- With our Nissan SR20 VE engine swap into our 350z race car,
one of the considerations was an inlet manifold or plenum chamber that was
going to suit the rear wheel drive application.
With the stock P11 Primera cylinder head, this only comes out in a front wheel drive
application and hence the factory plenum chamber wasn't going to work
for our rear wheel drive application.
On top of this however we also knew that we're going to be flowing a lot
more air than the stock P11 Primera inlet manifold was ever designed for.
This required a bit of a rethink.
And we're here at Plazmaman to find out exactly how our new inlet manifold
was made.
The design process starts with making sure that the base plate of the inlet manifold
is going to perfectly match the bolt pattern as well as the inlet port profile
of the P11 cylinder head.
Once this has been confirmed, everything can be designed in AutoCAD's
inventor software.
This allows a huge amount of freedom in manipulating the design and for
example in our case we've requested a plenum chamber with twin injectors
per inlet runner.
This is really easy for the team at Plazmaman to incorporate and modify
their base model.
A common question that comes up when discussing plenum chamber design
is the length of the inlet runners.
And we don't have the ability to get too in depth here.
But there is a lot that goes into this.
Of course like a lot with motorsport, it comes down to a compromise.
In general a longer inlet runner tends to favour low RPM torque,
while a shorter runner favours high RPM performance.
Of course we also need to factor in what can physically be fitted inside
the engine bay and how that may or may not compromise the volume
of the plenum chamber itself.
So there's a lot to take in there.
Before the design is finalised, it is run through a CFD or computational
fluid dynamics software package to ensure that the flow and the design
of the plenum and runners is optimised for the particular application
and the expected power output.
Once everything's finalised, tool paths are then created using Mastercam software.
These are the actual paths that the cutting equipment or cutting tools
will make in the Haas four axis CNC machines.
From here the raw block of aluminium billet is placed in the CNC machine
and the machining process can start.
Now the raw block of aluminium that Plazmaman start with weighs in the region
of 35 kilograms.
After around seven hours in the CNC mil, the finished product ends up
weighing only four kgs.
So you can understand there is a huge amount of material that needs to be
removed in the process of machining one of these manifolds.
Once the machining of the manifold base is complete, we can look at the other
components that go into the completed inlet manifold.
These include the two halves of the plenum chamber.
Now these are formed out of high strength sheet aluminium that's three millimetres thick.
Plazmaman also go to a lot of trouble to ensure that the entire plenum chamber
retains that full three millimetres of thickness to make sure that maximum
strength is retained.
These are then welded together and despite the look of those welds,
I can assure you that they aren't completed by a robot.
These are hand welded, and the finish is amazing.
With the plenum halves completed, they can then be welded onto that base
of the manifold that's already been machined.
With the body of the plenum welded to the base,
the produce is nearing completion, the last step really is adapting a throttle
body onto the front of the plenum chamber.
And this is where Plazmaman have the ability to use a variety of different
flanges to suit a variety of different throttle bodies.
These can include the CNC machined throttle bodies that Plazmaman make
in house, or you can adapt a range of off the shelf drive by wire throttle
bodies which is exactly what we're doing.
We're using a Bosch Motorsport 74 millimetre drive by wire throttle
body and one of the advantages with using a drive by wire throttle is it does
also allow idle speed control to function through the throttle body.
There are a couple of other finishing touches we'll discuss here.
On the underside of the plenum is a flange that gets welded on and this
has a range of ports on it, allowing us to fit take offs for manifold
pressure, for our MAP sensor, for our fuel pressure regulator and any other
sensors we may like to fit, such as an inlet air temperature sensor.
Of course we are also using a Plazmaman billet CNC machined
fuel rail and this is set up for our dual fuel injectors per inlet runner.
Lastly we'll discuss the options when it comes to adapting that drive by wire
throttle body out to the rest of our intercooler plumbing.
Now conventionally the Bosch drive by wire throttle body is set up for
a silicon joiner.
However these have proven to be a little bit unreliable,
particularly under high boost operation.
Instead we've chosen to use a TAARKS CNC machined adapter that allows
us to now use the Plazmaman Plazmaclamps.
Now these ensure that once they're done up there is absolutely no chance
of those clamps coming undone.
This ensures reliability out in the heat of competition.
With our specific manifold now only requiring throttle body adapter to be
welded on, we're really excited to get it back to New Zealand and fitted up
to our 350z.
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