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GM's 3.5L vs. 3.9L

Old Oct 6, 2006 | 01:37 PM
  #11  
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Well is the 3.5 a ohc engine? That would be the reason the hp numbers are so close to the ohv 3.9 engine. Love to rev get the 3.5 love to cruise get the 3.9
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Old Oct 6, 2006 | 03:02 PM
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I believe the 3.9 has a more linear hp and tq powerband. It keeps rising and not drop off. I've seen the hp/tq dynos for the 3.9 and it'* very linear (keeps going up to its rev limit) However that was the old 242 hp 3.9....

Some people like to have the biggest engine possible...
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Old Oct 6, 2006 | 03:06 PM
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I test drove a 2006 (GM Certified Used) Impala LT with the 3.9. That motor is AMAZING. It pulls so smoothly and hard, there'* no "loss of power" up high and it'* crazy smooth at idle. let me tell you... I would buy a Impala with the 3.9 in a heartbeat. Words cannot describe my shock. I would think it COULD keep up with a SSEi (stock for stock of course) It probably won't beat it but could keep up.
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Old Oct 6, 2006 | 03:40 PM
  #14  
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Originally Posted by fuelforthesoul1999
I test drove a 2006 (GM Certified Used) Impala LT with the 3.9. That motor is AMAZING. It pulls so smoothly and hard, there'* no "loss of power" up high and it'* crazy smooth at idle. let me tell you... I would buy a Impala with the 3.9 in a heartbeat. Words cannot describe my shock. I would think it COULD keep up with a SSEi (stock for stock of course) It probably won't beat it but could keep up.
Yep very impressive and without the use of a supercharger. I wonder if a supercharged version is in the works?
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Old Oct 6, 2006 | 04:04 PM
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Thats what I was going to say the hp rating is only a max you arent saying wheer and for how long is that # coming from. The 3.9 is a very impressive motor the power I felt when I test drove was good to me, and the 3.5 like the 3100 and 3400 has to rev to get anything.
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Old Oct 6, 2006 | 05:47 PM
  #16  
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I put a completely new catback on my Maxx LTZ (3.5 liter), and it woke up...majorly. Mike, Don, and myself looked under my car one time, and we all just laughed at how Chevy can get away with using a 4 cylinder exhaust under there. I put 2.25 from the rear manifolds on back, ditched the primary muffler, and went with a FM 80-series out back...the whole demeanor of the engine changed afterwards.

Also, the 3.5 performs much better in a Malibu than it does a Monte Carlo/Impala due to weight and gear tuning (plus the 3.5 uses a four-banger tranny as opposed to the '65...the 3.9 uses the '65 and I agree that it feels absolutely incredible in the Maxx SS)
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Old Oct 6, 2006 | 07:26 PM
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Gotta remember too, these motors are strangled by the PCM. They are down-tuned for the most part with TM and such. I'm sure you can squeeze a lot out of the 3.9 with a good tune.
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Old Oct 6, 2006 | 07:43 PM
  #19  
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Originally Posted by Sol
Gotta remember too, these motors are strangled by the PCM. They are down-tuned for the most part with TM and such. I'm sure you can squeeze a lot out of the 3.9 with a good tune.
Agreed. Even with Traction Control off, torque management is very apparant in Epsilon bodies. Couple that with DBW and it makes a pretty finiky system :?
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Old Oct 9, 2006 | 10:58 AM
  #20  
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Originally Posted by jr's3800
Lash, I don't believe those Milage numbers are correct... Brads 3500 actually does pretty good... And the 3900 is the same, it to does as well..

The ratings shown look like they are for the Minivan Platform with AWD... I believe the rating is more along the lines of 17 city 26 hwy for the vans...

Interesting to see how the ratings went down on the 3900 and the ratings for the 3500 went up.. Something doesn't seem quite right there... And with the newer technology and the Fact that the 3500 and 3900 are SFI engine should yield good fuel economy from both, even if you had the 3.05 or 3.29 gears..

Stock for stock the 3500 would give a 3800 L36 a run for its money... A 3900 would walk me( maybe not ultra fast, but it would still get away faster than I'd like....LOL )

So I am confused by the new numbers...

* Edit *... The GTP G6 must have some serious performance gears to get milage that bad..
that was one of the items that made me post the question to start with, especially since ads for the G6, on the same site, indicate milage numbers around 25/30, which sounds more like it, IMO.

While the numbers for the 3.5 vs. the 3.9 all look pale as written, I knew there had to be more to the picture, since I'd heard a number of good things about the 3.9 before.
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