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What can I swap into my '89 Grand Prix MEGATHREAD


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Won't happen. The 4.3 uses the Chevy V8 bellhousing pattern. The 4T60 uses the GM "metric" bellhousing pattern.

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it could be adapted, but oh god, why?

Anything can be adapted to everything but why go through that headache? I'd rather drop a 3800 over that 4.3

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I can see if he's got a fondness for the 4.3. The 4.3 would need a stand alone engine management system, the early 4t440 tranny is hydraulic so perhaps a 4th gear pressure switch to lock the converter? Could be a cool project.

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How difficult would it be to put a 3.8 from 03 Bonneville into a 1989 grand prix. What all would i have to do?

 

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Just put a 3800 out of a Lacrosse instead. Those were S3. Basically an updated 3800.

 

As difficulty, it's the easiest swap you've asked about but it's not a simple swap. You'd need to play raider at the GM section of the junkyard. 

 

Basically you need a lot of stuff from the earlier W's that did have the 3800... so the 95-96 Buick Regal, the 97-99 Lumina/Monte Carlo and 97-03 Grand Prix will be your friend. 

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You really need to search as this is one of the most documented swaps I can think of.  Google is your friend.  That being said..

 

There's nothing really to be gained from an L26, especially since you're going to need to end up buying an TB adapter and buy an L36 TB anyway.. just stick with the L36.  You will also need the mounting brackets from a W car, along with the ICM/coil bracket since I'm relatively sure the H body ones will not fit into a 1G.

 

I know the 1G cars use a doofy rear engine mount that that the 2Gs don't use, pretty sure you don't need it and can just use the front one. You will need to move to the W-body oil pan and engine mount bracket, and I'm pretty sure also the oil filter adapter.

 

For controlling the engine, you need a donor harness. You could get this from a 96 Regal or 98-99 3800 Lumina/Monte which will get you OBD2 and tuning capabilities.  You will need to play GM Legos at the junkyard and find some way to control the kickdown cable for the transmission, there might be some bolt-on solution for it, but I don't know. 

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There really aren't any super easy swaps. Regardless of which engine you use you are going to run into the same problems. It can be done, I put a L36 into a 90 grand prix myself, but it isn't easy.

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  • 2 weeks later...

3400 would be the easiest swap, no need to change the harness. 3500 is a little more work than the 3400. I have some information on the swap in one of my old post approximately 6-8years ago now.

 

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So you're fishing for the easiest way to make power and unless I miss my guess this is your first car? Honestly for the first year or two just take care of it and work on making it a solid car as it sits. If this is the car you love there will be plenty of time to mod it later so take your time and read everything there is to read and decide where the best places to put your money and time into the car are to make it into what you really want.

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Top swapping a 2.8 would be pointless. The 2.8, 3.1 and pushrod 3.4 (in the Camaro) use the same heads. The size comes from the block, and from what I'm told the heads on the Gen 2 V6's, except for the LQ1 are the same. 3rd gen engines (3x00) parts can be swapped onto the 2.8 but it's more work than it's worth. Searching up that idea for fun yielded me a post on a Fiero forum. Long story short, if you want to keep the 2.8, you'll end up swapping everything from a 3x00 but the block and still have less power than a 3x00. That's not to mention all the stuff that has to be swapped regardless because it's no longer a 2.8. At that point, you're better off getting the whole setup and bolting it in, then getting all the tidbits settled. 

 

Long story short, you want more power, get a more powerful car. The 2.8 is meant to be a cruiser, not a speed demon. 

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You can do it, you would want to use the big port 3400 parts (2000+), but you will need everything from the heads on up, this includes the exhaust manifolds and crossover, and you will also need the 3400 downpipe.

 

This isn't nearly as popular of a swap as it used to be, made even worse by the fact that the 2.8 cam is really anemic. It's gonna have trouble taking advantage of all that extra air. Do some searches on 60DegreeV6.com, there are lots of guys there who play GM legos all day long and could point you in the right direction.

 

Personally, I would not bother. I bought an '89 Cutlass 5-speed project car, and planned on swapping an entire 3400 into it for cheap power (and the engine was seized). Even if the engine wasn't seized, I still would have swapped to the whole motor before I bothered top end-swapping the 2.8.

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I think the bore on the 2.8 and 3.1 is the same, the 3.1 just has a longer stroke. If you are determined to swap motors, I would do something like a 3100 or 3400 from the 2000+ models like digital outsider suggested. Swap the trans at the same time and do an obd2 conversion. Tons of benefits to be had there but it will be a job.

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So you're fishing for the easiest way to make power and unless I miss my guess this is your first car? Honestly for the first year or two just take care of it and work on making it a solid car as it sits. If this is the car you love there will be plenty of time to mod it later so take your time and read everything there is to read and decide where the best places to put your money and time into the car are to make it into what you really want.

Yeah my first car im used to trucks i want to get my car 1989 hrand prix se running right the heads are shot but im thinking it might just be better to get the 3400 swap. What do you think? New head? another 2.8? Or 3400 swap?

 

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Yeah my first car im used to trucks i want to get my car 1989 hrand prix se running right the heads are shot but im thinking it might just be better to get the 3400 swap. What do you think? New head? another 2.8? Or 3400 swap?

 

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Define "heads are shot"... bad head gasket, bad valve, what's going on with it?

 

At the end, it's moreso "what can you afford?" and "What is your skillset?". The easiest swap would be from 2.8 to 3.1. It's plug and play, there's not much that really changed between a 2.8 and a 3.1 MPFI. It should be a direct bolt on. The later SFI 3x00 engines were the ones that had more revisions and as such will be harder to swap over.  The best swap as far as power goes would be an L67 supercharged 3800 out of the newer cars, but as DigitialOutsider has stated before, you have to be willing to play "GM Legos". Everything has to change up to the subframe. Your subframe won't have the provisions for the 3800 engine mounts. It's cheap if you can find a "U pull" yard with all the pieces you need otherwise you're in for a "fun" time...

 

For the record, the 3800 swap is well documented and it would serve you well if you searched that swap.  

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