New 3900 Pictures

[bszopi]

Thanks to AaronGTR for supplying these pics...

http://60degreev6.com/gallery2/main.php?g2_view=core.ShowItem&g2_itemId=1055&g2_page=2

Cutaway of a 3900 from a GM booth at a car show. Some interesting things show up in the pics. Definately some things to discuss. Take a look, then start the discussion!

[v6h.o.]

Awesome pics! Is it ok if I post a link to the pictures over at the G6 forums?

[bszopi]

Go for it.

[Manitcor]

hmm a fet intresting things I notice there, signifant changes to IAC. Intresting fuel rail, IIRC its a returnless desgin yes?

I notice they show the intake vane in the pics but I dont see the actuator. I might have missed it though.

The oil squrter clearnce to the bottom of the piston at BDC looks VERY close.

Also is it just me or do those rockers look an awful lot like the rockers on a stock 3800. Perish the though the first mods the 3900 gets are SLP 1.9 ratio rockers for the 3800.


for reference, stock L67 and 3800 rockers:

[GutlessSupreme]

holy weird ass intake design batman.

is that the special order bling bling edition?

that's a lot of pulleys.. they have anything to do with the VVT?

[Manitcor]

the intake is desgined to allow for the varible length runners, notice the plastic vane running the length of the intake. That vane adjusts to lengthen and shorten the intake runners to maxamize the powerband.

I think the extra pullies due infact have todo with VVT, indirectly. Notice the extra length of the cover for the cam with the 2 interlocking rings. I belive this unit is responsible for the cam phasing that the engine is capable of. Due to it sticking out so much addational idler pullies are neccassary to route the belt around the unit.

[v6h.o.]

the intake is desgined to allow for the varible length runners, notice the plastic vane running the length of the intake. That vane adjusts to lengthen and shorten the intake runners to maxamize the powerband.

I think the extra pullies due infact have todo with VVT, indirectly. Notice the extra length of the cover for the cam with the 2 interlocking rings. I belive this unit is responsible for the cam phasing that the engine is capable of. Due to it sticking out so much addational idler pullies are neccassary to route the belt around the unit.

Yup, the Cam phaser actuator unit is in that large protruding cam/timing chain cover section. The belt design is to route it around that unit.

It is also a returnless rail design same as the 3500 is, as the regulator is in the tank/fuel pump module.

The actuator is at the end of the unit it is the piece that is on the outside of the manifold. It is not visible due to its under the big ram horn section and hiden behind the p/s pump area.

The rockers according to GM are based off the V8 LSX family engines rocker arms. Much the same. Don't yet know the ratio though. All I know thus far is that the Intake and Exhaust lobes are a 0.2727 in lift each.

[AaronGTR]

Yeah, I noticed lots of differences on that engine. That's why I took so many pics... it's a whole different beast from the 3400 thats for sure.

I can't figure out how that intake is supposed to work though. If you look closely at it, the top section where it curls around has an inner and outer runner which would be the short and long... but they both dump out in the same place and go down into the gallery that feeds the lower intake. The flap in the middle only divides the cylinder banks and there isn't actually anything that closes or opens the short or long runners. I'm sure they designed the whole thing using computer modeled air flow characteristics and opening that flap must change the way the air flows inside, because you sure can't tell by looking at it.

Anyone else notice the cover bolted over the cam drip channels in between the lifter guides? That wasn't there before either. And the metal things around the bottom of the valve springs... some new shim design maybe?

The pistons have cut outs for valve clearance now that I'd imagine are necessary because of the VVT. The LIM doesn't have a water neck on it anymore and both coolant inlet and outlet are on the front engine cover now. They moved the water pump and the A/C compressor down to make room and had to make adapters for the compressor and oil filter. LOTS of changes...