Finally managed to get some time in the garage today. I tried fitting the diffuser I got off Graham / Scotlad to the back of my MK.

The front edge seems pretty easy, a few strips of aluminium angle and a few dzus should see it right. But the sides and back are more tricky. Any advice gratefully received.

Obviously I'm going to have to find something slightly more durable than masking tape to hold it on:



It seems to stick out the back quite a bit. Should I trim it back or leave it long?



If I leave it long, then I'll have to turn the no plate light round and relocate the plate:



Close up of the excess length:



Cheers

Mike

It doesn't need to stick out that far.

It also doesn't need to stick out at all over the whole of the width (if you didn't want it too!).

It also depends on whether you are going to put any "channelling" under the main body of your car to duct air toward the centre of the diffuser.

That also depends () on whether you have a full flat floor (in your engine bay too).

Cheers,

Cool

I think I'll trim it back then.

Yes the car is getting an undertray under the engine bay, along with ally angle the full length of the chassis.

Cheers

Mike

Deffo reccomend chaging masking tape to gaffer tape, make ure you get good stuff with a fine cloth weave

Caber

I didn't want to drill holes to mount mine so fitted al angle down the side of the car using large "P" clips (on the frame member below the rear axle) which sorted the sides. For the middle I was able to pick up some existing holes.

In every case, I just used nutserts - though I wish now I'd used Dzus fasteners

A very profesional job i must say Mr Jones, looks really good, now about my royalty cheque
Kaspa

[Edited on 10/2/08 by Kaspa]

A diffuser angle of more than 10 degrees won't produce downforce only more induced drag.

Britishtrident is right, the angle of that is much to steep and sudden to work. You'll get mainly drag and turbulance.
I always work on a maximum of 7 1/2 degrees rising to a maximum of 10 degrees from horizontal over a distance of 2-3 ft. length. But these cars have the aerodynamics of a brick anyway so who knows!

The upwards angle on mine happened to be 15 degrees (same as the frame). On the weekend I blew the rear seal on the gearbox which covered underneath the car (full width) with oil. It was interesting to see that the oil flowed in straight lines from the rear of the gearbox all the way to the tips of the diffuser [before tumbling out all over the back of the car!!]

The Fraser also has a flat tray under the engine as well which no doubt helped keep it all flowing smoothly.

quote:

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Originally posted by Phil.J
Britishtrident is right, the angle of that is much to steep and sudden to work. You'll get mainly drag and turbulance.
I always work on a maximum of 7 1/2 degrees rising to a maximum of 10 degrees from horizontal over a distance of 2-3 ft. length. But these cars have the aerodynamics of a brick anyway so who knows!

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