Got in the car last night, no boost (maybe 2 psi under load, car was a dog all of a sudden!). I had fortunately bought the stuff for this mod a few months ago and just hadn't done it yet. Well, rather than diagnose, I did the swap out this morning. Took me about 2 hrs, a fair amount of cursing (all by myself so it never happened ). But overall, a very doable DIY job.

I think it was successful, but here are my numbers. I would appreciate some feedback, especially if something looks funny.


Under hard acceleration, up slight incline, I get maxing out around 14 psi. I have a dash mounted boost gauge that only goes to 15, but never pegs it. It seems to lighten up after continued acceleration maybe a single psi or two, but holds pretty well while under acceleration load.

Under normal driving at 60-65 mph fairly level ~2400 RPM, I drop to about 5-7 psi continually held boost.

Let up on the accelerator pedal and it drops to approach 0 psi.

If I hit a bit of incline but am not standing on it and still just cruising, I bump up immediately to around 10-11 psi and it holds this pretty steady for the duration until I hit totally level or decline, adding a little more throttle and up to the max levels indicated above.

My actuator line is coming off a T-from the ALDA.

Does this all sound about right or am I going to grenade something???? The car feel much more responsive for sure. EGR and flapper valve are untouched, just all vac lines to the pass side of the car are disconnected above the vac pump (gotta have the looks for inspection times).

That sounds ok to me - that's pretty much what my car does

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1983 240D Silver/Blue "Sadie", unknown miles. 100k miles on WVO single tank, converted to 2 tank about 10k miles ago, FPHE, Injector Heaters, Aux Fuel pump. Alcohol/Water injection. Frantz oil bypass filter
1992 300D 2.5 Turbo Green/Tan "Jade" 267K miles Stock.
1992 300D 2.5 tan/tan "Rocky" on 2 tank WVO. Pressure actuated Turbo "rat's nest" surgery completed. 197k miles

While removing the vacuum lines and associated hardware for this modification I discovered two (2) lines heading towards the firewall (over the inner fender and down under the battery).



According to the attached vacuum drawing, the first line (marked in RED) goes to a Vacuum Amplifier and Vacuum Reservoir. The second line (marked in GREEN) goes to a vent.



After color coding the drawing I can see that the vacuum amp get's vacuum from two directions. So now I can understand why people say the GREEN and RED lines aren't needed.

However I'm curious if the reservoir is needed or not, comments?

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This car had a history, now it has a future.

Learn more about my Benz here.

Rather than read through 20 pages of thead. Simple question,

Why would I want switch to this setup rather than the factory setup, if it is working normally?

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Check here for compatibility, diagnostics, and availability!

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82 300SD 145k
89 420SEL 210k
89 560SEL 118k
90 300SE 262k RIP 5/25/2010
90 560SEL 154k
91 300D 2.5 Turbo. 241k
93 190E 3.0 235k
93 300E 195k

You wouldn't unless you fear it quitting on your way to Denver.

Sixto
87 300D

Oh come on now, where's your sense of adventure??



No need to unless you want to disable EGR for, um, off-road use. Or, the Denver fail-safe as Sixto mentioned.

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Do all .128s cut boost if the EDS notices an inoperative EGR system?

Sixto
87 300D

For USA-spec, AFAIK, yes.

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I tried to order one today from ATP Turbo and they emailed back saying they were currently out of stock of the p/n listed in post 61. I'll nose around on ebay.

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Jim

wastegate actuator

This is one of the styles I've come up with so far. Wonder how it is adjustable?

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Jim

is based on the "Pre-Load" tension you set up the Actuator with.

http://www.youtube.com/watch?v=p12g1PpIcjE

you tube,Garrett Turbo preload tension - Google Search

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"Recently we ran into an issue on my buddy's car when trying to achieve anything over 18psi. The car has a 34mm internally-gated Frank 5 20G (60-trim Garrett compressor, TD06H turbine) and we were using a T25 actuator (the turbo had a welded flapper when I got it, be he wanted to go internal and the T25 actuator was the only one I had that would fit properly.)

Anytime we tried to boost past 18psi, the flapper would blow open. The car has an external dump for the wastegate chamber, so we could hear when the wastegate would open....no hiding that. I began shimming the gate tighter and tighter and we were getting the same results. We were down to 1/4" of arm travel, and I had the boost source going to the actuator completely disconnected- same result. I ended up getting a universal AGP actuator with a much stronger spring and an adjustable arm and manufacturing a bracket to hold the actuator head.

The first time out with the new actuator the car made 28psi....I had far too much preload on the actuator arm. Plently of tuning later, we've found a sweet spot between the actuator having enough spring strength to hold the flapper shut and just enough preload that there isn't a huge spike in boost. The boost now spikes to 23-24psi before settling at 22 and holding it rock-steady to redline.

Lesson learned: If you want to run more than 20psi and have absolutely no issues controlling boost, an external wastegate is highly recommended.


By adding more tension than necessary to the wastegate arm you're preloading the spring which is delaying the opening of the wastegate, and raising the boost level.

Adjustable wastegate arms were previously the only way raise or lower your boost level until the boost controller became a popular item. Basically if you had an 8psi actuator you could run no less than 8psi when the arm was at it's loosest setting, and the boost level would raise slightly as you'd shorten the rod.

The downfall to this method is that by preloading the spring heavily to achieve a very high boost level you're taking the responsiveness out of the actuator. Many times if you have too much preload on the actuator you'll see a slight spike in boost pressure prior to the wastegate opening before it drops and settles to the desired level.

Many of today's solid-rod actuators (like those found on the T25 and 14B/16G) cannot hold much past 18 or 20psi before they begin begin to open on their own. The only way to control this is to use washers to shim underneath the mounting tabs of the actuator and add a bit of preload to the wastegate system. Of course there are tons of variables that determine the final pressure at which a wastegate will open- wastegate hole size and flapper size being the two biggest factors.

You'd be surprised- once you reach higher boost levels, wastegate arm travel and flapper size have absolutely NOTHING to do with controlling the boost level. If the wastegate opens as much as 1/4", the boost level will be limited. For those who think bigger flappers are better at higher boost levels, take a look at a 16cm2 Holset turbine housing for a large diesel truck running 35 or 40psi....the wastegate hole itself is barely big enough to fit your pinky into, and the flapper is about the size of a nickle.


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~Justin~ Rebuilding your journal-bearing turbochargers since 2004."

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If that's a Pressure operated WG the "Rod" length would have to be cut down
to the Specs GSXR provided before Pre-load.

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'84 300SD sold
124.128

Thanks, I'm going to remove the one that is currently in the car to confirm the same arrangement as what is shown in the pic on the ebay ad. If it is I'll get it coming.

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Jim

What about the 603.971?

I see 12-14 psi then its gone, turn the key off and it comes back for a few miles.
Tied WG to vacuum source to hold it closed and can only get 8 psi. Odd...

Yep, pretty sure the 3.5L does the same thing... if the EDS thinks you've killed EGR, it will kill boost.



Check the fault codes from the computer. You will need a hand-held blink code reader (or SDS).



Now that is odd. Are you sure it's a full 25" vacuum source? With full vac you should see >14psi at WOT.

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Vacuum was straight from the pump although, I did not measure it. All other vac operated devices work well.
Mity vac held the wg closed with no leaks. I did not test drive with MV.