Talk Morgan Forums Morgan Sports Cars Maintenance & Servicing Air Intake improvements

On the 3.7 Roadsters the only intake for air is via a hole cut onto the base of the Mustang airbox / filter housing here..



It's not very large in area and draws intake air from close to the back of the engine and the footwell bulkhead, and is only about 6 inches from the hot exhaust manifold

The filter sits flat in the top of the airbox & there's plenty of space below...





So I've cut some additional intake holes below the filter line to allow more air routes in, and hopefully some will be cooler air pushed in by the forward facing bonnet louvres, and I'm lining the 'box' with reflective foil tape





Next task is an air scoop to the back of the bonnet side louvres or a Naca duct

Great stuff Jon. You can certainly hear the air being sucked through that single inlet hole when blipping the engine at idle.

I think it will be difficult to make any subjective assessment of improvement due to the great variations in air temp at the moment and driving conditions. Nevertheless would be very interested to hear your driving observations following the mod.

I assume the airbox is standard Ford although not Mustang as this picture, albeit of a V8 Mustang belonging to a relative, looks of similar design but better location.



The V6 version has similar intake plumbing placing air box on the same front nearside, in cool air stream away from exhaust. Indeed press hype mentions cold air induction system to enhance power and torque.

Going for more power from a Roadster 3.7? Respect!

I am wondering how big is the opening in diameter regarding the original V6 Mustang airbox, that could be a benchmark for your experiments.
And also, if it is the same or a similar box in the Morgan, how is the stream of fresh air directed in the Mustang. The shape of and the flow in the airbox is an important factor to insure a good intake.
I would also experiment how it works when you close the original opening because - it must not but it could - happen that the air gets unwanted turbulences when the different channels meet coming from different directions and from the side vs. the bottom.

This is best image of V6 Mustang airbox I could find.



You can just see the dirty air inlet is moulded to a roughly rectangular shape taking air from forward and away from radiator.

There seem to be several airbox conversions available in the US involving K & N style air filters within custom casings and claiming various improvements to power and torque. The gains seem to involve cleaner route for air inlet by replacement or removal of silencer compartments as seen above in clean air inlet.

Doesn't seem the Roadster variant has this silencing though.

Tim, where on earth did you find that photo of me?

Colder the air, the denser it is and hence greater oxygen content. So that’s all to the good.
BUT, air box design is a bit more of a science than merely having as big a hole as possible. Boxes are designed by a combination of shape, volume and intake hole to achieve an optimum air flow at a resonant frequency designed to be at a point where torque might otherwise drop off due to engine characteristics. (Helmholtz Resonance principle)
So, don’t throw away the bits you’ve drilled out, you may wish to stick them back on!

Here’s mine, 1.6 Sigma engine though

I fully agree to your point! But in case of the pics of the original airbox of the 3.7 Roadster shown above the input opening doesn't look really professional and calculated, but rather like someone sawed out a piece where there happened to be some space left.
Of course I could be wrong about that, I also believe that the disappointment is great when the resonance of the airbox is no longer right. You'll notice that e.g. when at low revs this acute impact is missing and the acceleration feels weak and without initial torque but also at higher revs something could just feel wrong.

Because of that I have kept the airbox of my 4/4, a first trial without it gave worse results even if the way to the TB was shorter.

I have just as much respect for the engineers' airbox calculations as I have for a well tuned bass reflex speaker. (even if the air is flowing in the airbox and only vibrates in the bass reflex box).

Thanks for the comments Heinz & Deejay, but if you look at photo 1, the factory solution is just to saw off part of the bottom to create a hole, certainly doesn't look scientifically calculated to me

On the 3 ltr engines all the proper science took place after the throttle body in the intake tracts