This is not directly MB related but it is diesel. I have an 82 Bluebird Wanderlodge CAT 3208 with an aftermarket turbo mounted on the left exhaust bank and the air filter under the chassis, low in front of the left front wheel.
When I first purchased it, I was driving across country and noticed the EGT's climbing, eventually to about 1200 degrees on long steep hills. After experiencing some other problems, I discovered the air filter was dirty and upon replacement, EGT's maxed out around 950 degrees.
I installed a k&N air filter condition detector on the vacuum side of the filter and after about 5k miles, the detector is sucked down about halfway through the yellow. (Red is fully sucked). I've noticed the EGT's beginning to rise, maxing at about 1050 or 1100 on a long climb yesterday.
My question is, have other people noticed this same correlation and experimented with it?
My other question is, how effective is blowing out the filter. My CAT 3208 manual shows a procedure for blowing off a filter or washing with water. The filters are expensive at $80 per shot, but I don't like driving with higher EGT's than necessary.
Does anyone know what kind of vacuum range our 617's have between the air filter and turbo intake under normal conditions? My 307d with a 616 had an air filter condition detector between the filter and intake manifold but I've never seen one on an MB automobile.

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1977 300d 70k--sold 08
1985 300TD 185k+
1984 307d 126k--sold 8/03
1985 409d 65k--sold 06
1984 300SD 315k--daughter's car
1979 300SD 122k--sold 2/11
1999 Fuso FG Expedition Camper
1993 GMC Sierra 6.5 TD 4x4
1982 Bluebird Wanderlodge CAT 3208--Sold 2/13

The 3208 shouldn't be turboed, as you know there are lots of differences between the 3208Na and the 3208Ta (and 3208ATAAC). My 3208Ta and 3208ATAAC engines would often run 1450*F on long climbs at 15psi, considered normal for the turbo engines, they are designed to take the heat. The Na engine does not have the valves of the turbo engine or the piston-cooling oil sprays, I believe the pistons are different also, and the turbo engines have a roller-cam.

Yes, more air will mean a cooler charge. Getting the air from outside of the engine bay is also important, you're there. High EGTs are wasted power / efficiency.

I'd like to know also how much vacuum is normal between the air filter and the turbo, less is always better. I'm guessing that your 'Bird could use a bigger/better filter, talk to Mike Hohnstein about possibly getting an air filter system from a GMC top-kick or something that will better suit your engine, or if it is clogging quickly from being in dirty air beneath the coach, maybe something from construciton equipment with a cyclone to drop the initial large particulates before getting to the paper element. Most vehicles pick up intake air from as high as possible for this reason.

__________________

Gone to the dark side

- Jeff

The EGTs go up because vacuum before the turbo raises the pressure ratio the turbo has to work in to produce the same boost. Higher pressure ratio means its spinning faster and making the intake air hotter.

Just like a vacuum cleaner. Fire up the ol' vacuum, put your hand over the hose and you should be able to hear the blower speed increase. Put your other hand near the outlet and eventually you'll feel the air getting hot.

I know in an ideal world, the engine shouldn't be turbo'd. The original owner turbo'd the original engine in about 1983. It had a second engine installed (CAT rebuilt) in the late 90's but I'm pretty sure it still had the internals of the NA version and not the upgraded turbo internals.
The turbo doesn't produce much boost--maybe 7-8psi max and that very rarely. Typically it's putting out 1-3 psi. Its main advantage as I see it is overcoming the thin air in Colorado, as opposed to actually increasing engine power substantially. I see it as solving the breathing problems the NA's seem to have in the bus applications.
The air filter is listed as OE for a Detroit 4-53. I have considered the problems of location and size of the filter. Running a plastic pipe up the bus beside the driver's window doesn't seem like an aesthetically pleasing alternative. Room under the bus for any filter size change is extremely limited.
I've also thought that the fact that the filter is only about 18 inches off the ground may cause it to get wet in rainy conditions, accelerating the clogging process.
The K&N filter gauge doesn't show inches of vacuum. I wish it did. I initially considered installing a standard vacuum gauge but it was simpler to just install the K&N rather than running the tubing for a gauge up into the driving compartment. A ratcheting gauge similar to the K&N would be useful to get precise numbers.

__________________
1977 300d 70k--sold 08
1985 300TD 185k+
1984 307d 126k--sold 8/03
1985 409d 65k--sold 06
1984 300SD 315k--daughter's car
1979 300SD 122k--sold 2/11
1999 Fuso FG Expedition Camper
1993 GMC Sierra 6.5 TD 4x4
1982 Bluebird Wanderlodge CAT 3208--Sold 2/13

I like things that are aesthetically pleasing but I think if it were mine I would figure a way to get the intake up away from the ground and rain water.

My cummins has a filter guage similar to what you describe....perhaps it would be closer to what you need. I imagine it could be adapted.

Tom W

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[SIGPIC] Diesel loving autocrossing grandpa Architect. 08 Dodge 3/4 ton with Cummins & six speed; I have had about 35 benzes. I have a 39 Studebaker Coupe Express pickup in which I have had installed a 617 turbo and a five speed manual.[SIGPIC]

..I also have a 427 Cobra replica with an aluminum chassis.

Perhaps you could construct a baffled intake that allows the moisture and dirt to settle out of the bottom before entering the air-filter system.

And a 4-53 is a tiny engine, 206cid non-turbo compared to your turbo 3208 which is over 600cid, ... no wonder you don't have any boost! Get a good cyclonic air filter from a farm supply house with at least a 3" outlet, preferrably larger.

Oh, and if it's a turbo block, you'll see the mounting for the turbo on the top/rear of the block between the intake and the bell-housing.

__________________

Gone to the dark side

- Jeff

Add another one in parallel to your existing filter.

You could also do the dual external chrome filters semi-style.

The existing filter is rated for 300cfm's. Anyone know how to figure out how much CFM's a CAT 3208 would use?


Edit: Wix filters shows 2 filters for the 3208, one with 250cfm's and one with 390cfm's. It doesn't list them as NA/turbo but I assume that accounts for the difference. In that case, 300cfm's on an NA with aftermarket turbo is not completely out of line.

I think the difference between the air requirements of the smaller 4-53 and larger 3208 is explained by the 4-53 being 2 cycle and the 3208 4 cycle. I think that means that the 4-53 is swallowing air at the same rate of a double sized 4 cycle engine.

__________________
1977 300d 70k--sold 08
1985 300TD 185k+
1984 307d 126k--sold 8/03
1985 409d 65k--sold 06
1984 300SD 315k--daughter's car
1979 300SD 122k--sold 2/11
1999 Fuso FG Expedition Camper
1993 GMC Sierra 6.5 TD 4x4
1982 Bluebird Wanderlodge CAT 3208--Sold 2/13

Probably a lot more than 300. Diesels love the air.

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1981 300 SD 213k miles "Stock for now"
1999 Super Duty 7.3L 113k miles
1981 300 SD 180k miles "Heavily modified" SOLD

I had considered the 2-stroke factor, but even if you double the displacement for comparison, it would be a 412cid engine vs over 600.

Since the Na is a 3100rpm engine, vs the Ta at 2800, I' guess that the CFM requiremet is similar if not more for the Na. Remember, the idea of the turbo is to raise the intake air pressure, the idea of a larger filter is to raise the intake air pressure, ... the larger filter system is free as it is without the heat of compression, the turbo costs you power and engine stresses with the added heat of compression and heat exchange from a hot turbo.

Go bigger. My 3208Na benefitted noticably when the intake air system was modified to allow better flow.

If I were to guess at the CFM requirements, I'd say that a 600cid engine consumes roughly 300ci of air every revolution, at 3100rpm that is 930,000cim or ~538cfm, add 5psi of boost (~.33bar) = 717.4cfm.

You know we should be doing this at the Wanderlodge forum, and I should be selling my racks of NOS Wanderlodge parts there too.

__________________

Gone to the dark side

- Jeff

I looked up the WIX filter for an 81 Wanderlodge 3208NA. Shows a 520cfm filter.

__________________
1977 300d 70k--sold 08
1985 300TD 185k+
1984 307d 126k--sold 8/03
1985 409d 65k--sold 06
1984 300SD 315k--daughter's car
1979 300SD 122k--sold 2/11
1999 Fuso FG Expedition Camper
1993 GMC Sierra 6.5 TD 4x4
1982 Bluebird Wanderlodge CAT 3208--Sold 2/13

Yeah, it's pretty minimal, close to what the engine should be pumping without the turbo. To be completely accurate, the max. operating RPM is 3050+/-30rpm, and Full-Load RPM is something like 2800 or 2900rpm, my calculations was on 3100 where it won't develop full power unless you turn the high-idle RPM up to around 3400, the mechanical governor starts to reduce fuel around 2700rpm. I believe that I posted the procedure for turning up the high-idle (very simple) on the Wanderlodge forum along with the page from the CAT service manual. Use an optical tachometer to be sure it is accurate, the original 90* tach isn't extremely accurate (I have a spare with tach drive in the shop if you need it btw).

__________________

Gone to the dark side

- Jeff

The formula I remember from years of reading Hot Rod and Car Craft in my younger days is:

Flow=volumetric efficiency x (rpm X CID)/3456

If we assume 110% volumetric efficiency (from the little turbo) and 636 CID, which I think is the displacement on a 3208, along with 2800 rpm operating speed, we get 566.8 cfm.

BTW, I used to work on a couple of 3208 powered Ford cement trucks when I was in Guam. They felt like they had a lot more than the rated 200 hp. I think the 13 spd trannies helped.

__________________
Whoever said there's nothing more expensive than a cheap Mercedes never had a cheap Jaguar.

83 300D Turbo with manual conversion, early W126 vented front rotors and H4 headlights 400,xxx miles
08 Suzuki GSX-R600 M4 Slip-on 22,xxx miles
88 Jaguar XJS V12 94,xxx miles. Work in progress.

No danger of that happening in my case (Allison 4spd)

So it looks pretty conclusive that the 300cfm filter is too small. This would account for it's short working life.
It must be marginally adequate when new and clean since there is no measurable vacuum in the intake at that point according to the filter gauge.

I'll have to explore alternatives.

__________________
1977 300d 70k--sold 08
1985 300TD 185k+
1984 307d 126k--sold 8/03
1985 409d 65k--sold 06
1984 300SD 315k--daughter's car
1979 300SD 122k--sold 2/11
1999 Fuso FG Expedition Camper
1993 GMC Sierra 6.5 TD 4x4
1982 Bluebird Wanderlodge CAT 3208--Sold 2/13

Yep, too small.

A non-turbo 10.4L (633ci) 3208 @ 2800rpm eats 513cfm.
Add the turbo to your 8psi and its 707cfm.

You can play with the settings here:
http://www.not2fast.com/turbo/glossary/turbo_calc.shtml?FeetASL=5280&Tamb=30&Bore=114&Stroke=127&nCyl=8&RPM=2800&VE=100&Boost=8&Ec=75&Eic=0&PdropIC=0&TambIC=30&wiPercentMethanol=0&wiRate=0&wiTemp=0&SFC=0&AFR=0&maxInjectorDutyCycle=0