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  #1  
Old 05-02-2009, 10:08 AM
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617 Torque improvements, no interest in HP

Is there a way to search for more torque in the 617, rather than the more common desire for speed and high end power?

What does the 'torque control' screw do on the IP? (if that is what I remember it being called)

I would be looking for 1400-3000RPM improvements, and not so concerned with any improvements over 4000RPM and what is it called? Torque rise???


Is the best way to get there a VNT? and fuel adjustments?

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  #2  
Old 05-02-2009, 05:41 PM
ForcedInduction
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HP is a function of torque so increasing torque will increase HP.

A VNT is your best bet by far. Anything else will be severely limited by the ancient T3's poor performance. Nitrous being the exception.
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  #3  
Old 05-02-2009, 07:43 PM
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Originally Posted by ForcedInduction View Post
Anything else will be severely limited by the ancient T3's poor performance. Nitrous being the exception.
Forced,


How would Nitrous improve Torque.. or would it just allow more fuel right off the bat?

Also how would you charactorize a T3? slow to spool, or limited in airflow in all RPM ranges? or is it some other factor that has grown by leaps and bounds since the mid seventys?
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  #4  
Old 05-02-2009, 09:43 PM
ForcedInduction
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Originally Posted by JDmills View Post
How would Nitrous improve Torque.. or would it just allow more fuel right off the bat?
Yep, more oxygen to burn fuel.

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Also how would you charactorize a T3? slow to spool, or limited in airflow in all RPM ranges? or is it some other factor that has grown by leaps and bounds since the mid seventys?
Heavy rotating mass, pre-computer design (WWII basically), fixed geometry turbine and narrow compressor map.
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  #5  
Old 05-02-2009, 10:02 PM
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Remember folks- basics ----you need a top running stock engine and a quite good understanding of this engine and be mechanical and have tools, plus the space/time and/or money to alter your engine to obtain higher figures. A VGT turbo is the upper end- we'll all end up there ((if you continue to want more power (until you recognize that twins or super size is the power.)) Seeing that all of less than- what is it now?- ten people? 12 people? on the planet have a VGT on a 617-95X and publicly shown it, and of those 100% have done it themselves (and if there is a case where "you" paid a shop to install a VGT on your 617 what do you think the final bill was?) we all have to consider that this option is far down the line for most of us.
That brings us to this:
If you want more power out of your 617 you need a properly running stock engine and related components, proper additional gauges, and then remove (or try to alter on the engine) the Injection Pump (IP) and change the internal settings to deliver more fuel. You'll also need to change the stock boost settings on the turbo. Getting as much as 30 more HP with stock parts is pretty much the end of "stage one" it seems for the majority of w123/w126/w116 owners. When you get there moving onto a VGT is a much smaller, easier step.
To answer the question- get your engine running like new as best you can, add the gauges, up the boost and alter the IP internals, and add a intercooler if you can.
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  #6  
Old 05-02-2009, 10:50 PM
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Originally Posted by MTUpower View Post
A VGT turbo is the upper end
Not at all. Its one of the first things that should be done in the search for performance, after getting the engine in proper tune. The difference between the T3/K26 and a VNT is night and day. 200lb/ft torque below 2000rpm is normal with an otherwise stock engine. Thats at the wheels with a manual transmission, instead of the stock 180lb/ft @ 2800rpm at the engine. An automatic will have even more torque on the low end thanks to the torque converter's multiplication.

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we all have to consider that this option is far down the line for most of us.
Any weekend shadetree mechanic can do it. The flange for the Liberty turbo can be bought for a reasonable price, oil lines are cake to make if you know where to find a hydraulic shop for fittings and the stock exhaust can be used. The hardest part is making a decent air filter system (thats not just an open filter on a tube).

An intercooler will have no effect on torque, just top-end power.

Last edited by ForcedInduction; 05-02-2009 at 10:57 PM.
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  #7  
Old 05-02-2009, 11:18 PM
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Originally Posted by MTUpower View Post
Getting as much as 30 more HP with stock parts is pretty much the end of "stage one" it seems for the majority of w123/w126/w116 owners. .
I am exploring how close/if one can get the 617 to 150hp and 250LB.Ft.@ 14-2500 RPM--> which puts it about equal to the early sprinters. Then was gonna drop one in a P/U, As I don't need a truck that will 20,000 something GVRW.. Just something that would get around with a load of feed, or some firewood.. and the spinter is rated at just under 10,000GVRW. That would be enough for me.. and my Power wagon with a Diesel that will spin past 3200 would be just about perfect in my eyes.. Most seem to think the 4BT cummins is the way to go.. I'm not ready to be give in quite yet..

But before I start in that direction, I was wanting to know if the 617 would be the place to start.. It may not. But if it is, by the time I get a late model 5 speed transmission behind the engine, a turbocharger fitting ought to be fairly easy pickings..
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  #8  
Old 05-02-2009, 11:41 PM
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Originally Posted by ForcedInduction View Post
The difference between the T3/K26 and a VNT is night and day. 200lb/ft torque below 2000rpm is normal with an otherwise stock engine. Thats at the wheels with a manual transmission, instead of the stock 180lb/ft @ 2800rpm at the engine.


An intercooler will have no effect on torque, just top-end power.
Yeah Hoo.. the difference is night and day.. that may be more than I am looking for..

It kinda sounds like this MAY be worth still considering.. and I have no interest in top end power... and if a VNT can help the low end.. there may be life in this project yet.

How much Torque might a moderatly tweeked pump and VNT produce at the flywheel?

Is the power band more a result of the ability of the turbo to provide air, than it is a queston of bore X stroke , and injection pump limitations?
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  #9  
Old 05-03-2009, 12:02 AM
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Definitely. I can get 14psi on the intake while revving in park.
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  #10  
Old 05-03-2009, 12:11 AM
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Originally Posted by Simpler=Better View Post
Definitely. I can get 14psi on the intake while revving in park.
errr, I don't believe that. Prove it!
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  #11  
Old 05-03-2009, 12:44 AM
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Originally Posted by JDmills View Post
I am exploring how close/if one can get the 617 to 150hp and 250LB.Ft.@ 14-2500 RPM
You'll get close, but you won't see that at the wheels. To get more than 145hp you'll have to rebuild the pump with larger plungers or get an M-pump and send it to Myna in Finland.

Quote:
But before I start in that direction, I was wanting to know if the 617 would be the place to start
...
I get a late model 5 speed transmission behind the engine
If you want a 5-speed, the 617 is definately not the right engine. 5-speeds that fit are extremely rare, and expensive if the seller knows what they have. You should start with an OM602 from an 87 190D or 91-93 300D. It has much more power potential, its more efficient and 5-speeds are common and cheap for it.

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Originally Posted by JDmills View Post
How much Torque might a moderatly tweeked pump and VNT produce at the flywheel?
You might get close to 250. The stock pump only has 20hp worth of adjustment.

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Is the power band more a result of the ability of the turbo to provide air
Yes. As I said erlier, the stock turbo is a very old design and really holds back the engine's natural torque. My VNT (From a 2003 Sprinter) will spool to 10psi before 2000rpm, the T3/K26 isn't even be working yet at that speed. The Jeep Liberty's turbo will do it even quicker since it has a smaller turbine and lower compressor trim.

Last edited by ForcedInduction; 05-03-2009 at 12:49 AM.
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  #12  
Old 05-03-2009, 12:46 AM
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Originally Posted by dieseldiehard View Post
errr, I don't believe that. Prove it!
Check out my youtube videos. One shows me revving the engine without a load. Its an older video so it was only set for 11psi at the time, I have it set for 14psi right now.

(I'd link but the shop computer blocks youtube)
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  #13  
Old 05-03-2009, 07:18 AM
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Quote:
Originally Posted by ForcedInduction View Post
Not at all. Its one of the first things that should be done in the search for performance, after getting the engine in proper tune.
Any weekend shadetree mechanic can do it.
Quote:
Originally Posted by MTUpower View Post
Seeing that all of less than- what is it now?- ten people? 12 people? on the planet have a VGT on a 617-95X and publicly shown it
The first thing after getting the engine in proper tune ought to be more fuel and the boost to burn it- not boost sooner. That means IP adjustment not changing the turbo. A VGT is great option- but let's let the folks here know that you have more fingers attached to you than 617's have VGT attached to them.
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  #14  
Old 05-03-2009, 07:32 AM
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Originally Posted by MTUpower View Post
The first thing after getting the engine in proper tune ought to be more fuel and the boost to burn it- not boost sooner.
Spoken as somebody who truly has never had the pleasurable experience of driving a VNT equipped car.

A VNT is a far more noticeable change in performance than 20hp from the rack limiter. The rack adjustment and torque capsule will have no significant effect on low end torque since power is limited by the same air availability and the stock turbo's poor response time.

The graph curves tell all. The only difference between the two graphs is time and a GT2256V instead of a K26. There is no difference in fueling, only air.


Which curves would you rather have?

JDmills wants low end torque over anything else so clearly a VNT should be priority, if not a supercharger.
The GTA2056V from a Jeep Liberty or M90 supercharger from a Buick or Ford would be about ideal for his needs.

EDIT: Here is the video I was talking about earlier. Right is exhaust pressure, left is boost. http://www.youtube.com/watch?v=eM7SNOc3nMY Its interesting to watch the exhaust gauge, you can see how the vanes open and close to control boost through exhaust velocity (exhaust pressure). Try doing that with your T3!

Last edited by ForcedInduction; 05-03-2009 at 07:51 AM.
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  #15  
Old 05-03-2009, 09:14 AM
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Those are some nice looking graphs! I think they would look even better if you'd make the TC adjustment. I think bang for the buck wise and effort invested you get a better return from making IP and stock turbo adjustments first. Then once you catch the bug you'll have the motivation to design and execute a clean VGT tubo install like you have. I swear this summer I'm going to get that liberty turbo installed on my OM616 powered Unimog
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617 Torque improvements, no interest in HP-4072.jpg  

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