3900 FWD to RWD conversion

[bbeck]

looks like going price around here for an 06 model is around 800... What are the differences throughout the years?

[Superdave]

J and L bodies I would see the cam solenoid as causing issues with fitting. And they use the timing cover as mounts (at least the later years do I know), so something would have to be fabricated for that. And they have a torq strut down below on the front... and older years a mount. Hmm. Regardless of those issues, I'd really like to see one in a L/J body, and then with a little boost!

Unhooking the VVT causes no issues with running? It would function not retarded or advanced?

the 2nd gen Jbodies don't use a timing cover mount, just one that bolts to each side of the block towards the timing cover and one that bolts through the bellhousing of the tranny into the block.

Older Berettas are the same way, i forget what year they changed..

[IsaacHayes]

92 beretta's started using the timing cover upper mount. Those can take a 3x00 without messing with mounts. But it seems the older ones might take a 3900 easier.... Not sure when the L body started the lower torq strut.

[Joseph Upson]

I had not looked at the actuator in quite a while so I dug it out for review. Perhaps I am looking at this the wrong way but it appears to me that the locked default position is about 9 degrees advanced from straight up and the actuator can go to -18 degrees (measurements are in cam degrees, were taken with a protractor and based on the assumption that the pin is 90 degrees from the timing mark). My understanding was that advance was advancing the cam position relative to the crank. Or am I wrong about the way cam timing is measured? Doesn't a sloppy chain retard the cam timing? It can be confusing since all measurements are taken at the crankshaft.

I took a couple of pics for illustration and not accurate for measurements. I know... I'm not the best photographer. For those not familiar with the actuator, the pics were taken from the back side and the arrow depicts engine rotation. I need to get some accurate CMM measurements on this thing and make up some inserts to lock the actuator at zero degrees for those who want to run a stock or reground cam without VVT.

Your illustration is correct in regards to how my cam is rotated however, there was some confusion in the GM literature according to a GM tech on the Fiero forum regarding the VVT range discription. My suspicion is that full advance is the idle position and the cam is retarded from there as rpm climbs. My cam is installed slightly retarded at top dead center on piston #1 where the intake valve will start to lift off its seat when the crank is rotated from that point. At that point the VVT actuator is almost at its full retard position from the locking point. I'm not sure how much the regrind changed the lobe profile but it appears that the stock cam would start opening the valve at TDC with some room to spare from the full retard position.

I will probably take the 07 camshaft that was swapped out and have it reground for more lift and duration only and leave the LSA stock. When I ran the dyno simulation with both the OE and reground cam specs, the power rating was almost identical except the reground cam had to be entered at 0 degrees and the OE cam had to be retarded as far as I could take it, -15 deg.

There has to be something un accounted for because I mentioned the OE specs they gave me for the cam were different from what you posted CNC and it makes no sense for the performance grind to have nearly the exact same output as the stock grind.

The attachment option is not working at the moment so I'll try to add my cam spec card later.

[bbeck]

does anyone have pics of the stock mounts on the 3900? I had pics of the motor on my computer, but it's still apart until I move again.

[CNCguy]

bbeck,
Prices vary a lot and you just have to shop around. I bought a 6K mile '06 LZ9 from an Impala with a 4T65E transmission, wiring harness, starter, ALT, PS pump, ECM and TCM on Ebay for $650 plus $250 shipping from California to Ohio.

The LZ8 (3900) has DOD (Displacement On Demand) while the LZ9 does not. I believe the LZ9 came out in '06.

I didn't take any pictures of mine before I started taking it apart but there are a few on Ebay that have pictures of the mounts. Both are expensive but you can at least check out the pics.


The Impala bolts in just like all the older W-bodies.

http://cgi.ebay.com/ebaymotors/G6-IMPALA-MALIBU-MONTANA-MONTE-RELAY-BARE-ENGINE-3-9-06_W0QQcmdZViewItemQQcategoryZ33615QQihZ014QQitemZ330203756824QQrdZ1QQsspagenameZWD1VQQtrksidZp1638Q2em118Q2el1247

The Malibu is different but I don't know if it matches any of the older vehicles.

http://cgi.ebay.com/ebaymotors/CHEVY-MALIBU-3-9L-ENGINE-4T45E-TRANS-LZ9-IMPALA-FWD_W0QQcmdZViewItemQQcategoryZ33615QQihZ012QQitemZ220192477288QQrdZ1QQsspagenameZWDVW

[Joseph Upson]

I just reviewed the info on the 3900 on the GM site and it states that at idle the camshaft is in the full advanced position for a smooth idle, so on a stock engine fixing the camshaft in the full retard position should set it up for maximum output use.

A mild regrind on the stock cam to increase duration and lift a little along with some cylinder head work should be all that is necessary to push the power up a good bit. Since the head gasket is a multilayer steel gasket of superior quality increasing the compression ratio should be as simple as removing the rivets and taking out a few layers. On a relatively new engine I wouldn't be surprised if you could get away with as few as two. They also state that the heads are so similar to the LS1 and LS6 heads that I believe my suspicion is correct that the valves are interchangeable to the point where the 2.00" LS1 intake valve may be an alternate fit. If Superdave can get over 270 hp out of the 3500, the 3900 has to be capable of a naturally aspirated 300 hp.

[IsaacHayes]

Yeah a 300+ whp 3900 would be amazing.

Makes you wonder what it will do with 2 turbos.... haha

[bbeck]

we just need to get rid of that cam phazer to fit it in the j/l bodies...

[Joseph Upson]

Yeah a 300+ whp 3900 would be amazing.

Makes you wonder what it will do with 2 turbos.... haha

I can't wait to get back home and show you what it will do with two turbos. I have a video camera to take along with me this time.

[Canyonero]

Have there been any updates to this project?