Permanent Car Spotters

[Robert Hall]

I had a white 2005 Monte Carlo rental almost 20 years ago...I rented one in Denver and drove to Telluride for a week for my 35th birthday, sight seeing all over SW Colorado.. Durango, Silverton, Pagosa Springs...fun trip.  Had a sunroof, was smooth and comfortable IIRC.   Over the years, I rented many Impalas of that era, they were good cars. 

[Drew Dowdell]

1 hour ago, trinacriabob said:

I didn't know that about the difference.  They must have made some engineering modifications.  I'm almost sure the Chevy 3500 and 3900 are siblings (bore difference or similar), just like Buick's 3800 and 3300 were definitely closelyrelated.  I'm guessing the Chevy 3400 was based on the 3100.

To think that the 3500 can make 211 horses, lug around a heavy car, and come in at 6 or 7 mpg less than the 40 benchmark without a CVT was amazing.  I'd feel good about owning and driving that, and that it was American iron.

I lament the current absence of product I like.

There are two 3500s with some years of overlap. The earlier one called the LX9, you are correct, is built on the 3400 block and was offered from 2004 - 2007.  This one traces it history to the 3.1 from 1994, and even earlier to the 2.8 from 1980. This one made about 200 hp and between 215 - 220 lb-ft of torque depending on application.

The later one started production in 2006 and ran through 2010 as the LZ4 and is entirely unrelated to the earlier one aside from name. It was all new. It is a 3900 with a sightly shorter stroke. This one came with Variable Valve Timing. The blocks of the 3500 VVT and 3900 are basically identical.  Horsepower rating changed almost yearly, starting at 211, jumping to 224, then back down to 219 or 217.  There is a variant of this (LZE) for flex fuel rated at 211 horsepower and only available in the Impala and Monte Carlo.

To make things simple</s>, GM named ALL of these engines the 3500 High-Value engine, though the LZ4 and LZE are also sometimes referred to as 3.5 liter with VVT. 

The 3900 has all of that plus roller rocker arms (smoother) and a variable length intake manifold. While horsepower maxed out at 240, it has a nearly turbocharged-like torque curve with at least 90% of max torque (240 lb-ft) available from 1500 - 5500 rpm.  It had active fuel management and could run on 3 cylinders in certain years, only in the Impala