Back in episode 10, we covered the start of the new intake system.   We had basically taken the very large and heavy OEM intake system and cut it down to just the essential parts so that we could use that as a base to build our own intake system.  Obviously most cars take their air from the front or side of the vehicle, but in our case I’ve decided that I’d like to take it from the roof and replicate something similar to what McLaren did with the F1 and incorporate the air intake into the roof.   That means a total redesign of the intake system to suit.

Here’s where we left things……..

So we will start with some 90 degree aluminium bends that I cut into 2 separate sections which will be welded onto the OEM intake plate.

Next, OLS laser cut some plates for me so that we could tack all of the pipes in place, but know they were all in-line.



Some people may not know, but the length of the intake runner has a large effect on where the torque and power is delivered from the engine.   Usually the rule is longer means the engine will produce its torque lower in the rev range and of course, shorter runners will produce more torque higher up.  So you can see that it’s important to decide up front where we would like the torque / power to be produced.

Originally this engine was designed to work in a vehicle with a much larger weight than the FZ12 and also focused more on cruising than sports cars, so we certainly need to change what the OEM had and we will be aiming to get down to around 300mm from the intake valve in the head of the engine to the top of the trumpet.   That should give us a much more “mid” range power band vs before when it was much more about low down torque delivery.  Don’t get me wrong, this engine will still produce a massive amount of torque (close to 700Nm) but it will just shift it to what we hope will be a better place to suit the style of car.

With all that said,  I started cutting down the longer tubes that were welded in place down to something a little more realistic.

Next it was back to OLS to laser cut us the bottom plate for what will become the main intake plenum / airbox.  This plate will hold all of the carbon intake trumpets that Jason from Carboglass is going to make for us.


Next we needed to create some intake tubes that were the same diameter as the lower intake, but then have a larger diameter to allow the carbon trumpets to slide inside.   For this I visited Basil Jones metal spinners.  If you’re not sure what metal spinning is (I had no idea till I needed to find out)…….. then watch this video.  As the name suggests its basically just putting metal into a lathe and then using tools to pressure the metal into the shape of a pre-made template.

We were able to start with a 45mm tube and stretch that out to 53mm to give us room inside for the trumpet to be bonded.


Then I trimmed them all down shorter to try and keep within our length limit mentioned earlier.


Next I used a small bead roller to create a bead on the end of tubes to help with size and also allow the silicon joiner tubes to attach more securely.


Now the last part of this episode was to create a gasket to go between the airbox and the bottom plate, as well as create a frame for the bottom of the airbox that will allow the bottom and the top to seal together.   It’s critical that there are no air leaks between the 2 parts as it will mean the engine will not be able to control its idles or running speed properly.  If the airbox leaks then it will be like the throttle being pressed as the engine sucks in air that wasn’t meant to be there.

I decided to use neoprene as a seal.   For those that don’t know, it’s what they make wetsuits out of, so is a form of rubber so seals really well, but is also flexible and compressible so is perfect for filling gaps.  Mitch from OLS was my go to guy again with this and he was able to actually laser cut the neoprene sheet to make it perfect.


So the top part you can see with the threads will be bonded into the bottom of the airbox and it will be bolted from underneath to the bottom plate. This will pull the two parts together, compressing the neoprene gasket.   Well that’s the plan!


There’s a newer entry in this story, please click here – FZ12 – Part 23

If you’ve missed the last part of our story then click here FZ12 – Part 21 

or if you want to go right to the beginning then click here FZ12 – Part 1

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