VGT compounds

Diesel_guy86

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Jan 5, 2016
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Was doing some research because i think the gt4202r turbo i have will have a too small of a turbine for compound use. Started looking into swapping in a gt45 turbine wheel and found that garrett makes a vgt 4502 turbo used on the 14L detroits. Has anyone ever heard of using 2 vgt turbos in a compound setup?
 

blue09dmaxx

Too broke for this shit
Jan 15, 2012
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Was doing some research because i think the gt4202r turbo i have will have a too small of a turbine for compound use. Started looking into swapping in a gt45 turbine wheel and found that garrett makes a vgt 4502 turbo used on the 14L detroits. Has anyone ever heard of using 2 vgt turbos in a compound setup?

That turbo is a piece of junk
 

kidturbo

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Jul 21, 2010
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I brought this up once before somewhere. Maybe here a while back. Now I'm actually in a position ready to move on it in a real world project. So also seeking some serious advice on sizing, but in true parallel twins rather than compounded.

The electronics are actually the easiest part. Control options are now out there.

First for the "Rich" at heart, Bosch MS 15.1 ECU will control twin VNT's out of the box. That box runs just a little over 5k now without the harness. I priced one last month from a motorsport dealer. Big price reduction from a year or so.

Option 2; Pick up a couple non-feedback VNT turbos like the Garrett GT3782VA or PowerMax GT3788VA for a Ford 6.0L. Those models don't look at the vane position like the GM does. They basically take voltage in equals positoin X. Long as your pumping both into the same intake, things should even out. I'm leaning towards this for testing first.

Third; We build a little micro-controller similar to a dual CP3 setup that manages both turbos. It takes the position value being sent by the ECM and splits that to each turbo. On the other side, same box looks at each turbo vane position and give the ECM back an average of the two. This unit could also be designed to keep them in check. I could whip out a few of these in a prototype pretty quickly.

Option 4; Audi is way ahead of the curve on the parallel setup, and it's out there in the VW Touareg v10 TDI and A8. As 2014 they were running 2x ECM's linked up to manage each VNT turbo. Not sure of the reasoning there, but it runs and drive... After that whole EPA thing, probably find em cheap.. lol.

That's what I have to donate so far.

Now what size option VNT's are out there? And what would you pick to manage 1100 flywheel hp with enough air to operate at sub 1400 EGT's, stay spooled up under heavy load around 2200R's, and not run out at 4400R or so?

If someone educated can answer me that question, I will work out the electronics side and donate that data for who ever need help on the rest... :thumb:
 

Diesel_guy86

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Jan 5, 2016
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Im not aware of any vnt turbo capable of 1,100hp by itself. Even factory 1,200hp engines are using compound setups on each bank.
By going parallel, your going to be using a smaller turbo early in the rev range, and then switch over to the large turbo later on? Or are you running a turbo on each bank?
 

Burn Down

Hotrodder
Sep 14, 2008
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Boise Idaho
Was doing some research because i think the gt4202r turbo i have will have a too small of a turbine for compound use. Started looking into swapping in a gt45 turbine wheel and found that garrett makes a vgt 4502 turbo used on the 14L detroits. Has anyone ever heard of using 2 vgt turbos in a compound setup?

The GT4202 works sweet in stock charger compound setup.
 

kidturbo

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Jul 21, 2010
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Or are you running a turbo on each bank?
Personally I'm interested in doing 2 in parallel setup like this on the right.

1009dp_01_o%2B1009dp_800hp_twin_turbo_duramax_crate_engine%2Bbanks_supercharged_and_turbocharged_engines.jpg


The Banks engine on left uses a supercharger to spool up bigger twins down low. Which is cool, but i think a pair of VNT's could remove need for the charger. They don't have to be factory setups either. My MB 3.2l CDI uses and outside actuator control box like in video below. This one is off the V10 Audi engine.

https://youtu.be/0RsJx9aG5mU

I need 2000CFM up top to make the power we need.
 

Diesel_guy86

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Jan 5, 2016
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The GT4202 works sweet in stock charger compound setup.

As in being used in the valley, or as the second turbo?

Kidturbo, we have a cummins isx 15L, 600hp with a variable holset he551v turbo. 2 of those in parallel would definitely get you your 1200hp, not sure about your low end though.
 

Burn Down

Hotrodder
Sep 14, 2008
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As in being used in the valley, or as the second turbo?

Kidturbo, we have a cummins isx 15L, 600hp with a variable holset he551v turbo. 2 of those in parallel would definitely get you your 1200hp, not sure about your low end though.

Atmo turbo. MPI used them quite a bit until they switched over to the Borgs.

Simon has one in the factory location with a PBK feeding it.
 

kidturbo

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Kidturbo, we have a cummins isx 15L, 600hp with a variable holset he551v turbo. 2 of those in parallel would definitely get you your 1200hp, not sure about your low end though.

Those use a different way of controlling vanes don't they...

The Engine Control Module modulates the supply pressure to the turbocharger pneumatic control cylinder (actuator) which acts on a rod and yoke system to slide the nozzle ring and blades relative to the fixed shroud plate.

One could Tee that signal tube between the pair and likely keep them in check long as they don't stick a slider.

Thanks for the suggestion.
 

kidturbo

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Not VNT's, but yesterday I put a call in to Nelson Racing Engines about their symmetrical turbos. For the twin engine setup I'm doing theses puppies are the bomb when it comes to good looks.

While they specialize in gas setups, they've done a diesel with them too. Their suggestion for 1000hp with about 45-50psi and good low end was 61/62 with .68AR, or their 64/65 set with .68AR or a .84AR. Looking for some thoughts?
 

Awenta

Active member
Sep 28, 2014
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.68 seems a bit tight. Would definitely be good for low end though.

Sent from my SM-N910V using Tapatalk
 

PureHybrid

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Feb 15, 2012
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Those use a different way of controlling vanes don't they...

The Engine Control Module modulates the supply pressure to the turbocharger pneumatic control cylinder (actuator) which acts on a rod and yoke system to slide the nozzle ring and blades relative to the fixed shroud plate.

One could Tee that signal tube between the pair and likely keep them in check long as they don't stick a slider.

Thanks for the suggestion.

The early style Holset stuff is like that, newer version has a water cooled electric actuator on top to slide the nozzle.

If you do enough digging you can find the he551/ 561 with a Ti compressor wheel.
 

kidturbo

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What's interesting is those units from Nelson are small with divided housing. He's working on a housing with built in spool valves, which I had considered using on a previous build with big single.

One could conceivably use the ECM turbo maps and VNT control power to operate the two spool valves. Allowing to run a more open AR housing but lower spool RPM.

Sorry it's bit off topic but control concepts remain the same.
 

calereeves

Displaced Texan
Jul 13, 2011
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The symmetrical turbos are definitely the tits when it comes to looks! Funny how stuff changes though--I called Precision back in the summer of 03 when I was working on a twin BBC setup. The guy literally laughed at me when I asked if they had anything like that so that the whole setup would be symmetric. He said something to the effect of "man, do you know how much that would cost for tooling, when it's just for looks?!"

Then again, in '03, diesel performance meant a p-pump on a cummins and tons of smoke, 1000hp turbo'd gas engines were the incredible exception, rather than a relative norm, and the dmax was still the new kid on the block. :-/
 

kidturbo

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I haven't gotten around to trying it yet. The twin setup I've been working on is using standard twin scroll non VGT. Mostly because I couldn't find a suitable VGT built on T4 base.

Would be happy to help engineer a splitter / controller if anyone wants to give it a go.