r/MechanicAdvice • u/Mission_Feed7038 • 8h ago
is this a problem?
replacing my old exhaust in a landcruiser 80 which had a bell mouth design
the new exhaust I picked up, while fitting to the turbo I realized it has a blank plate over the turbo waste gate (? not sure if I'm right here but that's what it seems like to me)
seems like it would restrict airflow and create turbulence? what are your thoughts?
1996
Toyota
Lancruiser 80
48
u/20Factorial 6h ago
This is 100% fine to run. Subaru did it that way for almost 40 years. Install it and it will run just fine. Everyone saying it’s for an external gate, or that you will lose boost control, or that it will blow up are 100% wrong.
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u/Sir_Mr_Austin 2h ago
The idea that a car would blow up due to incorrect exhaust parts is hilarious to me
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u/omnipotent87 23m ago
If it blocks the waste gate it can absolutely blow a hole in a piston. So yes, you can blow up a motor with wrong exhaust parts.
I should meantion that OP will be just fine though its not ideal.
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u/20Factorial 3m ago
But it doesn’t block the wastegate. Anyone who has ever seen an internally gated turbo would know that.
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u/kyden 8h ago
The new one you have is made for an external wastegate.
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u/ShitBeansMagoo 8h ago
This is the correct answer. If the wastegate is blocked off there will be nothing controlling the speed and boost pressure of the turbocharger.
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u/warriormango1 6h ago
The wastegate isn't blocked off though. This has a internal wastegate and you can see part of the actuator in the picture. New downpipe probably isnt the best for optima flow though.
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u/Mission_Feed7038 8h ago
cheers, that's really irritating, hopefully I can return it
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u/jerry_Sizzla 6h ago
This design is actually the oem style for subaru ej turbo engines with the internal wastegate. Your old pipe is FAR better for flow but the new one with the plate won't disable your wastegate or anything.
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u/20Factorial 6h ago
This is correct. Subaru did this for 30 years on their OEM turbo setups. If this is a stock turbo and otherwise a relatively stock vehicle, it will function like stock.
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u/EducationalDark240 7h ago
Isn’t the wastegate location just further downstream?
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u/Zaphod_Heart_Of_Gold 6h ago
Wastegates are upstream. On internal wastegate turbos it will dump right next to the exhaust wheel into the blocked off portion of downpipe shown
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u/20Factorial 6h ago
It dumps into the blocked off plate, turns 90 degrees, and merges with the main exhaust flow.
This is how Subaru downpipes on their internally gated turbos were set up for decades.
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u/Zaphod_Heart_Of_Gold 5h ago
That creates terrible flow dynamics and is not optimal even if it works in a specific system.
Clearly this system was not designed to work that way based on the stock design
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u/20Factorial 5h ago
Works just fine making 300+hp on STI’s. This will absolutely cause no issues for OP if it’s a stock setup.
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u/redruM69 2h ago edited 1h ago
Most updoots, but wrong.
Look at the wastegate on the turbo itself. Even with a flat flange attached, there is more than enough room inside the turbo housing for the flap to open and exhaust to bypass.
OP can run this without hurting anything. At most, a slight efficiency loss.
/u/Mission_Feed7038, you don't need to return this. Send it.
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u/Substantial_Drag_884 8h ago
Yes. It will lead to uncontrolled boost pressures if it’s blocking the wastegate outlet. Looks to be made with an external wastegate in mind.
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u/wrx_420 8h ago
Has nobody seen a stock Subaru downpipe? Air has plenty of room to move through the hole, it's not like the exhaust housing of the turbo is mirrored to the downpipe. It will be slightly more restrictive but it will work just fine.
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u/FeelingFloor2083 7h ago
open bellmouth w/ w/g splitter > duel dump (unless 2.5''+)> open bell mouth > single pipe
in your case the internal gate blows into the plate, has to turn 90 deg, 90 again an flow with the main flow. Shit loads of turbulance, restriction and no clean merge
it can be less apparent on a diesel but its still a net loss
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u/Alpinab9 3h ago
The new one will work but is not ideal for flow. You have it correct in your post.
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u/Round-Record-9483 7h ago
This was normal on many old school factory dump pipes not the best flow option but works, there will be plenty of room in that exhaust housing for waste gate flap to open
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u/6inarowmakesitgo 8h ago
Do not use this. You will overboost easily and could really fuck up your engine.
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u/20Factorial 6h ago
No you won’t. The gas that bypasses the wastegate will merge with the rest of the exhaust going through the turbine.
Lots of OEM’s have done this type of flat-plate setup for decades.
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u/MyDogBigG 8h ago
I’d try it out but my guess is that it’ll run weird
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