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https://slantsix.org/forum/viewtopic.php?t=32945		 Page 2 of 2
Author:  JGTurbo [ Wed Dec 24, 2008 3:04 pm ]
Post subject: 
Click on a compressor map to plot the engine onto it. (CTRL+click to look at more than one at once)

Here's a response I left on the Ford six site. Forgive me if there are any Ford references in it:

The line on the left is the surge line. The engine should stay under
that line at all times. If the engine gets to the right of the graph, that can
lead to excess inefficiency and turbo overspeed. A little to the right is
okay at maximum engine rpm, but you don't want to operate the turbo over there too much.

The vertical axis is the pressure ratio (PR). That is turbo outlet absolute
pressure divided by turbo intake absolute pressure.
PR of 1.5 = 7psi
PR of 2 = 14psi
PR of 2.5 = 21psi... and so on

The horizontal axis is the airflow. Usually rated in CFM or lbs/min. This
value can be read just like horsepower. If it is rated in lbs/min (like the HX-35 Variant) then
30lbs/min=300hp
40lbs/min = 400hp
50lbs/min=500hp
This is pretty much just a coincidence, but it sure makes the maps easy
to read!
If the map is rated in CFM, it is a little harder to convert into horsepower,
but after doing it for a while, you'll get the hang of it.

So just learn to look at the map and see PSI and Horsepower instead of
PR and Airflow and things become a whole lot easier.

On the Squirrel calculator, if you hold down CTRL, you can select more
than one graph at a time. Spool up a 450hp@4500rpm 250cu.in. engine
to full boost at 2000rpm and compare the HX35 Variant to some of the
common T04B turbos (like the V1/V2). You can see that the HX35 can
spool much sooner than most others without surging. Now, I know that it
would be kind of crazy to run 19psi at 2000rpm, but I think it's cool that
the compressor could do it (and with the VNT, the turbine would be
up for it as well...).

I spend hours doing this......
Have fun!
Author:  gmader [ Wed Dec 24, 2008 10:39 pm ]
Post subject: 
Hi all,

I have been looking at this for a little bit. I agree that that HX35 would be a good choice, but I don't think anybody has gotten the electronics figured out to control the VGT version. I would stick with the internal wastegate version, and rig up an actuator that works at about 10 lbs of boost.
Author:  JGTurbo [ Wed Dec 24, 2008 11:35 pm ]
Post subject: 
I agree that the electronic box is complicated. I believe it is a stepper motor. Under the electronic box is a mechanical arm not too different from a normal wastegate. I took the electronic box off of mine and am going to operate the VGT mechanically (either through a wastegate actuator, or some other sort of setup). Initially I'll run it in fixed positions using a threaded adjuster. This will allow me to find an acceptable range of motion for the VGT before I make it live. The two ports that you see in the picture are water passages. I am using a plate to seal them off. Drilling a tapping them for plugs is another option. These turbos are nearly new, they are going for less than HX35s and have the adjustable VGT. That's why I opted for a pair of these. The full name is HE351VGT or HE351VE (it says both on the turbo). They are rumored to flow more than the HX35 and also have titanium compressor wheels.

Oh, and they also have speed sensors installed. That's what the wires are for in the previous pictures.

Image
Author:  jmccabe [ Fri Dec 26, 2008 10:28 am ]
Post subject: 
I thought You Couldn't use diesel turbos on a /6
Author:  Joshie225 [ Fri Dec 26, 2008 11:29 am ]
Post subject: 
Why not? I'm planning on using an old Holset H1C. Cost me all of $20, but it has the big 20cm exhaust housing which I expect I'll have to change in order to have much boost below 3500 RPM or so. The thing you can't do with a diesel turbo is run them in a draw-through configuration as the compressor seal won't handle vacuum.
Author:  Matt Cramer [ Sat Dec 27, 2008 7:42 am ]
Post subject: 
Quote:
The thing you can't do with a diesel turbo is run them in a draw-through configuration as the compressor seal won't handle vacuum.
Yep, that's the one big gotcha with deisel turbos. Set them up in a blow through configuration and you don't have to worry. The import guys use Holset HX35s off diesel trucks on slightly smaller inline sixes like the BMW M20 (another slant six) and Nissan L28ET (280ZX). An HX35 or HX40 would do pretty well on a slant.

Well, there is one other weird gotcha - I've heard claims that the variable nozzle turbos on diesels are actually lubricated by soot! Supposedly the vanes have a tendancy to freeze up if you put it on a gasoline engine. This doesn't apply if you are using an external wastegate turbo or locked the vanes in one position anyway.
Author:  JGTurbo [ Sat Dec 27, 2008 1:36 pm ]
Post subject: 
Quote:
I've heard claims that the variable nozzle turbos on diesels are actually lubricated by soot!
That's interesting. Both of mine were frozen when I got them. I tapped on them with a soft hammer to knock the soot out of them and now they work fine. Garrett has said that their variable vane turbos don't work on gas engines because of the higher exhaust temps. These Holsets are a different design than the Garretts.

Well, I'll give it a try and we'll see what happens!

(There's a good chance I'll just be locking them in place anyway.)
Author:  Matt Cramer [ Sat Dec 27, 2008 2:52 pm ]
Post subject: 
Ok, sounds like I probably heard that one wrong. It may have been the EGTs instead of the chemicals in the exhaust. But it seems that for some reason they're more prone to seizing up on a gas engine. Evidently the VNT on the Shadow CSX had similar clogging problems.
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