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  #1  
Old 12-05-2013, 01:42 PM
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om616 turbo... butterfly/ip?

i have an '74 om616 that is going to be swapped into a different vehicle ( build thread to come) while it is setting on the bench, i am strongly considering a turbo. the current stumbling block i am stressed out about is the butterfly/ pneumatic governor on the ip.

all of the writeups ive seen about 616+t show guys piping straight into the intake manifold with no butterfly if thats the case what do i do with the vac line going to the ip?

thanks in advance for the help, ill probably be needing more soon.


the pump i have is the same as the one in the third post in the link below.
http://www.peachparts.com/shopforum/diesel-discussion/184117-240d-om616-916-ip-oil-level.html

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  #2  
Old 12-05-2013, 10:06 PM
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You can't turbo a car with the pneumatically governed IP because it needs the flow of air over a venturi port to create vacuum which pulls the diaphragm against a spring to regulate the IP. If you pressurize this system you will not be allowing the diaphragm to work (since it will be under pressure) and the IP will be running against the rack stop at full throttle all the time.

Aside from this, adding a turbo to an OM616 will significantly decrease the life of the engine as the later turbo OM617s are built specifically for the added boost with extra oil ports to cool cylinder and valves/seats which are hardened to take the extra heat.

You'll make a few more HP out of a 616 with a mechanically goverened IP but maybe not enough over the long term to justify the work you put into it, especially if it kills the motor early. If you just want a car to bang around in until it kicks the bucket, a turbo might be fun.

Phil Forrest
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  #3  
Old 12-05-2013, 10:50 PM
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Didn't someone try that one time on here and the car would accelerate out of control any time it was under boost due to the way the governor worked?
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  #4  
Old 12-06-2013, 12:45 AM
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i am aware of the risks in torboing the 616. i am also aware of the potential gains. In my case this will not be my sole source for transportation so if it becomes problematic, its not the end of the world.

what would it take to make this injection pump work?

do i need a compleetly different pump?
can i retrofit a different governor on the one i have?
can i run the same butterfly setup between the turbo and the air filter?
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  #5  
Old 12-06-2013, 12:59 AM
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Quote:
Originally Posted by levi_456 View Post
what would it take to make this injection pump work?

do i need a compleetly different pump?
can i retrofit a different governor on the one i have?
can i run the same butterfly setup between the turbo and the air filter?
This injection pump cannot work with a turbo. At all.
No, you can't retrofit the governor because the IP is different enough to not allow it. There is no provision for the ADA of the later IP and your linkage would be different as well. The rate of injection is based upon the curve that ambient air pressure and the venturi vacuum create as a balance against a spring. The IP is designed for this method of assessing how much fuel to dump into the injectors. The vacuum line pulls the diaphragm against a spring. With the butterfly open, you are making more vacuum and pulling the diaphragm more which decreases the injection. As you open the butterfly, the vacuum is less and the spring is allowed to push the rack farther to the "WOT" end. Putting pressure instead of vacuum into the governor will basically cause a near runaway. Once you start the engine up, it will be at WOT and the pressure will feedback causing you to have to stop it with a 2x4, cutting off the air supply.

Since you need a different IP, you also will need to somehow add the lubrication system for the new IP. The pneumatically governed IP has its own oil sump and the mechanically governed ones have a source of oil from the engine. Your engine is not set up to pump oil to the IP and doesn't have the channels to do so without machining and some plumbing.

You can't use the same throttle body with the turbo either as your restriction of the air will cause the intake between the turbo and the butterfly to pop off.

It would be easier and probably cheaper, to get a later donor OM616 with a mechanically governed IP then stick on one of the mild turbo kits that are available.

Phil Forrest
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1972 220D "Trudy," named by a friend.

"The 220D sounds good... I suspect it is the only car that you need a calendar for, rather than a stopwatch, when doing acceleration tests."
Tom Abrahamsson

Last edited by Phil_F_NM; 12-06-2013 at 01:24 AM.
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  #6  
Old 12-06-2013, 01:44 AM
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I thought that I read somewhere that someone relocated the throttle body so it was between the turbo and the air filter.. That is how I get constant vacuum on my turbo gas motor. Do you think that it would produce the right amount of vacuum to make the governor work correctly
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  #7  
Old 12-06-2013, 02:07 AM
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A diesel engine does not create vacuum like a gasser does. It is only a consequence of their design that they can get a weak vacuum signal off of the venturi in the throttle body. Just enough to actuate the diaphragm to make the IP work as per their design.

You not only have that venturi vacuum line to contend with but the throttle linkage. The input from the pedal into the linkage transfers across the top of the engine (this is where part of your idle is set, the other idle setting is inside the IP) to the tickler and is balanced with the rate of the poppet valve to allow the IP to work at low RPM.

As for venturi vacuum itself, you *might* be able to it work with your throttle body in the air path before the turbo but you're going to have to do some crazy fabrication. I don't even know where you'd locate the throttle body in order to get the right linkage rate. This way you'd have to have a split linkage from the actuator on the exhaust side to both the throttle body somewhere as well as the IP linkage across the top of the engine. You'd have to change the spring rate in the IP (not the just the spacers that govern idle but the stiffness of the spring itself) to adjust for your much higher vacuum just off of idle when you start to make boost. You're pulling a lot more air and even with the butterfly wide open, I still don't think it would be right.

Then you get into how much vacuum is going into that IP governor. Please read about the pneumatic governors and runaways. The diaphragm is only designed to hold maybe 6in/hg of vacuum and it is a rather fragile piece of leather. If this tears, then your engine can suck all the oil out of the IP and feed it into the intake acting as fuel supply, creating boost and feeding the chain reaction for only a few seconds before parts start flying. There is a reason that Mercedes never used pneumatically governed IPs on their turbo cars. Part of it is this danger of runaway.

By the way, how much boost do you want to put on this engine? If I were doing this to a 240D, I'd stick below 6psi just for a little more oomph in accelleration but not too much heat for the engine to take. They aren't high revving either, remember.

I drive a 220D with the same IP and have plenty of power, even up at 7200 feet in the high desert of New Mexico. If I were to want to stick a turbo engine in it, I'd have a 240D built to really take all the stresses a turbo adds but by that time, I'd have spent enough money to buy a late 90's S class with a turbo diesel.

Phil Forrest
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"The 220D sounds good... I suspect it is the only car that you need a calendar for, rather than a stopwatch, when doing acceleration tests."
Tom Abrahamsson
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  #8  
Old 12-06-2013, 11:56 PM
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I think a turbo is a great idea, but I'm Biased!

Hi Levi!
I have been running my Turboed 240D since 2005. The engine had god knows how many miles when I started. The odometer was broken at 189,000 miles when I got the car, and I have no idea how far it had been driven with after the odometer broken. I personally ran it with the turbo for about another 160,000 miles. I used to drive the car 1400 (yes, Really!) miles per week, and never had any problems. Finally the rings gave up and compression went to hell, but I got plenty of reliable service out of it. I've just recently rebuilt the engine, so I had a the oppertunity to inspect everything inside for "turbo damage". Everyone seems to be terrified of turboing these engines because of the lack of piston squirters, but on teardown I saw no evidence of piston over heating, or lack of lubrication. The wrist pins were quite worn, but after that many miles, they should be! I have run as much as 15 PSI of boost on this engine with almost 3 times the stock 41.5 mm3 of fuel. Normally I keep boost at about 9PSI.

What Phil says about the vacuum IP is correct. If you want to turbo your car, go with a centrifugaly governed IP. I even have a couple laying around if you want one!
There's even an easy way to do this:

Mercedes 240D Turbo Adapter Plate | eBay
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  #9  
Old 12-07-2013, 12:30 AM
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The problem with adding a later IP to an early 616 with a stock pneumatically governed one is that you have to somehow get oil to pump from the sump into the new IP. This provision is not there in the early block.

Phil Forrest
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1972 220D "Trudy," named by a friend.

"The 220D sounds good... I suspect it is the only car that you need a calendar for, rather than a stopwatch, when doing acceleration tests."
Tom Abrahamsson
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  #10  
Old 12-07-2013, 12:37 AM
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Well turboing a car is a fairly major undertaking anyway. Tapping a feed line for the IP off of the feed line for the turbo is not much of a challenge.
On another note, I really enjoyed your photographs Phil!
Cheers!
Chris
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  #11  
Old 12-07-2013, 12:48 AM
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Thanks! It's what I love to do. I just took a photo of a bank of freezing fog moving over this little town where I grew up in New Mexico.

I'm not opposed to turboing a 240, by the way. I just think it would be so much easier (and possible) by using a much later motor with all the plumbing hooked up and ready to go instead of reverse engineering a solution that already exists in the later model.

I think that the extra power out of the lighter 240 would be great. I'd love to have that available in my 220D. Maybe one day, in a million miles after the motor is shot *knock on wood*

Phil Forrest

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"The 220D sounds good... I suspect it is the only car that you need a calendar for, rather than a stopwatch, when doing acceleration tests."
Tom Abrahamsson
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