1jz twin 'seals'

[Mk3*Supra]

So I keep getting told putting a downpipe on a 1jz causes the seals 'to go'


I've been looking into the workings of turbos because I am fairly new to them. I understand there really are no seals to go because there are piston rings and not the kind of seal most people seem to think of and besides damage from install the rings won't go bad.


So two options for why the engine would start having a blow by issue:

1) the downpipe somehow causes bearing assembly failure (aka 'shaft play')
2) the downpipe reduces pressure of the turbine side to less of the center housing allowing oil to sneak by


If it is option 1, why does this happen and can it be prevented?

If it is option 2, is a good catch can the best way to reduce crankcase pressure which would reduce the center housing pressure.. I have a cusco catch can to install.. just wondering it that is the best/only option

 

[foreverpsycotic]

I have never heard of this, only thing I have heard that were related are that the 1jz twins will blow up when spun faster (downpipe causes less exhaust restriction, spinning the turbos faster and creating more boost) and that the gen 1 1jz PCV system is prone to failures whereas the gen2 is designed better.

I have had the first happen to me before, with a y-pipe back 3" exhaust w/o cats and an intake, I was seeing 16psi from the stockers. They died after 1k miles.

 

[CRsupraiii]

I'm installing a y-pipe on my twins, as well as running a catch can. I'll let you know how my setup holds. I've been strongly considering porting the waste gates and running a larger sized flapper, but I'm gonna wait on that and just keep my eyes on the boost gauge as I drive. I have heard that allowing these turbos to breathe with intake+intercooler+exhaust produces too much air to be flowed through the stock baby-sized waste gates, causing massive boost creep. Just my thoughts, like I said I'll let you know how my twins hold up. Hoping to get a few weeks this year and then all summer out of them
next year.


- Joe
Sent from my iPhone

 

[nctexan]

I'm guessing that this must be happening to my 1JZ. I have stock twins, 3" downpipe and full unrestricted exhaust. When I get to higher RMP's under boost I hear the exhaust pop and the boost just falls off. In the lower range though it pulls hard.

 

[hvyman]

I have a y pipe on mine no problems here.

The 1j twins have ceramic shafts and they like to destroy them selves when boosted high. If there in good condition they couldast years depending how hard you are on them. If there in bad condition they won't last very long.

 

[te72]

I've been running the ebay y-pipe on mine for at least 18+ months now... I think that one of my turbos might be starting to go, but I'm not horribly worried about it. I do see an occasional oil drip run down the one turbo, but they've been boosted daily anywhere from 12-17psi.

 

[nctexan]

I've been running the ebay y-pipe on mine for at least 18+ months now... I think that one of my turbos might be starting to go, but I'm not horribly worried about it. I do see an occasional oil drip run down the one turbo, but they've been boosted daily anywhere from 12-17psi.

Does the oil drip on your turbo look like this:



Also is there supposed to be a bolt where the red circle is?

 

[CRsupraiii]

te72, hvyman and nctexan any of you have problems with boost creep? Also what boost controller setups do you have?


- Joe
Sent from my iPhone

 

[Moy]

they run ceramic turbine wheels because they're light and cause less lag. the problem with that is when you have a free-breathing engine (intake/full exhaust) the turbine spins too fast causing the wheels to shatter. if you want to keep the stock twins, have the turbos rebuilt with steel wheels and port the wastegates (or weld them shut, cut into the stock manifolds and Y them into a single external or run dual externals).

 

[Albert]

Look into my upgrades

 

[te72]

Does the oil drip on your turbo look like this:

Also is there supposed to be a bolt where the red circle is?

I think my seepage is near the oil drain on one of the turbos if I remember correctly. Been a couple months since I looked at it, so just going off fuzzy memory. The red circle there appears to be the front side of the turbo, the compressor housing, correct? If so, I think it should probably have a bolt there, Albert has WAY more experience than me on that subject though, perhaps he can help out here.

te72, hvyman and nctexan any of you have problems with boost creep? Also what boost controller setups do you have?

Joe, on my setup, boost peaks around 4000rpm or so, with a minor spike. From 4000 on though, it pretty much levels out, but boost pressure on my car is entirely dependent on the ambient temperatures. I don't get any noticeable creep, but I don't often pay attention to boost level if I'm revving past 5k.

As for setup, I don't run a boost controller during the winter, I'd kill my twins faster than Full House killed theirs...

 

[nctexan]

te72, hvyman and nctexan any of you have problems with boost creep? Also what boost controller setups do you have?


- Joe
Sent from my iPhone

Joe I'm not running any controller at all right now. I also don't think I have boost creep, but definitely not positive on that. I just know that all of a sudden when I get around 5k+ rpm now the boost just falls off and I hear this sputtering/popping. You think that it would like colder temperatures better but the colder air ~upper 40's to lower 50's is when it seems to run much rougher.

 

[CRsupraiii]

Thanks for the info guys!! Just been worried about this on my car.... If I can ever get it up and running....


- Joe
Sent from my iPhone

 

[nctexan]

So went in and removed my spark plugs. I had them gapped way to much (~.040"). Reduced them all to ~.029" and had pretty significant cracks on 3 coils. I heat shrinked them up and slapped everything back together. The car pulls hard to redline and I haven't noticed any of the previous symptoms!

 

[te72]

So went in and removed my spark plugs. I had them gapped way to much (~.040"). Reduced them all to ~.029" and had pretty significant cracks on 3 coils. I heat shrinked them up and slapped everything back together. The car pulls hard to redline and I haven't noticed any of the previous symptoms!

Good to hear sir, I was about to suggest the gap check myself after reading your last post. Funny how well they run when they're not cutting out.