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I have a 94 lesabre that is almost at 200k miles on stock engine and tranny and I want to be preventive in having a Rebuilt set ready for when the stock blows up. Would rebuilding a series one engine be best Or take the chance to upgrade to series 2?

Personal opinion: L67 swap Series 1 or Series 2 if you like to upgrade more once it in.

I tend to do a lot of cross country travel with the car so gas mileage is important, if i Could get the same gas mileage with regular gas in a supercharged series 2 as i do with my na series 1, I would jump on the swap in a heart beat. Part of the reasoning for the rebuild is to insure I can drive the car for another 200k without babying it the whole time. As it is with 194k I am a little weary of flooring it.

I'm not the authority on swaps but I know if you are not going OEM you will have a lot of little details to nail down and would be more likely imo to strand you on your cc trips.

That stock L27 should last way past the life of the rest of the car. Most L27 cars rust out or blow a transmission before the engine has any issues. I wouldn't lose any sleep over it.

L27's should last well over 300,000 miles.

Unless it's showing signs of weakness, I'd keep on trucking. If you have the capability to do a series two swap it would be neat, definitely more modifiable too.

The easiest Series 2 swap you can do is a L36 with a 95 H body L36 engine harness, throttle cables, a/c compressor + lines, 95 L36 memcal with the right transmission ratio, and a few other misc things.

94/95 pcms are the same and swapping the memcal is cake.

+1 on L36. Good jump in performance over the L27 and you can use regular gas with no worries. Will pull great gas mileage numbers.

Agreed on rolling along with what you have unless it's actively giving you problems, engine-wise. Transmission may be another story. Replacing that has been creeping into my mind for a while as I just passed 150K miles.

I say find out from your local Transmission place what a rebuild will cost you, find out what a "new" or remanufactured unit will cost, take the higher of the two amounts and just set the cash aside. That way, if you have problems you have the funds. I'd guess the transmission will die well before the engine.

Well I have decided a series 2 sc swap would give me the most bang for my Buick if i want to replace the drivetrain. Will the late 90s Bonneville or Olds 88 electricals play nice with my dash and ac system? Or am I stuck finding a 96 park ave ultra as a donor?

What fuel mileage do you get, and at what speeds do you normally cruise at?

I get about 30 at 60 and about 32 at lower 50s. I drive very reserved most of the time. I just want a sleeper and since lesabre were never equipped with the sc, I think it would be a fun swap. I get about 24 combined when driving in town as well.

If you have the 2.84 Final drive ratio, those conditions may be better suited to series 2. Not only would it gain you 35 horsepower in stock form, but the 2.84 FDR also gives the series 2 better fuel economy at those speeds.

The series 1 really shines with the 2.84 FDR, with a few mods, and at speeds above 65-70mph. Back in the day, Bonneme was able to squeak 40mpg out of his.

Supercharged WILL NOT net you better fuel economy, and if you drive very reserved, may not be worth the fun. If you are going to go for an L67 swap, I believe in obtaining a donor car. 200k miles is nothing in these cars. The transmission is the weakest point, but usually gives warnings before it fails. My example has served me for 6 years, and has done over 180k miles, 30k of which was me mercilessly beating on it. I hear a lifter tick, but it shows no other signs of letting up. Admittedly the rest of the car is starting to fall apart around the drivetrain, but the 3800 is notorious for running until it drops dead. If treated well, it could very well happen in the 3-400k mile range.

I agree 100% with the donor car thing. I just wonder what donor would be most compatible with my 94 lesabre. As in I would like to do a series 2 sc powertrain and PCM swap, but I want all my gauges and controls to work. Are the PCM the same between Bonneville's, 88s, 98s, park avenue's, and lesabre. The only car with my dash and a series 2 sc engine is a 1996 pa ultra, which may be hard to find as a cheap donor in wrecked condition.

Valid point. I just checked copart, found 7 96's, but no ultras, for the entire US. Anything hit behind the B pillar would be ideal as i think the front doors and foward are the same. Thankfully you have the luxury of time to lay low and let the deal come to you.