Safe boost level for a 1jz turbo's

[Ribfeast]

It was a piece of slag or loose metal inside the intercooler pipes. We had JUST welded them up in my mate's back yard, and went for a spin to test our handiwork, and on the 3rd application of boost we heard a strange noise and no more boost. I was lucky, sometimes the turbo wheel goes into the motor instead!

Funny thing is the shaft play on that turbo is still fantastic

[mamba]

ribfeast, can you explain how something capable of causing so much damage, made it through your air filter, through your inducer wheel, through over a meter of piping consisting of all sorts of bends, an intercooler, a throttle plate, the intake valves, went through at least 1 "BANG", came back out the exhaust valves, and munched your turbo?

or did it kill the inducer, causing it to be unbalanced, and killing the exhaust side?

Elmo.

On a turbo the turbine drives the compressor. So the more the car revs the more air blows over the turbine thus driving the compressor via a shaft. Now at 15-16PSI boost, the turbine will be spinning at an extreme rate of revolutions. The turbine is clearly seperated from the compressor or else the engine will be reingesting its own exhaust gases which will be a flawed design. However we know this is not the case.

I ran 15-16psi through mine for a few years with twin dumps perfectly until a bit of welding slag from my intercooler pipes hit the exhaust wheel on my front turbo.

Finding that debris in your cat might explain a high boost turbine failure. We don't know what shape your compressor wheel is in, but if the debris was sourced from the IC piping then there is no way for the compressor wheel to let go. As far as I know the IC is after the turbo (compressor section) Also remember that the 1J's have ceramic turbine blades, a no-no for high boost. So either one of three things is the likely cause, 1 - the turbine let go under high boost, 2 - The debris miraclulously made it through an entire cycle of your engine and made its way to the turbine, and at that extreme RPM's of the turbine it just went BANG, however this sounds ridiculous, or 3 - the welding slag might have been located in between your turbine inlet and exhaust manifold. I think number one is the likely cause. Remember ceramic CT12a, high boost = inevitable failure

[mr_mike]

my 1jz is currently runnin about 13psi no bleed valve or Ebc just purely what the wastegate opens at.
Stock dumps with 3" pipe straight off the dump no cat and a single muffler at the rear. I'm in 2 minds wether to buy some aftermarket dumps or just save money and get big single like i planned orginally.

[mamba]

my 1jz is currently runnin about 13psi no bleed valve or Ebc just purely what the wastegate opens at.
Stock dumps with 3" pipe straight off the dump no cat and a single muffler at the rear. I'm in 2 minds wether to buy some aftermarket dumps or just save money and get big single like i planned orginally.

If you have $10k dollars lying around go single. That will cover the turbo, wastegate, new exhaust manifold etc.
If not get twin 2.5 dumps into your 3" system. Will notice the difference. However pushing your twins for consistant high boost is unadvisable. Read some posts on here. Sub 15 PSI seems to be the safe limit. However that can be debateable depending on turbo conditions, age etc.
Read 1JZ.747's posts. He's the 1J man.

[1JZ~lux]

How does the US spec CT12B (steel wheel) compare? Can it run consistant high boost? I was thinking of getting a pair as an upgrade.

[wiso]

just doing this to subcribe, but i have just wound mine up to 14psi, with a hi-flowed t-peice and 3" exhaust.

if you drive fairly normally most of the time your turbo will hardly ever reach those high boost levels anyway. personally when i drive mine will usually hit about 5psi and be accelerating plenty quick enough for normal traffic, if you want to get off a bit quicker up to 10psi does the job. thats my theory, its not like you hit full boost all of the time, its just there if you do want to use it

[mr_mike]

If you have $10k dollars lying around go single. That will cover the turbo, wastegate, new exhaust manifold etc.
If not get twin 2.5 dumps into your 3" system. Will notice the difference. However pushing your twins for consistant high boost is unadvisable. Read some posts on here. Sub 15 PSI seems to be the safe limit. However that can be debateable depending on turbo conditions, age etc.
Read 1JZ.747's posts. He's the 1J man.

$10k for a single turbo thats brand new retail price plus labour thats just insane. I have already priced up the cost of goin big single and can get a 2nd hand kit plus injectors and tuning for under $4k

[jampac]

Some of us drag and circuit race, so boost is maxed nearly all the time. I know for me on a good run, I'll have between 22-23psi from stand still till just over the finish line, some 12 seconds or so later, so turbo needs to be good.

I did my single turbo GT30 (brand new turbo as with just about all the parts) conversion for $5700 including all the labour.

[Bowlsclubboy]

My 120,000km old 1j has either been steel wheeled, been replaced with brand new turbs at some stage, or is just a freak.

Been drifting it for over a year at up to 20psi (18 is normal) with just twin 2.5" dumps, straightthrough 3" zorst and a chinese cooler. I got an aircraft welder to weld my alloy cooler pipes though ribfeast

[Ribfeast]

Hehe I'll definitely get a pro to do it next time
Just seems like a massive coincidence that the exhaust wheel went bang only 3 acceleration tests after we welded it up. It's not that much of a stretch that a small piece made it from the cooler pipes near the TB and through the engine, the valves are big enough to let it through...guess we'll never know for sure though.
A piece of metal/slag hitting a ceramic wheel spinning at 100,000RPM is sure to do a fair bit of damage if that is what it was
.
Prior to welding, all the cooler pipes were joined with silicon hose pieces and clamps, on every spot that it was to be welded, so maybe it was leaking before that, making the turbos work harder than they needed to be to make that 16psi?

[EldarO]

my 1jz is currently runnin about 13psi no bleed valve or Ebc just purely what the wastegate opens at.
Stock dumps with 3" pipe straight off the dump no cat and a single muffler at the rear. I'm in 2 minds wether to buy some aftermarket dumps or just save money and get big single like i planned orginally.

my exhaust is much the same, im running 10psi.

ribfeast, only way to know for sure is to whip the head off and have a look for dents in the top of the pistons.

in other words, dont worry about it! im just amazed it happened

Elmo.

[Ribfeast]

I'm pretty lucky if that is what did happen lol

Wish I had one of those flexible camera and flashlight sticks that SWAT teams use etc, then I could stick it down the spark plug hole and have a look inside. Or even use an endoscope

[EldarO]

arent they called "boroscopes" or sumting like that?

Elmo.

[mr_mike]

my exhaust is much the same, im running 10psi.

ribfeast, only way to know for sure is to whip the head off and have a look for dents in the top of the pistons.

in other words, dont worry about it! im just amazed it happened

Elmo.

I think the extra PSI i'm gettin from my set up is due to havin no cat. previous owner deemed it not neccesary

[JZA70 R]

Thats because they're not...