Aftermarket Air Filter Mutation

[Mark_B]

When you arrive at the counter of a general car parts shop and ask for an Air Filter, chances are the helpful sales assistant will identify it out of a book, after asking you some questions about year and engine size, he'll come back with a box which contains what appears to be the exact part, shiney and new....

Now, I'm beginning to form the opinion that over the last 10 years or so that air filter has grown gradually, to the point where air flow is now affected, affecting engine breathing. (Newest: Fram CA4744A, equiv. to their CA3166). The air has to flow into a doughnut-shaped inlet area, between the inside of the airbox and the outside of the filter. This inlet area for the new filter turns out to be half my previous filter.


Has anyone else noticed this?

The summary of sums :

New filter fitted, effective inlet area = 2372 sq-mm
Old filter refitted, effective inlet area = 5840 sq-mm

Mass Airflow inlet Area = 3848 sq-mm

Now I wouldn't had thought 2372 was much less than 3848, enough to affect the breathing but it does seem to be.
When I refitted the old dirty filter, the engine performance returned to normal....

update... I ordered in another filter from Halfords of all places, and yes it's considerably smaller, same size as old (dirty) filter. There's not much difference engine performance between the old (dirty) filter and the newest, but the middle one 'Fram CA4744A' makes the engine a bit gutless.

Conclusion: I don't think a Fram 4744 is suitable, even though they list it suitable for XJ-S 3.6 1986-on.

[Gordon@1962]

Just a thought...................

How does a genuine Jaguar part compare?

[Mark_B]

I don't know how the original jag one compare, I haven't seen one yet. Be interested what the outside diameter is.

[poprivet]

AJ6 Engineering tend to use the K & N, JR, or Pipercross re-usable air-filters. I don't think I would argue with Roger about their suitability, so I may go in that direction sometime in the future.
Pop

[sinclairkbm]

Good topic this one....

How was the engine performance affected with the "new" filter?

Sinclair