Replacing Air Filter 250S

[Rennen]

Hello all. I am thinking of replacing the factory air intake & filter setup with a more open K&N style assembly. It runs much more efficiently and more economically without the original setup and so assume this might be a good way to go. Anyone here tried this already?

[W108-1967 250S]

Rennen,

I have had my '67 250S setup powder coated gloss black-(make sure you clean the sandblasting grit out the breather pipes)- and had the latches re-plated. Looks awesome. If that's your white car pictured on your post-man if you ask me it would be a pity to modify, I think 108's are starting to reach a stage when an original car will have better re-sale? But that is me-an originality freak!

[CraigB]

That's a very honest response - and a bit funny for me - that internal fight that goes on with " i like it original" but then accommodating other ways of thinking and that anyone can do as they please of course.

And sounds like anything is reversible in this area. But back to the question, hasn't there been posts of people fitting a K&N cylindrical filter into the standard housing? There is heaps of area so I doubt the tract would cause too much restriction. Actually I thought the standard oil bath wasn't that bad, but just an impression and I have no evidence. I think the conversion is just a matter of removing the wire bit and of course it need to seat somehow.... try doing a forum search but it may have been back in the really old, old format days.

[pastelgrey300D]

Matt Riots is running aftermarket style filters on his car - maybe send him a PM. From what I can remember the original filter box assembly is entirely removed and the filters just sit on top of the carbies - so the original setup can go back on there at a later date if you wanted to and the whole thing is entirely reversible.

Then again, you could always do something like this:



.... but I don't believe there is a standard 2.8 litre 6 under that hood!

[Rennen]

Not overly concerned with originality as its now MY car with no intention of resale. :pray: Not sugesting any dodgy mods either of course but subtle "period" enhancements...

I recall seeing a company in the US that makes filter housings to suit so will look into that. Then again the weber option appeals too.

[pastelgrey300D]

Here you go, speak to Murky one - he has the twin zeniths and is just about to do an engine swap so I assume the filters would bolt right up?

viewtopic.php?f=9&t=11486

[Rennen]

Here you go, speak to Murky one - he has the twin zeniths and is just about to do an engine swap so I assume the filters would bolt right up?

viewtopic.php?f=9&t=11486

I did see that - only its not quite what I am after. I think Murky's are Supercheaps Calibre brand and a bit too modern for the look I want. I can see in my mind a factory style housing, as in oval & black, and without sides, so a K&N sandwich really.

[pastelgrey300D]

Aha - on the same page now!

Sounds like something you could even fabricate yourself if you can't find one that is pre made.

[Mercmad]

perhaps your original filter was dirty ?
This is a pet subject of mine and good friend in the USA was intrigued enough to try his car on a dyno with the stock mercedes air filter set up. A few runs were made (for fun) to get an average then a few runs were made with no air filter and some runs were made with a k&N filter.
The results without the air filter showed a lower horsepower reading and a sharper torque curve. The K &N showed a complete loss of Horsepower and torque . *
The big issue is the feeding of hot under bonnet air into the engine. it's a sure fire way to lose power and it's been known about for at least 80 years.
The mercedes air intakes were designed using experience gained in both racing (where they were King prior to 1955) and Aircraft engines.
K&N filters were designed to be sold in places like Supercheap .

K&N Are great marketers but sell a product which has been shown time and again to be lacking .

* This is the same car here with it's factory aircleaner at the drags in Oregon Some years ago.
http://www.youtube.com/watch?v=v4M4tRf0eoo

[CraigB]

I get it about the cool air, you only have to look at the effect of an intercooler - and the theory of it is that cool air is more dense (opposite of heating and expanding) so when your valve opens you are sucking and fitting more fuel air mixture in and therefore a bigger bang. But if you use the same air cleaner set up, or better still something increasing the cold air intake (like Gregs mod on his 350slc) then I would be surprised if the K&N would be worse. I have a K&N replacement in my 500sec and using the standard cold air intake set up, and while I didn't do any 'parallel testing' in the dyno, it was still a respectable figure and about what AMG quoted despite 170k km of use - that is not many horses appeared to have got away! Still, it needs to find its way back on the dyno to rectify something, so I might buy a brand new standard one and see if any difference.

[Rennen]

Aha - on the same page now!

Sounds like something you could even fabricate yourself if you can't find one that is pre made.

The only problem is I want it to look professional!
The car is going through a bunch of subtle 60's 70's style mods so nothing too drastic or funky. Might not happen overnight but will happen

[Mercmad]

I get it about the cool air, you only have to look at the effect of an intercooler - and the theory of it is that cool air is more dense (opposite of heating and expanding) so when your valve opens you are sucking and fitting more fuel air mixture in and therefore a bigger bang. But if you use the same air cleaner set up, or better still something increasing the cold air intake (like Gregs mod on his 350slc) then I would be surprised if the K&N would be worse. I have a K&N replacement in my 500sec and using the standard cold air intake set up, and while I didn't do any 'parallel testing' in the dyno, it was still a respectable figure and about what AMG quoted despite 170k km of use - that is not many horses appeared to have got away! Still, it needs to find its way back on the dyno to rectify something, so I might buy a brand new standard one and see if any difference.

Craig,AMG ,and few blokes i know in Germany found that the 500 and 6.9 benefit from a very simple mod...a 560 aircleaner. in fact on a 6.9 you can actually feel the difference . The m116 and M117 air cleaners are so common ( I have a pile of the damn things) that you can cut another hole in the passenger side and use the plastic snorkle from another one . Connect it to the air in front using a W124 300E intake nozzle and you have increased your intake area. Saves hunting around the wreckers in OZ for 560 aircleaner which aren't that common here.

[Mercmad]

Hello all. I am thinking of replacing the factory air intake & filter setup with a more open K&N style assembly. It runs much more efficiently and more economically without the original setup and so assume this might be a good way to go. Anyone here tried this already?

A thought has occured,what type of aircleaner do you run at the moment?
There is a flat style one used on the later W108's with dual Zeniths that is really efficient. It's vast improvement over the oil bath type commonly found .

Drews new engine 001.JPG

[John Green]

Did you know that there is a paper element filter that can fit in where the oil bath elemnent used to be. No modifications required. Phone us for details.

[W108-1967 250S]

Interesting the cold air factor, that's the one, colder, denser, so more fuel can be mixed in, bigger charge. Rolls Royce took it seriously. The Merlin 60-70 series engines powering the Spitfire Mk IX's (umongst others) had a huge intercooler sitting between the supercharger and inlet manifold, to cool the supercharger output. It used it's own glycol liquid cooling circuit. The coolant was cooled by a radiator element that took up about half the one side of the (left or right, can't remember which) the underbelly radiator housings. This engine was serious metal-two stage, geared supercharger, 4 valves per cylinder (double OHC and sodium filled exhaust valves of course), 6 journal crank with two conrods (one split) per journal to keep engine short. 27 litres, that put out 1650HP at war emergency (through the gate), no re-build required! What on earth has this to do with Mercs? Nothing! Just impressive piston power!

[Rennen]

A thought has occured,what type of aircleaner do you run at the moment?
There is a flat style one used on the later W108's with dual Zeniths that is really efficient. It's vast improvement over the oil bath type commonly found .

Drews new engine 001.JPG

[/quote]

Hi Mercmad. That looks a bit more like it. I have the oilbath type but am thinking of simply opening up the carb covers and inserting an oval BMC/K&N filter as a first step. Might track down a spare one first though. If that fails on to plan B or A unless C crops up..

[250S1966]

Straight swap for paper filter VAICO V30-0803. Just bought one for my 66 250s from run auto parts which is an AUS site.

[VFRBoy]

Straight swap for paper filter VAICO V30-0803. Just bought one for my 66 250s from run auto parts which is an AUS site.

Have you got a link? Hey also I have a 1966 250S, I'm in Watsonia so pretty close by. Got any pics?

[CraigB]

This is an old thread and good to know that filter part number - but just thought i would add the point, what's wrong with the old oil bath? As the earlier dyno tests that Mercmad referred to, there is evidence that they work excellently - plenty of volume of air, don't get restricted as they get dirty like a paper filter and back in the day for some cars was a cost option because how much better they work, although more expensive to produce. What the original poster said doesn't make sense unless there was actually something wrong with the original. Seems like a retrograde step to me but at least if you just replace with paper in the original you retain the cold air intake that took a lot of manufacturers a lifetime to use the principle. Also bear in mind people will tell you all sorts of things if they are trying to sell you something and if half the products that claim to increase HP actually did it there would be a lot of fast cars around. As i said earlier, i put a K and N in my W126 cold air intake system, but only to replace paper. I don't think there is any HP increase but it probably flows better longer and I can clean it rather than ordering and chucking paper - and at the time wasn't much more than paper (although these seem cheaper these days).

And for most circumstances, with regular changes, the paper replacement will work fine, just making the point why bother.... Unless i am missing something that somebody has some evidence for like Mercmads post.