| Author |
Message |
David Wilson
Tinkerer
NSW
Soarer TT
Posts: 67
Reg: 07-2005
|
I know that the maximum boost pressure for ceramics is currently agreed on as 14psi, however, what I would like to know is, how many people have set their boost to 14psi and left it there?
What im trying to clarify is, is a few shots of 14 psi the ABSOLOUTE MAX before a ceramic turbo is guaranteed to go in the bin, or is a constant 14psi a 'safe' amount to leave as a PERMANENT setting. I hope this makes sense. Any personal expereience would be GREATLY appriciated. Thanks!! |
Steven Nanevski
Goo Roo
New South Wales
HKS T3G equipped TT coming soon... 
Posts: 1232
Reg: 07-2005
|
I run my ceramics at 16psi without fault and have been for 6 months now....
All depends on the condition of them mate... |
Cihan Aday
Goo Roo
The blue pill or the ultimate pill, make your choice.
JZZ30
Posts: 1960
Reg: 07-2005
|
David, there's no real 'maximum' boost pressure.
Power level - 200rwkw with an exhaust system, modified intake setup and
As you approach and go over that, you're reducing life expectancy to a more significant degree.
That said, Steven is correct in saying it depends how worn they are to begin with. The better the clearances the less chance of float and eventual bearing failure. |
Gary Morriss
DieHard
SA
TT
Posts: 625
Reg: 07-2005
|
Had mine on 17psi for ages, took them off a while agao, still fine.
also gave them a boot to 22psi once hahahahaha |
Brian Timms
TryHard
New South Wales
TT Soarer Goodness.
Posts: 327
Reg: 12-2006
|
Any turbo should be able to boost upwards of around 16 - 18PSI reliably, but it depends on condition of the turbochargers, the oil your running with them, how hard you tend to drive the car, etc.
I used to have a GT28 Ball bearing turbo on my previous car, and was told that it will do no more than 18 psi.
I never drove really hard, and didn't know that someone had frigged with my boost controller one day.
Anyway, the time came for me to overtake someone and try to get some power fromt he car, so I opened her up, and all of a sudden I was seeing 26psi on the boost guage, and hitting boost cut constantly.
Did no damage to that particular turbocharger, but the smoke belowing from the exhaust didn't say the same for the engine (only while on boost).
I have always run top quality oil, always changed oil at 5,000kms, and I dont drive hard (maybe 1/2 throttle is all I need for average driving).
If you tend to use •••• oil (yep, seen people use 2nd hand oil in turbocharged cars to save a few bucks), thrash them sconstantly, it wont matter if your overboosting, or running stock boost, it will die much quicker.
B. |
Braden Murdoch
DieHard
NSW
Cressida 1JZ TT
Posts: 551
Reg: 04-2006
|
I think heat is the main killer, a few intermittent stabs to 18psi is probably fine, but fanging off every set of lights for 10 minutes would quite likely accelerate their destruction. Also 18psi at 7000RPM is going to kill them a lot quicker than 18psi at 4000RPM.
Removing the factory dump pipe and replacing it with twin dumps will help remove that heat but they still will grenade eventually with abuse.
Clean oil is always essential, I change mine every 3000. |
Aaron Mead
Goo Roo
NT
TT
Posts: 1570
Reg: 03-2006
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David Wilson wrote on Monday, May 07, 2007 - 05:35 pm:I know that the maximum boost pressure for ceramics is currently agreed on as 14psi
That would be for the entire life of the turbos if the original jap guy never boosted them. Thing is, no one knows how their turbos were treated FOR SURE by the previous owners.
For example, the twins on my soarer died at only 13p.s.i. on a very fresh secondhand engine. The tuner reccommended I go no further than 11p.s.i. (they used to be on 17 p.s.i.) but I said "she'll be right mate" (tool) and on the dyno, I lost one.
So really, getting a Soarer, and running up 14pounds doesnt guarantee anything at all, but is merely an agreeable figure based on the past experiences of many many years of Soarer enthusiasts. Just remember that there are no guarantees with epoxy'd ceramic turbines after 15 years....and besides the worst that could happen is you upgrade to steel wheels/big single/big twins and make big power!
or be unlucky enough to have the engine swollow bits of turbine back through the exhaust valve or shards of aluminium through the cooler and intake 
|
Brian Timms
TryHard
New South Wales
TT Soarer Goodness.
Posts: 333
Reg: 12-2006
|
You wont know unless you know the EXACT history of the car.
Let me re-iterate.... THE EXACT history
Simply, unless you know your turbos are perfect, never been boostet over stock, always had clean oil, always been timed down, always warmed up before spooling, etc, etc, farkin etc.
You wont know the abilities or lifespan.
Even then, manufacturing imperfection could see a brand new turbo give up life within 20,000 kms, and the first thing the manufacturer is going to claim is "they where over-boosted, and failed", they wont say "sh1t, we frigged up and made a dud".
B.} |
Cihan Aday
Goo Roo
The blue pill or the ultimate pill, make your choice.
JZZ30
Posts: 1963
Reg: 07-2005
|
Brian Timms wrote on Tuesday, May 08, 2007 - 10:47 am:Any turbo should be able to boost upwards of around 16 - 18PSI reliably
Boost pressure means little when you modify an engine. Power output is what we need to look at here.
In reality turbo's have bearing RPM limits, how fast the compressor needs to rotate to engulf enough air to make a set boost pressure is determined by the size and efficiency of the engine.
Exhaust back-pressure is caused by restrictiveness; so is intake boost pressure. The less restriction means less boost, but more power..
In either scenario, the compressor is spinning at the same RPM, whether it be 10psi or 18psi at a given power level. Saying most turbo's can push 16psi reliably is wrong, because its completely application dependent.
--
Stock ceramics don't have much life pushing over 200rwkw - its been proven time and time again. Over 240rwkw the chance that they'll complete a full days racing on Phillip Island is slim, for the occasional hoon and dyno day they should live for a while.
But the above has no weight if they've been abused all their lives. |
Lew Radbourn
Trader
Queensland
jzs147 92 / 95 jzz31 98' / jzz30 ute92' / uzz30 93'/ 2 X uzz31 92' s
Posts: 1962
Reg: 07-2005
|
I ran my ceramic turbos (CT20)at 18psi for near on 2 years and didn't have a drama.
Stock ceramics don't have much life pushing over 200rwkw ......Hmmmmmmmmmmmm you sure about this?
Over 240rwkw the chance that they'll complete a full days racing on Phillip Island is slim,
.......Now that bit is crap.........
the phillip Island bit Cihan has been done over and over again by several people and the turbos are still fine.
In either scenario, the compressor is spinning at the same RPM, whether it be 10psi or 18psi at a given power level.
Mate what drugs have you been taking when you wrote this.
explain to me what a wastegate does ?
I have a good idea but i what to see if you actually know your self. |
Cihan Aday
Goo Roo
The blue pill or the ultimate pill, make your choice.
JZZ30
Posts: 1965
Reg: 07-2005
|
Lew Radbourn wrote on Wednesday, May 09, 2007 - 07:33 am:I ran my ceramic turbos (CT20)at 18psi for near on 2 years and didn't have a drama.
Stock ceramics don't have much life pushing over 200rwkw ......Hmmmmmmmmmmmm you sure about this?
Im talking about ct12a's.
Even if they don't explode, bearing noise and oil leakage grows, they smoke and become noisy and should be overhauled.
How many sets have you replaced for others in the past 5 years Lew?
Countless people have blown stockies and lots are in shocking condition even though they still run.
Lew Radbourn wrote on Wednesday, May 09, 2007 - 07:33 am:the phillip Island bit Cihan has been done over and over again by several people and the turbos are still fine.
Its a moot point when they're blowing while pushing much less power in better conditions than track day. Who are we talking here to begin with?
Lew Radbourn wrote on Wednesday, May 09, 2007 - 07:33 am:Mate what drugs have you been taking when you wrote this.
explain to me what a wastegate does ?
I have a good idea but i what to see if you actually know your self.
Lew, i wasn't on drugs when i wrote this mate.
In this context the wastegate can be left out of it.
Take a standard 1JZ soarer with ct12as, and boost them to 15psi.
Then take a worked 1JZ soarer with ct12as and boost them to 15psi.
One makes 180rwkw, the other makes 240rwkw.
Are the turbine/compressor's rotating at the same RPM in both examples? No they're not.
Another example,
The modded 1JZ runs 10psi and makes 180rwkw
The standard 1JZ runs 15psi and makes 180rwkw
Are the compressor speeds close? Yes, they are.
Will the modded 1JZ's turbo's live much longer than the standard 1JZ's at 180rwkw? Only a little.
--
Flow rate and pressure ratio are measurable mediums to determine compressor speed.
Its not easy to say the turbo RPM limit is "125,700rpm" for example, because it can't be measured without a compressor map.
When we're talking boost pressure, its only relative to the same engine setup and between cars with very similar mods.
Once you throw in some cams or perfect the intake or exhaust setup the relationship is out the window.
Flow rate is the largest factor determining power output and as such has the largest effect on required compressor speeds.
Boost pressure, hence pressure ratio, is more important in determining compressor efficiency at a flow rate.
Flow rate determines potential power output and efficiency corrects it. |
Lew Radbourn
Trader
Queensland
jzs147 92 / 95 jzz31 98' / jzz30 ute92' / uzz30 93'/ 2 X uzz31 92' s
Posts: 1966
Reg: 07-2005
|
regardless of mods to the engines
in fact take the 2nd car away from what i read
what you stated (or i think you did)
that if an engine has EG:
10psi and then you raise it to 18psi that the compressor wheel will not spin faster?
am i correct in stating that is what you said. |
Cihan Aday
Goo Roo
The blue pill or the ultimate pill, make your choice.
JZZ30
Posts: 1967
Reg: 07-2005
|
Cihan Aday wrote on Tuesday, May 08, 2007 - 11:07 pm:whether it be 10psi or 18psi at a given power level.
I think you may have misread that mate, otherwise we're on the same page. |
Chris Davey
Goo Roo
QLD
Corona
Posts: 1366
Reg: 07-2005
|
What about a boost leak?
2 identical engines, 1 with a boost leak makes 10psi on the guage (5psi leaked), 1 with no leak makes 15psi on the guage. I would say that both are spinning similar speeds. Obviously, the first car will make less power than the second one.
Interesting topic. |
Cihan Aday
Goo Roo
The blue pill or the ultimate pill, make your choice.
JZZ30
Posts: 1968
Reg: 07-2005
|
There's no guess work here Chris, its basic compressor map stuff.
Its like putting twin ct12a's on a GENIII LS1, trying to run 10psi and measuring the RPM of the compressor, then running 10psi on a 1JZ and doing the same. Would the compressors be spinning at the same speed in both cases?
Of course not, and its silly to think they would.
Think of turbo's as air pumps, boost pressure means little between different engines and modified versions of the same engine. The only similarity is power output, thats why i'm saying its a more accurate measure of longevity etc. |
Richard Johnson
TryHard
Florida, USA
SC300 1JZ-GTE Swap
Posts: 238
Reg: 06-2006
|
I ran them @ 18psi for a year daily driven, and I would dyno them at 25psi (ran 25psi on them for around 10 dyno pulls)..... No real power gains at that boost level, but it's fun.
I took them off to go single, and they were still like new. The new owner of them has been using them flawlessly since. |
Jarron Young
Newbie
NSW
1JZ Cressida
Posts: 5
Reg: 08-2007
|
Daily driven at 19-20 psi for the last year, no issues at all. I know all are different and tend to give up at differnt boost levels, but this is the second set we have done this too, and there was nothing wrong with the first set, we were just trying to fix another problem.
seen 24psi out of them with no nos.
constantly run at 25psi with nos and have seen 30psi out of them with the nitrous.
some people say they dont make any power past 18psi, they just produce more heat.. i would set that level to about 23psi and would also say that if running nitrous (keeping everything cooler) would still make power in the 25psi> range.
Jak |
Braden Murdoch
DieHard
NSW
Cressida 1JZ TT
Posts: 689
Reg: 04-2006
|
I made 3-5kW more when I went from 18psi to 20psi. So going past around 18psi is probably not worth it unless you can cool the intake charge greatly before it hits the throttle body.
The biggest killer of the turbos is heat, getting twin dumps alleviates this problem remarkably. |
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