Variable geometry turbo "VGT" implementation on an sti.

Bluedemon_II

New member
The timer circuit generates a PWM signal that has a period of 20ms with a duration of .9 to 2.0 ms. This is an universal pwm signal to control servos. That circuit that I posted uses a variable pot to determine the pwm signal output. By moving the pot you would move the servo.

The problem:
The signal that I want to use has a 0-5v value. I want that circuit to reference the pwm signal output to the 0-5v output instead of a variable potentiometer. I think some one achieved this before. I will be using a boost signal output from a 0-30psi sensor. No vac reference. While in vacuum the vanes will be at their max closed position "Not fully closed but a preset using a welded stopper". When the car begins to develop boost, the signal while be go into the circuit, and this will in turn move a high performance servo to actuate the vanes. to a certain position.


Current issues: Mis calculation of servo travel could result in servo damage since it will try to go further past the maximum allowed open point and burn the motor. Measurements must be made to be very exact. This is not really a problem but a issue that must be considered and addressed with care.

Threads of interest on this route.
http://www.rcgroups.com/forums/showthread.php?t=1090355
http://forum.allaboutcircuits.com/showthread.php?t=19763

Thats all I have seen for now. This would be the most simplest way to go, no programing needed, just an input and an output.
 

Bluedemon_II

New member
Please add one here for reference and idea gathering. I'm consulting on a electronics project forum about the 555 based controller "boost referenced"
 

Bluedemon_II

New member
Wow, thats a lot to read.

Going to see if I can get one locally for cheap and clean it out by my self using the overhaul manual. Lets see how it goes.
 

Bluedemon_II

New member
Well the thread is about VGT or VNT application on an EJ257. Still, I find that placing a carpc is ads a lot more into the final cost and for some user will be a lot harder. Unless im getting your approach wrong. Side note, how easy is it to find a garret vnt turbo? Which vehicles was it installed in?
 

Bluedemon_II

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Found 2 on ebay for about 400 bucks. Still I'm hovering around the mp3car site attempting to understand the car pc setup. The website layout confuses me a little.
 

Bluedemon_II

New member
While we are on the vnt topic. What is the oil pressure requirement, what type of pwm signal is it needed? A boost control solenoid controller could be employed since it uses a pwm to control a solenoid?

I want to see more info on the Garrett unit to do some comparisons on paper.

The Vnt turbos aren't rebuild-able?
 

Bluedemon_II

New member
Wow, that wouldn't be bad but the holset can be rebuilt. Even so it seams that the garrett unit can be easier to fit. Size wise they look about the same, the Garrett one has a bigger compressor housing.

I will start reading to see if I can get a comparison paper done on the installation method and components.
 

Paul.c

New member
The nasioc thread was interesting, are there any cars that you know of running the Aerocharger setup, specifically subarus? With the aerocharger turbo would you just use one of their controllers? If so that seems like the best way to go. That is if the porsche units are really that hard/expensive to come by.
 

Bluedemon_II

New member
The aerocharger is to small for my application, still it seams like a sexy idea if it where a little more bigger.

I'm going to start reading up on all the garret vnt threads.
 

Bluedemon_II

New member
Why do some of the best ideas come to ppl when in use of sweet rum nectar? lol.


Looks like where going to have 2 different type of variable exhaust turbo builds here. As far as the Cad software goes, and I don't know if the forum rules will spank me for this "Bad be gentle" Download Autodesk auto cad 2010. Torrent.

I replaced and relocated my IAT sensor to cold my intercooler pipe so when I delete the intake, I will not worry about missing the sensor. Funny story, while I was Tack welding the bung to my pipe, I left the sensor in so it would remain centered. Totally forgot that the sensor was there and went to the second tack and when I noticed it the plastic cover for the sensing element was on fire... Quickly took it off and put it on a glove. I was sure that the sensor was dead, but I was wrong. The Aem registered correct temperatures and the response time is amazing. Guess that I was lucky.

Still lesson learned, don't tig weld with anything plastic near lol.
 

Bluedemon_II

New member
Email them the part number and maybe a photo of the controller to see if they can give more info. They seam willing to help.
 

Bluedemon_II

New member
For some reason I think that the garret vnt setup wont work so well on out displacement range. On the Porsche they actually work because they are smaller in size and are correctly sized to the engine, so a change on the nozzle area would have a more prominent effect. Remember that even if you change the nozzle are the Garret vnt unit is quite large in it self and even if you change the vane positioning. The approach on the Holset seams more logical to me since you are changing the A/R more efficiently and the control. After talking to a turbo specialist that actually has replacement parts for the holset, they told me that the holset would be more capable to get the job done in the manner that I explain it. They say that their experience with the garret is that the vane dissing isn't optimal to route the exhaust flow towards the blades. I for one will go with the holset since I can find parts locally, and will be easier to adapt for me.
 

Bluedemon_II

New member
What are the pricing options for the biggest aerocharger alone? Warranty period? I think that this info is excellent to add to the thread. After all, it fits with the goal at hand.

What are the flanges that need to be used? I would suspect that it uses a T3 inlet and a 2.5 V-band outlet?
 

Bluedemon_II

New member
Still I don't understand the design of their compressor. If you could swap the compressor housing for a bigger unit I would consider it. The other thing that has me on the fence is the self lubricating system. How will I know when I will be running low on lubricant? I dont find a low fluid warning sensor. I don't know man. I like it, but I really want to see it working.

On a side note, Right now I was thinking about what you said about running shorty headers etc. I need to visualize to see if there is enough space on the lower part of the engine bay to see If I could place the holset down low and cut some piping. Still I have my doubts due to the massive of the holset. My tial makes it easier to place it since it's the smallest vband wg that tial offers.

Stainless tubing would make this quite expensive and to tell you the truth, I don't want to hack my equal length headers.
 
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