Re: 95 TSI AWD Project VGT Holset no 56k
 

You can do something like this.
https://i6.photobucket.com/albums/y2...I/P1251448.jpg

Fully open may be acceptable spool for you, and it may be quicker than what I am thinking.

D16Y8-z6 on here seems happy with the spool of his H1c in an 18.5 Cm housing, that turbo uses a similar sized turbine wheel to the VGT fully open is 25cm.

I like quick spool and the lowend torque that comes from using the VGT fully though, makes it more fun for me to drive IMO. Also makes the car SO much quieter when driving normally.

I'm not sure if these turbos(the HE351VE that is) are worth it for guys not wanting to use the VGT, the main reason being the odd flange so you can't just swap to another turbo.

Re: 95 TSI AWD Project VGT Holset no 56k
 

I agree that the VGT function should be retatined. I just installed mine (garrett) and am controlling it with MegaSquirt 2 Extra code. Its not perfect and may never be, but it does the job and will be much better with the addition of a wategate.

Re: 95 TSI AWD Project VGT Holset no 56k
 

Took it apart today and took some measurements and more pictures. It is one big SOB. :shocked:

Wheel measurements.

Compressor
Inducer 71.75mm
Exducer 108.1mm

Turbine
Inducer 86mm
Exducer 75mm

From some clay and my calculations the VGT has an operating range of approximately 9cm^2 - 31cm^2
The compressor is a machined wheel that looks like what people refer to as a "billet" machined wheel. I stupidly forgot to try and determine whether it is aluminum or titanium. The backing plate was a bit rusty, otherwise the thing looks like its in great shape with normal shaft play.

https://i6.photobucket.com/albums/y2...V/P2080073.jpg
https://i6.photobucket.com/albums/y2...V/P2080077.jpg
https://i6.photobucket.com/albums/y2...V/P2080075.jpg
https://i6.photobucket.com/albums/y2...V/P2080078.jpg


https://i6.photobucket.com/albums/y2...V/P2080082.jpg

Here as a size comparison to the HE351VE turbo I have on my car, the one most people think is big.

https://i6.photobucket.com/albums/y2...V/P2080083.jpg
https://i6.photobucket.com/albums/y2...V/P2080084.jpg
https://i6.photobucket.com/albums/y2...V/P2080088.jpg
https://i6.photobucket.com/albums/y2...V/P2080090.jpg


VGT fully open
https://i6.photobucket.com/albums/y2...V/P2080086.jpg

VGT fully closed
https://i6.photobucket.com/albums/y2...V/P2080087.jpg

Re: 95 TSI AWD Project VGT Holset no 56k
 

omg. i had the he351ve and that thing was enormous.. that red turbo is just unbelievable.
i want to see it next to a 14b LoL

Re: 95 TSI AWD Project VGT Holset no 56k
 

Here is a 14b next to the HE351VE.
http://i6.photobucket.com/albums/y21...r/P8021422.jpg

Re: 95 TSI AWD Project VGT Holset no 56k
 

Thats because its restricting the exhaust. An ideal controller will vary the vane position based on throttle input and engine load.
The trucks these turbos were put on use the fully closed vanes as an exhaust brake.

Have you measured your exhaust manifold pressure? I'd bet you'll find its quite high except at full throttle.

Re: 95 TSI AWD Project VGT Holset no 56k
 

Yeah I know thats why its pretty quiet. I don't think it is choking it too badly though in the cruise/low boost realm. A stock turbo on a 1st gen DSM uses a 6cm turbine housing with a MUCH smaller turbine wheel. This thing closes to 3-4 cm by my measurements but still has a much larger turbine wheel.
Before hooking up a boost source to the VGT rack, so it stayed closed at all times. I had the thing up to 20-25lbs of boost, and it still pulled pretty hard. Its obviously not ideal and it makes more power now at 15-16lbs and opened up fully by 11lbs or so. I had planned on testing the backpressure with a gauge, but the bearing spun too soon. When it gets running again it will be one of the first things I do.

Engine braking on agasoline engine from exhaust restriction isn't effective like it is an unthrottled diesel. The diesel is still running all air through the engine so it has prentty of air in the exhaust to restrict. The gasoline engine is only getting 15-20% of atmospheric pressure into the cylinder when the throttle is closed.

I'm sure having an ideal controller would help with tuning and fuel economy if everything can be worked out. I really look forward to that day. On a speed density controlled spark injected engine that controller has the potential to really make tuning more difficult too though. Variable backpressure changing VE and therefor AFRs too. Since I can't control boost with the VGT on my engine then its not quite as beneficial as it may be to a diesel. There is simply too much exhaust energy for it to regulate boost low enough. Opening it early works the best for me right now.

Hopefully I got that into words in an understandible manner lol. Sometimes its hard to explain what I'm thinking haha.

Re: 95 TSI AWD Project VGT Holset no 56k
 

If a 9cm housing is enough for 20psi (~35psi absolute), the 2-3cm opening is enough for cruising (~10psi absolute).

I think this turbo would work even better with a vtec head, since most cams tend to have much less overlap on the low cam. This greatly reduces the bad effects of high exhaust backpressure, meaning you can let it crank boost with it fully closed, then open it very close to full boost.

As I think I said before, the typical diesel motor "drops off" considerably in the higher RPM's, meaning exhaust mass (per stroke) does too. Thats why diesels can control boost easily with the turbine, but "we" can't.

Re: 95 TSI AWD Project VGT Holset no 56k
 

If you could use the original actuator with an EMS, you should be able to control backpressure under light throttle. Thats what I intend to do with my garrett. Have a switch for street and race mode. Street would open the vanes under light to moderate throttle, and close them under heavy throttle to WOT, though it will likely have some delay in response. Race mode would keep the vanes closed untill desired boost is achieved, then open up for flow and boost limitation.


BTW: CAN is a communication protocall, not a control method

Re: 95 TSI AWD Project VGT Holset no 56k