I purchased my 1986 Fiero GT from a scrapyard, after missing out on a chance to buy it a few years prior. Apparently the old owner gave up on it. A set of shift cables later and the trusty 2.8 served me well for 2 years and 38,000 miles reliably. (That's not a typo). The car travelled to every corner of the Midwest before the old girl finally gave up the ghost along the Mississippi river heading south out of St. Paul. It made it the 170 miles home knocking like a Jehovah's Witness.
I had recently purchased a 3.4 DOHC on a 85 cradle which was destined for my 84, however the 84 has been very dependable, seeing over 20k miles on the duke. Closer inspection of that 3.4 found too many faults to ignore, the biggest being water ingress to the cylinder heads (came out of a running car my keister). I then acquired another DOHC from a friend, the engine ran at one point, it was installed in the car, on its first drive turned sideways and quickly introduced itself to a large oak tree. He said it ran after, but after being parked the engine would only pop and sputter. I wont go into it but the entire wire harness was assembled exclusively with wire nuts. He said if Id scrap the 88 I could have the motor and cradle.
The 88 met the crusher and the DOHC came home (No you cant have the brake calipers, they went into my parts stash).
I've always like this motor, its a stupid, half-assed, rushed design. But what it lacks in classy execution it makes up for in pure character, intoxicating exhaust note, and smooth power. I find it neat. Im not really worried about raw power, I just want a OEM style engine that fits the vibe of the fiero and I think this is it.
Originally I was planning on swapping to what I thought was a good condition 88 cradle, however after seeing welded log chains substituting engine mounts, cracked cradle welds, more through-hole rust than clean metal. The 88 cradle reunited with the rest of the car at the crusher. Shocks were shot, brakes were broke, swaybars were snapped. It was junk
Off came the 3.4 which promptly found its way home to my very nice 86 cradle, mounted up on new, but otherwise stock fiero transmission and engine mounts (The front mount needed a small cut to make it work, but a little trimming and its a-ok)
Here's my buddy working as our counterweight swinging this big ole motor around.
I had to remove tons of random mounts and crap the original installer, uh, improvised. Including the log chain, wrapped and welded around the transmission as a substitute transmission mounts. beyond that everything cleaned up okay and the engine was ready to plunk in.
Inspecting the timing belt, it looks relatively fresh, no cracking or wear to mention, however I have no proof its been replaced, so Im going to do the right thing and put the cover back on and pretend everything is okay. (lol)
After that it was a simple matter of removing the torsion bars from the rear deck (BRACE YOU WINDOW WITH PLYWOOD) . Trimming the bottom half of the passenger deck hinge and stripping the engine bay of everything except the battery tray and the purge canister. . .
...the old girl finally gave up the ghost along the Mississippi river heading south out of St. Paul. It made it the 170 miles home knocking like a Jehovah's Witness.
Wiring the LQ1 is simple but also confusing, DOHCFiero.com has a few inaccuracies but has the best documentation by far. Your two option really come down to reusing and modifying a 2.8 harness or a 3.4DOHC harness or starting from scratch. As an engineer I decided to go from scratch. I snipped all the need connector off the original harness. Bent up some mounts to place ECM in the oem location, and passed it through the bulkhead with a watertight disconnectable 37pin CPC connector. After that its just a matter on splicing the computer wires into the back of the CPC, labeling the connection (eg. D3/D9 Injector Driver - CPC 3)
after that pin into the connecter and run it the rest of the way to wherever it needs to go.
Looks good so far Those DOHC engines weigh 450 lbs without the flywheel so that is a weight increase over the 2.8L of up to 100 lbs. The heads are massive. The swap gives you extra power so the end result is faster.
------------------ " THE BLACK PARALYZER" -87GT 3800SC Series III engine, custom ZZP /Frozen Boost Intercooler setup, 3.4" Pulley, Northstar TB, LS1 MAF, 3" Spintech/Hedman Exhaust, P-log Manifold, Autolite 104's, MSD wires, Custom CAI, 4T65eHD w. custom axles, Champion Radiator, S10 Brake Booster, HP Tuners VCM Suite. "THE COLUSSUS" 87GT - ALL OUT 3.4L Turbocharged engine, Garrett Hybrid Turbo, MSD ign., modified TH125H " ON THE LOOSE WITHOUT THE JUICE "
Yeah they certainly aren't a lightweight (I can't believe they are 450, i'm gonna have to weight it out, I stand to be corrected). As far as this NA build goes, I couldnt care less if its even a 10th of a second faster than the 2.8, I just want a engine I can wring out to 7000+ rpm. I just want the feel of the engine over the truckish 2.8
Hi Dukespro. I would love to have a go when you finish your project with my "truckish" 85 GT V6. There is a few of us that decided to work with what GM gave us and have been quite successful at upgrading and tuning the 2.8 without basterdizing our beautiful cars. good luck on your conversion and I hope it works out well. sleek
Oh, don't think I'm in some high road 4 cam superiority attitude, the 2.8 and 3.4 can absolutely whoop a DOHC when built correctly. I just think that stock for stock the 2.8 feels a bit more like a truck motor (for better or worse) But I will never turn down a opportunity to race another Fiero. If we ever have a chance to meetup, ill run one out with you
Originally posted by Dukesterpro: ... the 2.8 and 3.4 can absolutely whoop a DOHC when built correctly.
Maybe a stock DOHC. As installed in a W Body, I think they were rated at 210 HP or thereabouts. Probably worth a bit more in a Fiero. I probably got that much out of my pushrod 3.4 by the time I was finished, but holy schnickies, it cost a fortune. (This was in 2006 or so, and I had ~$800 just in head work.) About the only thing that wasn't done to it, other than balance and blueprint, was to up the compression or add boost.
Originally posted by Dukesterpro: I just want a engine I can wring out to 7000+ rpm.
I always liked the LQ1. It was from the era where GM engines looked good w/o engine covers and had the extended power band. I worked on one for a buddy and got to drive it for a few weeks and it was fun and sounded great in the 3000 to 7000 lb range.
Driving that car is why I built my first LS4 to target less torque off idle and peak hp at 6800 rpm (rev limiter set to 7200 rpm).
Yeah they certainly aren't a lightweight (I can't believe they are 450, i'm gonna have to weight it out, I stand to be corrected). As far as this NA build goes, I couldnt care less if its even a 10th of a second faster than the 2.8, I just want a engine I can wring out to 7000+ rpm. I just want the feel of the engine over the truckish 2.8
The 3.4L DOHC engine is basically a 3.4L P/R engine with two massive heads, 16 valves/springs and four camshafts. Weigh it and see but I don't believe 450-500 lbs is far off. Many years back there was a guy by the name of Matt Hawkins who built a turbocharged 3.4DOHC. It was so powerful that Matt kept blowing transmissions. With 4 valves per cylinder with some boost that engine is a real powerhouse.
------------------ " THE BLACK PARALYZER" -87GT 3800SC Series III engine, custom ZZP /Frozen Boost Intercooler setup, 3.4" Pulley, Northstar TB, LS1 MAF, 3" Spintech/Hedman Exhaust, P-log Manifold, Autolite 104's, MSD wires, Custom CAI, 4T65eHD w. custom axles, Champion Radiator, S10 Brake Booster, HP Tuners VCM Suite. "THE COLUSSUS" 87GT - ALL OUT 3.4L Turbocharged engine, Garrett Hybrid Turbo, MSD ign., modified TH125H " ON THE LOOSE WITHOUT THE JUICE "
Since my last post I have since finished the plumbing and wiring. I took the car for its first drive, overheated twice since I forgot to install a expansion tank (Overheated being relative, I watch my temps with a manual gauge like a hawk) After that I got about 60 trouble free miles before trouble caught up with me. I have yet to determine what failed, but ether the throwout bearing exploded (it started squealing when you push the clutch in) or the throwout fork exploded. I lost my ability to disengage the clutch. (lots of scary noises) I am okay with this, I was unhappy with the MY17 4 Speed and have a Isuzu 5 and all the accoutrements on hand ready to go. Worse however, my battery tray busted loose. Dropped the battery down enough to grind on the AC Compresssor pump, blow out battery acid all over the engine bay and then catch fire.
Nothing more amusing then pulling over in a burning Fiero.
However on a good note, when I got out to extinguish the minor fire, the battery acid weakend the heater core line, which burst and extinguished the fire! So win win!
However on a good note, when I got out to extinguish the minor fire, the battery acid weakend the heater core line, which burst and extinguished the fire! So win win!
