3900 versions and configurations for swap use

[Will'sFiero]

Thanks. My biggest concern with the system is trying to get it to work with a manual trans. if Paul couldn't make it work with a much more decoded V8 PCM, I would bet it will be on the verge of impossible with a V6 PCM all the big tuning companies don't make money on.

http://www.fiero.nl/forum/Forum3/HTML/000123-26.html#p1011

Originally posted by fieroguru:

Nope. The E67 ecm requires the BCM for the brake switch input and my swap doesn't have one.
DoD has been proven to work w/o the BCM, so my next LS4/F40 swap will use that ecm for further testing.

That's why... I asked on that thread if he meant using the 24x PCM for his next swap in order to try getting AFM/DOD working.

All 3900's are 58x, right?

[Will'sFiero]

it's not bad at all, and that was without DOD/AFM, and a 5.3L Vs. a 3.9L with VVT. which makes me think the AFM/DOD wouldn't be worth the work unless you netted a huge gain in mileage from it.

He's also using the F40, which lets him turn the engine slower.
AFM/DOD won't reduce frictional losses due to 6 sets of piston rings moving at 3000 RPM at 80, but it will reduce pumping losses from turning that RPM at light load, as well as moving the cycle to a more thermally efficient starting pressure (increasing the effective expansion ratio on the power stroke).

[Will'sFiero]

Will,

I figured you've probably seen all this, but if not, thought you might like it.

LZ9 build thread (died before complete, but still lots of info,)

http://60degreev6.com/forum/showthread.php/41450-3-9L-LZ9-engine-internal-upgrade-amp-performance

Pictures that go with the thread.

http://s296.photobucket.com/user/mrt...?sort=2&page=1

LZ9 article (not much but still kinda neat.)

http://60degreev6.com/forum/local_links.php?action=jump&catid=14&id=55

-Eric

Thanks! I'll take a look.

Thought: Can I swap LZ4 3500 pistons into an LZ9 engine to bump compression? Are the piston dish/dome specs around anywhere?

[ericjon262]

http://www.fiero.nl/forum/Forum3/HTM...-26.html#p1011


That's why... I asked on that thread if he meant using the 24x PCM for his next swap in order to try getting AFM/DOD working.

All 3900's are 58x, right?

as far as I am aware, the 24x PCM (0411) doesn't have provisions for AFM/DOD, just the later PCMs.

He's also using the F40, which lets him turn the engine slower.
AFM/DOD won't reduce frictional losses due to 6 sets of piston rings moving at 3000 RPM at 80, but it will reduce pumping losses from turning that RPM at light load, as well as moving the cycle to a more thermally efficient starting pressure (increasing the effective expansion ratio on the power stroke).

sure, but how much is there to be gained?

Thanks! I'll take a look.

Thought: Can I swap LZ4 3500 pistons into an LZ9 engine to bump compression? Are the piston dish/dome specs around anywhere?

Probably not without custom rods. IIRC, Joseph Upson used LS1 pistons in his LZ9, might be a cheaper route than trying to make LZ4 pistons work.

[Will'sFiero]

The LX9 is the early 3500 with 94mm bore, right? And the LZ4 is the later 3500 with 99mm bore, right?

Are the wrist pins a different diameter between the 3500 and 3900? Why wouldn't LZ4 pistons just drop in?
I would expect that the 3500 pistons would be flat tops or at least have smaller dishes than the 3900 pistons. If both engines have 9.8 compression and the same head castings, then a 3900 with 3500 pistons would have 10.9 compression.

[ericjon262]

The LX9 is the early 3500 with 94mm bore, right? And the LZ4 is the later 3500 with 99mm bore, right?

Correct

Are the wrist pins a different diameter between the 3500 and 3900? Why wouldn't LZ4 pistons just drop in?

I doubt it, but I would imagine the compression distance is probably different, so you would probably need a set of rods that are a tad shorter than stock.

I would expect that the 3500 pistons would be flat tops or at least have smaller dishes than the 3900 pistons. If both engines have 9.8 compression and the same head castings, then a 3900 with 3500 pistons would have 10.9 compression.

it would be cool, but I don't think it would be a drop in and go thing. FWIW, gmpartsdirect lists the 3.5 and 3.9 piston as the same.

[Will'sFiero]

Will,
http://s296.photobucket.com/user/mrt...?sort=2&page=1

-Eric

This casting spans the front of the heads and has the radiator outlet and a heater core connection to the waterpump. Interesting difference from previous engines. I had heard of this part, but was under the impression is was on the BACK of the cylinder heads... which would make more sense for transverse mounting.
I'll have to see how well (or not) it works with the minivan exhaust crossover when mounted on the back... however, that would point the coolant outlet toward the trunk, which wouldn't make much sense either.

If use on the front of the engine, it looks like it puts the alternator mount location in almost exactly the right place for use in a Fiero as the dogbone mount.

The accessory drive will have to be worked a bit to mount the alternator low, about where it is on the 2.8.



A bracket could pick up the right two holes out of this 4 bolt pattern and the upper Fiero-style mounting hole.
Or an entirely new saddle bracket could pick up those two bolts and the forward two of the three bolt pattern on the other side (photo below) and not bother with the Fiero-style mounting holes.
The oil filter adapter may need some diddlage to clear the Fiero front cradle crossmember.





Good photo of the missing mount boss.

I don't know if the oil pan will work or not... it kind of looks like it's cut out enough at the front to make room for a Fiero engine mount, but I probably won't be able to tell until I get one. This is about the only photo I could find of it:



The heater hose connections are in almost the perfect spot to use the '85-'86 Fiero heater pipes:

[ericjon262]

The oil filter adapter may need some diddlage to clear the Fiero front cradle crossmember.

if it's anything like my LX9, you can unbolt the filter housing, remove the oil filter threads from the housing (mine used a big allen wrench) and just install the threaded adapter right into the block.

Edit:

Threads visible here...

[Will'sFiero]

Correct
I doubt it, but I would imagine the compression distance is probably different, so you would probably need a set of rods that are a tad shorter than stock.

it would be cool, but I don't think it would be a drop in and go thing. FWIW, gmpartsdirect lists the 3.5 and 3.9 piston as the same.

The powdered metal conrod is much more expensive to make than a hypereutectic piston... I would expect that the rods would be the same before the pistons.
However, I could be wrong...

Per parts.nalleygmc.com

LZ9 conrod: 12609561
LZ4 conrod: 12609562
LX9 conrod: 12568557

LZ9 piston: 89018065
LZ4 piston: 89018065
LX9 piston: 12584528

Interesting... only conclusive about the LZ4 and LZ9 using the same piston... Consecutive part numbers for the two conrods is interesting... that typically means they were designed together as different members of the same family. That's also to be expected, as with using the same piston, the LZ4 needs longer rods than the LZ9. I wonder... Since they needed different rods ANYWAY, did they tune the lengths up slightly so that the LZ9 assembly has the piston further in the hole than the LZ4 assembly?

Ok, so no compression bump for using LZ4 pistons.

[ericjon262]

any reason LS1 pistons couldn't be used?

[Will'sFiero]

any reason LS1 pistons couldn't be used?

None at all... just getting a handle on the different configurations.
I haven't looked at Upson's thread in a while...
Are the wrist pin diameters the same? LS1 ring pack or 3900?

Edit: Upson says 3900 rods are 5.827" long. Have you seen any info on LZ4 3500 rod length?

Edit2:
The LX9 has the water outlet manifold on the back of the cylinder heads, as I thought the LZ9 did.

[ericjon262]

None at all... just getting a handle on the different configurations.
I haven't looked at Upson's thread in a while...
Are the wrist pin diameters the same? LS1 ring pack or 3900?

Edit: Upson says 3900 rods are 5.827" long. Have you seen any info on LZ4 3500 rod length?

sorry, I don't have any rod info. pin diameter for the LZ9 is listed as .943" LS1 is listed as .945" little machine work and that's not a problem.

Edit:I wonder how accurate upsons rod measurements were. all the published specs I've seen say the LZ9 got 5.9" rods, maybe the 3500 got them though. stroke is .3"less, .3"/2+5.827"= 5.977" maybe the rods stretched a bit?

Edit2:
The LX9 has the water outlet manifold on the back of the cylinder heads, as I thought the LZ9 did.

nope, it's part of the lower intake manifold. the LX9 doesn't use a separate water manifold

[Will'sFiero]

http://60degreev6.com/forum/showthread.php/50665-V6-curiosity?p=459520&viewfull=1#post459520

I'm guessing the piston pin is located differently and it too is a different diameter (.9055 for a 3.4 and .9447 for a 3.5).

Did Upson have to do anything about wrist pins to install his LS1 pistons?

Edit: https://www.gmheritagecenter.com/doc...let-Impala.pdf
Pages labeled 35 and 42 have LZ4 and LZ9 rod lengths... both listed at 150mm; We know this is incorrect, because the engines have the same pistons but different strokes.

Upson measured 3900 rods at 5.827" long... Just to make up for the difference in stroke, LZ4 rods would have to be 5.984" long. They're probably a little longer than that to put the piston higher in the bore to keep the compression up.

[caffeine]

The 3900 water crossover could be moved to the other side of the heads. Since the 3900 has different head gaskets left and right, however, you might need to also swap the heads/head gaskets to get proper cooling. For a RWD conversion this is almost essential in order to make room for accessories with a flipped upper intake.

[caffeine]

And yes the oil filter can be moved directly to the block. However some 3900s come with an oil cooler that would be nice to keep.

Also a note on the oil pan. I do now remember that it is different from a 3500 oil pan, as it has a 'notch' in it for oil filter clearance. With the oil filter moved closer to the engine on the 3900 there's a chance it could clear the Fiero cradle with some more minor notching compared to, say, the stock 3500 oil filter location.