Trying to decide what would be the better of the two engines to install? And why? Choices are - Series 2 Supercharger 3800 OR the Northstar 4.6 GXP engine? My current engine is the 3800 series 2 in my 01 bonneville base model with 309,000 sewing machine mi.. My primary concerns are; performance, less cost for maintenance and not so difficult to work on mechanically, decent to good fuel mileage.. I may decide to beef up the exhaust and maybe some tuning for added horsepower! Nothing too heavy, just enough to have that little extra huff whenever i want to play around! I can get either engine with under 80,000 miles if that matters.

3800 would be my strong preference - it's a bullet proof engine that goes forever with regular maintenance. The supercharged version makes plenty of power for the average person stock. As for upgrades, it has a larger following and better aftermarket (in both selection and prices)

Northstar didn't really clear up it's head gasket issues till around 04/05ish. There are kits that appear to provide a permanent fix to these head gasket issues but are pricey. In addition, if you're not doing the labor yourself on fixing the cylinder head studs it's going to be a lot of money out of pocket just getting yourself to a stock engine that you feel good about. It's a *dang* nice engine outside of this issue.

You also mention not so difficult to work on mechanically as something you're concerned about -- take a look in the engine bay of the STS/Bonneville with a northstar under the hood and you'll see it's absolutely jammed in there. It makes every little thing that much more difficult

Reliability differences aside, dropping the 3800 in is much easier since your car is already pretty much ready to accept it.

Given your primary concerns, the 3800 is clear winner here. You can easily make the 3800 outperform the N*. It costs less to maintain, gets about the same or better fuel economy, and is certainly easier to work on. You'd have to re-stud and re-gasket the N* before dropping it in or you risk doing all your work for nothing. Additionally, once the N* is in the car, it will be harder to maintain, given the lack of space mentioned above.

The only real benefit of the N* is the sound and smoothness. Maybe bragging rights about it being a V8 if you're that kind of person, but then it's still FWD... So...

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-Car Guy Carl
"Penelope" - 2003 SLE - 247k Miles
"Sydney" - 2000 Honda S2000 - 98k miles

If I was going to choose between the two cars, one with the 3800 and one with the Northstar, it wouldn't even require any thought. I'd take the N* in a second.

However, to install one in a car that currently has a 3800 isn't something I'd even consider. This would be a lot of work for you, the need for a different transmission, mounts, brackets, etc. Good points have already been made about space to work on it later. Mitigating the possible head gasket concern before hand is a no-brainer if it's already out of the car but adds to the cost and time.

Based on your goals, the 3800 is an obvious choice.

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My assessment is going to sound familiar, but here it is any way.

My previous daily was a '98 GP GT coupe with the 3.8 N/A.
Awesome engine, and pretty easy to work on. I learned/taught myself quite a bit wrenching on in it. Obviously not quite the same as the supercharged version, but same basic concept.

Once I had my first kid, I knew it was time for a four door. A number of people suggested I just get a newer GP knowing how much I loved my car.
However the newer 04+ body style just never peaked my interest, and I'd been lusting over the body lines of the Bonneville GXP since it came out.
Personally I wish that the N* wasn't the motor under the hood, but I absolutely love driving it and it's got plenty of passing power.

But I degress...

For performance, the L67 (supercharged 3.8) produced 240hp (260hp in the series 3 L32).
While the the LD8 N* produced 275hp (300 torqe) and the L37 N* has 300hp (295 torque).
But like the others have said, you can easily bump the L67s horse power, because it has crazy aftermarket support compared to the N* (virtually none).

On the maintenance /difficult to work on front the 3.8 wins again. It's just way easier to get to everything and you can work on it like like a normal motor. I think the jobs that pissed me off the most were the rear spark plugs and O2 sensor on the back side of the motor. Even replacing the lower intake manifold gaskets wasn't to bad.
Meanwhile the N* is thirstier in the oil Dept (7.5qts compared to 4.5qts), and EVERYTHING is hard to get to.
My alternator crapped out on me on vacation one year, this requires the rad fan assembly to be pulled, you're supposed to drain the coolant so you can pull the radiator hoses, and I believe you're supposed to remove the trans and oil cooler lines (I managed to avoid this step on my vacation, but could not replicate that luck in my own driveway) before you fish the alternator out from the bottom...
Did I mention the starter is under the intake manifold?

Looking at some old brochures I have, the fuel mileage for the L67 is rated at 18/27 (00 GTP) and the LD8 is 17/24 (05 GXP).
However this maybe the one place the N* is slightly ahead, because while it's a thirstier engine, it runs on 87 while the L67 needs premium.

Also, since you mentioned exhaust, the N* sounds way better.

Having said all of that, I have a love hate relationship with my N*. I love driving it, hate wrenching on it.
Going by your stipulations, the L67 is what you want hands down.
And if my N* ever dies, I might just get one too.

Hope this helps with out being to repetitive.

Drew

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Pontiac stable:
2005 Bonneville GXP - Black -daily driver
2004 Sunfire - Arrival Blue Metallic -Wife's
1998 Grand Prix GT - Black -seen better days, awaiting fate
1985 Fiero Sport Coupe - Black (mostly) - long term rebuild

hey! I'm really glad I joined this forum! you guys really know these engines, and all of your responses are very helpful. As of now I'm definitely going to go with the 3800, but I need a little more clarity about which engine.

DRWBRTq19 mentioned there are tons of aftermarket horsepower support for the L67 (supercharged 240hp). Does the same apply - horsepower support for the L32 (260hp)? And is the L32 supercharged or not?

the L32 is the 04+ Version of the Supercharged Series 3 3800. Major Changes were Powered Metal Connecting rods, GenV M90 Supercharger, and electronic Throttle Body.

there has been much discussion on the strength of the Powered Metal vs the Cast Rods on the Series 2.

You can adapt the Gen V SC onto a Series 2 that was equipped with a Gen 3 M90 with no issues besides tuning.

you can not use the electronic TB, you should use the L67 TB with the Series 2 and the M90 application