# anyone with experience with the Holset VGT system



## clarksongli (Nov 4, 2003)

So i would like to get a VGT system going for a project......it would be nice to cut down on the lag a little bit with a variable hotside
anyone with experience with these systems?
the VGT actuator is a gear driven unit with 5 wires.....i am thinking of some sort of PWM system, but i would like to see if someone can nail this down for me......


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## Noobercorn (Aug 17, 2007)

*Re: anyone with experience with the Holset VGT system (clarksongli)*

i have looked into this, and as i recall, super high EGT's make it less than ideal for a gasoline motor without MAJOR mods. 
the 997 TT has this technology on it. 
a lot of diesel trucks do too.


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## ValveCoverGasket (Mar 20, 2002)

*Re: anyone with experience with the Holset VGT system (clarksongli)*

these systems are really sensitive to high exhaust temps, which in a diesel is anything over 1200F
i think youd have to start looking at something like the porsche parts if you wanted it to last on a gas motor.
would be fun though, really opens the door to some crazy turbo setups http://****************.com/smile/emthup.gif


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## clarksongli (Nov 4, 2003)

*Re: anyone with experience with the Holset VGT system (ValveCoverGasket)*


_Quote, originally posted by *ValveCoverGasket* »_these systems are really sensitive to high exhaust temps, which in a diesel is anything over 1200F
i think youd have to start looking at something like the porsche parts if you wanted it to last on a gas motor.
would be fun though, really opens the door to some crazy turbo setups http://****************.com/smile/emthup.gif 

well this is the benefit to the VGT system.....the variable comes not from pivoting vains, but from a slideplate which increases and decreases the hotside volume directing it towards different cross sections of the turbine wheel
without the pivots, there is nothing within this turbo that shouldn't be able to handle the EGTs
not to mention the 351VE has titanium wheels


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## ValveCoverGasket (Mar 20, 2002)

*Re: anyone with experience with the Holset VGT system (clarksongli)*


_Quote, originally posted by *clarksongli* »_
well this is the benefit to the VGT system.....the variable comes not from pivoting vains, but from a slideplate which increases and decreases the hotside volume directing it towards different cross sections of the turbine wheel
without the pivots, there is nothing within this turbo that shouldn't be able to handle the EGTs

edit, i take that back, it looks like the cummins turbos arent pivoting the vanes. im still skeptical of how well that system could hold up in a gas engine, but id love to see it happen http://****************.com/smile/emthup.gif
either way, its neat stuff, and itd be awesome to see someone do something with it in the aftermarket gas world http://****************.com/smile/emthup.gif


_Modified by ValveCoverGasket at 6:21 PM 8-21-2008_


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## clarksongli (Nov 4, 2003)

*Re: anyone with experience with the Holset VGT system (ValveCoverGasket)*


_Quote, originally posted by *ValveCoverGasket* »_
edit, i take that back, it looks like the cummins turbos arent pivoting the vanes. im still skeptical of how well that system could hold up in a gas engine, but id love to see it happen http://****************.com/smile/emthup.gif
either way, its neat stuff, and itd be awesome to see someone do something with it in the aftermarket gas world http://****************.com/smile/emthup.gif

_Modified by ValveCoverGasket at 6:21 PM 8-21-2008_

well get ready.....HE351VE on a 1.8T.....shooting for 450whp.....in a 1700lb mk1


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## KubotaPowered (Jan 27, 2005)

*Re: anyone with experience with the Holset VGT system (clarksongli)*

Got a pic of the turbo? Some of them are oil pressure controlled, some are linkage controlled, other are mix of both. As stated before the EGTs are the hardest obstacle to overcome, 1200-1400degrees are the highest EGTs most diesels see and they are not sustained and cool quickly, gas engines will be higher


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## clarksongli (Nov 4, 2003)

*Re: anyone with experience with the Holset VGT system (KubotaPowered)*

the turbo is linkage controlled.....it uses a motor and PWM system to operate a swing gear....i am not too worried about the temps as:
1. the vains do not pivot like most VGT systems
2. the turbo uses a titanium turbine wheel


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## Noobercorn (Aug 17, 2007)

*Re: anyone with experience with the Holset VGT system (clarksongli)*

i too was looking into this for a 1.8t, but ended up going a different directio. i am interested in seeing how you make out


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## ValveCoverGasket (Mar 20, 2002)

*Re: anyone with experience with the Holset VGT system (clarksongli)*


_Quote, originally posted by *clarksongli* »_
well get ready.....HE351VE on a 1.8T.....shooting for 450whp.....in a 1700lb mk1









good luck, and keep us posted


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## Scrampa1.8T (Feb 10, 2003)

*Re: anyone with experience with the Holset VGT system (ValveCoverGasket)*

Yes please do let us know how this works out. I've been told they were CAN controlled so if someone is able to get it to work that would be nice.


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## aero83 (Sep 28, 2008)

*Re: anyone with experience with the Holset VGT system (clarksongli)*

I just did this with a different method on my own project. 
Maybe it might give you something useful.
http://www.homemadeturbo.com/f...770.0


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## Scrampa1.8T (Feb 10, 2003)

*Re: anyone with experience with the Holset VGT system (aero83)*


_Quote, originally posted by *aero83* »_I just did this with a different method on my own project. 
Maybe it might give you something useful.
http://www.homemadeturbo.com/f...770.0



Nice, kickin it back to basic mechanicals...I like that.


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## aero83 (Sep 28, 2008)

*Re: anyone with experience with the Holset VGT system (Scrampa1.8T)*

So far its been working extremely well for as simple as it is. I have an 8" length of 3" 90 degree bend after the turbo and at cruise and no boost the exhaust is just as quiet as my full exhaust. The only noise is turbine whistle. Sounds like a jet when you drive next to another car. Going under and overpass sounds like a business jet flying by at low altitude. Its really pretty weird, but I love it.


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## thetwodubheads (Dec 6, 2004)

*Re: anyone with experience with the Holset VGT system (aero83)*

I think I may need to swap over to one of those for the corrado. My guess, and you can confirm this, is that if using a wastegate to control the vane shut off deal, it would just open things up at a set boost level? Like get a 10lb spring for the wastegate housing and when the turbo is spooling enough to produce 10lbs it opens up for more flow. Now would this cause a flat spot in boost, like spooling quick to 10lb and then having a flat spot from there up to 20lb? Or would you MBC that and just put it at the same as wastegated boost pressure so it spools as quick as possible to set limits then cracks open to flow more exhaust at high rpm?


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## aero83 (Sep 28, 2008)

*Re: anyone with experience with the Holset VGT system (thetwodubheads)*

Here is a log showing boost with the current setup. 
Stock 14b wastegate actuator on the VGT rack. Which is 7-8 lb actuator with no MBC on it,. External gate has a 15lb spring in it with MBC turned all the way down.
I think an MBC on the VGT actuator will bring the boost up to the external gate's set point quicker than it does now.


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## thetwodubheads (Dec 6, 2004)

*Re: anyone with experience with the Holset VGT system (aero83)*

I am not familiar with that type of system, what were the levels? Can you make a single gear pull, like 4th or something from really low rpm so I can see what the boost curve looks like, and can you also assign the scale to it?


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## Boardinjew0 (Sep 12, 2007)

*Re: anyone with experience with the Holset VGT system (thetwodubheads)*

this is an ingenious idea. i would love to reduce my turbo lag and have my car pull hard as hell through all rpm's.


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## aero83 (Sep 28, 2008)

*Re: anyone with experience with the Holset VGT system (thetwodubheads)*

Left of the graph is the beginning, right is the end so it reads left to right. Bottom line graph has boost and rpm graphs. That is a launch through 5000rpm in 4th gear. They are color coded with peak and minimums on the left. Where the teal line passes vertically through, there are the values marked there next to the line. 
I will try and get a pull sometime later, but I'm pretty busy at the moment. The top graph also has boost, rpm and also throttle position. 
Higher gears after the shift boost goes straight to 12-13lbs, then 16-18 at the end of the gear. I'm pretty sure adding a MBC to the VGT will make it go straight to the external gate's boost setpoint quicker.


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## aero83 (Sep 28, 2008)

*Re: anyone with experience with the Holset VGT system (Boardinjew0)*

So far it spools about 1200 rpm faster than the HX40 in the tiny ~.55a/r Bullseye bolt on housing I had before. I had before on basically the same setup. This has a 2mm larger compressor than that turbo, 60mm inducer vs 58mm. It pulls harder at high rpm at a given boost compared to that turbo also, thanks to the extremely high a/r when it opens up.


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## thetwodubheads (Dec 6, 2004)

*Re: anyone with experience with the Holset VGT system (aero83)*

You said you have a 2.4l right? I wonder what sort of usable RPM this would make on a 1.8l? It is almost cheap enough to try. What type of flange is on it? T4?


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## aero83 (Sep 28, 2008)

*Re: anyone with experience with the Holset VGT system (thetwodubheads)*

Yes it is a 2.4l. 8-8.3:1 compression. How it would behave on the 1.8t I really have no idea, I have NO experience with them other than driving my friends chipped 05 golf a couple of times. 
Here were my initial spool results with the VGT rack fully closed and fixed there. This is just the first log I opened. 
Here are the the most important things affecting spool

I can't remember what gear for sure but I think its 4th. 
8" of 3" pipe for an exhaust
No intercooler
E85
8-8.3:1 compression
stock head, cams, intake manifold
Fairly low timing
1800 1psi
2000rpm 3psi
2500 8psi
2600 10 psi

Its a little slower now, the actuator starts to open the thing up a little sooner than I'd like. 
Keep in mind this thing has a compressor in the GT35R size class. 
The flange is not a standard flange, which is the biggest obstacle that most people are going to run into. The other biggest thing is the physical size its just big. I'[m not sure how much room you have in your application. 
I don't have the measurements of the flange anymore, but I might be able to get them off the turbo my friend just picked up sometime over the weekend. Its longer/thinner than a t3 or t4 if my memory serves properly. 


_Modified by aero83 at 9:56 PM 10-1-2008_


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## thetwodubheads (Dec 6, 2004)

*Re: anyone with experience with the Holset VGT system (aero83)*

Those are pretty impressive spool times for such a large turbo








Some people using a t3 sometimes won't see 10psi by 3k








I may be picking one up when I get some money. I'd probably end up using some sort of MBC set-up for both boost and spool control. This may be one of those things that gets to be very popular.... Later down the line there will be a which big turbo and 40 people will be saying 'cummins vgt'


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## aero83 (Sep 28, 2008)

*Re: anyone with experience with the Holset VGT system (thetwodubheads)*

The transient response is what I really love. Here is a log going from 70kpa in vacuum, to 9psi in .95 seconds, spool then continues but slower. This is going from steady cruise at 70mph in 5th gear, which is between 3000-3100 rpm. You can see the first 9lbs pretty closely follow throttle position, which doesn't go over 70%. 








Passing in top gear is fun.


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## thetwodubheads (Dec 6, 2004)

*Re: anyone with experience with the Holset VGT system (aero83)*

That is absolutely what I want in a car. Now just imagine having a MBC on the vane controller set to 15lbs, it'd be like driving a car with a screw blower that actually pulls up top.


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## thetwodubheads (Dec 6, 2004)

*Re: anyone with experience with the Holset VGT system (thetwodubheads)*

I just re-visited your HMT post, and it looks as though MS 3 can power more stepper motors, I wonder how hard it would be to just set one up to make like 4 positions for this thing for cruise/idle, then 3 seperate boost levels. Like 100% closed until 6lbs, 75% until 10lbs, 50% until 15lbs, then wide open after that. That might be really good to help prevent rods from shattering


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## aero83 (Sep 28, 2008)

*Re: anyone with experience with the Holset VGT system (thetwodubheads)*

MS3 isn't out yet, I'm sure you mean MS2. Yes it will drive a stepper idle motor, but you could probably accomplish 90% of that just by running an electronic boost controller on the VGT actuator. Rpm specific boost control. 
The stock VGT actuator runs on the CAN bus from my research, which if you could figure out the protocol could be useful, but its a digital signal. Internally it appears to be a stepper when I took it apart, so if you gutted it you might be able to get it to work the way you described with a stepper driver.


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## storx (Dec 6, 2006)

*Re: anyone with experience with the Holset VGT system (aero83)*

when i was in college last year i took a advanced course on electronics and our final exam was we had to make a project using a stepper motor... which is controlled by a simple micro controller. I know it is fairly expensive to have a new chip pressed with the code once your done. But i was thinking that there are tons of hobby project kits that come with the CD for the software to control the microprocessor and stepper motor. I wander how hard it would be to regut the box with a unit that is already not encrypted. my other idea i have been thinking of for this setup would be to get one of the fast acting solenoids and attach it to the linkage via gear or somewhat and hook it to a hobb switch were.. at a set boost it just goes from closed to open on the slidevein. from my calculations using the excel document they have on dieseltruckresource for tuning the VGT for twin turbo setups is that we could leave it closed tell 13.7psi (1.8T), or 8.3psi (2.4T) which at that point the engine should have enough in her to make her climb faster with the slidevein open tell redline.


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## aero83 (Sep 28, 2008)

*Re: anyone with experience with the Holset VGT system (storx)*

Do you have a copy of that excel document or a link to it? I'd be very interested in seeing it. 
If that's for twins I have to think the faster boost response is from letting more exhaust energy past the first turbine wheel to the second is why it would spool faster with it open. That would be my guess from running a HE431V VGT on an 8.3 cummins that I installed this summer. 
A two position setting was what I was going to try if my actuator didn't work out. It would still be pretty advantageous compared to a fixed size housing IMO. Sort of like swapping from a .48a/r to a 1.2 a/r (numbers just pulled out of my butt) at high rpm.


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## storx (Dec 6, 2006)

ya got an email address.. its an open office excel document i picked up a while back.. its pretty cool playing with it.


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## aero83 (Sep 28, 2008)

*Re: (storx)*

aero83 at gmail.com


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## aero83 (Sep 28, 2008)

*Re: (aero83)*

I took apart my friends turbo he picked up today and clayed the VGT opening when I closed it all the way. I definitely found out why it spools so quick and muffles the exhaust so much. It closes down all the way to around 3.5cm^2 nozzle area. So variable from 3.5cm^2 all the way to 25cm^2


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## aero83 (Sep 28, 2008)

*Re: (aero83)*

Here is a picture of the clay showing the flow area. Its somewhere between 1.4-1.8mm. Its hard to get the measurement exact because of the softness of the clay.


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## thetwodubheads (Dec 6, 2004)

*Re: (aero83)*

Wow, that looks to be less than a standard K03








So I think I need to hang around the local diesel tuner shop and try to get one of these pretty cheap.....


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## cant get a password (Sep 24, 2004)

*Re: (thetwodubheads)*

I ran a garret vnt 15 off of a tdi on my old corrado g60 when the charger decided it didn't want to play anymore.I could hit 20 psi at 1,200prm with it but it ran out of air quickly by 4,500 rpm.I would have to adjust the vanes out to only make about 8psi then it could rev out to redline that way.It would get up and move at 15-20 psi at low rpms it was a fun experiment for $200.


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## storx (Dec 6, 2006)

im going to install one of these over a garret i called the local cummins dealer trying to get a map of the turbo possibly and they said that they have been replacing these under warranty with an newer improved version with a stronger actuator motor and metal gearing not plastic cause the soot is causing the slidevein to stick and its brakign the gear in the actuator. he said he talk to his boss about them and get back to me.. but he said he didnt see a reason why i couldnt have them for a few dollars cause they have been scrapping them for metal at the local recycle center for a few dollars and he has 17 on the shelf from just this month alone.


_Modified by storx at 6:44 PM 10-6-2008_


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## aero83 (Sep 28, 2008)

*Re: (storx)*

Everything inside the actuator that came on my turbo was metal. I bought it unused back in February. Brand new turbo for $400 wasn't bad. Now you can pick up used ones so cheaply on ebay though. I've heard of them replacing turbos for the sticking vanes also, but never heard of the breakage issue. I know at first they tried a cleaning procedure as a TSB (or something similar). They would drill into the center section abe spray cleaner behind the slidevane mechanism. 
Sounds like an awesome deal for you if you can get hold of them.


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## storx (Dec 6, 2006)

ima head up there today... and see what he said.. hope i can grab a few of them off him so i can let some fellow members have some for a steal of a deal.


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## clarksongli (Nov 4, 2003)

*Re: (aero83)*


_Quote, originally posted by *aero83* »_Everything inside the actuator that came on my turbo was metal. I bought it unused back in February. Brand new turbo for $400 wasn't bad. Now you can pick up used ones so cheaply on ebay though. I've heard of them replacing turbos for the sticking vanes also, but never heard of the breakage issue. I know at first they tried a cleaning procedure as a TSB (or something similar). They would drill into the center section abe spray cleaner behind the slidevane mechanism. 
Sounds like an awesome deal for you if you can get hold of them.

wow this thread is still going............
i bought mine for 200bucks shipped rebuilt, works amazingly well, fun to play with the controller
I will be controlling this with a EBC with a step setup....it is hard to get the smooth operation from this, but i am hoping for 3 or 4 staged steps for the VGT
as far as the VNT15......those are quite small......too small to function well on gas motors.....the 351VE opens to over 2.00A/R
the other benefit to this turbo......Titanium wheel and slide fins.....good for gas temperatures.....

on a side note....i have the flanges made on a waterjet......as well as AEB bigport flanges......perfect for a manifold








let me know if anyone needs the flange.....i can cut them for people, if i can do all the cuts at once it would be better cost wise


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## storx (Dec 6, 2006)

i might take you up on that.... were you source your turbo from>?


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## boost is better (May 26, 2007)

what about a vnt turbo from a dodge daytona vnt?bigger then the tdi unit


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## storx (Dec 6, 2006)

still to small that is like running an K04


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## aero83 (Sep 28, 2008)

Well my testing has come to an abrupt halt. Spun a rod bearing yesterday.


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## storx (Dec 6, 2006)

that sucks.. im still trying to work a deal with the cummins place.. he is telling me there 576.14 brand new.. which is got me all wound up... i hope they stay that cheap... for a long time.. cause when he brought them up on the pc.. they are linked to insane amount of diesel engines... commercially


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## KubotaPowered (Jan 27, 2005)

*Re: (storx)*


_Quote, originally posted by *storx* »_that sucks.. im still trying to work a deal with the cummins place.. he is telling me there 576.14 brand new.. which is got me all wound up... i hope they stay that cheap... for a long time.. cause when he brought them up on the pc.. they are linked to insane amount of diesel engines... commercially 

are you sure thats for the vnt turbo and not the standard wastegated holset turbo? I know that even through 2005 Cummins was putting regular turbos on their B and C and M series engines


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## storx (Dec 6, 2006)

he said it was the VE... turbo


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## thetwodubheads (Dec 6, 2004)

*Re: (storx)*

Less than $600 new







Cheaper than a Garret T series of similar size.... Let's take this thing to Private so we can enjoy low prices until our projects are done then flood the place with awesome response and top-end


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## aero83 (Sep 28, 2008)

I remember having people tell me retail one of these was around $1700 or so. Maybe it all changed since then.


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## storx (Dec 6, 2006)

i am going by there tuesday... but i swear he said it was VE.. ill double check..


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## aero83 (Sep 28, 2008)

*Re: (storx)*

Did you make it there? I'm curious what you found out.


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## storx (Dec 6, 2006)

i went by there.. but he (head honcho) was out of the office.. told me to come back next week he is still waiting on word from his boss on what they will do with the turbo's cause from what he told me there was suppose to be agreement that holset is to send someone to pick up the salvageable units and writeoff the bad ones or something along those lines but they dont come tell there is a pile of turbo's/


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## aero83 (Sep 28, 2008)

*Re: (storx)*

Did you ever find anything out about this?


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## storx (Dec 6, 2006)

*Re: (aero83)*

ok, so its been a few days.. and yes i found out some info...
this is the catalog numbers and cost to the cummins shop for the turbo brand new.
010C/4089945NX
(4089312D) TURBO, HE341Ve
w/core $307.00 
wo/core $637.70 
Then here is some info i found out about the turbo.








*This is the procedures to test the electric actuator:*
Disconnect the sensor at its electrical connector. Using
a multi-meter, check the resistance between connector
pins 1 and 3 is 800 / 1200 ohms with the sensor at
20°C.
Apply key-on calibration check and measure voltage
from position sensor pin 1 to pin 3 is in the range
1 to 5 volts dc.
_This makes me think the system runs off 1-5 volts..._ 



_Modified by storx at 11:54 AM 10-23-2008_


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## storx (Dec 6, 2006)

if i knew someone with an cummins diesel truck with this turbo installed i would hook an multi-meter up to it and have them drive around for a little bit to understand how the voltage fluctuated with boost. From my understanding from the guys at cummins is the Cam-H/CAM-L bus actually doesnt control it.. the only reason that is there is to open the turbo completely open when the SPEED SENSOR detects the turbo rpms overspooling while closed..


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## aero83 (Sep 28, 2008)

*Re: (storx)*

1-5v is pretty normal for most types of feedback sensors. I wouldn't bank on the rest of it being the same voltage range.
Is that a typo or is that really the price for the 341ve? The one I have is a 351ve. I wonder what the differences are.


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## storx (Dec 6, 2006)

the HE341ve comes on the base model automatic 07-09 dodge cummins the HE351ve comes on the 06-09 manual cummins, and High Output automatics.
the catalog price for the HE351ve was 1249.00 wo/core the HE341ve only has titanium compressor and exhuast wheel the HE351ve has Extended tip titanium compressor.
HE341ve is 6-21cm2
HE351ve is 9-24cm2

_Modified by storx at 9:52 PM 10-23-2008_


_Modified by storx at 8:23 AM 10-24-2008_


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## aero83 (Sep 28, 2008)

*Re: (storx)*

Where did you get this information? I haven't seen nearly any mention of the He431ve an the forums. 
The HE351VE first came on the 07.5MY 6.7 cummins. 
THe HE351VE definitely closes tighter than that. I measured the nozzle area when fully closed using clay at between 3-4cm2. Also if it only closed to 9cm it wouldn't spool like it does on my car, or be able to be used as an effective exhaust brake on the truck they came off of. Since the stock late model 5.9 came with a 9cm2 hotside on the HE351CW (non vgt) turbo, 9cm wouldn't be enough of a restriction to provide braking. This turbo also spools far faster than that 9cm2 HE351CW would on my engine. 
From my observation I don't believe its an extended tip compressor, BW is the only ones I know of that have that. Holset has superback compressors, where the backing plate is extended for durability. Here is a picture of the compressor wheel in my turbo. Not the perfect angle though. 








I may be wrong, but the compressor wheel in my 351ve seems too soft to be titanium. 
I hope that doesn't come off as rude, just trying to find the right information for us all.


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## storx (Dec 6, 2006)

im just quoting the details in the catalog... the turbo also comes on like half a million other engines from Catapillers to cummins engines...


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## aero83 (Sep 28, 2008)

*Re: (storx)*

I'd be very interested in looking through that catalog. Is it online or a paper one?


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## storx (Dec 6, 2006)

paper one


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## aero83 (Sep 28, 2008)

*Re: (storx)*

Damn


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## NOTORIOUS VR (Sep 25, 2002)

*Re: (storx)*


_Quote, originally posted by *storx* »_paper one

possible to scan?








This thread gave me the extra 'kick' I needed to start my own turbo build. Just won a HE351VE on ebay... and the fun begins!


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## Series8217 (Nov 21, 2005)

*Some enlightment on the VGT actuator operation...*

The HE341VE does NOT use the same actuator system as the HE351VE. It is very different. The 341 uses a linear actuator rod and a position sensor for ECM control of the actuator. The 341 has an EXTERNAL actuator position sensor. The 351 doesn't have this at all. I don't think any of the 341 actuator information applies to the 351.

The HE351VE actuator control does not use a stepper motor at all. It's a 3-phase brushless DC motor. There is an ST microprocessor on the board that runs a Freescale motor control chip. The chip controls the 6 MOSFETs you see on the top of the board. You can't see these devices in your partial disassembly because they're underneath the board and you have to carefully desolder the motor pins and external wires in order to take the board off. This isn't easy. Another interesting note, the board is multilayer; it looks like there are at least 5 layers. Not fun to trace. 
There are 3 hall effect sensors in a cage around the brushless motor. I haven't figured out what they're for yet but probably for determining relative motor movement. To figure out what the actuator position is.
The motor is geared very high against the actuator crosshaft. One of the gears in the gear set has a magnet on it. I think this may do some position encoding but I'm not sure yet; I don't see any detector that the magnet goes near. It may have been installed in the system but not implemented on board. Perhaps the prototypes did not work correctly.
A serial bus EEPROM is on board (also hidden on the backside IIRC) and may contain some usable program data.

Anyone here have access to electrical schematics for the Dodge truck that uses this turbo?


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## thetwodubheads (Dec 6, 2004)

*Re: Some enlightment on the VGT actuator operation... (Series8217)*

OK, lets bump this up....
Let's get some suggestions as to spooling one of these.
I am guessing that on a smaller motor, just swapping out the electronic actuator for a diaphragm style wastegate actuator would work just fine. But, do you set it for your max boost pressure, or for a level less so you don't have a very peaky torque spike? I think you may end up with either having a stepped spool, or K03 type spike.
My logic behind this (I am not a veteran tuner and haven't built a bunch of motors so this may all just be crap), is that with the actuator set via manual boost controller, would not allow partial throttle low boost driving. I suffer this surge from my boost controller in the GTI. On a small turbo it isn't too terrible, but on this thing, it would be shoving a whole lot more into the engine at very low rpm. Great if you are always racing around, but bad if you want to drive normally.
I also thought you could set it to a lower, more drive-able boost level. This could work out just fine. I am concerned that if doing it this way, you may not have flexibility, it's either all or none for the vane shroud. Would this cause a good spool up to the lower set-point, but then lag to spool to full boost until you reach the point of how it would spool without the vane shroud? I made a quick paint picture to try to illustrate what I am saying.
Lets keep this alive and see if anyone can play with one of these to see what they act like.


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## aero83 (Sep 28, 2008)

*Re: Some enlightment on the VGT actuator operation... (thetwodubheads)*

MY setup gives a somewhat stepped spool. It goes to 9-11 psi early then given its a ~11psi actuator by then the VGT is fully open. Spool slows down rising to the ~15 psi the external gate is set to at a slower rate. 
Its all in how you set it up, how far apart the VGT actuator and external gate pressures are set. A boost controller on the VGT actuator, or a higher pressure actuator would cause it to spool fast straight to the external gate setpoint removing the step. Keeping the VGT set slightly lower than the external should maximize efficiency of the turbine wheel though preventing wasted exhaust energy. 
There is the opportunity to tailor the spool quite a bit. I would like to experiment with an EBC on the VGT actuator to see what could be done.


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## thetwodubheads (Dec 6, 2004)

*Re: Some enlightment on the VGT actuator operation... (aero83)*

Thanks for that. I guess I was somewhat thinking in the right direction...
do you happen to have some more pics of your engine bay? I'd like to try to gauge size of this thing.


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## aero83 (Sep 28, 2008)

*Re: Some enlightment on the VGT actuator operation... (thetwodubheads)*

Its pretty damn big externally.
There are pictures of it during the fab work in my engine bay and compared to a stock 1g DSM turbo in the first page of my build thread on HMT.
http://www.homemadeturbo.com/f...770.0


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