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Engine swap: Putting a Cutlass 3.1 into a 2.5 Lumina (both '92)?


a_t_and_e_service

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:question:Hi W bodgods: Please don't laugh me out of here (everyone seems to have 3.4s, turbos, etc.) Anyway, I'm new to these W bods, so please be as gentle as possible. :smile: Here goes: I just got (cheep, I think--$100.) a 1992 Lumina with 2.5 and 3 speed auto. Overall the car is nice, but knocks when revved. (Pretty common over 100k I've heard?) Also have the ability to get a 92 Cutlass Supreme SL (no title) for $150. with a supposedly good 3.1 & tranny. (Also a 3 speed I think according to the D-2-1 picture of Cutlass dash I saw.) Now the million dollar question: What will I be up against putting the Cutlass motor into the Lumina? I'm willing to move harnesses, computers, swap cradles, etc. but do NOT want to do any big time fabrications/mods. :frown: I'm a relatively decent mechanic but don't have time/tools for engine mount changes, reinventing the cradle, etc. The intended end result is a low-cost (low performance too, I know!) decent daily driver for my future daughter in law to go to college with (and who knows what else :biggrin:). Is this doable? Has anyone ever done this? Any tips/tricks/things to know going in? Is there more info you need? (I know the Cutlass has the flickering digital dash, alloys and is fairly optioned-up, while the Lumina is real plain---right down to manual windows.) I couldn't seem to find anything on this in previous posts here. :confused: Once finished, I guess the leftover Supreme pieces will be scrapped/sold cheap/given away here? I will appreciate any and all helpful replies! Thanks again! Ken P.S. my number is 920-979-5800 if talking is better than typing endlessly :idea:

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I believe you need the computer, engine mounts, and tranny, + all the rest of the stuff attached to the 3.1 (pullies, belts, wires, sensors etc) plus the exhaust might be in a diff spot, not sure.

 

Hope that helps, and some of the "more experianced" chime in.

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lets see... i want to say that the interior wiring is the same since both are fairly base model cars. and i'd be tempted to say that the cradles are the same.

 

i could see a possible fuel pump change, as the TBI on the 2.5 does not require the fuel pressure that a MPFI 3.1 does. however i could be wrong there.

 

but it would probably be best to swap the trans while you are at it as i'm sure the 4cyl trans has the best gearing for a 4cyl

 

it should be a fairly simple swap overall, i could see the AC being a pain to keep working as i'm sure the lines run different on a 2.5 car versus a 3.1 car

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Thanks White93z34 for your input. I hadn't thought about these systems. I'll research replacement fuel pumps for matching P/Ns (I assume the 3.1 pressure regulator is up on the fuel rail somewhere so it is coming along anyway, so I s'pose raw pressure & capacity are the "real" issues. Regarding the A/C lines I'll do the same. Worst case I guess an evac/line swap/recharge would be in order. Finally I'll check the harness connectors and compare pin outs, etc. between the two as well. Thank you very much...Great stuff so far...I'm liking this site!-Ken

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Actually, why not drop the entire cradle, harness, trans, suspension out of the cutlass and then transfer it over to the Lumina? Seems about the easiest and least time consuming to do.

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Actually, why not drop the entire cradle, harness, trans, suspension out of the cutlass and then transfer it over to the Lumina? Seems about the easiest and least time consuming to do.

 

exactly what I would do.

 

most of the harness between the engine/ecm/drivetrain goes through one single connector the c100 on the passenger side of the firewall.

 

You could disconnect everything, wires, a/c lines, unbolt the struts, frame, steering shaft connection, and all the items like the wiring and ecm should be tied to the top of the engine and remain fully attached. lift the body off the frame(about 3 and 1/2 feet in the air). drag it out. do the same to the other car. slide or roll the subframe from the donor into your project, drop the car. hook eveything up.

 

for ease of use, you could use two skateboard or some sort of low lying roller platform to have everything sit and move upon.

 

I have done this... almost. I transfered a total drive train from a 92 lumina to a 92 CS! I removed the struts and cv shafts before dropping the frame to make the load more manageable. I also swapped the engine and transmission from the lumina subframe to the CS subframe, but only because it was in better condition.

 

last but not least, keep the struts and springs that go with the 3.1 motor when your transfere it, since the 4 cylinder's spring would be too light duty.

 

and check the fuel pump out, change if necessary.

 

 

 

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Thanks Crazy K & Slick, those are very good ideas! and I really appreciate them! i agree that'll save lots of time and trouble. Good point on the suspension, too. Also it's comforting to know that this has been done, albeit in reverse. Hopefully the Cutlass cradle, etc. is in good condition so to avoid having to swap. I'm leaving tonight to get it. -Ken

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Don't listen to CrazyK he's a moron when it comes to W-bodys! J/k I also agree it would be set to just drop the cradle of both cars and swap them. It would save you the most time and from below it can go in as a complete unit.

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That.. doesn't look very safe.. :lol:

I assure you... I was as careful as i could be with what I had on hand.

 

Without the drivetrain installed the car is actually very light in the front. Keep in mind that the car is parked on slimy mud, preventing use of normal 'non-redneck' type equipment. I stacked and used stepping stone squares as a base, and raised the car higher and higher. I used two OEM scissor jacks and proggresively raised each about an inch at a time, and both jacks rested on about 3 blocks each (what I had on hand). The rear wheels are blocked to prevent movement.

 

As the car was raised I set a mounted inflated tire below each side of the body as soon as clearance was sufficient. These would stop a total collapse in the event I lost a jack. I continued raising the car until I was able to double both stacks, and then lowered the jacks slightly allowing the body to contact the tires. This stabilized the car.

 

if you notice, I removed the struts and cv shafts to prevent anything from interfering or contacting the body during extraction.

 

besides.. the trunk was stuffed with struts and cv shafts and miscellaneous junk... the front of the car was practically levitating.

 

Oh, I had no engine lift. How did I swap the total drivetrain without anything to lift it?

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