Well I've owned my 97 LS for three days and the block is cracked.

So... Moving on with it's life, what motor should I drop in it? Is the Z34's 3.4L the best option for this car?

Please Discuss: power, reliability, ease of install, warnings or anything you care to add.

 

3.8 N/A would be a good start!

 

Is that a 98 LTZ motor?

 

Z34 3.8

see wiki

[edit] Fifth generation

Fifth generationProduction1995–1999AssemblyOshawa, Ontario, CanadaBody style(s)2-door coupeLayoutFF layoutPlatformW-body 1.5 GenEngine(s)1995-99 3.1 L (~189 cu in) 3100 V6
1995-97 3.4 L (~207 cu in) LQ1 DOHC V6
1998-99 3.8 L (~232 cu in) L36 V6Transmission(s)4-speed automatic overdriveWheelbase107.5 in (2731 mm)Length200.7 in (5098 mm)Width72.5 in (1842 mm)Height53.8 in (1367 mm)Fuel capacity16.6 US gallons (62.8 L; 13.8 imp gal)RelatedChevrolet Lumina
[edit] 1995-1999

For the 1995 model year, the mid-size Lumina was split into two models with the sedan continuing as the Lumina and the coupe reviving the Monte Carlo nameplate for its fifth generation. The new car rode on an updated W-body chassis shared with the Lumina, Pontiac Grand Prix, Oldsmobile Cutlass Supreme, Oldsmobile Intrigue, Buick Century and Buick Regal, and by its nature was the first front-wheel drive Monte Carlo. In 1995, the LS was $16,770 and the Z34 was $18,970. All 1995 to 2007 Monte Carlo's were built in Oshawa, Ontario, Canada. Unlike Monte Carlos of previous years, the distinctive bulges to the front fenders and rear quarter panels were gone.
A special run of 400 1995 Z34's were made called the Monte Carlo Brickyard 400 Pace Car. The $2195 option included Interior Ornamentation, Embroidered Leather 45/55 Seating with Full Floor Console, an Aero Wing Spoiler, and an Accent Stripe Package.
For its four year run, the Monte Carlo was available in two trims, the LS and the Z34. Appearances were largely identical between the two models. Styling changes consisted mainly of the special red-colored badging on the Z34, the real difference being under the hood. LS models were powered by the 3.1 L 3100 V6 putting out 160 hp (119 kW) at 5000 rpm (119 kW) and 185 ft·lbf (251 N·m) while Z34's featured a more powerful 3.4 L DOHC V6 engine with 215 hp (160 kW) and 220 ft·lbf (298 N·m). Aside from minor equipment changes, the fifth generation remained virtually unchanged during its life (In 1998, the 3.4 L was replaced with the 3800 Series II, a simpler engine).
All Z34 models came with 16-inch 5-spoke alloy wheels, optional on LS models in place of the standard 15-inch bolt-on wheel covers. For 1998 the Z34 received redesigned 5-spoke wheels, though the older style alloys remained on the LS.
Though derided by some for its indistinct lines (called the 'Lumina Carlo') and its front-wheel drive drivetrain, the fifth generation sold well enough for Chevrolet to continue the line with a more original redesign in 2000. The 1995 bodystyle was also a favorite on the NASCAR circuit and enjoyed considerable success at the track.
This generation of the Monte Carlo was the last 2-door vehicle featuring 6-passenger seating, although bucket seats were available as an option with a floor mounted shifter.

 

For ease of install and reliability, go with the 3.8. The swap has been done many times and there are alot of parts for it. The 3.4 is more powerful and definately more fun to drive than the 3.8 but you can easily beat its numbers with a few bolt ons on a 3.8.

 

Ah the Z34 from the '98s. Would there be any more difficulty installing the 3.8L than the 3.4L? What would have to be swapped out with it? ECU and wiring harnesses?

 

With a 3800 supercharged or N/A, you will need to swap out the PCM and the engine wiring harness. You will also need both inner axles from the donor car.

 

The 3.4L wont be any easier to install than the 3.8 will. Like nighthawk said, you will need a PCM and wiring harness whether you use a 3.4 or a 3.8. I would recommend swapping in a 4t65e transmission in place of your 4t60e. If it were me, I would find a J/Y donor with the 3.8 if I could and just drop the entire engine cradel and get the wiring harness and PCM and swap everything into your car. Use the axels from the donor. Im not sure if you need hubs from the 3.8 car or not to make the axels work. That will be the easiest, most reliable option with the greatest availability to upgrade from there IMO.

 

Well I called around today, and it looks like for $1000 I can get a rebuilt 3.1L installed, or my friend told me he'd help me install a 3.4L he can get for a few hundred bucks. So, it looks like I might be getting a 3.4L from a lumina Z34.

 

that sucks about the block being bad, but thats way cool that you can get the 3.4 for cheap. i wanna add to what everyone else said about the needed wireing harness & axles, make sure you put plugs & whatever you can on that engine before its in the car... you might even wanna spring for a full rebuild, if $ permits. working on the 3.4 with it IN the car is almost as much as a PITA as just yanking the engine. especially rear plugs & wires, and anything else in back of the engine. you wanna be ahead of the game with that stuff

other than that, the 3.4 is an awsome engine till they get high in miles, the differance between a 3.1 ls (like my '97) and a 3.4 dohc Z34 ( like my dad's 96) is quite amazing, the 3.4 really almost begs to be opened up on a deserted strech of road good luck with the swap!