Talk Morgan Forums Morgan Sports Cars Morgan Three Wheeler & Super 3 DIY air filter housing upgrade

Seeing a lot of people looking for less restrictive filter covers (and some being quite expensive) I thought I’d just try and modify the stock one. After all I didn’t want anything chrome or with skulls.

So, the cover simply serves to sandwich the filter between itself and the intake to force the air through the side of the filter. As such only the frontal area is functional and everything around the side is restrictive. The side only has a cutout at the bottom, meaning only about 1/6th the circumference of the filter is getting direct air. If you look at the stage one filter, it’s open all the way around and there are no issues with water ingestion or anything of the sort.

So, a very simple modification. Remove filter cover (4 small hex bolts) drill more holes.

The metal is very thin and easy to drill (It might even be aluminium?). I made one 1.5” hole on the top, opposite the standard hole, and one hole on each side at the half way point between the top and bottom. The bottom hole being a bit wider means the side holes are slightly higher than the middle of the filter, which actually looks better I think. If you wanted you could put 5-6 holes, or just cut off the whole back of the cover!

I just used a spring punch and drill bit as per the picture below. Did the drilling under running water in the sink to keep it cool. I suggest using very little force but making sure you’re even. It will get ugly if you break through on one side unevenly and the cutter then catches and jumps.

The metal is quite flexible so it will bend. No worries as it bends back just as easily.

I then just filed the edges of the holes smooth and cleaned thoroughly to remove any loose metal.

I nicked some paint with the drill bit around the holes but nothing a permanent sharpie or quick layer of black spray paint won’t sort.

Improvements? There may be a marginal increase in engine response, I’ve only tried revving stationary (note that the engine is more exhaust than intake restricted I’m told so you may not get any change with a stock exhaust, I’ve punched a 1-1/4” hole in my front baffles and it made a difference). One thing I’ve definitely noticed is that the sucking/hissing/whistling sound my car was making at idle and light throttle is gone. I think this was caused by the restricted air flow.

In any case, costs less than an hour with some basic tools, glad I did it, hope this is helpful.

For the anti-chrome anti-skull lobby you can always consider https://www.garage56.co.uk/carbon-composite-air-filter-cover-released/

Saw that, but I’d rather have it in plain black plastic. Carbon on a Morgan? Not for me!

Now the issue will be how the air is delivered through the venturi as the OEM filter does not have the "Stinger".

+1

Good job GregA10.

That is the best part of the S&S I bet.

I wonder if someone could make a simple collar that could be placed on the throttle body opening with a few blades to create some swirl. Would be simple enough to machine.

If you get concerned about exposing the filter directly to the elements, why not try a rain sock ?

This sort of thing :
https://www.ebay.co.uk/itm/Pre-Filter-Rain-Sock-for-Stealth-Air-Cleaner-Kit-S-S-Cycle-170-0193/184217887475?epid=202987013&hash=item2ae43de2f3:g:SKgAAOSweZ9ec9Ns

I got mine from Matts Machine Shop , cheaper as well from what I remember.
I have one fitted for many years with my Morgan Stage 2 filter where the filter element is completely exposed ( and been caught in torrential rain a number of times ) with no issues.

Yeah really not concerned about the rain. You could soak your filter while stationary and the car would likely start fine. Plus it’s covered by the scoop. At speed any water entering one of the holes would fly out the back of the housing before it made it though the filter.

Any residual water will be steam by the time it hits the combustion chamber, helping cool them, clean them, and give a nice octane boost!

My last Golf GTI had water injection and on boost it could go through almost half a litre of water sprayed directly into the intake manifold per minute, on purpose, to HELP performance. People worry a little too much about rain 😅

The stinger shapes the air flow and not create turbulence or a swirling effect. If there is a swirl coming off that stinger I would love to see the wind tunnel testing showing it.

Years ago i saw the wind/liquid turbulence created by a round ball flying through the air. You would normally think it would be smooth, but it was not, it was very disturbed as the rear side of the ball was creating very uneven flow of air where the air tried to go behind the ball. Bullet shape and air flow are a real science and speed of the object going through the air or the speed of the air over an object dictates shape. I suspect S&S used a wind tunnel to test the shape of the stinger.

I use a rain sock on my S&S Stealth filter primarily to stop the dust which is my biggest issue on the dirt tracks up here, it traps an amazing amount of debris which is easier to clean off than cleaning the filter.