question about boost creep/ wastegate..

[Dylan JZ]

I was doing some research here at work on the stock twins with open dump (mine being 3" Trust) and came across an aussie post on how relieving the back pressure does increase power obviously, however that the stock wastegates cant seem to keep up right away with the boost running away due to being small and inadequate for this scenario.

Now im still learning so im sure some of that didnt make all the sense, but the question is does this wastegate problem cause the seals to go bad pre-maturely?

They kept saying that the US guys denied this fact about the twins and would rather go with the 1st gen vs. 2nd Gen 1jz excuse relating to PCV valve and intake piping changes.

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I have searched a bit, though at work i cant seem to use the search on the forums.. so if I overlooked posts please forgive me as i usually do extensive browsing before stating a question.

 

[OneJoeZee]

I was doing some research here at work on the stock twins with open dump (mine being 3" Trust) and came across an aussie post on how relieving the back pressure does increase power obviously, however that the stock wastegates cant seem to keep up right away with the boost running away due to being small and inadequate for this scenario.

Now im still learning so im sure some of that didnt make all the sense, but the question is does this wastegate problem cause the seals to go bad pre-maturely?

I didn't have any really bad boost creep problems when I was still on stock twins. It would creep up 1-2psi by redline finally but nothing that had me worried. I was running 3in exhaust, 3in downpipe, and upgraded y-pipe.

Contrary to popular belief, the twins CAN run higher boost for an extended period of time and be ok.

Bad(unchanged) oil will hurt the oil seals. You're much more likely to have the turbine wheel crumble and fall out the back of the housing and out the exhaust because of high EGTs.

The turbos will burn oil eventually even at stock boost...

They kept saying that the US guys denied this fact about the twins and would rather go with the 1st gen vs. 2nd Gen 1jz excuse relating to PCV valve and intake piping changes.

That's because it's not true. I haven't seen anyone prove anything to suggest that the "2nd gen" setup helps save turbos. My own experience(I've had both setups and multiple sets of turbos) and those of some local cars are what I base my beliefs on primarily. I have never seen any correlation and definately no causation.

 

[Dylan JZ]

That's because it's not true. I haven't seen anyone prove anything to suggest that the "2nd gen" setup helps save turbos. My own experience(I've had both setups and multiple sets of turbos) and those of some local cars are what I base my beliefs on primarily. I have never seen any correlation and definately no causation.

Alright well Joe, ever since I bought this car a few months back I usually look to posts by you and a select other few jz guys for insights. So I think with that said being that you seem pretty experienced I'll go with what you're telling me.

I had never heard on any of the US forums about boost creep essentially killing turbos because of wastegate design. I mean that would be a pretty big and careless fault IMO.


At the end im not sure I was entirely clear and may have steered you in a different direction than intended. I was merely saying the particular aussies on this forum (forget which one..) said that we, the US guys, dont adhere to the wastegate theory, rather that we blame the 1jz faulty PCV valve instead of also considering this wastegate issue.

They seemed confused as to why we would group the 1j into the category of 1st and 2nd gen because of a pcv valve and intake piping change as well.


In any case, thanks man. So I should be fine with an open DP on the stock twins, thats what I believe you to be saying.. (im gonna go with a CT upgrade within 6 months anyhow just wanted to know how reliable these twins were gonna be)

 

[OneJoeZee]

Alright well Joe, ever since I bought this car a few months back I usually look to posts by you and a select other few jz guys for insights. So I think with that said being that you seem pretty experienced I'll go with what you're telling me.

I had never heard on any of the US forums about boost creep essentially killing turbos because of wastegate design. I mean that would be a pretty big and careless fault IMO.


At the end im not sure I was entirely clear and may have steered you in a different direction than intended. I was merely saying the particular aussies on this forum (forget which one..) said that we, the US guys, dont adhere to the wastegate theory, rather that we blame the 1jz faulty PCV valve instead of also considering this wastegate issue.

They seemed confused as to why we would group the 1j into the category of 1st and 2nd gen because of a pcv valve and intake piping change as well.


In any case, thanks man. So I should be fine with an open DP on the stock twins, thats what I believe you to be saying.. (im gonna go with a CT upgrade within 6 months anyhow just wanted to know how reliable these twins were gonna be)

Oh. I see what you're saying now. You meant to say that the australia guys agree that the 1st gen 2nd gen still has zero to do with blown turbos, right? I don't really agree with their explanation of boost creep correlating with blown turbos either though.


How reliable your twins will be will depend alot on how they were treated before you got the engine and of course what you do once you have it. Even if you only run stock boost, you could have blown turbos in 2 months or 2 years. Without knowing exactly how the car was maintened for the 10+ years of its life before we get them, it's hard to say exactly how long you can expect your turbos to last. At the very least, you are aware that they are a weak link so you won't be surprised if/when they give out on you.

I've never heard anything about boost creep being an issue or causing turbo failure on CT12As either.


But yes, you will be ok with a full exhaust. I haven't had any direct experience with a set of turbos with tired wastegates causing bad boost creep problems, but I'm not saying it isn't possible.

I ran my car at 1-1.2BAR daily with full exhaust, including ypipe, for about 10 months with no problems. The turbos that were on the car when I bought it died about 3 weeks after getting it though... And those had no boost controller hooked up.

 

[Dylan JZ]

Yeah I mean its impossible in most cases to know how well they were maintained.. I hope well, but who knows.

Thanks for the info. I didnt really know what to think of the wastegate situation, though one would assume that even if it did creep it would be a small amount not enough to hurt anything. I forgot to mention, they said running without cats (IE. cat-less) was what cause the failures. But i dont see why open DP would be different that your full exhaust really so..

 

[Spaniard]

I had some boost creeping issue's when I was boost towards 18psi. I welded the stock twin wastegates and used an external wastegate. Temps when down, response was better and made some more horsepower. It was a lot of work though.