306TD K&N Induction

I did try to be vague, as I know that how I described is not exactly how the process works. A standard diesel engine I presume, is set up to inject as much fuel as it can burn per revolution (or every 2 revolutions if you like) with the air restriction present in the ports, inlet tract and air filter. As much air as it needs to burn all the fuel that has been injected. More air and no extra fuel doesn't make it go faster. Is that not as much air as it needs?

I understand that part. The OP's question was not about fitting a partially blocked filter to his car though, so I didn't add that in.

Right, I understand this part too, I think I mentioned the part about altering the fuelling. However, we agree that simply adding a more freely flowing air filter won't really make the blindest bit of difference?

However, fresh filters, be they cheap and standard or aftermarket and expensive not really restrictive enough to make any significant performance difference to an otherwise stock turbo Diesel car?

I think that for the intents and purposes of getting a few extra BHP out of your diesel runabout, buggering with the fuelling and throwing the filter away is not a particularly good plan, assuming you want to keep it for any length of time.

Douglas

The kit alone wont make much (if any) difference, apart froma bit more noise. Howver if you combined this with a few other modifications, namely additionaly fueling/cooling you will see a bit mor benfit. Howver, this is best left to the professonals.

none, but engines are engines. If its underfueled enough to matter the manufacturers may have noticed it...

K&N verses a clean standard filter in terms of power / torque, no.

With the K&N you may get the turbo to spool very very slightly quicker, but I doubt you'd notice, due to the filter being slightly less restrictive than the standard one.

More power = more fuel + more air.

With a 306 of 98 vintage with anymore than 50k on the clock you can almost guarentee the actuator has gone soft, and lost you some power, so first thing would be to hook up a boost gauge and replace / reset the actuator to stock boost, which for this engine is 1 bar. You'll probably then find its going lovely for you.

However, you can safely run 1.1-1.2bar *on a healthy engine* before EGT and charge temps become a problem, with the fuelling opened up slightly to suit (before soot becomes a problem) which properly set up will give around

Any more and you;ll need a front mounted intercooler, and replacement downpipe from the turbo (stock is restrictive) afterwhich a safe 1.5bar can be had and 120bhp. Personally I'd be using a hybrid turbo at this point though.

The stock XUDT won't stand any more on the stock turbo and headgasket.

Tim..

Except the OP isn't likely to be.

Wassup? Still trying to work out how to measure -ve voltage using a multimeter on the AC range?

What he said. And as we hate each other but agree on this, it's pretty much spot on.

If the K&N actually meant 2% more air, then it would be a good idea. But in practice, I don't think there is much difference even if you take the filter out altogether, on most engines, unless they are very high revving.

Conversely, taking off all the trunking and putting a simple cone or pancake on instead will change things, possibly for the better.

Revs are not important, just filter area, and mass airflow.

Hot air is always worse as its less dense, all that trunking is designed to give cool air to the motor. And pancake filters are ok if they are huge!

Just wanted to say thanks to everyone contirbution.... I've decided to just stick with a normal airfilter. I did think about the post where someone mentioned about trunking? Not sure what that is, but if its all the twisty pipework linking airfilter to pipe that goes into the engine - then boy, the air must get fed up going round such a distance.

But i'm not car bod, so i listen to you guys. Thanks one and all

cheers ant

I just fitted a large K&N to the locost, had to cut a bigger hole in the bonnet for it, then make a "trim ring" to cover the old hole. It's far too big, but was only £20 and it's shiny :) It can't be any worse than the old one, and it'll do it's proscribed job fine (to keep rain out of the carb ;).

Oh yeah, and the extra 20bhp O'course :)