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  #1  
Old 01-23-2004, 02:43 PM
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Cool Diesel performance Mods - What have you done? What HP do you get?

For a little background on what instgated this topic look at: http://www.peachparts.com/shopforum/showthread.php?threadid=84937&pagenumber=2

I have been researching diesel performance and estimated roughly 200+ horsepower output could be developed by the 617.

Are there much gains in just pocket porting/smoothing the factory iron head? Does anyone know of or have any experience in porting/polishing techniques or advantages with diesel engines? I have a spare engine that I wanted to rebuild. I have the intake and intercooler thing pretty much figured out on paper, but wanted to investigate mods in the stroke/piston and cam/head areas for HP gains.

Anyone?

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  #2  
Old 01-23-2004, 02:59 PM
LarryBible
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Those folks who are accustomed to hopping up gas engines are usually quite surprised to learn the differences when it comes to diesels. They are a TOTALLY different animal.

With a gas engine, most anything you can do to increase the flow of the fuel AND air mixture will add horsepower. This is all out the window with a diesel. With a diesel, horsepower is increased by adding fuel. There is no throttle plate, the engine is drawing a full gulp of air with every intake stroke. The power is regulated by adding more fuel.

It is possible to up the horsepower by simply adding more fuel via injection pump or injector size modifications, but you will do this at the expense of drastically decreased engine life.

In the case of a diesel when increasing fuel flow you must adequately increase air flow to maintain an acceptable fuel air ratio. The acceptable ratio is quite wide, but adding fuel without increasing air flow will quickly reach a point of excessive and intolerable combustion chamber temperatures.

Without adding fuel, you can port heads, increase exhaust flow, add turbo chargers, intercoolers, superchargers or anything under the sun to increase air flow and you won't get one single extra horsepower to go with it unless you add fuel.

Matching the specific fuel flow increase with the specific air flow increase is the tricky part.

The turbo charged 617, of course, does manage to make more horsepower via the turbo charger and the ALDA that actually causes added fuel flow based on boost amount.

That said, don't think that you can do similar modifications to a non turbo 617 and have it live very long. There are many modifications to the turbo'd engine to achieve adequate durability. These mods include piston design and squirters that squirt oil on the underside of the pistons to help cool them.

With the mods to the turbo'd 617, the limit was pretty much reached at which you can achieve horsepower increase without suffering engine life.

Unless you want to build an engine which has its life measured with a stop watch, don't exceed the horsepower of the factory turbo'd engine by very much. Remember these are VERY expensive engines to rebuild or purchase.

Good luck,
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Old 01-23-2004, 03:10 PM
ForcedInduction
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Quote:
Originally posted by LarryBible
Remember these are VERY expensive engines to rebuild or purchase.
Wow, that really shot down my hopes...

Gurkha might be able to get a hold on some of the direct injection 617's. They have the design of the MB engine over thre, no doubt they have made some changes to it.
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Old 01-23-2004, 03:19 PM
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I have gone as far as contacting Bosch and Denso, and asked them if they would enter into a project to develop a retrofit for older diesel engines to CDI. Bosch never replied, and Denso said they weren't interested at this time. This does not mean I will give up on the concept. From what I read it could be done. Yes the R&D would be huge$$$$$$, but just think of all of the older engines that would benefit from CDI. Not to mention the greater economy, performance and especially better emmisions.

From what I read about the technology, it could be as easy as swithching a points/coil gasser to electrinic ignition. Not that, that prcedure is easily done, but that, electronics aside, it would be on that level of a conversion in my mind.

Just a dream or...?
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'85 300SD 'Otto' new to us Sept. '07
'82 300SD 'Jurgen' (July '06 fan shaft broke, toasted rad, 3am in the morning 60km from home, walked 16km hitchhiking.... )
'70 SS Chevelle (finally back on my property, in the shop on stands)



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Old 01-23-2004, 03:32 PM
ForcedInduction
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It's not just th injection system. If you have ever had the heads off of an IDI and DI engine to caompare, you will see a HUGE difference in the piston design. IDI (I.e. OM617) have relativly flat pistons, DI (I.e. Cumins 6BT) have the combustion chamber molded into the piston design. It's not just that, the angle of injection makes a BIG difference in ho combustion is completed.

I'll try to find some picturs to compare.
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  #6  
Old 01-23-2004, 03:48 PM
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Direct injection. Notice the combustion chamber in the piston.
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Diesel performance Mods - What have you done? What HP do you get?-di.gif  
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  #7  
Old 01-23-2004, 03:48 PM
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IDI. Notice ho flat it is. This is from a Mack, i don't know for sure if it's IDI.
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Diesel performance Mods - What have you done? What HP do you get?-idi.jpg  
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  #8  
Old 01-23-2004, 03:52 PM
VeeDubTDI
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Lightbulb TDI piston picture

Here's a pretty crappy picture of the piston design in the VW 1.9L TDI engine. It's direct injection, and you'll notice how the combustion chamber is a bowl in the center of the piston. If you look closely, you will see the shape of the combustion chamber and its design to create swirl for more efficient burning of the fuel.

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  #9  
Old 01-23-2004, 04:03 PM
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The combution cavity on the VW looks like a great place for carbon build up.
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'85 300SD 'Otto' new to us Sept. '07
'82 300SD 'Jurgen' (July '06 fan shaft broke, toasted rad, 3am in the morning 60km from home, walked 16km hitchhiking.... )
'70 SS Chevelle (finally back on my property, in the shop on stands)



"The thinking required to solve a problem cannot be the same thinking used to create it!"-Einstien
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  #10  
Old 01-23-2004, 04:07 PM
VeeDubTDI
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nah...

I've seen a few VW pistons with a number of miles on them that were fairly clean. It builds up a little bit, but not enough to make any sort of difference.

However, soot WILL build up in the variable nozzle turbine system on the turbocharger if you neglect to do an Italian Tune-Up periodically, causing a catastrophic and expensive failure of the turbocharger.
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  #11  
Old 01-23-2004, 04:11 PM
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The idea of adding CDI technology to our older IDI engines may not be an economical idea. However, changing a CDI engine/trans to fit in our older cars might be a better idea.
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  #12  
Old 01-23-2004, 09:19 PM
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I'm with 82-300td here. I think it would be alot easier to put a newer turbo diesel engine in a W123 than change the head to a direct injection design. You would have an issue with getting a fuel injection pump to pump up the pressure necessary for the DI system. In addition, I would be surprised to see someone build the head out of cast iron which is one of the things that make these cars what they are.

ot - the highest pressure I have ever seen a diesel engine being run to was 40 psi of boost. It was a big turbodiesel 6 cylinder that had been highly modified and was running a big intercooler. It was in an antique Freightliner tractor (50's model) that the guy used to pull his custom show car trailer with. Really good looking custom ride.
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  #13  
Old 01-23-2004, 09:30 PM
ForcedInduction
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Quote:
Originally posted by engatwork
ot - the highest pressure I have ever seen a diesel engine being run to was 40 psi of boost. It was a big turbodiesel 6 cylinder that had been highly modified and was running a big intercooler. It was in an antique Freightliner tractor (50's model) that the guy used to pull his custom show car trailer with. Really good looking custom ride.
I have seen a 2002 Dodge 2500 Cummins 6BT up to 50PSI. This was a VERY highly modified engine. I have also seen a TWIN turbo setup (pic).
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Diesel performance Mods - What have you done? What HP do you get?-ttcummins2.jpg  
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  #14  
Old 01-23-2004, 09:36 PM
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wow
I would think that they would be able to make more hp by installing one turbo with an intercooler versus the two turbos in series. I'm sure they are running an egt to monitor the temperatures. Does anyone know what kind of boost a stock Cummins (in the Dodge) can run without melting the pistons?
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  #15  
Old 01-23-2004, 09:55 PM
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Dodge Cummins before and after Banks PowerPack

91-93 stock: 13psi Banks: 21psi
94-98 12-valve: 16.4 psi Banks: 32psi
98-02 24-valve: ?

I would imagine you could go higher psi than that if you were to get an intercooler from a semi or some other large truck.

I would think they run two turbos as to not over-speed them. A 5.9L engine turning 3500rpm @ 50psi is ALOT of air.

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