Bigger bore 4.2L?

[Greg55_99]

Since the 2.8L and 3.5L engines have been punched out to 2.9L and 3.7L respectively with a new 3.76" bore, I'm wondering if GM will get around to upping the displacement of the 4.2L.

In addition to their larger displacement - delivered through larger, 3.76-inch (95.5 mm) bores - the 2.9L and 3.7L engines feature improved airflow in and out of the combustion chambers, which helps boost power. They also share additional upgrades and changes, compared to the previous engines:

* Larger, 1.52-inch (38.7 mm) intake valves, vs. previous 1.45-inch (37 mm) intake valves
* Larger, 1.32-inch (33.5 mm) exhaust valves, vs. previous 1.18-inch (30 mm) exhaust valves
* Revised camshaft profile optimizes valve lift and duration in accordance with larger valves
* Cylinder head airflow increased to match capabilities enabled by larger valves and revised camshaft
* New, noise-reducing oiling system uses cylinder wall squirter system enabled by a hole in each connecting rod that delivers a precise oil stream onto the cylinder wall beneath the piston
* New aluminum camshaft cover helps reduce noise
* Tighter-clearance balance shaft bushings promote quieter operation
* New, 2-megabyte powertrain control module houses new diagnostic information storage
* New cartridge-type engine block heater, which fits neatly into a specially machined block orifice; for use with available engine block heater.

Additionally, the 3.7L five-cylinder engine has several features that help it meet new BIN 5 emissions requirements, including a larger, close-coupled catalytic converter and A.I.R. system.

VVT-enhanced performance



http://www.fullsizechevy.com/blog/?p=24

The 4.2L already pumps out 291HP stock. A few more cubes would push it over 300 no doubt.

Greg

[ylab]

Hate to be a downer, but with the GMT360/370 platform being phased out around 2009, I don't expect GM to spend any great sums of money working with the beloved I6. Keep in mind that the ONLY platform the I6 has been used in was our GMT360/370s, so with only 2 more model years to go, highly doubtful they'll spend the money. - We're in the 2007 model year now, so that only leaves 2008 & 2009 before production is stopped. *sigh* While I like the look and design of the Acadia and its twins, I don't plan on buying one....don't want something bigger than my current SWB Envoy and early reports indicate the 3.6 is just too under-powered for that beast.

[MTPockets]

It would be cool if GM did increase the displacement a bit on the 4.2L. Maybe make it a 4.5L+. It will probably never happen though, since many owners already complain about the fuel economy of the 4.2L.:rolleyes: Like ylab says, the 4.2L will most likely go away with the GMT360 platform anyway.:(

Joel

[JJ]

A couple of years ago I believe there were 2 Trailblazers that were running 5.0 liter I6's. I was hoping they would show up again. I believe they won their class despite wrecking and rolling over into a ravine.I read this in an internet article somewhere.

[Turbo4200]

You can use new sleeves and go up to a 3.78" bore. there is a bit of block work involved.

JJ- Are you speaking of the 2000 Pikes Peak truck (Larry Ragland)?

[JJ]

No. I'm thinking it was the Baja 1000 in Mexico.