Question about my LZ9...oil pan/exhaust manifolds

[domestikdemon]

Haven't been around much lately so here's what I got going on these days:

'00 GAGT is NOT dead....comatose for now but not dead. I have the F40 and L36. I scrapped the idea and decided for all the work I'm doing that an L67 is worth waiting for. I'm about to get a $20/hr job so the GA will be alive again!

'07 G6 GT w/ 3900 and F40....picked it up back in November....got Helo '18s w/ OEM Goodyears with my tax return and just painted the driver side calipers yesterday. Gonna do the other side today hopefully...

So anyway, the manifolds on my 3900 do not have a traditional 60* bell housing cross over. Instead, the exhaust on the front side is routed straight down and curves under the oil pan. I see the oil pan is shaped a little different to accommodate this. OBX headers for the LZ4 look to be a bolt up- minus the EGR tube location. My question is this- couldn't find much info about the 3900 or modding it, but I did come across Joseph Upson's 3900/Fiero swap. Why isn't his the same as mine? His manifolds are set up in the same manner as traditional 60^ engines....but mine is not? http://www.fiero.nl/forum/Forum2/HTML/084972.html

I do have an LZ9 right? They only made this engine in '06-'07 right? I've been out of the game for a while so my mental dictionary of tech stuff needs a major update. Thanks folks!

[robertisaar]

if i had to guess, i'd say the exhaust difference would be due to the different platforms. the G6 has that oddball routing, but W-bodies would still be the normal style IIRC.

[Maple Leaf]

Could you post a picture of the manifold and oil-pan? Curious how this is set up...

[robertisaar]

W-body routing, at least, looks like the "classic" layout. i've seen headers for the 3900 G6 on ebay with the oddball setup a few times.

[domestikdemon]

Ok I'll get some pics. Yesterday I painted my calipers red...but only on the driver's side. Gonna finish it up today! Since the car will be jacked up I'll easily be able to get pics of it. Ever seen the exhaust setup in 3000GT/Stealth w/ 3.0 non-turbo? It's the same setup on my G6.

I must say, having had a few months to get used to my car, I love the power band of this thing. Below 2G, it's finicky and bucks especially under a load, keep in mind that I have a manual. Above 2G, it's got power. Above 3G it has a lot of power all the way to 6G. I hit the fuel cutoff once...it's 6200. I saw someone on this board, I think, who posted that the fuel cutoff on the 3900 is 6400...not true in my car anyway. My G6 is limited at 115 (bone stock, OEM air filter and all) so I can't test it all the way, but at 110mph it's pulling just like it was at 70. I'm impressed with how this thing acts. Try this on for size, lol:

6th @ 65 @ 2200 rpm....floor it....starts pulling a little immediately of course, but for a split second it mild. Then the power kicks in and I'm suddenly 70+. I think what Im feeling is the cam retarding itself a little. All my years of powerblock tv have taught me that advanced cam = low end. Retarded cam = high end. It seems like something happens when you step on it at a lower RPM, it always delays a little then grows some balls. The 3900 would certainly make a lighter car scream. I raced my girlfriend from a dead stop in her dad's '06 Impala SS. My G6 ate it (great launch) till I let off around 65 and then she passed me. How long would I have stayed ahead? I'll let you know when I know lol... When the light turned green I left the Impala at a standstill until that LS4 actually woke up.

[NateD4]

What are you trying to ask?

I have an LZ 3.5Lfrom a Malibu and LZG 3.9L from an Impala. The exhaust manifolds are different between these two.

What car are you putting the 3.9L into? Or are you keeping it in the G6?

[domestikdemon]

Keeping 3.9 in my car. I think my question is answered though, seems the different exhaust setups are for the different vehicles they will be used for. Are the G6 and Malibu manifolds the same? IIRC, I saw an '06 Impala LTZ w/ 3900 and it had the normal crossover. I remember looking at it and thinking it would fit in the GA, and that headers for any 60* would bolt up to it. At the time I was not aware of the G6's design until I bought one.