Someone stuffed a 3.8NA in a 3.4 car... now what?
- Thread starter wmstecker
- Start date
RareGMFan
New member
Thought you were looking for a Grand Am GT. This guy has a Grand Prix GT. Rare model sedan from '94 - '96 (GT was a coupe prior to '94) that came standard with hood louvers and the 3.4 DOHC.
Where have all you guys been? The 3800s have been swapped into just about anything you can imagine for YEARS. Fiero, Sunbird, Cavalier, Sunfire, Cobalt, FWD a-bodies, etc. And yes, even quite a few Gen I w-bodies. There was even a whole website devoted to swapping the L67 (Series II 3800 supercharged) into anything. MotorSwap
Your GP being a '94, you have OBD1.5. First thing you'll want to do is find out what year motor it is, and what it came out of. If it's a '96+, it's going to have OBD2. Easiest thing to do would be to grab the whole wiring harness from the appropriate year/car. Personally, if you're going to go through all that trouble anyway, I would just find a '99 & up L67, and take the motor, trans and computer from it. They can be had cheaply enough these days to not make the savings of sticking with the n/a motor you have worth it. If you can find the wiring harness from a '97 or '98 Chevy Lumina/Monte Carlo, that will be the easiest to work with for you, as it was a "Gen 1.5" w-body, so it's designed for a Gen I. You'll also want to snag the exhaust/downpipe from one so it'll fit the Gen I. I think you also may need different/custom axles, too. Here's a good thread:
3800/L67 swap questions
I don't disagree with you, but it was easiest for me in the situation.
Z34Phoenix
Florida Tuner
Take it from me. I swapped a 3800 in place of my 3.4 DOHC. You will need an harness from a 98/99 z34 or lumina police car. Throttle cable, power steering lines, PCM, fuel lines. I have the pin its for the different harnesses if needed. I have heard some people need to swap dash gauges as some aren't comparable with obd2. There really is no point to swap in obd1 or 1.5 as you can't tune it. If you want boost still stay with the NA engine and Trans but do a top swap. You will have more power and by using the NA Trans you won't have to build the hybrid axles that are required to install the hd Trans from a L67. Axles from a z34/lumina police car will drop right in. I have a build thread for my swap on here. Look it up. I recommend headers, but you have to cut and pound the firewall to make room. So do that now or aim to get a plog and down pipe.
Ok, first I don't have the money to be swapping out all the stuff to make this car OBD II . There have been a few e-mails already sent to me about keeping it OBD I. I think I'll stick with that. Already purchased axles and HD trans kit, and a gentleman has been kind enough to build me a tunable OBD-I PCM, although it is STILL based on the 3.4 wiring harness and I'll have to make some mods. The aftermarket PCM does mean I'll have to install a control panel in the car, probably in the storage pocket under the radio, to make any adjustments as I see fit. I'm computer knowledgeable (like home PC's,) and I don't think it would be impossible to make a small solid-state unit to control the PCM settings and just have a button panel for "Winter - Sport - Normal - High Performance." Still working the details out of this, but I am getting ahead of myself, as it still doesn't shift.
An OBD-II swap would be ok for the future when I can afford to have a custom dash cluster built. But, since I'm a purist who hates aftermarket gauges, I'm going to just deal with what I have for now.
UPDATE**UPDATE**UPDATE**
Ok, here's what I know at this point.
Engine and Trans is from a 93 Buick Regal Custom, as is the ECU. The harness is from NEITHER of the cars. I'm still trying to decide where that came from. Whatever vehicle it was, had similar locations for the ECU and all the parts. But, all the wiring going to the trans is a different color and such. I'm exploring connector end views now just trying to figure out if there is power everwhere there should be.
Ok, here's what I know at this point.
Engine and Trans is from a 93 Buick Regal Custom, as is the ECU. The harness is from NEITHER of the cars. I'm still trying to decide where that came from. Whatever vehicle it was, had similar locations for the ECU and all the parts. But, all the wiring going to the trans is a different color and such. I'm exploring connector end views now just trying to figure out if there is power everwhere there should be.
94grandprix
New member
That's exactly what I want to do bad lol
It's a series one motor according to the numbers with a series two intake. Someone said it's possible the intake is off a camaro? I have no clue. Once again, this is the area where it's not a V8 or a turbo 4 or a Subaru H-engine or a Chrysler E-series 6 (3.3, 3.8) so I have no clue about it and the parts that normally interchange. That alternator is not an AC-Delco according to another buddy, but an AC Delco replacement that is manufactured by Leece-Neville for emergency vehicles, law enforcement cars, and stereo comp (which is the case here) cars. This project is currently outside awaiting more work, I'll put it back in sometime this month.
I was run off the computer prematurely by the timer going off on some baked goods. To finish my statement, We're going to begin by sourcing the harness from a mid-nineties Buick. All the wires and connectors seem to be the same or very similar. I did notice a tag on the current harness noting it to be from a Bonneville. I will de-pin the ECU connectors and start over from scratch. Hopefully this will fix the shifting issue, the tachometer issue, the high-idle, and the constant cooling fan run/fuel pump run without relay or sensor control... the fuel pump relay is bypassed under the relay box and the fan relay is being commanded from an incorrect ECU lead causing it to come on a few seconds after ignition on and stay on until a few seconds after key is turned off. This ought to be fun.
Scottydoggs
Killa Bee
thats a coolant elbow, they leak all the time for us. you take the alt bracket off theres 2 elbows, unless its a 97 or 98 theres a cast lower elbow on the bracket.
http://www.grandprixforums.net/showthread.php?t=49779&highlight=change+coolant+elbows
EJOUIE
New member
This.
Alright then, I was just going off what my friend who was actually under the motor reading off the block casting number said. If I had to guess, the heads have been swapped for different ones, is it possible that the block itself is a series one, as thats really what I was originally referring to? Perhaps I should be more clear, I do tend to misstate myself from time to time without thinking about it.
The local Carquest store is just a block from my shop, and they're fantastic people. They carry EVERYTHING in stock, including the metal elbows to replace the plastic ones, thanks to Dorman's HELP! series of parts. I knew I had bought replacement heater fittings for my 96 Vortec 350 there, so I figured they would have such a beast.
Alas, the car is still outside. I did, however, drive it around the block yesterday. Impressive amounts of power and acceleration for being stuck in first gear, I must say.
Harness is supposed to be here on Monday, but I haven't the slightest clue if it will fit. They're sending two: one for a 97? Bonneville SSEI, and the other is from a Buick of the same time period, but I cannot remember what model. We already know that the computer is from a 93-only Buick Regal GS. According to the gentleman that owned it after it was built, it was quite a peppy, yet fuel efficient vehicle, and everything seemed to "work just about the way it is supposed to.... except that tach. That stupid thing would leap when you turned the key to start and as soon as you released it, right back to zero it goes."
We are hoping to get the engine and trans fully operational with the instrumentation, etc, and then move on to a topswap. I'll probably have less than salvage value in the car at that point, so why not?
The local Carquest store is just a block from my shop, and they're fantastic people. They carry EVERYTHING in stock, including the metal elbows to replace the plastic ones, thanks to Dorman's HELP! series of parts. I knew I had bought replacement heater fittings for my 96 Vortec 350 there, so I figured they would have such a beast.
Alas, the car is still outside. I did, however, drive it around the block yesterday. Impressive amounts of power and acceleration for being stuck in first gear, I must say.
Harness is supposed to be here on Monday, but I haven't the slightest clue if it will fit. They're sending two: one for a 97? Bonneville SSEI, and the other is from a Buick of the same time period, but I cannot remember what model. We already know that the computer is from a 93-only Buick Regal GS. According to the gentleman that owned it after it was built, it was quite a peppy, yet fuel efficient vehicle, and everything seemed to "work just about the way it is supposed to.... except that tach. That stupid thing would leap when you turned the key to start and as soon as you released it, right back to zero it goes."We are hoping to get the engine and trans fully operational with the instrumentation, etc, and then move on to a topswap. I'll probably have less than salvage value in the car at that point, so why not?
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