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Old 02-22-2014, 10:02 PM   #1
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Questions about a supercharged 347

I just picked up a new to me 94 Mustang GT with the following mods:

347 forged stroker
Eagle 4340 crank
Eagle 4340 h-beam rods
SRP inverted domed pistons 9.2:1
.542 lift intake and exhaust
36 lbs injector
professional product aluminum intake system
Pro Topline aluminum heads with 200cc intake runner 2.02, 1.60 valves
80mm polished throttle body
75mm mass airflow
BBK shorty headers and H-pipe with 40 series Flowmaster exhaust system
MSD 6AL CD Ignition
Vortech V1 running 10PSI
Built TKO 600 5 Speed
Spec Stg 3
Auburn Posi LSD
Moser 31 spline axles
aftermarket rear suspension (unsure of what it is)
Other miscellaneous things

This car supposedly made 430rwhp and 484rwtq a few months ago (I honestly doubt it).

The issue with the car is that it simply doesn't run correctly.

Under any load (only in gear) the engine pops and pings, it seems to be coming from around the passenger side, sometimes sounds like it's coming from the Vortech, it sounds like a muffled backfire.

The wideband O2 is getting crazy readings from full lean to full rich (20 - 10), never in the stoich range (13.5 - 15). Always from one extreme to the other, several times a second. Previous owner said it has always done this since it was tuned a few years ago when the car was built. He also stated the car only got about 9MPG regardless of how you were driving it.

The entire time this is happening, the car is not in boost at all (haven't went past 3,000 RPM at more than half throttle). It does do it when idle but rarely. Under any sort of load it is every few seconds.

I am assuming it's either a tune issue (timing?) or maybe something else like bad fuel, I think it's unlikely though, never heard a car act like this before on bad gas.


I will be digging into it tomorrow a bit more.

I planned on dropping and draining the fuel tank, checking out the plugs and wires, and changing the oil. The car has less than 1,000 miles since the 347 build two years ago. Might even do a compression check if nothing else stands out.

Any thoughts on what the issue could be or where I should start looking?

Should I swap in an LSx with nitro booze and a T56 and call it good?


Pictures of the car..



Engine picture - huge picture



As it sits currently

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Old 02-23-2014, 08:53 AM   #2
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Quote:
Originally Posted by Ish416 View Post
I just picked up a new to me 94 Mustang GT with the following mods:

347 forged stroker
Eagle 4340 crank
Eagle 4340 h-beam rods
SRP inverted domed pistons 9.2:1
.542 lift intake and exhaust
36 lbs injector
professional product aluminum intake system
Pro Topline aluminum heads with 200cc intake runner 2.02, 1.60 valves
80mm polished throttle body
75mm mass airflow
BBK shorty headers and H-pipe with 40 series Flowmaster exhaust system
MSD 6AL CD Ignition
Vortech V1 running 10PSI
Built TKO 600 5 Speed
Spec Stg 3
Auburn Posi LSD
Moser 31 spline axles
aftermarket rear suspension (unsure of what it is)
Other miscellaneous things

This car supposedly made 430rwhp and 484rwtq a few months ago (I honestly doubt it).

The issue with the car is that it simply doesn't run correctly.

Under any load (only in gear) the engine pops and pings, it seems to be coming from around the passenger side, sometimes sounds like it's coming from the Vortech, it sounds like a muffled backfire.

The wideband O2 is getting crazy readings from full lean to full rich (20 - 10), never in the stoich range (13.5 - 15). Always from one extreme to the other, several times a second. Previous owner said it has always done this since it was tuned a few years ago when the car was built. He also stated the car only got about 9MPG regardless of how you were driving it.

The entire time this is happening, the car is not in boost at all (haven't went past 3,000 RPM at more than half throttle). It does do it when idle but rarely. Under any sort of load it is every few seconds.

I am assuming it's either a tune issue (timing?) or maybe something else like bad fuel, I think it's unlikely though, never heard a car act like this before on bad gas.

I will be digging into it tomorrow a bit more.

I planned on dropping and draining the fuel tank, checking out the plugs and wires, and changing the oil. The car has less than 1,000 miles since the 347 build two years ago. Might even do a compression check if nothing else stands out.

Any thoughts on what the issue could be or where I should start looking?

Should I swap in an LSx with nitro booze and a T56 and call it good?

Pictures of the car..

Engine picture - huge picture

As it sits currently
I would bring it to a speed shop and have them put it on the dyno. They'll make it run the best it can. Only 430rwhp with supercharger? That doesn't seem right that's low. My brothers 91 fox has a forged 347 stroker and car dynoed at 425rwhp . Just call your local speed shop and see.
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Old 02-24-2014, 02:35 PM   #3
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The fact that it has Pro Products anything on it and Pro Topline heads makes me seriously question the rest of the motor. Those are low quality pieces not to mention putting a forged rotating assembly in a stock block is kind of a waste... stock block lets go at around 500whp or even less sometimes. The stock rotating assembly is good for more than that but w/e.

Anyway, it could be a number of things. Fuel, electrical, might have an internal problem who knows. If you got it for a really good price it very well might be better to just part out the drivetrain and do the LSX/T-56 swap. That supercharger kit alone is $1500-$2k just by itself. Could probably get close to enough money with the parts/motor/blower/trans to be cost neutral on a LSX swap.
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Old 02-24-2014, 03:26 PM   #4
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Hmmm ... I don't know a lot about the Ford small block stuff.

Good to know about the Pro Products stuff, couldn't find a whole lot of info on them.

As for the block, I am really not sure if it's a stock Ford block or something else. Will check on that tonight. I have heard that the stock Ford blocks let go around 500whp, doesn't make sense to put all this money and labor into something that is a known weakness.

Just going through the receipts on the car, there is almost $40,000 invested in this thing including the original cost of the car ($8,000, 10 years ago), parts, tuning and labor. Apparently this thing is on the 2nd engine, which makes me think that either the PO didn't know what they were doing or they had entirely too much faith in their builder/tuner (same one for each build). Neither of which would surprise me.

As for the LSx swap, that was a joke. I got the car cheap enough that I could likely sell just the transmission and likely break close to even.

I dropped the fuel tank and drained the gas from it, changed the oil (looked fine), pulled a few of the plugs, they look alright (dark brown/black). Will put fresh fuel in it during the next few days.

If it still acts funny, I will do a compression check, if that tests out alright, then borescope inside the cylinders to see how everything looks, then timing,

If after all of that, then I would guess it's the tune. Only one way to find out...
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Old 02-24-2014, 03:30 PM   #5
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I actually thought LS swap would have been a good idea lol


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Old 02-24-2014, 03:54 PM   #6
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Jeez Ish, you're really jumping into this Mustang thing head-first.

I'd hook up a fuel pressure tester to that car and see what that looks like. My suspicion is the fuel pressure regulator.
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Old 02-24-2014, 04:36 PM   #7
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Originally Posted by straybullitt View Post
Jeez Ish, you're really jumping into this Mustang thing head-first.

I'd hook up a fuel pressure tester to that car and see what that looks like. My suspicion is the fuel pressure regulator.
Never thought of that, will check it out.

As for jumping into the Mustang thing, no, not really. With this car, it was literally my phone rang, a price, a trip to my safe for some cash and I was on my way. 30 minutes after leaving to look at the car, it was in my barn and on jack stands.

I bought this car to make a profit on. Once it's running properly, a current dyno sheet and a few time slips and it will be up for sale. If it looks like it will cost more than it's worth to fix, I will part it, sell it or LSx it.


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I actually thought LS swap would have been a good idea lol
If I keep it (because who doesn't need a 3rd car with over 400whp?) and this does go LSx powered, it's going to be a drag car. I'm thinking built 408 with 300 shot, a 9" in the back and a built/stalled 4L80E. I'd be looking for 9's @ 140+ on a small tire.

As is, I would be happy with mid - low 11s @ 120+. I figure this should be slightly faster than my Z28 on motor. I could run slicks and not worry about the rear exploding, which would be nice.
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Old 02-24-2014, 06:22 PM   #8
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You can build the 8.8" to take that sort of power too. For this car, yeah just try to figure out what is going on. You are good with the LSx motors, that's a small block, this is a small block too, just with a distributor. If the A/F is off first I'd check to see what sort of MAF is in there, what brand etc... Check injectors/connections, check fuel pressure and it very well might be in the tune.

Oh, as for the tune, just FYI MANY tuners treat the 94/95 computers like they are some sort of Rubix Cube that is impossible to figure out. Call around to different tuners and ask if they can tune for 94/95 computers. Any competent tuner should have no problems but it amazed me how many shops I needed to call when I had my 95 before I found my tuner in South NJ who was like "hell yeah I can tune them bring it down" and +40whp later I was a happy camper.
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Old 02-24-2014, 08:17 PM   #9
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I knew the 8.8 was a pretty stout rear end.

I'm just going through things one at a time. The MAF is clean (never checked to see what it was), all wiring connections look good, I know it has spark, so fuel system is next on the list of things to check.

BTW, the engine compartment in this thing sucks. There is no room for anything.

I called around to a few friends in high places and asked if they knew anything or anyone about tuning on a 94 Mustang. Both people I talked to responded with "Ooooooo, that's the SN95 5.0, correct?" Followed by something like, those things suck to tune and they both think they know a guy.

I already have a guy who is coming to look at the car towards the end of this week. Would be nice to get it running correctly. O' well, guess we will see what happens. Won't be able to work on it until Wednesday evening. Damn weather needs to warm up, my barn isn't heated and working in 28F temps sure does suck.
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Old 02-24-2014, 11:21 PM   #10
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A F body guy saying the Mustang engine bay is tight to work in???


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Old 02-25-2014, 05:59 PM   #11
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I knew the 8.8 was a pretty stout rear end.

I'm just going through things one at a time. The MAF is clean (never checked to see what it was), all wiring connections look good, I know it has spark, so fuel system is next on the list of things to check.

BTW, the engine compartment in this thing sucks. There is no room for anything.

I called around to a few friends in high places and asked if they knew anything or anyone about tuning on a 94 Mustang. Both people I talked to responded with "Ooooooo, that's the SN95 5.0, correct?" Followed by something like, those things suck to tune and they both think they know a guy.

I already have a guy who is coming to look at the car towards the end of this week. Would be nice to get it running correctly. O' well, guess we will see what happens. Won't be able to work on it until Wednesday evening. Damn weather needs to warm up, my barn isn't heated and working in 28F temps sure does suck.

My guy had my 94 tuned and running great in a hour and half with 4 dyno pulls !
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Old 02-25-2014, 08:59 PM   #12
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So did mine, I'm just saying that for every tuner like ours you'll get 4 or 5 guys who are afraid to tune them. And honestly, IMO, someone who can't tune a 94/95 computer has 0 business tuning anything.
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Old 03-01-2014, 09:16 PM   #13
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Who did you use for tuning Scotty?
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Old 03-01-2014, 09:20 PM   #14
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Who did you use for tuning Scotty?
Radical Racing in Atco, NJ.
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Old 03-02-2014, 11:38 AM   #15
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Sweet thanks. I've heard they do great work, I'm sorting out some issues with my car now, going to pay them a visit
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Old 03-12-2014, 08:52 AM   #16
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Well .. after much work, I still have not resolved the issue.

I believe it is now something internal. My guess is that it's a wrist pin as the issue does not seem to be fuel related at this point.

This weekend I will start pulling the plug wires to see if that makes any difference. Regardless, it's looking like I will be pulling this engine sometime soon.
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Old 03-12-2014, 12:50 PM   #17
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These engines come out ridiculously easy. Sorry it appears to be something internal but honestly from some of the parts that were used like the PP intake, it would not shock me if the motor was built poorly or not even as advertised...
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Old 03-12-2014, 02:44 PM   #18
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Having never pulled one of these before, it looks like a pain in the ***. I'm sure that will change once I get it on the lift though.

Just need some nice weather now. Yesterday in Indiana was 67, today it's -15 with windchill and 6 inches of snow.
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Old 03-12-2014, 03:18 PM   #19
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Having never pulled one of these before, it looks like a pain in the ***. I'm sure that will change once I get it on the lift though.

Just need some nice weather now. Yesterday in Indiana was 67, today it's -15 with windchill and 6 inches of snow.
You can pull one of these motors in a few hours, there is room to work and not very much to remove.

Obviously disconnect all accessories, fuel lines, vac hoses, ground wires, connectors etc... Remove shifter from trans/unhook VSS/reverse pigtail, remove midpipe/driveshaft. Support tailshaft with jack, drop crossmember, remove nuts from motor mounts, hook up cherry picker with load leveler and the whole shebang comes right out.

Pretty much it in a nutshell.

And you definitely want to remove the hood but I'm assuming you know that.
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