Questions about LS4s and Pontiac G6s (Page 2/3)
dobey MAY 03, 12:38 PM

quote
Originally posted by thesameguy:

The two scenarios weren't actually related to each other. I am still on the fence between a high value V6 swap and an LS4 swap and am considering the ins and outs of each. California has weird rules about engine swaps and transmissions can be (but aren't necessarily) a sticking point. The G6 is one if the few/only cars that came with a high value and an F40, so it makes a great source for those parts. The LS4 never came with a manual, but since no rule addresses longitudinal/transverse swaps, fudging the swap as, say, a CTSV swap even if it's an LS4 (because the CTSV was an LS6 with a 6-speed) might just make everything easier. Packaging adjustments - like an intake manifold and an alternator relocation - probably wouldn't earn anyone's ire whereas a transmission change might.

I am mostly thinking out loud here, trying to get a handle on options. Both are on the table, but I am really hoping a G6 with a 3.9 falls into my lap.



If you want to smog an LS4 as anything other than an LS4, then you should do the LS2 intake swap, tweak the cam sensor programming in the LS2 tune, fix the injector and other maps for the lower displacement, and do it as an LS2 swap. The LS2 used the same ECM as the LS4, and came with manual transmissions in several different vehicles. The LS6 is a Gen III and the wiring is quite different from the Gen IV engines, which the LS4 and LS2 are.

As for a 3.9, I doubt one will fall in your lap. But I'm sure you can find one for around $10k somewhere.
Raydar MAY 03, 12:48 PM

quote
Originally posted by dobey:


If you want to smog an LS4 as anything other than an LS4, then you should do the LS2 intake swap, tweak the cam sensor programming in the LS2 tune, fix the injector and other maps for the lower displacement, and do it as an LS2 swap. The LS2 used the same ECM as the LS4, and came with manual transmissions in several different vehicles. The LS6 is a Gen III and the wiring is quite different from the Gen IV engines, which the LS4 and LS2 are.

As for a 3.9, I doubt one will fall in your lap. But I'm sure you can find one for around $10k somewhere.



car-part.com found a few of them. They're not very common. Price was ~$1K or less.

I believe they came with the E38 ECM. I'm not sure how difficult it is to run it stand-alone, however. At around MY 2007, GM switched to a separate TCM.
(The 2010, as I understand it, came with the E37. Just mentioned that because that's what I had to buy software for. Probably used the E37 for Flex Fuel capability, but I'm not sure.)

[This message has been edited by Raydar (edited 05-03-2015).]

dobey MAY 03, 12:59 PM

quote
Originally posted by fieroguru:
**The PCV routing is very different between the two, but you can convert it with a LS6 intake, valve covers and valley cover swap.
**Neither had EGRs, so no work there.
**Probably want to run the LS6 Evap system as well so as they look for components, what they find matches the story of the engine being an LS6.
**You will need to run the LS6 ECM and calibration (and an LS6 VIN in the computer) to fool the smog ref, as they will scan your car looking for DTCs and can see the specific vehicle the calibration is for. If they can see the displacement of the engine specified in the ECM while doing their scan, then you might get caught.
**To run the LS6 ECM, you have to stick with the 05 and 06 LS4 engines (or do the 58x to 24x conversion), and I would keep the LS6 TB.
**Since you will have the LS6 valley cover, you might want to run its valley knock sensors vs the LS4's on the side of the block.
**You will also need to run a RWD timing cover with the cam sensor in the correct position for the ecm as the LS4 uses a different location.
**The block # will be visible from the backside of the LS4 engine, but the stamp showing it being 5.3L is inside the bell housing. So you might want to relocate your coils like mine to obscure the casting # on the block (10:30 on the pic).

If you were able to get it through, you probably couldn't tell anyone or post about it... Hate for them to find out you snuck it past them...



Is the displacement noted in the ECM tune outside of the VIN number? I think you'd just need to pull the fuel map and such, so it's like a 5.7 running a little lean. The LS4 also has a lower compression ratio of 9.9:1 vs LS6's 10.5:1 or the LS2's 10.9:1, which will affect the map.

The LS6 valley cover won't fit on the LS4. The LS4 has the oil towers for AFM (as all Gen IV engines do), which interfere with the Gen III valley covers having the knock sensors in the valley.

I think the RWD timing cover is also thicker, which will mean needing a crankshaft with the longer snout (or maybe a spacer could be used), to fit the RWD balancer pulley and accessory drive. This also increases the total length of the engine, and prevents using the LS4 water pump (I'm not sure if the rear A/C pulley on the RWD balancers gives the proper alignment for the LS4 water pump, but I expect not). It should be possible to change the timing map in the ECM to match what the LS4 needs, though.

To run as an LS6 (or better yet, an LS2), you'll also likely want to do a full AFM delete. You can use an LS2 valley cover, which blocks the oil spires, as well as an LS2 oil pump, pan, and lifters. A stock LS1 or LQ9 camshaft will make a good OEM replacement for the LS4 cam, when going with AFM delete. Or you can go wild after-market there, if you want.
dobey MAY 03, 01:01 PM

quote
Originally posted by Raydar:
car-part.com found a few of them. They're not very common. Price was ~$1K or less.

I believe they came with the E38 ECM. I'm not sure how difficult it is to run it stand-alone, however. At around MY 2007, GM switched to a separate TCM.
(The 2010, as I understand it, came with the E37. Just mentioned that because that's what I had to buy software for. Probably used the E37 for Flex Fuel capability, but I'm not sure.)



Oh sure. I thought he was talking about possibly getting a complete and running car in decently good condition that comes with the 3.9/F40. The F40 changed in 2007 as well, so depending on which swap you actually want to do, you might want the earlier or later version of the trans. The earlier version is much easier to find, and much cheaper.
Raydar MAY 03, 01:59 PM

quote
Originally posted by dobey:
Oh sure. I thought he was talking about possibly getting a complete and running car in decently good condition that comes with the 3.9/F40.
...



Yeah, I figured that when I read $10K.
Although I didn't figure in the cost of the F40, since that's not the direction I'd be going.

That $1K I mentioned was for a motor with 37K on the odo.
cvxjet MAY 03, 04:45 PM
I live in CA also and have done the 3.4 F-body swap....It has some issues with throttle sensitivity, so I was thinking of going with the 7730 computer. But I may also want to go with the 3500- and obviously, GM never hooked it up to a manual. So is there any way around this situation(The 3500 would be substantially cleaner than the original 2.8)? And is there a way to make the 7730 pass smog in CA?

Not trying to jack the thread, just hoping someone can answer these questions....
fieroguru MAY 03, 06:50 PM

quote
Originally posted by dobey:
Is the displacement noted in the ECM tune outside of the VIN number?



Yes, the calibration has a field where you have to enter the displacement per cylinder as well as a drop down for the overall displacement:



quote
Originally posted by dobey:
I think you'd just need to pull the fuel map and such, so it's like a 5.7 running a little lean. The LS4 also has a lower compression ratio of 9.9:1 vs LS6's 10.5:1 or the LS2's 10.9:1, which will affect the map.



You might be able to get it to work with the wrong displacement value, but you will have to change the idle airflow and VE tables quite a bit. vs. entering the proper displacement value. Even then you might have to tweak some other tables if it has drivability or other issues related to the overstated displacement.


quote
Originally posted by dobey:
The LS6 valley cover won't fit on the LS4. The LS4 has the oil towers for AFM (as all Gen IV engines do), which interfere with the Gen III valley covers having the knock sensors in the valley.



Correct, forgot about those extra oil bosses for the DoD and that the LS4 probably doesn't even have the bosses in the valley to mount the knock sensors. So they should remain in the stock LS4 position. The main thing if you want it to look like an LS6 is for the PCV tube to come out of the valley cover. If you use one of the Gen 4 versions with the vent, then it will also have the needed seals to block the oil passages for DoD. If you use one without the seals, you can tap the 8 bosses and insert plugs to block them off.


quote
Originally posted by dobey:
I think the RWD timing cover is also thicker, which will mean needing a crankshaft with the longer snout (or maybe a spacer could be used), to fit the RWD balancer pulley and accessory drive. This also increases the total length of the engine, and prevents using the LS4 water pump (I'm not sure if the rear A/C pulley on the RWD balancers gives the proper alignment for the LS4 water pump, but I expect not). It should be possible to change the timing map in the ECM to match what the LS4 needs, though.



The RWD cover clears the LS4 balancer and water pump just fine. Don Kraus used it on his 427 swap:


The issue between the LS4 and RWD timing covers is the sensor itself is mounted about 180 degrees apart, but use the same camshaft timing gear. There is no provision for the Gen 3 ECMs (or at least not visible with HP Tuners) to change the phasing of the camshaft or the placement of the camshaft sensor.



quote
Originally posted by dobey:
To run as an LS6 (or better yet, an LS2)...



I think it would be better to go the LS2 clone as well. The LS2 & LS4 are very closely related, both mechanically as well as electronically. If you open LS2 and LS4 tunes to compare, 40-50% of the tables and other data entry cells are the same, but that also means that 50-60% are different... There are about 330 data entry tabs or tables within the LS4/LS2 calibrations... So while they are closer than the LS4/LS6 which goes across ecm generations (which changes in the shapes/sizes of tables), they are still quite different.
Will MAY 03, 07:13 PM

quote
Originally posted by fieroguru:

Yes, the calibration has a field where you have to enter the displacement per cylinder as well as a drop down for the overall displacement:



The Referees don't use HP Tuners... Does displacement show up in the "PCM data" of a scanner? I don't think it does.
fieroguru MAY 03, 07:36 PM

quote
Originally posted by Will:
The Referees don't use HP Tuners... Does displacement show up in the "PCM data" of a scanner? I don't think it does.



Within HP tuners scanner, there are no selectable PIDs that would share displacement within the data stream, but I have no idea how sophisticated the scanners the smog refs would use.
thesameguy MAY 04, 10:52 AM
In my limited OBDII experience, the refs don't have any specialized hardware. They will hook it up to a pretty generic OBDII scanner to look for smog readiness but I don't think they will investigate beyond that. They definitely don't have anything like a TechII or HP Tuners or anything like that. It's not anything more than a regular smog shop would have.

The same goes for looking for part numbers, etc., because they just don't have the references to figure out compatibility - any given part could have dozens of part numbers and they're not going to figure out whether it *actually* belongs or not. If it's made by GM and looks to be in the right spot, that's about all they care about. They will check for the presence of specific smog equipment (PCV, EGR, etc.) but they typically don't test for functionality. They don't have the equipment or procedures to do it. Sometimes they get intense about placement ("PCV valve is in the wrong place") but sometimes they don't. Typically, if it looks like it is performing the intended function they tend to ok a little fudging dimensionally. Typically. It's all a judgment game. The thing I am most worried about with an LSx swap is actually the catalytic converter. I'm honestly not sure how to get that part installed and placed satisfactorily.

The LS2 tip is excellent - that makes a world of sense. an LS2+manual that just happens to have a weird intake manifold and an unusually placed alternator. That's the ticket.

WRT the 3.9, I've actually been surprised by how available they are. There is a G6 GTP with a manual in Stockton or something for five grand, the third I've seen this year. With an automatic it would get substantially more, but I think the market for manual transmissions in this class of car is really pathetic.

http://modesto.craigslist.org/ctd/4999390632.html

High miles, but they are sturdy engines. Worst case it needs a rebuild, but five grand nets everything needed to do the swap except mountains of time and talent. I keep thinking about seeing if they'll take four for it and just having it around for when I decide to do the work.