ViperKlr1

If rear mounting turbos results in lower turbo temps wouldn't it be a good idea to take advantage of that and use variable nozzle turbos?

With variable nozzle turbos a person could use larger A/R housing turbos while still theorectically retaining the responsiveness of a turbo with a smaller A/R housing.

stevieturbo

good thinking...but Im not sure there are large enough units available, and VNT would cost a fair bit more.

Boost control is a little more complex too, and is usually performed by vacuum controlled by the ecu.
Instead of simple pressure control like normal setups.

1320

iTrader: (6)

I think mostly because the 67 turbo that comes with them are about 600$ turbos, and the prices I ve seen on VVT are in the 2600+ area. Just no market at that price.

Zombie

iTrader: (2)

there was a guy on here who used one, but it was too small.

flawless35th

iTrader: (1)

so the turbo on the duramax ist too small?

ViperKlr1

$2600.

Is this the price of a diesel spec turbo or the price for one of those gasoline spec Porsche 997 turbos?

I do agree the Porsche 997 turbos would be too small although they are apparently heat treated to take the temperatures of a front mount location.

abbaskhan

vtn turbos only go so big from what i found if some one could find a bigger one im sure it would be doable

plus im sure cost would be alot higher than a comparable turbo even DBB


which leads to reason why not use a same/or bigger DBB turbo with more effective heat management ...read header and pipes wrapped all the way to a jacketed turbo and coatings in conjuction
plus fabrication with thicker walled pipes would be something to look at

DrTurbo

iTrader: (3)

Their are bigger ones now available. We have the new Billet 71mm VNT units built by Garrett. They are LARGE units and over 3K! Much better to just stick to conventional design.

ViperKlr1

Are these the "heat treated" gasoline spec turbos?

P.S. I don't know how they would compare to convential DBB turbos on a LS motor but I have seen some impressive numbers featuring a Supra as the test vehicle (in a magazine article). The supra was a 800-900 hp modified motor.

It seems either the low end torque is better with the VNT or the there is more high-end horspower (all things being equal)

DrTurbo

iTrader: (3)

No turbo is heat treated that I have ever heard of. All use 713C inconel turbines.

ViperKlr1

Sorry maybe the term "heated treated" is incorrect.

Borg Warner apparently does something to the VNT Turbos used in the Porsche 997 Twin turbo to enhance their durability. Maybe they put some kind of coating on their turbos?



Does Garrent say these new VVT could be used with a gasoline motor in a front mount location?

Thanks.

StingrayCrazy

iTrader: (5)

You could go with a large frame garrett TVXX with a dual scroll exhaust housing and do something like this to give you the same effect on the cheap...





You would be using half the housing AR when the gate is closed giving faster spool, and as soon as max boost is reached it opens and gives you full housing AR for max power...

The best part about it no ECU is required

ViperKlr1

I even wonder if Variable Nozzle turbo would be even better on a road course where not needing to have a wastegate keeps the turbo cooler (lap after lap). I am pretty sure the driveability would be better.


In a road car this would seem to be higher yield than a drag strip only car that only has to do one run at a time.

Silver_TransAm

iTrader: (2)

Wow that is thinking right there. Let us know how it works.

98Camarod

iTrader: (43)

^^^No ****, I wanna hear how that worked^^^

StingrayCrazy

iTrader: (5)

It's not one of my build pics but it's exactly how I'm building my rear mount thumper... This is the actual picture...



Guys in junkyard DIY forums have been blocking off half of exhaust scrolls on big truck turbos for years to build boost when smaller AR housings were not available.

This will work... Just set the boost where you want (Being carful not to surge) and it will maintain by opening the second inlet to the exhaust housing. This increases the AR ratio which maintains boost by increasing the cross sectional area (exhaust flow) across the turbine, just like taking your thumb off of a garden hose... A second gate set a little higher or controlled with a boost controller, would be required once the first gate was fully opened and max AR was achieved. Depending on the combination a second gate may not be required...

I've thinking of ways of doing this internal to the housing for a couple of years and then this was posted on a mustang forum. This and other like builds have been kept hush, hush, why I don't know... Spread the word...

chuntington101

a guy on here installed a garrett GT45 with VNT buit it was a front mount. it work ok. he flet it would work really well as a rer mount setup.....

dont think he paid alot for the turbo.

Chris.

chuntington101

StingrayCrazy, have you got any more info on this twin scroll idea?? seems to be a stroke of genius!

Chris.

exodus

iTrader: (15)

you said stroke!

StingrayCrazy

iTrader: (5)

Chris, I agree...

I'm building an older Garrett TV series with a twin scroll T6 housing using this design in a rear mount. I think if paired to a large compressor wheel w/anti-surge mated to a smaller turbine w/twin scroll housing it would be the perfect solution for a street-strip combo which would boost like crazy and then bypass to the second scroll for max flow and Horse Power. All without the need of electronics and could be controlled by a simple spring diaphragm wastegate…

I was blown away when I saw this picture and changed my design right then and there...

Here is the link that I've been following for sometime. Like I said, I completely over looked this solution and was trying to think of a way to achieve the same internal to the housing. When I saw this post it blew me away... Frank

http://www.theturboforums.com/smf/in...?topic=45148.0