Here are the results from this morning’s plenum swap.  The results are… ummm… about what we expected.

This car is a 02/06 350z with an automatic transmission.  There is an extensive list of aftermarket components on this car ranging from a carbon fiber diffuser to a custom painted roll cage, but this post has nothing to do with any of these mods, it is about the before and after dyno numbers.

The plenum install went off without a hitch and the car was back on the dyno in no time.  This mod was a straight plenum swap with no fuel or timing changes made (the owner did not want to install a Uni-Chip or other tuning hardware at this point.)

Run 003:  Stock Nissan Plenum (BLUE)
Run 005:  Cosworth Plenum (RED)

On to the dyno graph you can see that the Cosworth plenum LOST a healthy amount of horsepower and torque through the entire rev range except between 5,800-6,000 RPM where it gained two, yes two, horsepower.  The design of the plenum just doesn’t seem to work on lightly modified normally aspirated cars.  Unfortunately this is a loss that will really be felt when driving the car.  This plenum is so beautiful that we really wanted to make a ton of power with it so that we could improve the looks and performance of the engine.  At this point I would find it really hard to recommend this to a customer.

Mind you that this is the first normally aspirated car that we have installed the Cosworth on.  My full post with all of the boosted car tests is still to come this week.  That post will include all of the dyno results and all other pertinent test data.  Very, very interesting….