA" lower it is an Edelbrock Performer RPM II. Look at the number above and to the right of the "Made in USA" logo and you will see 31-7120 which is the same part number on mine and the one in this eBay add:

1986-1995 Ford Mustang 5.0L Edelbrock Performer RPM 2 Intake Manifold Cobra GT40 | eBay

We use the most economical carriers for you depending on the item & your location. They are sold as is. I will try my hardest to respond quickly to your problems.
www.ebay.com

11) The heads are Edelbrock 60379's. The 6025 casting was used on several heads. These are not killer heads or anything but waaaay better the the stock piles of . Flow data is as follows (got it from Edelbrock's website):

Cylinder Head Part # .100" .200" .300" .400" .500" .600"
#60379 62/56 126/101 179/133 220/152 238/163 243/169

I probably could come up with more but its not my build.
Click to expand...
Thanks for the help and suggestions, really appreciate the detailed feedback.

Good point on the standing motor. I agree , it's definitely worth the time and money to tear it down now and do it right the first time rather than risk issues later.

The fuel pressure regulator is notedm ’m considering this one (Fuel regulator).

As for fuel injectors, I was leaning toward 40 to 50 lb/hr , sounds like that should be safe for tuning headroom, especially if I plan to boost later down the line?

I also went back out and re-measured my throttle body , turns out it's actually a 70mm, not an 80mm. So I’m glad you pointed that out.

And thank you for the clarification on the Edelbrock Performer RPM II manifold — I’ve updated my original post accordingly. I didn't realize the "Made in USA" cast marking wasn’t the actual model ID.

Appreciate all the insight, this helps a lot as I piece the build together.
 
S

So_Flo

Member
Jul 26, 2025
15
7
13
Miami FL
Jul 27, 2025
#18
  • Jul 27, 2025
  • #18
FastDriver said:
Hard to follow Aerocoupe up. He's good. Just keep the ECU or get an A9L and get a quarterhorse to tune. Saves money. Your parts with an intercooled S-trim or better maxes out the safe limit on the stock block. When you push 500rwhp, upgrade to a T56 or TKX so you can plant the power.
Click to expand...
FastDriver said:
I've been both directions. After all, 2 out of 3 of my foxes are stand-alone ECUs. That said, the stock EEC, with an MAF in my case, is the best driver. Granted, if you have electrical issues with your harness, that changes the calculus. If there is a computer or harness problem, then I'm open-minded. But, with these modern kits, what's the total time & $$$ investment? Seems like you can go from the $1.5k Terminator X kit to the $3.4k Holley Dominator... Then, what kind of gauges do you want? The $800 small screen or the $2k 12-13" dash screens? After all of that, I like the stock, free, gauges more. Weirdly, and just perhaps my bias, I like the UDX dash more in its own way. It's not trying to be pretty... It's all business.

Me? $300 A9L (I have one in black jack for free and another from another SN member), a $250 Quarterhorse with BE/EA licenses. And, I'm done. Got a spare wiring harness on the shelf, too. Seems like a no-brainer, to me.

I'm not afraid of tuning a stock SD, pre '89, EEC either, but I'd need to research tuning with a blower on it. A9L, though? No problem.
Click to expand...
Noobz347 said:
Who makes the kit that has the digital replica of the Fox Gauge cluster?\


Also...

There's a kit that integrates with the OEM gauges someplace too.
Click to expand...
AeroCoupe said:
Autometer
https://www.autometer.com/invision-lcd-dash-kit-87-93-ford-mustang-direct-fit-digital-dash.html?srsltid=AfmBOooc51aHQbNSujGiv4eI_3Luys1PDfFRLMRX88PjeswVXhJAT3Ok

Dakota has some offerings as well but you have to configure it.

Digital Dash for Megasquirt

12.3

Introducing the Digital Dash EFI Plug-N-Play Digital Dash with Internal GPS for The Megasquirt Community. Simply plug in your ECU Tuning Cable, and have a FULLY user customizable digital dash that runs the Full Version of TunerStudio MS. NO tuning laptop needed sitting in the passenger seat anymore!
dd-efi.com

12.3″ Pro Dash 87-93 Foxbody Mustang

DD-EFI 12.3" Pro Digital Dash for 87-93 Foxbody Mustang is the 1st fully Plug-N-Play Digital Dash that can be installed using any Megasquirt equipped vehicle.
www.diyautotune.com

Holley / Anderson Motorsports

Holley 6.86" Digital Dash Kit 87-93 Mustang w/EZ Install Harness

Anderson Ford Motorsport is the ultimate source of high-quality Ford Mustang performance and racing parts. We provide parts for classic and modern engines.
www.andersonfordmotorsport.com

Holley / MF Kustoms
Utilizes the stock gauge cluster

1986-1993 Ford Mustang MFAdapter

www.mfkustoms.com
Click to expand...

General karthief said:
Wow, the barrel on the parts cannon is melting
All good suggestions, let me say (not that anybody around here will stop me mostly 'cause it's entertaining) get the thing running and driving good in 'stock' form and repair/upgrade the brakes and body ie: subframe connectors, shock tower brace a K member brace, wheels/tires and get the 'look' you want like a little lower front to rear (not 70s jacked up but slight rake?) or lower all around.
By then you'll know about how good your engine is for a power adder.
Now the 'old timer' in me thinks this is gonna go one of two ways, you build the car for the boost and actually get it running and driving but you rarely drive it cause stuff goes wrong (part of the fun of forced induction) and after period of time want to return it to a more drivable driver.
Or..... it never gets done mostly due to too many things and not enough time/interest is lost and now you're looking at a pile of parts.
Don't let me discourage you, it can and has been done a gazillion times,
A lot of the members here have a power adder street car but the bulk of them have another mustang that's mild
Continue posting your thoughts and plans here in this thread and we can and will help you spend money....er plan your build.
Oh and check out some of the existing progress/build threads,
Post picks and ask those nagging questions you've had for years
Click to expand...

Noobz347 said:
I would agree with that except for the 30+ year, multi-owner, unknown condition of a harness that still requires a conversion. Plus the cost of a stock EEC, plus sending it off for a health check, plus having to get the thing tuned.


Nope... We're firmly in the aftermarket ECU territory now, me thinks.
Click to expand...
Haha, yeah the parts cannon got hot real quick!

Appreciate all the responses so far, seriously. I haven’t used forums in a while, but instead of replying to everyone individually, I wanted to give an update and share my thoughts based on all the great feedback.

Previous Owners:
This ’88 LX 5.0 has been in my family since day one, bought new by my dad in 1988, and only passed between him, my uncle, and me.



Where I Stand Now:
I’m really trying to approach this the right way. I don’t want to rush into a big build and end up with a pile of parts and a project I lose interest in. I’ve come to realize there’s a big difference between building a "go-fast" car and building a good driving car. Right now, I’m focusing on drivability and making sure the foundation is solid.

Last month, I changed the fuel tank and pump, topped off all fluids, and was able to get it running. To my surprise, it fires up on the first or second crank! I also found and fixed a nasty electrical issue with the brake and turn signal lights, turned out to be a burnt switch. So now the lights work again!

Current Issue:
The one major issue that caused me to park the car back then...and is still there, a bad vibration. It vibrates at idle, under revs, and when driving. Almost like something is loose. I’ll be lifting the car with help from a friend who owns a shop to inspect:
  • Motor mounts
  • Driveshaft
  • Flywheel
  • Possibly a misfire (but the engine sounds solid with no noticeable misses)


Plan Moving Forward (Pre-Motor Swap):

Here’s my current checklist. Not in a strict order, but here’s how I’m thinking.
  1. Fix the vibration – priority #1.
  2. Subframe connectors – after reading everyone’s input and my past experience, I’m convinced this is a must.
  3. Inspect the preassembled block– check for any rust, corrosion, or bad gaskets, ensure the motor is still functioning.
  4. Consult with a local tuner/electrician – I’m not a tuner, so I’ll need a quote from a shop and see what it can run me $$ for installation.
  5. Upgrade brakes – planning to get rid of the rear drums and go with discs, especially since I’ll be adding power down the line.
  6. Tires/wheels – temporarily used tires for now. Debating a 5-lug swap, so I’m holding off on committing to new wheels until I decide.
Transmission and suspension, I'm going to let it ride for now. The electrical dash looks cool and is on my wish list for sure!

Final Thoughts:
I really appreciate all the advice; it’s helping keep me grounded and motivated. I do want to boost this car eventually, but I also don't want that headache of fixing boosted problems monthly.. Looking forward to more feedback on other members with boosted mustang's and if they go through monthly issues or problems.

Let me know if y'all have other questions or details I missed out, and keep the ideas coming. I’ll keep posting updates and pics as I go!!! @Noobz347 @FastDriver @General karthief @AeroCoupe @Sparky714 THANK YOU !!
 
Reactions: General karthief

gkomo

now i can hopefully expect to receive the shaft
Aug 2, 2024
2,185
1,432
133
San Diego, CA
Jul 27, 2025
#19
  • Jul 27, 2025
  • #19
For the vibration, how’s the harmonic balancer looking? Didn’t see that on your list but could cause vibrations, especially since you said at idle.
 
Reactions: So_Flo and AeroCoupe

Noobz347

Stangnet Facilities Maint Tech... Er... Janitor
Admin Dude
Jan 4, 1985
43,107
21,284
234
Box behind Walmart
Jul 28, 2025
#20
  • Jul 28, 2025
  • #20
So_Flo said:
Consult with a local tuner/electrician – I’m not a tuner, so I’ll need a quote from a shop and see what it can run me $$ for installation.
Click to expand...

And this is where you have to weigh the cost of a dyno-tune against the cost of an aftermarket unit that self-learns.
 
Reactions: General karthief
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