Cone filters are cool. Everyone likes a big ol’ cone filter, especially if it’s sold in a ‘cold air intake’ kit. Not only does it make your engine bay give the impression you’re a pro-tuner, it also adds that wonderful induction noise that makes the car sound and feel faster.

All MX5s have the same issue, if you want a cone filter you’re going to end up putting it smack bang in the hottest part of the engine bay – the passenger side (if you drive on the CORRECT side of the car / road) right next to the exhaust manifold.

I wonder why it heat soaks?

This, as Mighty Car Mods proved in their video all the way back in 2012 (HERE) is a little pointless and if anything, robs you of power.

The solution for the MX5 comes in 2 flavours and both of them generally require standalone ECUs and generally when you have a standalone ECU like an ME221, MegaSquirt or otherwise you’re running boost – so granted this specific situation is a little, well, specific – to me, and a few other like minded people perhaps.

Anyway, you either hang the intake out on the drivers side or you do something a little more brash and try a ‘Randall Intake’ .

Its a little counter intuitive but hot air actually builds up in this area of the engine bay.

Cold Side Intake

This style of intake requires you to dill a hole in the firewall, its more permanent but is also backed by science!

Randall Style Intake

There is, another way – its futuristic and comparably expensive, but there is a way and by jove I’ve man maths’d my way to justifying it. It’s what we’re calling the Cobra Cold Air Intake.

Snaking its way to cold air.

What makes this a complex and somewhat expensive solution to a problem I created for myself is a couple things.

  1. It’s a 3d printed part and it ain’t no small piece either.
  2. It requires some decent silicone bends to make it fit
  3. If you want to maintain the IACV you’ll need a takeoff for it

All told, you’re looking at circa £200 for this type of intake, but that does include the filter itself – hold on, it’s cheaper than the K&N hot air intake? Oh, well, see for yourself LINK

Whats more, it’s supplying air as cold as it gets to the engine, and it’s nice and stealth too.

Sitting in the mouth itself, the cone isn’t visible unless you really try looking for it.

Credit where credits due here, I must admit I’ve had the idea of utilising the space in a similar way but a very clever gent across the pond did all the leg work, his website is here –

Utilising expanding foam, a laser scanner and flow analysis to create a tested and proven part – so its a serious bit of kit really.

So whats the point? Why all the fuss about a cold air intake anyway.

With the car being on an MS Labs MS3 (megasquirt) ECU I can datalog (read; piss about) and one of the main issues I find is heat soak as the car idles. This impacts the cars power somewhat when queuing in traffic or when queuing for the next autosolo run. So it’s one more thing to blame my poor race performance on, clearly it has to be modified!

When we say heat soak, as the car has an IAT (Intake Air Temperature sensor) its easy to see the graph running up to 90-100c intake temperatures, this is bad regardless of how good a tuner you are, it promotes detonation at the worst and at the best it causes the car to run poorly.

Look how it follows the line of the hood, it makes for a tight fit.

This isn’t something many others will have hiding under their hood.

I don’t think heat soak is going to be an issue now – but we’ll keep you updated with how it performs!

If you’d like one of your own, you’re going to need the following;

Part Quantity Supplier
E45-70 – 45° Silicone Elbow Hose, 70mm ID 1 Viper Performance
ER70-63 – 90° Silicone Elbow Reducing Diameter  70mm to 63mm ID 1 Viper Performance
 SSTO-19 – Self Seal Take off Breather Outlet 1 Viper Performance
K&N RC-9310 1 Amazon

If you’re working on a 1.8, you’ll join it all up by using the MAF. If you’re working on a 1.6 you’ll need a section of 67-70mm OD pipe, trim it to fit, add some clamps to stick it all together and you’re away. It’ll take some fine tuning to get everything to sit right and expect a tightly fitting bonnet afterwards.

If you have any questions or if you’d like one printed – please feel free to drop us a line via our contact page.

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