An air filter question.

Post by **jed the spread** » 28 Sep 2006, 20:57

does anyone know anything about performance air filters for the t25?
my brother in law put one on his honder and he says its really good but he really needs a twin exhaust for it to work best.so i thought as ive just had a twin exhaust put on the van i may as well have the flashy air filter to try and get more horse power.

jed

Website · Post by **CovKid** » 28 Sep 2006, 21:44

Not sure I follow the logic on this one. An air filter in its own right has little if any effect on performance. Performance is certainly dictated by an engine breathing correctly (ie sucking air in and blowing spent exhaust out) but really you'd need to be looking at a whole host of things to gain any real performance benefits to this end.

The T25 isn't the cheapest engine to modify and its probably a better bet to consider a different type of engine altogether if you're looking to improve its performance (which will on the whole also increase petrol consumption) - its certainly not as efficient as more modern engines - or indeed as quick.

Post by **jed the spread** » 29 Sep 2006, 06:21

im just going off what my brother in law says.i know nothing about them and am open to any advice or facts on these.it must make some difference to be called a performance air filter.the cold air is sucked in through a tube that runs to a point outside the engine bay.something to do with cold air being more dense than the hot air in the engine bay.
i think it works best at the top end.

jed

Post by **T'Onion** » 29 Sep 2006, 07:01

Jed
you run a 2.1 don't you ?
I think you'd have to have an adaptor made to fit on the air intake sensor box.
probably would make a little differance but not that much
Have a look or post a thread on the brickyard. or acidento (sp)

Website · Post by **CovKid** » 29 Sep 2006, 07:17

The wedge does take its air from outside - controlled by a thermostat. When the engine is stone cold it theoretically doesn't - drawing engine from inside the engine bay instead.

Perhaps if you had a progressive carb and a different exhaust it might make a very tiny difference. The idea of a 'performance' air filter is its designed for a performance engine, not to gain any noticeable in increase in power in its own right. After all, if you bore an engine up and change camshafts, that kind of thing, its breathing requirements change considerably but on a stock engine - waste of money.

It might come in a pretty box and the retailer might well sing its praises but you'll get just as much an increase in performance if you put stripes down the side of your van.

Post by **matt** » 29 Sep 2006, 07:56

But, Jed just loves shiney things, and is a millionaire

Post by **Dubstar** » 29 Sep 2006, 08:28

Technically speaking a performance air filter and exhaust would give a greater benefit to a modified engine with a decent cam, in terms of better breathing abilities, but it will also benefit a standard engine too. Not massively, but enough to notice. Should gain a couple of BHP over the standard with slightly better fuel consumption if set up properly on the rollers. This is because of the fact that the engine can breath better and expell the exhaust gases quicker, and is therefore more efficient at burning the petrol/air mixture. I've had Mini's and XR2's and Opel Mantas in the past, and it all worked well on them, especially the Mini. The aim of it all is to get the engine breathing more efficiently. If you can also get a cold air feed going to the carbs, then this helps too, as the air is denser, and contains more oxygen to help with the burning process. You just have to make sure it doesn't ice the carbs in cold weather. Hope this helps and that I'm not talking bollox. I'll be soooo embarassed, but I think I'm right. Please!

Post by **syncroand101** » 29 Sep 2006, 08:50

Jed

I don't know about the performance improvements - if you can get cold air to it better - then possibly.

When I investigated this. You can either replace the standard filter which is in the box with a K&N one. Alternatively this company in the states supplies a filter with an adapter to get rid of the airbox (or did when I was looking at it)

Might also make your exhaust sound a bit raspier as well

Post by **Arvi** » 29 Sep 2006, 09:26

air filter that is standard draws cold air from the rear off side top grill to insure that the coolest air poss from the out side is always put into the engine plus less chance of water getting in

if you put a replacement cone filter you will most likely have to put it in the engine bay meaning that your engine will get hot air which is less good for power

Website · Post by **CovKid** » 29 Sep 2006, 13:33

Yep Dubstar - if its been modified. A standard engine on a bog standard exhaust won't benefit from a different air filter though. A clean replacement might but then only marginally. The costs involved in modifying a T25 are hardly worth the extra BHP potentially created. Makes more sence to fit something more efficient and ready to go.

I'm not saying that the T25 is already maxed out, you could get more out of it but not without additional cooling and even then, with petrol the price it is, it doesn't make economic sense. Reliability becomes an issue too once you start pushing it past its limits. The bug engine was a different thing since so many custom parts were available for it but the T25 never really had that luxury. Air filters, 009's, its all a waste of time without pulling the thing apart, doing all the maths and in a lot of cases, having parts machined to do the job. As mentioned elsewhere on the forum, I did build a monster Beetle engine for a T25 crewcab (has the height in the engine bay) and that thing REALLY shifted but jeesh it drank fuel too. Engines have come on a long way in the last 20 years and there are many alternative engines that are more economical and frankly faster than the wedge engine.

I may be lucky but my stock 1.9 petrol pulls incredibly well - drives like a car. I've built probably hundreds of VW engines over the years for all kinds of purposes but I have to admit, there are better alternatives these days - hence the 'Alt Engines' forum.

Post by **jed the spread** » 29 Sep 2006, 14:22

thanks for the info guys very interesting points

jed

Post by **syncroand101** » 29 Sep 2006, 15:00

To conclude for you Jed... Put a subaru engine in.

Website · Post by **CovKid** » 29 Sep 2006, 17:53

Yeah we're not trying to put you off - just saving you money and a headache really.

Post by **DiscoDave** » 29 Sep 2006, 18:10

well i'm amased!!! all these answers and no one has sugested the most blindingly obvious, get rid of that stupid box off the back, remove the ridiculous sunvisor, hey presto another 63mph on to your top speed! it cost's nowt, and you may actually be able to sell the items to another retard with more money than sense, i wondered how long it would take for you to get bored at 17mph!!

Post by **jed the spread** » 02 Oct 2006, 06:28

thanks again for the very kind words dave

jed