Can a restrictive exhaust kill a turbo?

[olympic]

I've put together a 2018 F150 5.0 with an On3 twin turbo kit. It has the upgraded 60mm ceramic ball bearing turbos. Anyways, within 10 miles and a couple 5k rpm pulls on the base tune the drivers side turbo bearings failed and the turbo locked up. Checked the oil feed to the turbos, no issues, lots of flow and pressure. Called On3 and they blamed my stock cat-back, said I can't use a chambered muffler with their turbos.

Ordered a new center section for the turbo and a 4" MBRP exhaust. Drove the truck easy for several hours for some break in, no issues. Then I did two 7k RPM pulls for data logging and the drivers side turbo locks up again. I'll be calling On3 on Monday but if they don't warranty this I'm going to be pissed and will look elsewhere for better turbos.

My question is: can exhaust back-pressure instantly kill a turbo? Do I literally have to drive around with the cutouts open? I know more back pressure = less power but it shouldn't kill the turbo. I've seen plenty of turbo builds where they have stock exhaust for the street and cutouts for the track, so I'm leaning towards On3's turbos just being garbage. Any feedback is welcome.

 

[MG0h3]

Well the easiest response is how do all the factory turbo setups live?

Back pressure can cause heat and slower spool time.

If your oil situation is good, it’s probably just cheap turbos. They are actually On3 turbos like they manufactured them?

Is a little suspect that it’s the drivers side again. I recall you saying you put the drain in a different spot than the instructions, but typically a drain issue will show up as smoke.


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[CobraSam]

Well you already answered your own question.
You blew a turbo with stock exhaust system.
You blew a turbo with a 4” MBRP.
What does that tell you?
That tells me, that in your situation, the exhaust wasn’t the cause.

If it was, why did it do the same thing with a larger exhaust?

 

[olympic]

Well the easiest response is how do all the factory turbo setups live?

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Exactly! I think it's just a case of cheap chinese turbos. I've read most everything On3 sells is made in China. I have no complaints about the IC, manifolds and piping, everything fit and sealed perfect but the turbos are suspect. I have no idea why the drivers side died twice. I verified oil flow/pressure at both turbos. The drains go almost straight down and enter the pan well above the oil level. Only thing I can think of is the drivers side down pipe crosses over to the passenger side and merges with the passenger side so it may see more back pressure.

Well you already answered your own question.
You blew a turbo with stock exhaust system.
You blew a turbo with a 4” MBRP.
What does that tell you?
That tells me, that in your situation, the exhaust wasn’t the cause.

If it was, why did it do the same thing with a larger exhaust?

Thanks for the reply. This is my first turbo build so I'm learning as I go. I'll see what On3 says but I'm leaning heavily towards just biting the bullet and getting some Precision Turbos. $5k CDN for a pair of ball bearing 60mm's thought....ugh!

 

[CobraBob]

Well you already answered your own question.
You blew a turbo with stock exhaust system.
You blew a turbo with a 4” MBRP.
What does that tell you?
That tells me, that in your situation, the exhaust wasn’t the cause.

If it was, why did it do the same thing with a larger exhaust?

THIS! The exhaust didn't/couldn't kill the turbo with two different exhaust setups. The issue IMO is with the turbo. Also, in both cases the turbo failed pretty quickly at upper RPMs. One to 5K and the other instance two 7K pulls.

I'm anxious to hear what On3 tells you tomorrow when you call.

 

[olympic]

I sent On3 an email with an explanation of what happened and a bunch of pics and they are shipping me a new turbo under warranty. I made a thread on the high performance F150 Facebook page and other On3 owners are running the same setup through a 3" exhaust with no cutouts so that's a non-issue. I think I'm going to remove my oil drain lines from the oil pan and start the engine just to verify oil is actually going through the turbo. Not much else I can think of to check.

 

[DSG2003Mach1]

sounds like cheap turbos and you have luck similar to mine

 

[01yellercobra]

Isn't there a time test to make sure the turbos are getting the right amount of oil? IE a certain amount of oil should flow through every minute. I've seen it discussed before when guys were talking about oil being pushed through the seals and needing restrictors.

 

[olympic]

Isn't there a time test to make sure the turbos are getting the right amount of oil? IE a certain amount of oil should flow through every minute. I've seen it discussed before when guys were talking about oil being pushed through the seals and needing restrictors.

Journal bearing turbos need full oil flow and pressure. Mine are ball bearing so they have a restrictor. They don't really need flow or pressure, just oil to be present in the bearing. I verified there's plenty of oil coming through the feed lines. When I pull the turbo (maybe tomorrow) I'm going to have a good hard look at the restrictor. IIRC I re-used the same restrictor on both failed turbos. Maybe it's deformed or clogged.

 

[CobraBob]

That's good that they're sending you a new turbo under warranty. Hopefully this one will be perfect for you. Keep us posted.

 

[geoffmt]

On3 is famous for cheap turbos failing in just a couple hundred miles. I have seen 3 here in Billings. They seem best for the setup, but get quality turbos


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[gimmie11s]

Thanks for the reply. This is my first turbo build so I'm learning as I go. I'll see what On3 says but I'm leaning heavily towards just biting the bullet and getting some Precision Turbos. $5k CDN for a pair of ball bearing 60mm's thought....ugh!

Dont do that.. the result will be exactly the same although now with much higher $$ turbos.

It sounds like you may have an oiling issue somewhere that needs to be solved. Is your oiling system gravity drained back to oil pan or returned via a pump?

How are you getting oil to both units.. where is the T?

Are you using any restrictors?

On3 is famous for cheap turbos failing in just a couple hundred miles. I have seen 3 here in Billings. They seem best for the setup, but get quality turbos

Fair enough, but not exactly correct. The 60mm ceramic bb on3 turbos are built by Magnum and they are actually a unit of decent quality.

MXT60/65 MPTurbos for midsize engines

I had them on my 2014 TT mustang and they worked flawlessly.

 

[olympic]

Dont do that.. the result will be exactly the same although now with much higher $$ turbos.

It sounds like you may have an oiling issue somewhere that needs to be solved. Is your oiling system gravity drained back to oil pan or returned via a pump?

How are you getting oil to both units.. where is the T?

Are you using any restrictors?




Fair enough, but not exactly correct. The 60mm ceramic bb on3 turbos are built by Magnum and they are actually a unit of decent quality.

MXT60/65 MPTurbos for midsize engines

I had them on my 2014 TT mustang and they worked flawlessly.

Drains are OK. 5/8" hose straight from the turbos down to the pan. Lots of slope and they enter the pan well above the oil level.

Oil supply comes from a sandwich adapter. There's a short piece of line leading to a T, then 2 long lines to the turbos. I've verified oil flow at each supply line by removing it from the turbo and starting the engine. I got about 1/2 a quart in 10 seconds so no problems there.

I'm using the restrictors supplied by On3 with the turbos. I'm going to have a good look at them because I reused the same restrictor on both failed turbos. As a final check once the new turbo is on, I'll remove the drain lines from the pan and start the engine to verify oil is actually going through the turbo.

I fully agree with you though, an oiling issue is the only thing that makes sense.

 

[gimmie11s]

Pull both restrictors to see if you see anything different visually between them.

As a final check once the new turbo is on, I'll remove the drain lines from the pan and start the engine to verify oil is actually going through the turbo....

This is a good idea too.

 

[olympic]

Restrictor off the failed turbo on the left, brand new restrictor on the right. Spot the issue...lol! I dug out what was clogging it up, definitely metal but hard to tell anything else it was so small. Impossible to tell how long it was in there.

From what I remember of the sandwich adapter, the fitting supplying oil to the turbos is on the unfiltered side. Maybe I should consider installing a filter on the turbo supply line?

 

[gimmie11s]

Holy cow, good catch! Damn.

 

[DSG2003Mach1]

Glad you figured it out!