Engine pic

[Bruce Nunnally]

This shows the CTS 3.6L engine.

It uses a single intake --versus the dual intake in 2003-- fed from the same airbox as 2003.

[98Concours]

I wonder why they went from a dual intake to a single intake? Think you can add the dual intake and get more air?

Jeff

[Bruce Nunnally]

Confusingly, looking at the K&N part for the 3.2L, those dual intakes neck down to a single intake further up stream? I think the dual flow was replaced with the new setup on the 3.6L -- the 3.6L has a dual stage variable intake manifold that (quoted from GM literature as posted at http://www.60degreev6.com/index.php?p=sections&sid=32 ):

The V-6 VVT variable intake manifold (VIM) contributes significantly to the engine’s outstanding balance of flexibility, driveability and peak performance – its mix of linear torque delivery and high specific output. And like virtually every component on the HF V-6, the intake manifold does its part in improving overall NVH control.

The manifold’s key performance-enhancing feature is its dual-stage plenum. A valve in the plenum, managed by the ECM, opens and closes according to engine speed. At idle, the valve is open. From just past idle to mid rpm, the valve is closed, effectively creating two separate plenums, each feeding the intake runners and ports for half the cylinders. This optimizes airflow and boosts charging at lower engine speeds to maximize low-end torque. At higher engine speeds, the plenum plate opens, creating a single higher-volume plenum feeding all cylinders for freer breathing and high-rev horsepower. The VIM allows optimal airflow for a given engine speed without the compromises of a fixed-volume plenum. In combination with cam phasing, it allows impressively linear torque delivery, with as much as 90 percent of peak torque available 1500 to 5800 rpm, depending on the application.

Moreover, the manifold’s intake runners are precisely equal in length to deliver consistent, symmetrical airflow to each cylinder bank. This maximizes flow to the combustion chambers without the thrashy, uneven intake noise sometimes associated with high-output, high revving engines. The manifold is manufactured entirely of aluminum (sand cast A319 alloy for the upper portion, A356-T6 for the lower). It is lighter than a conventional manifold, reducing overall engine mass, yet it dampens noise more effectively than a composite manifold and further reduces engine noise that might find its way to the vehicle cabin.

[98Concours]

That sounds great! What will they think of next. I'm really excited about your new CTS.

Jeff