3900 versions and configurations for swap use

[Will'sFiero]

I'm running stock 3900 injectors.
Getting 200miles to 55 liters at around 0F.
2500 rpm cruise
About 10-12 cold start ups per tank, but it will run 14.7-15.5 afr when cold.
I've tried cruise timing from 30-45 degrees with no change. I was told run the cam fully advanced for fuel economy. But seemed to not help. Also tried running at about 30 degrees retarded from fully advanced. Going to try running the cam fully retarded during cruise and see what they does. Cam makes lots of tq down low when fully advanced.

What RPM are you turning at what speed? I'm guessing that the Legacy is gearing pretty short because it was originally a 4 cylinder car.

Lightly loaded at 3000 RPM will get much worse mileage than more heavily loaded at 2000 RPM, as long as the heavy load scenario doesn't get into power enrichment (PE) mode.

That's how C7 Corvettes can get damn near 40 MPG in real world driving.

[farmerz24]

I'm running stock 3900 injectors.
Getting 200miles to 55 liters at around 0F.
2500 rpm cruise
About 10-12 cold start ups per tank, but it will run 14.7-15.5 afr when cold.
I've tried cruise timing from 30-45 degrees with no change. I was told run the cam fully advanced for fuel economy. But seemed to not help. Also tried running at about 30 degrees retarded from fully advanced. Going to try running the cam fully retarded during cruise and see what they does. Cam makes lots of tq down low when fully advanced.

[niceguy]

I wish I could get that mileage in my 3900 swapped Subaru legacy

What are you averaging currently? I've gotten up to 26-27 in my Uplander Cargo 3.9 stock on consistently flat highway in the summer which is pretty good for a 3.9 with a 4spd auto in a 4400lb carcass. However, 24-25hwy was about average. Of course since the engine and tranny PCM tunes, I'm only getting about 22-23 highway...the tranny just loves to downshift now, a little too much in fact.

[caffeine]

The bigger the injectors the harder it is to tune for great fuel economy

[farmerz24]

It would be nice to add 90 RWHP, 1.1 liters and pop gas mileage over 30 mpg with a $600 engine (although my 2.8 already gives 28 mpg at 80ish mph).

I wish I could get that mileage in my 3900 swapped Subaru legacy

[ericjon262]

Just don't know if the wheels are the same diameter. The LS crankcase can hold a 4" stroke, so that wheel is big enough to make it around those throws and trigger a sensor in the wall of the crankcase. The V6 wheel may not be that large.

Also, it occurs to me that the E40 may have a "crank trigger resolution" flag like the V6 PCM's you've been investigating... It won't be necessary to swap the wheels if the E40 can understand the 58x trigger already in the 3900 and still do DBW, DOD/AFM and cruise control.

EDIT: The E40 will need some info from the G6 GTP manual transmission calibration (or a different manual trans LS calibration?) in order to run the engine with a manual transmission. It may need a clutch anticipate switch like I had to install in The Mule for the Shelby computer.

IIRC, the newer PCMs use a clutch position sensor instead of a switch, but I could be wrong.

[Will'sFiero]

assuming all of the 24x wheels are the exact same... hence why I said use the LS4 wheel if you plan to change the cylinder count in the LS4 programming. that why the computer is getting what it expects.

Just don't know if the wheels are the same diameter. The LS crankcase can hold a 4" stroke, so that wheel is big enough to make it around those throws and trigger a sensor in the wall of the crankcase. The V6 wheel may not be that large.

Also, it occurs to me that the E40 may have a "crank trigger resolution" flag like the V6 PCM's you've been investigating... It won't be necessary to swap the wheels if the E40 can understand the 58x trigger already in the 3900 and still do DBW, DOD/AFM and cruise control.

EDIT: The E40 will need some info from the G6 GTP manual transmission calibration (or a different manual trans LS calibration?) in order to run the engine with a manual transmission. It may need a clutch anticipate switch like I had to install in The Mule for the Shelby computer.

[ericjon262]

That may be an option...
EFI Connection ( www.eficonnection.com ) sells 24x wheels... There are probably other sources in the aftermarket as well. If I can buy the part cheaply, I don't see a need to make it.

Also, the 24x wheel is really two wheels that are the "inverse" of each other (one wheel's high is the other's low) put together.



I don't know if the LS4, LNJ and LZ8 use the same diameter journal where the wheel installs to the crank.

assuming all of the 24x wheels are the exact same... hence why I said use the LS4 wheel if you plan to change the cylinder count in the LS4 programming. that way the computer is getting what it expects.

[Will'sFiero]

That may be an option...
EFI Connection ( www.eficonnection.com ) sells 24x wheels... There are probably other sources in the aftermarket as well. If I can buy the part cheaply, I don't see a need to make it.

Also, the 24x wheel is really two wheels that are the "inverse" of each other (one wheel's high is the other's low) put together.

with this being said, I would say you need the LS4 trigger wheel.

I don't know if the LS4, LNJ and LZ8 use the same diameter journal where the wheel installs to the crank.

[NateD4]

Why not order a reluctor laser cut and then hone the bore to fit?

[ericjon262]

Originally posted by fieroguru:

The E40 (and E67 for that matter) has a field where you enter the # of cylinders and individual cylinder volume. Who knows what happens if you set it to 6 cyl.

with this being said, I would say you need the LS4 trigger wheel.

[Will'sFiero]

So to make AFM/DOD work...
Start with LZ8 engine from '07 Impala or LZG engine from '08 Impala

AND (
Swap in LNJ 24x trigger wheel
Swap in 24x crank sensor?
Use LS4 E40 PCM reprogrammed.

OR

Install Impala BCM
)

To verify:
-LNJ trigger wheel fits LZ8 crankshaft
-Compatible crank sensor fits LZ8 block OR LZ8 sensor is compatible
-LS4 E40 (or another app) can be programmed to operate a V6

That's starting to sound like work... and would be mostly for bragging rights
It would be nice to add 90 RWHP, 1.1 liters and pop gas mileage over 30 mpg with a $600 engine (although my 2.8 already gives 28 mpg at 80ish mph).

[ericjon262]

I'm not familiar with the LNJ trigger wheel...
There has to be something in the software that relates firing order to crankshaft position; it may not be a "cylinder select" like the earlier computers had, though.

true. it might be possible to swap the V6 data into the V8 program.

[Will'sFiero]

is there a cylinder select option in the LS4 programming? I haven't seen one in the later PCM's that I've looked at (doesn't mean it's not there though...)

I like the idea of the LNJ trigger sounds like the best option to me, I would bet it could be installed as long as the 58x trigger isn't machined into the crank like the earlier triggers. even then a quick trip to the lathe could fix that.

I'm not familiar with the LNJ trigger wheel...
There has to be something in the software that relates firing order to crankshaft position; it may not be a "cylinder select" like the earlier computers had, though.

Edit: Found some LNJ info: http://www.enginebuildermag.com/2011...4l3-5l-engine/
Engine Builder Mag is typically pretty thorough about parts interchangeability... they noticed the same piston part number and other fun configuration management trivia, for example.
It says GM doesn't sell the wheel separately... I thought it WAS available separately for the LS engines... is that not the same wheel as the 60 degree engines?

[ericjon262]

FWIW, it looks like tunercat obd2 doesn't support the E40 LS4