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Turbo Install

Manimalmother
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dave110

dave110

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Sorry if I missed something here. We went from rebuilding to drilling and milling. I can do those things easy enough. What is the improvement in drilling the hole to 7/8 and milling the divider? Is this just a standard HX 35 or is it a hybrid or being used for twins or something?

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Manimalmother

Manimalmother

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6 minutes ago, dave110 said:

Sorry if I missed something here. We went from rebuilding to drilling and milling. I can do those things easy enough. What is the improvement in drilling the hole to 7/8 and milling the divider? Is this just a standard HX 35 or is it a hybrid or being used for twins or something?

 

This is a standard HX35.  While apart for rebuild I am doing machine work per DAP's advice.  Opening the hole and milling the divider allows the flow to the wastegate from all 6 cylinders instead of just the front three.  Results in lower EGT's.

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Dieselfuture

Dieselfuture

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20 hours ago, Manimalmother said:

Results in lower EGT's.

But that should only be affected on high PSI when wastegate is set to open? Am I thinking correctly. 

My wastegate isn't even hooked up it's always closed, I rely more on tuning and defuel settings as backup. I can see where milling divider may help in better spooling, unless it has nothing to do with that.

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Manimalmother

Manimalmother

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2 minutes ago, Dieselfuture said:

But that should only be affected on high PSI when wastegate is set to open? Am I thinking correctly. 

My wastegate isn't even hooked up it's always closed, I rely more on tuning and defuel settings as backup. I can see where milling divider may help in better spooling, unless it has nothing to do with that.

 

I'm just doing what DAP said to since I have a mill.  Lol

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dieselautopower

dieselautopower

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On 3/27/2019 at 3:07 PM, Dieselfuture said:

But that should only be affected on high PSI when wastegate is set to open?

Correct,  It will help top end power.  Low end spool up will be slightly inhibited as you will lose some of the pulsing of the twin volute.

 

Reducing back pressure is important.  1.2psi back pressure or lower  to 1.0psi Boost otherwise you are leaving HPon the table.

 

Running a waste gate or getting a larger turbine wheel or housing will reduce back pressure.  You add more exhaust gasses/ from fuel/ boost/ higher RPM and it gets constricted.

 

The stock hx35 is about 58mm exducer on the turbine (25.4mm = 1")   =2.3"  figure you have a 7mm shaft, + hub (lets say 2x 3mm=6mm)  and a number of blades on the shaft.  So with bad math we get to about 45mm with blades in the way.  So thats about 1.8" with blades.  Enter the wastegated housing... 17mm to 22mm are common sizes,  S300 turbos usually have 2 of them. 

 

So with the wrong size turbine/wastegate/ turbine housing its common to have over boost (less efficient), over speed of the compressor wheel (reduced life from centripetal forces on the wheel = deformation, oiling problems, less efficient, more wear),  and restriction to the flow of the exhaust).  Its about flow in and out of the engine (boost does help). Think of a water hose.  Low pressure... high flow.  Kink the hose and you get 40-60psi.... and no flow. :(   There is a sweet spot and a good place to start is 1.2back pressure to 1.0psi boost.

 

No one would recommend ditching a 3" or 4" exhaust and putting a 2" exhaust on just to overspeed the turbo, make it less efficient and wear out your turbo faster to create greater pumping losses in HP and a pressureized engine/box).  But that is what blosking off the wastegate can do for you if you do not know your boost /drive pressure ratio.

 

Who has measured their back pressure/ drive pressure and lowered their boost to bring back pressure to a more beneficial #?  Please post your experience.

 

Manimalmother,

 

Looks like you did a nice job.  The more you pull out of that center divider the more the sides can equalize pressure and gate from both sides, but the more it disrupts the pulsing and therefore the spooling of the turbine.  If more power is your goal do aggressive machining  as pictured.  If you want a small reduction in drive pressure/ with less reduction in spool go milder.

 

 

 

Again the machine work looks great.

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trreed

trreed

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I have everything to monitor drive pressure, but then decided ignorance is bliss and never followed through. 

 

If it gets any more serious than how it currently sits, it’s going to get a 73mm turbine on the s300 and then I’ll be fine. 

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Manimalmother

Manimalmother

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We'll test drive was an absolute failure.  Half a mile from the house I heard something let go.  The noise it made sounded like a boot getting blown off.  I shut it down and pulled over.  First thing I saw was the large snap ring holding the compressor housing on had let go.  Then I pulled the bhaf off and saw the damage to the wheel.  Not sure what happened first, but she's toast.

IMG_20190406_181341.jpg

IMG_20190406_181338.jpg

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dripley

dripley

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20 minutes ago, Manimalmother said:

Got the turbo back off and it appears that I didn't have the snap ring fully seated.  Shaft spins perfectly fine.  Coincidentally, here's a screenshot of where I was when it let go 

 

 

Screenshot_20190406-195128.png

Did happen to come down TURKEY creek road first? 

Man I hate that for you. This head gasket replacement weighs heavy on my mind of what I might miss. Hope to crank it tomorrow.

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