Anyone familiar enough with the 3800 series 3 to comment on why this motor seems to perform so much better than any of the series 2's I've had over the years? This one is in an '09 LaCrosse and seems to have much better throttle response than my older Monte's, Impala's, Bonneville, etc. I don't believe there was any change to the 4t65e trans, correct? The series 3 really feels significantly more powerful. Any chance this is simply programming in a Buick vs how Chevy and Pontiac did their tunes, or updated electronics in an '09 vs the mid-90's to early 00's I'm comparing to?

 

There was a thread talking about the two motors. A series 3 and Series 2 are virtually identical (same block). Noted differences:
- UIM on the S3 is aluminum
- Throttle body on a stock S3 allows more air in then the S2 (that's probably the biggest difference).
- S3 engines from '05 up had some forged internals (I believe just connecting rods) for improved durability. S2 and 2004 S3 engines have cast parts.
- Even though the trans is the same model, does NOT mean it's got the same gearing. That can be another key difference.
- It can all boil down to the tune on the PCM.

There is a lot of additional info out there. Compression ratios may be another factor. Tough to say without further research (but what I listed is a bulk of it).

 

Thanks Maniac. I had found some of that information - ie the updated components such as connecting rods, the differences in the manifolds starting in 2004 that effected both the series 2 and 3, etc. What I've read about the trans did indicate no change to gear ratios. I hadn't heard about a larger TB - that would certainly explain some performance gains. I also read compression ratios remained the same - 9.4:1 if memory serves. So it could be a combination of the TB and tune I suppose. As I mentioned I've had a number of the series 2 motors and as soon as I test drove the Buick I noticed a significant different - doesn't even seem like the same motor/trans. It really has the feel of newer cars with 6 or more speed gearboxes where the gears are shorter and the motor is always in the power band. Anyhow, it's nice to still have a 3800 under the hood. Thanks for the input.

 

There's also the note that the series 3 has a computer controlled throttle, also since it's so much newer you probably have a lot less caked in carbon.

 

To my knowledge, the only manifold change was the UIM. On the S2 it was nylon and on the S3, it's cast aluminum. The S2 nylon ones have had a history of degrading and having coolant leaks that cause all sorts of issues.

But, you CAN adapt an S3 UIM to go on an S2 engine.

 

I believe besides the UIM there may have been a change to the exhaust manifolds as well, but I can't recall where I read that or if I'm confusing it with something else. For the S2 when the nylon UIM falied the dealer repair would be to replace it with the aluminum one. I'm not sure when they started doing that, but I believe it was prior to the S3. I know a couple of my S2's had that fix. I haven't dug around for it, but I believe there was a TSB regarding this with instructions to install the aluminum UIM in place of the nylon directly from GM. Other improvements to the S3 - ie stronger connecting rods, etc - were rolled back into the S2 for the last couple of years worth of production. I didn't mean to imply the S2 became the S3 or that the two didn't coexist for some period.

 

In F-Bodies in 2000 there was a change to the exhaust manifolds which made them more tubular.

We have tubular rear exhaust manifolds and moonshaped front.

 

I'd be curious to see a factory/dealer aluminum UIM replacement. If you currently have a S2 powered car with an aluminum UIM, can you post a pic? To my knowledge, when the UIM failed, the dealer replaced with another nylon UIM (possibly a re-design to include a re-enforced bushing around the stove pipe and a narrow stove pipe to avoid future damage. If GM had a direct bolt on aluminum UIM, I would think more people would be after it instead of retro-fitting the S3 aluminum UIM.

But I have heard it's very common now when the LIM gaskets fail, those nylon gaskets are replaced with aluminum ones.

As for the exhaust manifolds.... I looked on RockAuto's site and they have the crossover pipe and manifold gaskets, all the same from the first S2 until the last S3. But that does not confirm the mani's themselves are the same or not. I suppose it's possible GM altered them a little for improved flow, but I have not seen that documented anywhere.