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Car Forum / Mercedes-Benz Cars / August 2007

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Aftermarket Air intakes for a 5-cyl Diesel

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DougS - 02 Aug 2007 18:02 GMT
I was looking at my 84 300D engine and realized that the air cleaner
really puts a lot of twists and turns in the flow path for the air
coming in. I was thinking about streamlining this flow with an
aftermarket air cleaner/intake piping.
Has anyone else done this, or can recommend this for increased fuel
mileage and/or power from their engine?

Additionally, the engine has 263k miles on it, does that make a
difference?
Tiger - 02 Aug 2007 19:35 GMT
MB filter housing is the best... I would not change it for anything. Alot of
time, these aftermarket filters makes things worse... especially for gas
engine.... like those conical one that requires you to eliminate your
factory airbox... those  are just dumb as it is sucking hot engine air
rather than colder denser air via air duct.
DougS - 03 Aug 2007 20:38 GMT
> MB filter housing is the best... I would not change it for anything. Alot of
> time, these aftermarket filters makes things worse... especially for gas
> engine.... like those conical one that requires you to eliminate your
> factory airbox... those  are just dumb as it is sucking hot engine air
> rather than colder denser air via air duct.

Thats my point though. The factory airbox has a lot of restrictions
and turns to get to the turbo intake. Additionally, the "cold" air
intake for the factory air duct is only about a 1"x6" slot mounted
above the passenger headlight with a 2" plastic hose leading to the
filter housing. Not nearly as large as an aftermarket pipe would be
pulling in air directly from below the car (i.e. away from the
engine). Whether it is 50F hotter air or not doesn't make a difference
if there is 4x the volume getting to the turbo (or 4x less depending
on your POV). Another concern is to get the housing off of the top of
the turbo and exhaust. That is the hottest part of the engine, and it
basically turns the housing into an oven.
My thought was to provide a K&N filter housing that would draw air
from a cooler part of the car (not the hood) lower in the engine
compartment, with a much larger pipe to get the most air into the
turbo, while also moving the filter from atop the turbo and exhaust
manifold. I should mention that since this car is my daily driver at
the moment, I won't actually be performing any of this work yet. I
just want to do a little research and thought that I would bounce some
ideas off of this newsgroup.

Secondly, has anyone noticed any adverse effects when removing the PCV
tube that goes to the air filter? I don't mind recycling those blow-by
gases, but it sure does get the air filter nasty.
Tiger - 04 Aug 2007 00:08 GMT
With turbo, it doesn't matter... because the turbo takes care of the
restrictions like any compressor would. It is trivial... or othertwise MB
wouldn't design it that way.

Drawing cool air from bottom of engine compartment will lead to suction of
water in rainy day from splashes and will destroy the turbo and engine. You
can't compress water

On 95 E300D, MB actually made snorkel fins on the passenger side fender for
cold air intake. On your car, I think it is from behind headlight area.

Turbo will heat up the air... and it doesn't matter if you could get 4x more
air... turbo will only pushes as much as it can... 11 PSI... and drawing hot
air at that pressure will lead to even hotter air and less O2 than the
factory air duct routing.
-->> T.G. Lambach <<-- - 03 Aug 2007 00:58 GMT
The turbo boosts the intake pressure to as much as 11 psi at full
throttle. That's about the limit for the engine, especially after 26K
miles. Forget it.
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© 2007 T.G.Lambach. Publication in any form requires prior written
permission.

DougS - 03 Aug 2007 20:43 GMT
On Aug 2, 7:58 pm, "-->> T.G. Lambach <<--" <"T.G. Lambach at
NoHamorSpamcomcast.net"> wrote:
> The turbo boosts the intake pressure to as much as 11 psi at full
> throttle. That's about the limit for the engine, especially after 26K
> miles. Forget it.
> --
> ? 2007 T.G.Lambach. Publication in any form requires prior written
> permission.

While that is true (about the turbo), it can only compress what gets
to it. The more air you can get into it, the more it can move (and the
more completely the fuel will burn). I basically just want to get it
to be the most efficient it can be. 11psi seems to be about the
average for the turbo boost, but the spec is closer to 15psi isn't it?
I know someone else was saying that 16psi is the mechanical limit due
to fuel deliver and safety valves, but you still have to get enough
air into the turbo/engine for it have something to compress and burn.

I assume you just mistyped my mileage. It was 263,000 miles, not
26,000 miles.Yes, over a quarter of a million.I'm shooting for 3 more
quarters on it.So I won't be hot-rodding it, just trying to increase
efficiency and gas mileage.
Tiger - 04 Aug 2007 00:10 GMT
There is much easier way to get 5 extra MPG... just put in Marvel Mystery
Oil into your fuel... 4 to 6 oz per 10 gallons of fuel. It is cheap enough
and no messing with air filter.

Routine Diesel Purge will make sure you injectors are clean... this is much
more important than anything else.
-->> T.G. Lambach <<-- - 04 Aug 2007 02:38 GMT
The turbo boost specification is 10.2 - 11.6 psi at 4,000 engine rpm,
under load in L or S gear.

The safety switch on the intake manifold opens at 16 psi to prevent a
runaway engine.

These engines were "efficient" in their time - about 40 HP / L. That's
what gas engine were making at that time too.

The way to have an efficient engine is to regularly change its oil and
filter, keep its valves adjusted, replace the injectors with Bosch
remanufactured ones (to improve the spray pattern) and keep the paper
air filter clean. Then leave it alone to do its job.

I've driven a '80 300SD since new and do those things and it runs like
it did when it was new.
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© 2007 T.G.Lambach. Publication in any form requires prior written
permission.

DougS - 06 Aug 2007 20:36 GMT
On Aug 3, 9:38 pm, "-->> T.G. Lambach <<--" <"T.G. Lambach at
NoHamorSpamcomcast.net"> wrote:
> The turbo boost specification is 10.2 - 11.6 psi at 4,000 engine rpm,
> under load in L or S gear.
[quoted text clipped - 15 lines]
> ? 2007 T.G.Lambach. Publication in any form requires prior written
> permission.

Thanks for the responses and the recommendations. I've definitely
decided that my money is better off somewhere else in my car (like
fixing the vacuum leak in the passenger door). I haven't used the
Marvel Mystery Oil in a while. I had been using the Lucas Upper
Cylinder Lubricant (I had a quart of it in my garage), and my uncle
recommended it (he's a farmer and a real diesel nut). I will probably
look at the Marvel and see how its price compares to the Lucas. I have
always changed oil and filters regularly in all my vehicles, and am
pretty good about keeping up on other routine maintenance.

This is totally off-topic to this thread, but I was wondering, what
kind of oil (weight, brand, synthetic, etc.) do you (i.e. anyone
reading this) put in your diesels when you change the oil? I bought
two gallons of Mobil Delvac 15W-40 when I changed the oil the other
day, how does this compare to the normal run of diesel oils?
Tiger - 06 Aug 2007 22:16 GMT
Most popular is the Chevron Delo... followed by the Mobil Delvac followed by
Shell Rotella. All three are excellent oil and all can be bought at
Walmart... (I am not sure about Delvac)

15W40 is the standard oil for diesel engine.

5W40 is the standard for diesel synthetic oil.... Shell Rotella Synthetic
oil is the best deal at $4 a quart when bought in gallon size. Better oils
are Mobil 1 and Amsoil... but they are much pricier... 50% more.
trader4@optonline.net - 06 Aug 2007 22:30 GMT
> Most popular is the Chevron Delo... followed by the Mobil Delvac followed by
> Shell Rotella. All three are excellent oil and all can be bought at
> Walmart... (I am not sure about Delvac)
>
> 15W40 is the standard oil for diesel engine.

For my 1980 300SD, the manual lists 15-40 as acceptable for temps
above 23F.  Below that, it's 10-40.  So, I use the Rotella in most
months, and a diesel rated 10-40, think it is Valvoline in winter.

> 5W40 is the standard for diesel synthetic oil.... Shell Rotella Synthetic
> oil is the best deal at $4 a quart when bought in gallon size. Better oils
> are Mobil 1 and Amsoil... but they are much pricier... 50% more.
DougS - 07 Aug 2007 20:12 GMT
> Most popular is the Chevron Delo... followed by the Mobil Delvac followed by
> Shell Rotella. All three are excellent oil and all can be bought at
[quoted text clipped - 5 lines]
> oil is the best deal at $4 a quart when bought in gallon size. Better oils
> are Mobil 1 and Amsoil... but they are much pricier... 50% more.

Thanks for those recommendations.
Does anyone see any issues with using synthetic in a diesel with
263,000 miles on it. That has presumably used conventional its entire
life? I did notice that Wal-mart had the Shell Rotella Synthetic the
other day for only a few bucks more than what I paid for the Mobil
Delvac at Autozone. So I might go with that next time.

I wrote an summary of how my oil change went on my Mercedes on my blog
here: dougsmb.blogspot.com If anyone cares to read about it, or wants
to see pictures of my MB, then check it out.
Tiger - 07 Aug 2007 23:43 GMT
If you have no leak or excessive oil lost, then it should be fine. I
switched to synthetic when engine are at  like 205,000 miles or 196,000
miles... two different cars. Another one at like 115,000 miles. no problem
with any of them.

That's what I used.... the Shell Rotell Synthetic. It is great in winter.
JD - 08 Aug 2007 01:06 GMT
> If you have no leak or excessive oil lost, then it should be fine. I
> switched to synthetic when engine are at  like 205,000 miles or 196,000
> miles... two different cars. Another one at like 115,000 miles. no problem
> with any of them.
>
> That's what I used.... the Shell Rotell Synthetic. It is great in winter.

What kind of oil change interval do you follow with the synthetic?

JD
Tiger - 08 Aug 2007 15:18 GMT
10,000 miles.

For the diesel, it would be extra nice to just change the oil filter at 5000
miles and change both at 10,000 miles.
-->> T.G. Lambach <<-- - 07 Aug 2007 17:43 GMT
Chevron Delo 400 15 - 40 CI - 4Plus and an OEM filter (Mahle-Knecht)
that I buy from www.autohausaz.com
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© 2007 T.G.Lambach. Publication in any form requires prior written
permission.

 
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