My lr defender td5 1999 went to a lr specialist due to a lack of boost problem. Found out runs great without an air filter what so ever. As soon as a standard one goes in power dies significantly...

They suggested trying a good panel filter to see if it works. So I need one which allows maximum air through but to filter. Standard one does not work.
Any recommendations. There not cheap and for it to still not work will be a bit of a pain.
Thanks in advance.

I'm a bit suspicious about that solution though, IMO this thing should be fixed for good as to restore the engine's functionality as it left the factory, if the turbo doesnt have enough power to create sucction through a genuine filter the problem is there somewhere ... my advice is to bring it to a real specialist or to someone who knows it's job for a second oppinion.... i have no confidence that the "specialist" made a proper diagnose if he came back with such childish suggestion.

I haven't seen this happen on a TD5 but I have seen this happen on a roadtrain engine where the genuine brand new air filter has still created loss of power

the pipe between the air filter and turbo could be collapsing when trying to suck in air on demand ... the genuine air filter could just be enough restriction for a fatigued intake pipe..
under bonnet temps play a big role when diagnosing a collapsing air intake pipe as the fatigued pipe has become warmer

other possibilities the genuine filter is damaged the media may be clogged or has the genuine filter been wet before damaging the filter media

is there is a snorkel fitted and if so .make sure this is clear and nobody has deliberately pushed a rag inside I only mention this as I have seen allot of sabotaging at work ..not on our own vehicles but the company vehicles
if the vehicle doesn't get used much I have seen wasps making a nest inside of snorkels creating a restriction

if this is the case that you have a air restriction I would try fix this asap ..as the turbo will want to pull from another source ie oil bearing seals damaging the turbo

ps when this restriction is happening is there any smoke coming from the exhaust ? and if so what colour

I have a k&n panel filter I could sell you if you want to try one

Utter bollocks, TD5's work well with standard filters and don't need a different filter at all.

Either the current filter's blocked or been wet, or the pipework is blocked or broken when under boost.

I'd strip out all the pipework between the filter and inlet and between the filter and engine and see what's not working/blocked/collapsing or otherwise fecked. Some original hoses can collapse, creating a flap and an airflow problem, right when it's needed. The filter, if it's got wet, loses all integrity and doesn't allow air through.

I also wonder if the exhaust has an issue, but doubt this would give the symptoms of air filter not working, no filter working.