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| Questions about LS4s and Pontiac G6s (Page 1/3) |
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thesameguy
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MAY 01, 02:35 PM
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My plan to start on an engine swap this winter got delayed, but I'm still trying to pursue it... got a couple questions:
If I ended up with a G6 with a 3.5l or 3.9l and a manual transmission, what in broad terms would be involved with divorcing the engine management from the body control? Is there a magic bullet here, or is it just a big PITA? 
What would be the obvious visual cues that an engine was an LS4 and not some other LS, like an LS6, aside from the fact the motor is facing the wrong way.
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dratts
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MAY 01, 05:02 PM
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The ls4 intake is canted to one side and the alternator is on top.
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Gall757
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MAY 01, 05:11 PM
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thesameguy
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MAY 01, 06:55 PM
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| quote | Originally posted by dratts:
The ls4 intake is canted to one side and the alternator is on top. |
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Yeah, but forgetting about anything beyond the block and heads, there is nothing all that obvious, yeah?
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Raydar
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MAY 01, 11:33 PM
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The LS4 has the GM "metric" bellhousing pattern, that allows a Fiero (or similar) tranny to be bolted up. (The starter will still be an issue.)
The others have a modified version of the usual SBC (small block chevy) pattern.
The LS4 accessories are more "wrapped around" the front side of the engine than the others, in order to save space.
Are you planning on an LS4 / G6 swap? As the owner of a G6 GT, the idea intrigues me. 
For ECM/TCM software, check out Tunercat.com, to see what's what.
You will have to acquire a set of his OBD2 tuner software. Since he apparently has a license with Jet, that may be a problem, but once you do, there is software available to tweak most anything G6 related.
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thesameguy
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MAY 02, 04:45 AM
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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.
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Will
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MAY 02, 10:29 PM
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If you get it referreed as an LS4 and it has a manual transmission, it will fail for the reason you cited... GM never mated that engine to a manual transmission. The Cadillac Northstar is in the same boat. If you remove external indicators that it's an LS4 (IE, grind off the casting marks) you may be able to get it smogged as an LS6 using an LS6 PCM, but you'll still need all the emissions equipment from an LS6 donor, including exhaust manifolds and catalysts. [This message has been edited by Will (edited 05-02-2015).]
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thesameguy
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MAY 03, 01:38 AM
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I have had reasonable luck with the referee ok'ing non-stock parts where packaging is a concern, plus I've never had a referee actually look up a part number when it looks like it should be there. Since an LS4 would all look right together, I don't think they'd get bent out of shape about any of it. I've never actually met a referee who could reasonably tell one engine from another anyway. If it looks like it's supposed to be there, they usually assume it is. I think what would really be on the table is whether LS4 and 6 have identical smog equipment, and I think they do.
It's all speculation of course. And I still really hope a G6 3.9l falls into my laptop before a Beigemobile SS.
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fieroguru
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MAY 03, 10:07 AM
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| quote | Originally posted by thesameguy:
I think what would really be on the table is whether LS4 and 6 have identical smog equipment, and I think they do.
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**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...[This message has been edited by fieroguru (edited 05-03-2015).]
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Raydar
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MAY 03, 12:25 PM
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| quote | Originally posted by thesameguy:
...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...
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The 3.9 would be my engine of choice. The (LZ4/LZE) 3.5 is rated at 221 HP, and the 3.9 is only rated a few more.
I would suspect that there's a good bit of untapped potential, there.
(Even the 3.5, as installed, is "managed down" a great deal. It's only bolted to a 4T45E. If they let it run at its full potential, I have to believe that they would be toasting transaxles at a pretty good clip. )
If I ever do this swap, I'll probably bolt it to a late (~93) Beretta Gatrag. Lots less trouble than the F40.[This message has been edited by Raydar (edited 05-03-2015).]
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