How many of you guys are doing this? And if any of you are, what are you using to do so? Is it worth it, and does it cost a fortune?
Ive searched the net only to find very little results

The reason i ask...
Im currently running a Precision 6765 on our drag car. The car has only been through dyno time and maybe 6 full passes at the strip. The turbo has failed twice now. Once on the dyno and once at the track. Both times the turbine shaft has bent on the compressor side. Enough to where the wheel comes into contact with the housing. After a short talk with these guys on the phone today after they tore the turbo down i was asked, was i monitoring these two things (nope). I was told that back pressure is what caused the damage.

The first time Precision helped me out at no cost even though they claimed that oiling issues caused the bent turbine shaft . Now they are telling me its a back pressure issue, and that i have to buy a new chra which is almost the cost of the turbo itself. Im not sure which way to go at the moment. No i was not monitoring these things, and im just not understanding what will need to be done to solve this issue.

By the way this is on a built/sleeved LS/Vtec. Both times the turbo failed boost was around the 40psi mark.

 

What BOV do you have on the car? Compressor surge? Just an idea im throwin out there

 

I questioned this the first time it happened so it was changed. Now there is a tial on the car.
I have heard no compressor surge at all. Not the slightest bit

 

Is the car smoking/having the seals in the center section go bad also when this happens? Or is the turbo just having the turbines bent? Is there in and out play in the shaft?

 

journal or ball bearing?

 

I've had a few issues with my brand new 6765 smoking and leaking oil sent it back twice and I still have the same issue. Journal bearing

 

No smoking. It broke one of the tapered washers inside the chra this time around. If i had not caught this issue in time the second time around, and kept running the car im sure there would have been tons of in/out and side/side play. Smoking would have come along with the shaft play as well. It hadn't happened yet..

Journal

 

Hows the return line look? No bends in it that could cause a back up at times of higher oil pressure?

 

Oil feed, oil pressure, and return is fine. By no means is this my first stroll in the park.
Oiling is fine

 

Back pressure is easy, throw an 1/8" npt compression fitting on the elbow of the wastegate tube on the manifold, run some steel line 30" away, coil it if you have to and then hook it to a nice rubber/silicone vacuum tube and then to a pressure sensor.

What cams and head/headwork are you using and how much power is the car making on the dyno at what psi?

 

i never had much luck with journal bearing turbos over 30-35psi. my guess would be go bb and you wont have this problem

 

Thank you. I figured that about the back pressure, but it just seemed to simple to be true.

Now what i don't know is, how much back pressure is to much? And how exactly does to much pressure cause just the compressor side of the turbine shaft to bend?

The car has a b16 head, stock b16 cams (i know), supertech valvetrain, and the head is worked to death. The boost level has been turned up since it was last on the dyno. I was saving the car for the track due to tearing up 4th gear on the dyno. The boost level is now at 43psi. The last pull on the dyno was at 36psi making 778

 

You need to measure TIP. Not on the wastegate, measure the pressure going into the turbine, preferable on the exhaust housing near the manifold flange. If its way higher than MAP you have a problem/overworking the turbo or exhaust restriction.

 

I was planning to put it at the turbo flange on the manifold. There is no way to incorporate it in at my wastegate.

So its that easy? You say way over map readings, so i take it a little over is ok?

 

How much Two step does the car see? Journal bearing turbos don't last long under heavy fuel bombs.

 

You can install a Garrett compressor turbocharger speed sensor on the turbo + gauge to monitor turbine/compressor RPM. I haven't seen one in person yet, but would awesome to see one in action.

 

I would think Precision should be able to help you set all of this up as well...since they are asking you to monitor it.

 

ideal back pressure is 1:1, but as long as its not over 1.5:1 youre ok. i recently had some issues with this same journal bearing turbo. they asked me what my back pressure, because thats what they believed was the reason for failure. i had the data and it threw that reason out the window. basically what they are going to tell you is to upgrade to a ball bearing with that amount of boost.

 

If u change the cams it won't blow the turbo anymore

 

We mounted ours like this to monitor turbo speed/rpm

 

What's the shaft sensor look like? Is it a mag/hall setup or does it use light?

 

same thing i was thinking i killed a t3t4 60 trim with a bad return line and high boost. most of the cars with the larger PTE turbos were running a -10 return. i thought the PTE turbos would be cheaper to rebuild but from the sounds of it. Its not any cheaper then when a garrett dies on ya.

 

X2....would like more info on this

 

the shaft speed sensor just counts the blades on the compressor wheel as it spins. If you have a racepak they have all the math writen for you and if you are using a motec or something else to log you can write the math to figure out the rpm.

Shaft speed and backpressure are super important when really tryin to figure a turbo combo out.

 

lol