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I was thinking about fitting some K&N air filters to my TR7 2.0 L and l was wondering if you would need to change the jetting on the carbs?

Hi, you will need to change to richer needles as the K&N filters allow more air to enter the carbs than the restrictive standard air filter. The jets do not need changing as it is the shape and profile of the needles that dictate the amount of fuel that is metered into the carbs.

My 2 litre has BAL needles to complement the deep K&Ns along with an extractor exhaust manifold and sports exhaust system. I believe that this is the usual recommendation for this combination. I am not sure what needles would be needed if you are only adding the K&N filters.

Rich.

After reading this up a bit, it is also my understanding that if you have k&n air filters on you need to up-rate your needles to BAl and you need a sports exhaust manifold system.

While you will gain more from improving your exhaust at the same time as you improve your inlet breathing, most of the increase in power comes from the inlet side, & is a really worth while improvement.

I don't use K&N filters, I use Ram Flow, which are about equivalent, with BAL needles, & the response was more than I expected.

Hasbeen

Thanks for the help guys now just need to get some money together and get on with purchasing the items.

The needles are reasonably priced. Its the filters that cost more than you'd think.

If it came to it you could do it in stages. I got a price check from Robsport for BAL needles and they came in at just over £11 each. My car currently has the filters and the exhaust but not the needles and she still moves

Your filters must be full of dirt Phil, you drive gently at low revs, or you have the BAL needles.

With free flowing filters & standard needles the thing will go into fuel starvation a bit under 4000 RPM.

Hasbeen

Mmmm that has me thinking Hasbeen. I have not taken the cars apart to see if I have BAL needles. I just thought that I had normal as I put the k& n filters on.

I agree. Without the needles it will feel dead flat above 4000 rpm

It's an easy check, just a flat screwdriver required. Replacement is also very easy

Cheers guys, it has got me thinking now about it. I will have to have a look the weekend.

I have never run a 7 with BAL needles & a restrictive air filter.

I should do it some time, as an experiment, to find out how it runs, & how the performance is effected.

Hasbeen

Short of changing the camshaft to a higher lift item I think the best thing you can do to a TR7 is to remove the original fan and the whole pulley assembly and stick an electric on. K&N air filters might not do a darned thing other than affect cold running... badly.

John_C wrote: .. K&N air filters might not do a darned thing other than affect cold running... badly.

Depends were you locate them!
http://tr7beans.blogspot.nl/2015/04/cool-air-and-noise-reduction-part-2.html

After fitting KN filters on previous cars and finding it affected the performance badly I tend to stay away from them.I would like to see some "scientific" analysis of the air/fuel mixture before and after fitting and adjusting things.Note I am not saying good results are not achievable.I have some injected cars with datalogging and fitting a new "standard" exhaust system affected the driveability noticeably,confirmed by the datalogs showing greater fuel mixture adjustment.Just my thoughts,Steve