re-purpose OEM Benz compounds onto a BEW?

sardo_67

Veteran Member
Joined
Feb 15, 2010
Location
CT
TDI
2015 Golf SEL 6spd
looking at some threads and TDI swaps where a few have used the twin turbo system found on the OEM sprinter vans, the usual compound set up with 2 VNT vacuum actuated controllers.

my question is if i run my BEW in an XJ with a stand alone computer harness how would the turbos be tuned and controlled, 2 separate controllers for each VNT or both off one?

since this will be a larger lifted jeep on 35s i need more power, however its a jeep and not a car so i want to not have the turbo lag and no low end tq that typically comes with single large turbo systems. easy to make 250hp but in a lifted jeep it won't be very fun to drive or usable.
 

Turbo Z

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Mar 6, 2012
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Sweden
TDI
Audi A2 mercedes c270
a lot of knowledge bot basic in turbo machinery and software programming...
starts with the basic...
 

sardo_67

Veteran Member
Joined
Feb 15, 2010
Location
CT
TDI
2015 Golf SEL 6spd
a lot of knowledge bot basic in turbo machinery and software programming...
starts with the basic...

i am reading that using compound waste-gate turbos are pretty simple to tune since you just set the max PSI you want for each one.
 

mrchill

TDIClub Enthusiast, Super Secret Diesel Ninja Vend
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Those are wastegate turbos. You can control them a few ways...but I suspect you will have to tune it for your application
 

sardo_67

Veteran Member
Joined
Feb 15, 2010
Location
CT
TDI
2015 Golf SEL 6spd
Yea the more I look into this the more is see why NOT to do this lol.

I saw a guy on a FB group from Canada who's running the Benz turbos on an ALH long block with 12mm M pump and says the set up is pretty amazing. Instant boost and can easily burry the needle on his 35psi gauge.

While I am NOT looking for all out max boost and HP I am just looking for decent power with the widest power band since this will be in a 4500lb Jeep Cherokee lifted on 35" tires.
Also I am looking to not burn all my money on this either.
 

sardo_67

Veteran Member
Joined
Feb 15, 2010
Location
CT
TDI
2015 Golf SEL 6spd
Link to the FB post in question would be helpful.

it is a closed group "TDI swapped trucks" and one of the admins there has the silver XJ in question that looks to make some good power.

some pics on his FB or you can request to join the page.
also "TDI owners group" is another page that i posted on and had more info.

https://www.facebook.com/nick.vandervalk.14


after more research i was looking to go with a custom compound waste gate set up kike a K03 and XH35.

ideally I'd use a CJAA for the swap as the intake and exhaust are on opposite sides of the head but then i'd have to buy a new motor and so on, i already have a BEW with harness and such.
 

TDIMeister

Phd of TDIClub Enthusiast, Moderator at Large
Joined
May 1, 1999
Location
Canada
TDI
TDI
I prefer VNTs on both stages of a 2-stage setup. Control is straightforward using a single common PWM signal directly actuating both turbos simultaneously with electronic actuators.

The only thing you'd need are compressor and turbine bypasses - again, common signal - that, depending on the combination HP and LP turbos used need to activate at about 3500 RPM otherwise the EMP:IMP ratio soars because the HP becomes a restriction in the system. The smaller the HP and the larger the difference between HP and LP turbos, the earlier the bypass needs to activate. The control strategy of the bypass needs a hysteresis to prevent the bypasses from going in a loop of opening and closing near the switching threshold.

If you keep relatively similar-size turbos or rarely anticipate operating over 3500 RPM or care about posting dyno queen numbers, you could do away with the bypasses entirely making it a true "compound" rather than series sequential, but transient response and low-end torque are compromised by the larger HP stage turbo.
 

TDIsyncro

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Nov 14, 2005
Location
Saskatoon, SK
TDI
Audi/TDI x 2
I think your best bet is to stay with bew engine and not cjaa engine. You will have a lot more support from local tuners for successful standalone. Bew is a good engine. If you go with a common rail engine you will want a spare sitting in shed in case you need to replace parts on fuel system, etc (cheaper to buy spare engine than buy fuel system parts). No need to do that with common bew. I would recommend two fixed geometry turbos in compound before trying to go with two vnts. It is simplist way to go. Do a search on the forum, there are a few compound setup that members built and got running well. I am working on two vnts and its certainly a lot more complicated. I am using microcomputer to control everything beyond the limitations of the ecu. Its not working yet. It all depends on how quick you want to get to successfully using your rig.
 

sardo_67

Veteran Member
Joined
Feb 15, 2010
Location
CT
TDI
2015 Golf SEL 6spd
ya i just started looking into 2 turbo set ups on TDIs like 3 days ago and i'm more confused now than when i started lol.

i read what you said Meister but i think only understood like half haha.

it's a toy jeep that i would like to use as a DD when i feel like it (50-60 daily work commute) or when its winter time since i get 16mpg now with the 4.0 gas job and it's bone stock.

this will be done the correct way as i have learned the hard way many times before.
stock XJ, will put in a mostly stock freshened up BEW (new Tbelt kit, maybe cam/port/polish), PD150 injectors or similar, then an old KP39 just to get all the swap kinks worked out and driving around. going from gas to diesel, fuel lines, drive line adapters, electronics, wiring, radiator, etc etc etc......

after i feel comfortable with that i would add the turbo and HP getting parts with an IC system so i am only fighting one demon at once. not dealing with electrical, fuel, IC system, exhaust manifolds, adapters and so on.

i sent you a PM for some info as i'd like to pick your brain a little more.
 
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