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Variable Geometry Turbos for Late Model Dodge Cummins

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For those of you interested in variable geometry turbos for the late model Dodge Cummins trucks, be sure to watch Xtreme 4x4 on the Spike network on the weekends of March 5-6 and March 12-13. You will see one installed on a 2005 truck. The show airs at 1:00pm Eastern on both Saturday and Sunday.
 
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Peter, I noticed that they mentioned 500hp several times, but they didn't dyno 'prove' the truck on the show. Are there any dyno charts for that kit? That entire package is SWEET for the third gen trucks!
 
Peter, hows the response off idle to say 1800rpms? I have heard they are a little slow for a variable geometry turbo. Is that true? We all would love to see a dyno graph. TIA... ... ... . Brad
 
If I remember right from the show, it is a Garrett. I wouldn't be suprised if Holset and Cummins bring us VGT in the near future. Hopefully without EGR though. All the Cummins engines with VG turbos also have EGR.
 
Sorry for the delayed response guys. Right before the show we had a very limited amount of time for dyno work, really just enough to get the turbo operational. At that time we were seeing about 450 peak HP at the rear wheels, and with our experience on drivetrain loss, that puts us somewhere over 500 at the flywheel. I don’t have complete curves to share with you because we did not complete a full set of tests at that time. Now that the vehicle is back in our possession, we are installing instrumentation and preparing for more dyno work, primarily to fine tune the turbo operation. We were only making about 35 PSI boost in those early runs, when we start increasing boost and adding fuel to match, we may wind up over 500 at the rear wheels. When that information becomes available, I will try to share it with you guys.



I drove the truck a lot during the taping, and I would say that to me, the initial throttle response felt a lot like a stock HY35 turbo that had been adjusted for more boost. That may not sound impressive, but remember that this is a much larger turbo that will produce more boost with significantly less backpressure than the stock one. That is where the power is made. As far as the response of the variable geometry mechanism, it is virtually instantaneous, but you are not likely to know when it is active. At low RPM’s the turbo will be adjusted to a small size, and as boost, exhaust backpressure and airflow increase, the mechanism will gradually increase the size of the turbine. This is a Garrett turbo, and as far as I know, there is no appreciable difference in the response rate of the Garrett vs. the Holset. We ran a Holset HY55 VGT on the Bonneville Dakota. One major advantage of the Garrett is that the mechanism is hydraulically driven by the oil supplied to the center section of the turbo, while the Holset is pneumatically actuated, which requires an additional support system.



Although it is necessary for emissions in many cases, I am not a big fan of EGR from a performance standpoint. The way I understand it, the purpose of EGR is to introduce an inert gas into the cylinder during combustion, which essentially reduces NOx emissions. But this also effectively reduces the displacement of the engine, making your 5. 9L engine act like something smaller. I always like to see emissions handled by some means other than EGR if possible.



Peter Treydte

Banks Power
 
Thanks for the update, Peter. I am not one to jump in and try things immediately, but the potential is huge. How about any info regarding an application for 2nd gen 24v trucks... ?

Does the impeller move in the compressor side only, or does the wheel in the exhaust housing move as well?
 
Beast2B,

We are planning on designing an exhaust manifold for the 98-02 24-valves so that this turbo can be used on those applications as well.



The variable geometry aspect of the turbo is vanes that are adjustable in the turbine housing of the turbo. The turbine wheel is no different in basic structure from a typical turbine wheel. The vanes in the housing adjust to change the way that the exhaust gases are introduced to the wheel. There is no variable aspect present in the compressor side.



Peter Treydte

Banks Power
 
CATCRACKER,

In my opinion, it sounds slightly louder than stock, no appreciable whistle. The difference between the 2003 and 2004-later Fords is a design modification in the turbine wheel that eliminated the need for a resonator in the stock exhaust system. Some people like the whine that the early turbo produced. I think it is neat for about 30 seconds, and then it gets old to me. The turbo used on the Dodge project is more like the 2004 turbo, so there is no whine. You can still hear the turbo about as much as you would with a modified stock turbo. Keep in mind that we ran it with a full exhaust including the cat converter. I really don’t know what it would sound like straight piped.



2broke2smoke,

Yes, the turbo is controlled by its own electronic unit. The signals that are required to run the turbo were easily attained from the Six-Gun wiring harness, so what you saw on the show was a simple interface to the Six-Gun, but the controller could easily be set up to capture that information from other sources.



Peter Treydte

Banks Power
 
Just curous here.

Peter, what are the equivalent exhaust housing range does the VGT equate to?

Something like 9-18cm2???

Are their maps available or would you have to kill me if you told me??? :)
 
thanks for the answer Peter ...

i'm interested in a new turbo for my wifes '03 ...

are these available yet?

any links with info related to instructions and pricing available yet?



again thanks for the informative post
 
Rotty,

That is a good question, but it is a difficult one to answer, first because this turbo is a Garrett and Garrett typically uses an A/R ratio to size their turbines, and second, because it is a variable geometry unit, it doesn’t really have a size. If we had multiple turbine maps of all the various turbines, both Holset and Garrett that are within a usable size range, then we could make some valid comparisons. I would estimate (and that is all it is, an estimation based on personal experience) that the VG can act smaller than an HY35 with a 9cm2 housing when the vanes are closed down, and about as large as an HX40 with about an 18cm2 housing with the vanes open. This is only an estimate (did I make that clear?). There are compressor maps available, and I may be able to supply that if you are interested, and I wouldn’t even have to kill you.



2broke2smoke,

These turbos are not yet available, nor is pricing info or installation instructions. I can tell you that installation is not much more difficult than installing an HX40 or some such turbo, the main issue being the bolt clearances. We are working on improving those details as we tool the manifold.



Peter Treydte

Banks Power
 
i did get a chance to watch the show, and was impressed. there was one thing that stuck out for me, and it was the compressor wheel... it looked like the wheel had alot more "fins" that grabbed the air, than any other compressor wheel that i have seen. . in other words instead of 6 fins it looked like it had 10-12 fins. why is this? is it a new/old design that is being used, or that im not aware of?



wes
 
WDimig,

You have good eyes. I went out to the shop and counted the blades on the compressor side of the turbo. There are 11 blades on the Garrett VG unit. The stock turbo on a late model Dodge has 7 full blades and 7 half-blades, called splitters. For the most part, the variations in blade count are more about sound quality issues than about performance. Full bladed designs tend to have less whistle than a splitter design, and the number of blades can affect the frequency range of a turbo. The compressor designer can sometimes move the sympathetic frequency beyond the range of the human ear by adding a blade or two. There are occasionally performance issues that come about as a trade offs, but it is usually in very specific areas of the compressor map. A good example is when Ford went from a splitter design to a full blade design in the 1999 model year trucks, trying to make the turbo whistle less, and as a result, the compressor has more of a tendency to go into surge.



Peter Treydte

Banks Power
 
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