Monday, February 26, 2007 - 05:00 pm, by: Joel Moore(Ttsoai2ei2)
I need help to establish once and for all, what acceptable boost level for my ct12a's are for a daily driven car. i am told 14-15psi by one 13psi MAX by another, 11 psi by someone else. I need to know once and for all.
Monday, February 26, 2007 - 06:08 pm, by: Shane McInnes(Soarin_tt)
You can run 14psi but to be safe and to factor in boost spiking i wouldnt run no more than 13psi. Because if it spikes on 13 you shouldnt really hit boost cut. Boost cut is around 14.7psi i think. Unless you have a EBC then it shouldnt boost spike and you can run 14psi. Either way id still stick with 13psi to be safe. But there is the odd few who run 15 - 16psi on standard turbos. Thats probally reducing the life of the turbos a fair bit though?
Monday, February 26, 2007 - 11:13 pm, by: Cihan Aday(Cihan)
I think the question here should be how much power should a ct12a + 1JZ combination be limited to.
In that case i'd say not more than 350hp at the flywheel, the further over that the higher the chance of failure.
The CT12a's rotating assembly spins at the same RPM whether you need 15psi or 10psi to make 350hp. (We're assuming changes in engine efficiency, the power output at a certain turbo CHRA rpm will vary depending on transmission and ancillary losses.)
Thats why manufacturers like Garrett rate turbo's at specific power level intervals.
In our example that would be 350hp or 200rwkw.
In correct tune that should be achievable running 14psi with BPU+ mods and 13psi or so with camshafts.
I would say ~260rwkw (425hp) is about the limit with standard CT12a's in an unopened 1JZ. You're only going to get a little higher pushing them any further. Obviously the integrity of the bearing assembly and ceramic bonding material would be reduced after repeated runs if the turbo's aren't in pristine condition to begin with, but they can definitely flow about 210hp each at the limit.
Tuesday, February 27, 2007 - 07:57 am, by: Luke Nieuwhof(Luke_nieuwhof)
I'm one of the 15psi brigade. That said I'm not boosting it every day to those levels, only at the drags. Plus relatively low kms on the car. I think it may get riskier with older turbos. It depends on your definition of daily driven. Having a boost controller which will allow you to run 15psi isn't going to kill your turbos, but your right foot may.
Tuesday, February 27, 2007 - 08:08 am, by: Brian Timms(Turbo_brian)
The right foot is always the deciding factor when boosting....
A while back in my old Nissan, I didn't realise that someone had tinkered with my boost-t controller, and just opened it right up.
It would have been a good 6 weeks later when I went to overtake someone on the highway, I dropped back a gear, flattened the foot, and suddenly the boost shot up to 22PSI, and the car was hitting boost cut quite harshly.
I rectified this by easing off the foot, still being able to push the higher RPM's needed to get the power to overtake, but not getting enough power to have to spool the turbo quite so savagely.
Anyway, for the previous 6 weeks, I hadn't driven hard, thrashed, or taken off like a tool, therefore I didn't notice the boost controller had been tinkered with.
The right foot will always decide the fate of your turbos, your engine, and your gearbox.
And for the O/P's question, the safest boost level to set the stock engine and turbochargers to is stock, anything higher than stock will start to place strain on working parts.
I know and completely understand that it's 'safe' at higher levels, but it's not safer than at stock levels.
B.
Benjamin Burgess Goo Roo NSW Toyota Soarer GT-TL, Toyota Corolla Conquest
Tuesday, February 27, 2007 - 08:54 am, by: Benjamin Burgess(Jampac)
One of my ct12a's did the bearing (blade hit compressor housing) on 16psi after only 2 months. I did run for quiet a long time on 13psi, for around a year.
Tuesday, February 27, 2007 - 10:42 am, by: Jeff Bedsor(Jeff_bedsor)
Just increased my boost to 15psi as well, it does peak slightly higher(16)for maybe 1 sec in overdrive. I did notice a good increase in power from the 12 psi it was before. I installed the Mines ecu on the weekend as well, very happy with it.
Tuesday, February 27, 2007 - 03:18 pm, by: Braden Murdoch(Ribfeast)
Buying twin dump pipes for the turbos will prolong their life significantly. I ran 15psi daily on mine for over a year with dumps and probably could have for a lot longer. I blew the ceramic exhaust wheel off the front one when a piece of welding slag or foreign material dislodged from my freshly welded intercooler pipes and hit it. Found the wheel rattling in my cat lol
Haven't looked back since getting eBay steelies, they take 18psi fine with safe AFRs, I usually run 15psi through them daily though using the Blitz EBC. Twin dumps are the best investment you can make in prolonging their life, as it helps them flow better, and removes the heat from the exhaust wheel far more effectively. The stock Y-piece has them blowing exhaust gas at each other.
You can probably run higher boost on ceramics than 15psi, but I wouldn't advise revving it to redline. It may also depend on how OFTEN you indulge the right foot - you might get away with 18psi daily on ceramics, but one or 2 blats every 10 mins, instead of just repeatedly hammering them until they heat up. There is just so many factors. Anything over 15psi will not get you much more power due to the turbo being out of its efficiency range. 18psi is about as far as I'd take any CT12A design, I made less power on 20PSI with my steelies compared to 18.
Benjamin Burgess Goo Roo NSW Toyota Soarer GT-TL, Toyota Corolla Conquest
Tuesday, February 27, 2007 - 03:43 pm, by: Benjamin Burgess(Jampac)
You were lucky you found it in the cat. I know of two owners of 1jz's were the exhaust wheel has collasped and been sucked back into the engine due to the extremely short exhaust manifold runners. The engine of course was completely destroyed in both cases.
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) and you will be fine.
