3.9 LZ9

[CNCguy]

guys, i dont understand why you would want to eliminate the VVT. I mean, it will boost power if used properly. Recent discussion indicates a controller box can and had be made, so why eliminate this system altogether???

My desire to do it is for swaps where space dictates its removal and for those who are trying to keep costs to a minimum. Also, I believe the 3900 without VVT is still a step up over previous engines. Elimination is also the quickest way to go until there is a controller that can be easily used for swaps. I am trying to come up with an alternative controller but am nowhere near having one for a while.

I could be wrong, but I think Joseph is planning to use VVT... not sure though.

[Joseph Upson]

Yes, no one is trying to eliminate it, just make sure they can run without it until a practical method of controlling it can be devised. I would hate to have to wait until a controller is developed before I can use the motor, even without VVT it's still 3.9 litres.

[swathdiver]

Update on 2006 Pontiac Montana SV6 with LZ9 3900

Motor loosened up significantly at around 9000 miles. Acceleration and gas mileage improved noticeably.

Now at 30,000 miles, it just keeps getting better. Replaced original air filter with stock sized K&N. Highway mileage averaged 22mpg fully loaded at 84mph on a recent trip. Interestingly it gets better mileage above 75mph then below it, to a point of course. Highest mileage seen was 23.5mpg at 78mph.

Something to note though. At about 4000 miles and 80 hours into last oil change oil level was down 1 notch on the stick. At 5500 miles and 135 hours engine has lost 2 quarts. Oil is Mobil 1 5w30 synthetic. Dealership stated this was normal to burn 1 quart every 1000 miles. Not normal for a healthy engine IMO!

Have decided to change oil every 4000 miles and or 80 hours from now on. Currently, oil is about 3000 miles and 50 hours old, hasn't dropped at all on the stick.

[swathdiver]

Guess we're long overdue for an update. Once drove 91 mph for twenty minutes and it averaged 21 mpg at that speed. Every couple of years the motor would consume all of its oil suddenly. Guess all the gaps in the rings aligned together. The transmission's forward apply band broke in 2015 and the van has been parked since. Would like to get it running again, at 12 years old, it's time for an overhaul throughout the interior and freshening up on the outside. Since this one went down, we bought another Montana, a 2004 with the 3400. Not as modern as the SV6 but it is fully loaded and has served us well thus far. Starts and runs everyday. Also bought a GMC truck for my daily driver, so if the Montana gets fixed, it'll be a spare or replace the 2004 should that one give up the ghost. The '99 Montana was still on the road last time I saw it.

[niceguy]

I have an '08 Cargo version with the 3.9. Just under 200,000 miles on it and the only significant issue in 6 years is a progressive rear head gasket leak that leaves drips on my driveway. But still a strong running engine. Tranny is still working fine, though I credit having a TCM tune for keeping it going well despite my aggressive driving style.
Definitely a fun engine IMO, if only the van had another gear or two, it would really move!

Jeremy

[swathdiver]

Thanks for responding. Yes, these were fast vans with great engines in their day.