L47/Aurora 4.0L powered Fiero.


…and an F23 5-speed Getrag triple-layshaft trans from an 02 Cavy with the 3.94 final drive. I’ve been working on this one for a few years now.

Here’s the motor with exhaust. Just prior to me replacing all of the timing wearables.


The motor ran great last summer; I just tore it down over the winter to finish those nit picky little details that make it worth not rushing to register a bullshit car in September. It didn’t have brakes, shifter cables, a busted CV…shit like that.

I bought most of the parts to get it back together.

Front mount battery shit:


Even has cruise control:


I finished the audio system tonight. Composed of ‘custom’ digital coaxial source into Fiio DAC directly into NVX JAD900.5 amplifier in 2-channel mode. It runs two CDT ES-04 4" woofers and two 1" Aura tweeters plus one 8" ProTech sub in .35in^2 sealed enclosed packed with PolyFill. Sounds amazing. Really that close to being done. Hoping early April.


Even pulled the dash to get the sub and 5-channel amplifier mounted.


Lest ye not believe it was ever in the car, here’s an old pic; before the engine wiring harness was ever even constructed.


I’ve got an OBX LSD coming in that I need to ‘refurb’ and install in the F23. Then fab up the shift cable mounts and bolt the motor in and fill the fluids. Almost there.


… but will it do burnouts? :mpd:


Seems like a cool project


Starting with a fastback not a notchie… So that gets a :tup:




LOL. Proper first post.


Cool project, man…mid-engine cars rule…


woah. a car project!


I’m even using a GM computer with a legit GM operating system. It’s an LS1 PCM from a '98-'00 F-Body, but I can’t remember the service number off the top of my head. It’s flashed with the GM-written operating system from a '99 Shelby Series One and tuned with HPTuners. I just had to build the wiring harness, really.

I still need to fab up some shifter cable mount(s), get some headlights in it and bolt the motor back in after I paint the valve covers. Hoping to have it legal around the end of the month or mid-April at the very latest.


I’ve even got the regulator for the fuel rails I’m going to make. Just need to fire up the lathe to make some bungs and -AN fittings.


Oh, and a few bonus shots from when I had the motor torn down:






very cool. surprising how similar the intake mani looks to an LS. maybe this was a precursor.

how’s the trans hold up to that power? what does it even make for power? She’s gonna rip with a 3.94…


I guess all of my posts need to be approved? That many trolls around here?

Anyway, here’s a youtube video of the motor running in the car last summer. I shot it with my OnePlus 1 cell phone, which has an awful mic. Gives you an idea though. The intake is really that loud. Exhaust sounds pretty good with just the resonator. Loud, but good.


The SpeedHut gauges I installed:


Transmission mount porn (or so I think):

I do keep forgetting to gusset those strut tower brace struts. I need to write that down on the whiteboard. Don’t let me forget.

I had the car somewhat back together last summer when it was working, and here’s what that looked like:


One more, of my bomb-ass re-upholstered leather seats with factory emblems stitched back on. No slots for harnesses, though. Sad face.

Shittier picture, but I had an HTC One Mini when I took this last year. That thing was awful with pictures. Purple. Everything was GD purple. What the hell?

Anyway; I’ll keep working on it.

Oh, and to answer a few questions:

These F23 boxes have been in 500hp+ L67 (3800SC) powered Fieros on Pennock’s in the past handling 6K+ clump dumps and nonsense. Even if I do manage to break it, they’re rather plentiful and have been around for the last 10 years or so in various cars with different bellhousings. The only differences were related to shifter cable mounting and final drive ratio. I’ll update when I pull the trans apart. I have all of the important Kent-Moore F23 specific tools:


…and the motor was rated for ~300/300 or something like that in the Shelby. My motor came from the Aurora and those were rated for ~250/250, so I wonder the Shelby just has a 50HP tune? I mean, my intake is as as least restrictive as it can be and my exhaust is pretty free-flowing. I’ll likely have a dyno session with it this summer.

Thanks for the interest, ladies and gents.


Why not use the 4.6L? Just wondering. Cool build though.


Cool build for sure. Looks like the engine fits well in there, surprisingly.


L47 is similar to the cadillac northstar v8s.


awesome !!


Very cool. :tup:



I wonder if this Fiero project every got completed?


I hope it doesn’t think I’m spamming by trying to update this thread, but I’ve been working on this car for the last five years already, so there’s been a bunch of progress. Good amount of pictures. Here’s some background on the ‘radio’.

Well; it’s not a radio. It’s actually an empeg. It’s an MP3 player, and it doesn’t even have a built-in FM tuner. There’s a plug-in add-on module that used to be available, though. It’s a defunct product produced by a small UK firm in 1999-2000 for a high initial MSRP of around $1,300 for a single ~20GB[all of t3h geebeez] IBM hard drive. It’s a tiny, low-powered Linux computer with a single available IDE bus for storage [master and slave, of course] and a beautiful VFD display up front. Less than 2,000 were produced. I loved mine so much, I bought another. Then it died, so I swapped to the spare. I can’t resurrect the old one. Two of the parallel address busses are hosed from the StrongArm processor, so it couldn’t find the ethernet controller or hard drive. I just don’t think I’ll ever find a replacement chip. It’s strictly a parts machine, for sure. I was devastated. These aren’t easy to find or really all that cheap. I hunted another down in Germany, though. Hopefully be here soon.


The yellow Pelican case background is it’s home when it leaves the car. I wrapped paracord super tightly around the handle and lashed in a carabiner so that I can clip it to my backpack when I have to hike anywhere from my car. I use it daily in my Subaru and I very rarely leave it in the car. It slides in and out of a cage so that it can very easily be taken inside to be updated. I’ll get an orange Pelican for the new joint once I get it up to ‘hot spare’ spec.


For the mega-nerds; it’s so old that I have to run a patch kernel ~[2.2.9] to feature LBA48 support to address my twin 160GB drives. Yup. That’s 320GB of 2.5" 44-pin IDE storage in my dash. Mostly random VBR, 320CBR. I think it supports FLAC, too.


I mentioned in the first post the digital sound card. I hand-assembled that little board and spidered in the harness. It’s basically an i2s sound card that spits out a standard S/PDIF signal over digital coaxial. I borrowed the two rear RCA outputs from the car’s sled harness for digital audio purposes, so I don’t have to worry about any extra cables. I just have to run a little DAC at the amp to get the signal back to analog. Zero noise in the Subaru. I’m expecting the same of the Fiero.


Answer questions:

I didn’t use the 4.6L because it wasn’t reasonably available to me. I got this 4.0L somewhere around 7 years ago and I didn’t have much money at the time. I think I paid $300 for it? Similar Ns were $1,000+. Nothing against them whatsoever. The '96-'99 blocks are identical, save for bore size. Every single thing that I’ve made for this motor would bolt right up to the 4.6L N big brother. In fact, I’ll likely use one when I build up a stout shortblock and put steel inserts/studs in the block for the heads and mains. Anybody notice the turbo flange up in the first few posts there?

Engine does fit pretty well, but that’s no accident. Had to do come creative packaging and chassis clearancing, aka beating the piss out of some places with a BFH. Here are a few more packaging-type photos to give you an idea.

Coolant hoses mounted through oil intercooler to get to the rocker panels for tubes for front mounted radiator.


Strut tower clearance and valve cover -12AN black braided nylon breather lines. These go back to that rad-ass fire extinguisher. Yea, I made that into my catch can.

The closer valve cover fitting is kind of close to the brace [1/8"], but I’m still working on the PITA valve covers [magnesium] so I think I can try to move it up at least 1/4"-1/2". I’m sanding the pits and oxidation out and trying to make them somewhat presentable so I can paint them wrinkly red. Kinda Ferrari-y. Hope it’s not too douchey. Also gives you a better view of the clearance. It’s probably around 1/4"; but the [minimal] movement of the poly-mounted drivetrain is in a fore-aft direction, not lateral. Should be sufficient. Again; gussets.

Forgive me, I didn’t scrub the front crossmember before installing the tubular front suspension with coil-overs, but it’s got them. Along with front/rear Addco sway bars.

Rear sway bar:

That lame Eibach sticker is gone.

Answers a bunch for now, anyway.


Yep, spam filter thought you were trying to sell us Viagara. You should be set now :tup:


Hah. My fault. Thanks for clearing it up!