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….

We are working are a few updates this week for all of you Z-car fans:

Behemoth RB28 240z: I went to William’s Autobody on Monday and saw the progress on this car and i was amazed.  The entire interior of the car has been painted gloss black to match the under hood and exterior.  As of yesterday the exterior paintwork has begun and I will be headed up there to check out the progress.  I will have photos up by tomorrow evening.

Cosworth Plenums: I’m still gathering more information for this post to make it as accurate as possible.  We will be installing one on another customer’s car today and I should have some dyno numbers and graphs by tomorrow.

240z Upgrades: We are doing work on a 240z here that is currently equipped with an odd dual down-draft Weber carburetor setup and will be swapped over to triple 44mm Mikuni carbs.  We are also installing a Motorsport Auto 6-into-1 ceramic coated header.  These modifications will remove all of the performance robbing SMOG equipment and will also enhance the engine appearance greatly.  The baseline dyno showed that this car has a really strong torque curve and we will be hoping to keep that intact while bringing the horsepower up to match it.  I should have the final numbers and photos by the end of the week.

Hot Import Nights in San Mateo: There is an import and tuner show in the bay area this Saturday night from 5pm-11pm at the San Mateo County Event Center.  We were going to be showing off a couple of our cars but the show has sold out and we couldn’t pull any strings to get us in the event this time.  Come meet us at the show and check out what the aftermarket scene has to offer.

HIN San Mateo website

There are a few other things on our plate this week so check back soon.  Happy April FoolZZZZZZ.