3900 Swap discussion

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[DiscoStudd]

With all the talk of swapping a 3500 top-end onto a 3400, why not take it a bit further:  Dropping a 3900 motor/PCM/trans into a 2G that originally had a 3x00.

With the assumption being the motor is out of a 2006-07 Monte (arguably the one "3G" that has the most in common with the 2G's,) list some questions to ponder.  I'll start:

-Will the fuel system need to be modified to accomodate the returnless fuel rail of the 3900?

-What mods will need to be done to the exhaust?

-Will the AC compressor from the old 3x00 bolt up?

-What wiring would need to be changed on the 2G's bulkhead to accept the 3900's engine harness?


Let's discuss this further...

[DiscoStudd]

Man, I thought at least the "Monte Man" would want to continue the discussion.  :?   Well, I suppose we could always shift the discussion towards "L67 Swap" territory  

Anyway, does anybody have access to wiring diagrams/pinouts for a 2004 Impala (3400) and a 2006 Impala/Monte (3900) ?  I could try and look them up at the local library, depending whether or not they even have any publications pertaining to the latest models.

I can't imagine this swap would be all that difficult for a shadetree like me to pull off.  I just want to get as much "thinking out loud" out of the way before going through with the swap...

[Darin]

I can't see the swap being to big of a project, I am researching this as we speak. My intentions are to put a 3900 in my 99' GP

[DiscoStudd]

I can't see the swap being to big of a project, I am researching this as we speak. My intentions are to put a 3900 in my 99' GP

Cool!  :mrgreen:   Post whatever you can dig up...

[Darin]

Here is a good place  to start reading.  http://60degreev6.com/showthread.php?t=34223

[DiscoStudd]

Here is a good place  to start reading.  http://60degreev6.com/showthread.php?t=34223

Good info on the motor for sure (11 pages  :shock: guess I've got alot of reading ahead of me!!!)  Well right off the bat he says it'll physically bolt right in (which I expected) so we're headed in the right direction...

[Dstanic]

I can see it being worth it over a 3400 MC/Impala, but is it worth it to do to a base SE 3100 Grand Prix?  I don't see much of a point in swapping out a 3800 motor, but whatever.  How about a Buick Century?

[Darin]

I can see it being worth it over a 3400 MC/Impala, but is it worth it to do to a base SE 3100 Grand Prix?  I don't see much of a point in swapping out a 3800 motor, but whatever.  How about a Buick Century?

Run that by me again? Your saying it isnt worth swapping a 3100 out for a 3900?

[mfewtrail]

I can see it being worth it over a 3400 MC/Impala, but is it worth it to do to a base SE 3100 Grand Prix?  I don't see much of a point in swapping out a 3800 motor, but whatever.  How about a Buick Century?

Run that by me again? Your saying it isnt worth swapping a 3100 out for a 3900?

Depends on how costly the 3900 is. I doubt they're going to be cheap from a junkyard since they're relatively new...

EDIT: Found one on ebay including the transaxle from an '06 Malibu.
http://cgi.ebay.com/ebaymotors/3900-V6-ENGINE-MOTOR-TRANS-3-9L-GM-OE-IMPALA-STREET-ROD_W0QQcmdZViewItemQQcategoryZ33615QQihZ011QQitemZ320055209656QQrdZ1QQsspagenameZWDVW

Price isn't that bad considering it's new and includes the transaxle.

[Dstanic]

I can see it being worth it over a 3400 MC/Impala, but is it worth it to do to a base SE 3100 Grand Prix?  I don't see much of a point in swapping out a 3800 motor, but whatever.  How about a Buick Century?

Run that by me again? Your saying it isnt worth swapping a 3100 out for a 3900?

No, I don't see it being worth swapping ANYTHING into a GP SE or Buick Century (no offence to anyone, I just think the cars aren't very desireable to begin with).  Maybe swapping out a 3400 from an Impala or Monte, cause I like those cars better. That's JMO.

[Darin]

I can see it being worth it over a 3400 MC/Impala, but is it worth it to do to a base SE 3100 Grand Prix?  I don't see much of a point in swapping out a 3800 motor, but whatever.  How about a Buick Century?

Run that by me again? Your saying it isnt worth swapping a 3100 out for a 3900?

No, I don't see it being worth swapping ANYTHING into a GP SE or Buick Century (no offence to anyone, I just think the cars aren't very desireable to begin with).  Maybe swapping out a 3400 from an Impala or Monte, cause I like those cars better. That's JMO.

Obviously you need to see a pic of my SE. Id have to say it looks a lot better than 80% of the GT's and GTP's

[DiscoStudd]

No, I don't see it being worth swapping ANYTHING into a GP SE or Buick Century.

I take it you don't subscribe to the "speak loudly and carry a big stick" theory.  

Sleeper FTW!


I don't see what could be so wrong with swapping a 3900 into a GP SE or a "Sentry."  How would it be any different than those who have swapped L67's into early 1G W's?  


The whole reason I brought up this topic is because now there are 2 easy routes to go in obtaining 240 hp.  Option one, of course, is the cliched L67, and option two is the 3900.  The #1 reason I'd choose option two is because the 3900 runs on 87 octane (#2 reason would be the L67 is prone to engine fires...)

[TurboSedan]

i think the issue with L67 engine fires has most to do with the ridiculous design of the fuel rails.  quick disconnect fittings running right over a HOT supercharger?  WTF?  that can all be fixed with the ZZP fuel logs but man they are expensive!  they do make the L67 look alot better though.  IMHO the L67 is one of the ugliest engines GM has ever made and the ZZP fuel logs help alot with appearance.  i'd love to buy another Regal GS next year and seriously the ZZP fuel logs would probably be the first mod i'd do.

personally, i'd stick with your 3400 and turbocharge it!  it would probably cost as much as an L67 swap and definately cheaper than a complete 3900 swap!  some guys on v6z24.com are putting down some awesome numbers with a turbocharged 3400.  there are even forged 9:1 Wiseco slugs available for them now.

[DiscoStudd]

personally, i'd stick with your 3400 and turbocharge it!  it would probably cost as much as an L67 swap and definately cheaper than a complete 3900 swap!  

Might be something to consider   .  When it comes to engines though, I'm more of a "parts swapper" than a hardcore "test & tune" type, so I don't know how far I'd get into a turbo installation before I'd screw something up .  

I think short-term, the 3500 top-end swap sounds a bit more feasable, but who knows .  I guess it all depends on how bad the LIM and/or head gaskets blow when they finally let loose...

[LownSlow]

my problem with the 3900 vs. the L67 is fuel economy.  the 3900 is only rated at 26 mpg highway and you can get 30+ out of a stock L67 (although there is the cost of fuel).  i really liked the malibu maxx ss and G6 GTP 5spd i drove, but i couldnt justify the price with fuel economy.  i got the cobalts for a lot less, has much better fuel economy and i can run it on 87 too. the other problems with swapping from a 3100 to a 3900 instead of an L67 is cost and establishment of support (as well as cost of modding).  i think it would be really cool, though.   i think a 3.6 DOHC swap would be even sweeter.