max boost on stock turbo's???

[C4ORCE]

how much boost can the stock turbo's put out before they turn into giant hair dryers i'm planning on upgrading later but im just curious what the stockers can handle and i think i heard anything over 14psi the injectors couldn't handle is this true? i have a set of 740cc injectors i just dont have them installed yet, but when im done i want to run between 16-18psi are the 740's suitable for this boost level? as always any help is appreciated

[itsa300zx]

What fuel are you running? I think the fuel octane rating will be your limiting factor with the stock turbos.(or any turbo for that matter) 91 oct about 15 psi. Larger injectors help a bit, but still doesn't change the knock resistance of fuels.

[C4ORCE]

93 octane no ethanol, i live in the upstate of South Carolina i've also heard differences in sea level makes a difference in the amount of boost you can run???

[NolimitZ32]

14 psi, after that the drop off in compressor efficiency is almost exponential, by 18psi you are blowing air at such high temps that you are almnost guaranteed constant knock. If you want the turbos to live longer than a few weeks keep the boost at or below 12psi, the difference between 12 and 14 on the stockers isnt that great and you will keep your car running longer.

[theSLOWz]

14 psi, after that the drop off in compressor efficiency is almost exponential, by 18psi you are blowing air at such high temps that you are almnost guaranteed constant knock. If you want the turbos to live longer than a few weeks keep the boost at or below 12psi, the difference between 12 and 14 on the stockers isnt that great and you will keep your car running longer.

My stock turbos made it a month pushing 15psi, from 104 to 105k miles... needless to say they spent alot of time at full boost and that might not have helped

My point is that what NolimitZ32 said is very true.

[C4ORCE]

like i said im just curious about the stockers hopefully i will be investing in some jwt 500 or 600's soon. i guess i just mainly need an answer to my question about the injectors. are 740's appropriate for 16-18psi or are they overkill and would jwt 500 sports be sufficient for that amount of boost. sorry if i sound like a noob lol most of my experience and knowledge is with naturally aspirated small block chevy's and i still have alot to learn with imports and turbo charging. dont get me wrong im a fast learner just need a little help here lol

[NolimitZ32]

For me it was a little over 1k miles on used stockers running 18-22psi before blowing a seal and I mean oil squirting into the turbine houseing kind of blowing a seal. C4ORCE, sstudy up on how turbos work, in short higher psi is bad, higher cfm is good, a stock T22 at 16psi equals somewhere around 10 psi on a 2860rs (these arent exact numbers and I don't have time to dig through my files to find the compressor maps atm) pressure.psi is the resistance to flow. A bigger turbo will provide more air volume (molecules) for every rotation of the impeller than a smaller turbo. Sport 500s aren't huge but will give you a nice boost in power and overall "FUN" factor. NIsmo 740s will support upto a 2860rs (JWT700) given that you have a good tune. Before you make a turbo selection of in effect do anything to your car you should read up a bit on HOW turbos, tuning, compression, and air/fuel ratios (chemical reaction) works. Knowing these thing will help you make a more informed and ultimately better decision. www.ztechz.net is a great place to start your learning.

[C4ORCE]

thanks alot for all your replies NolimitZ. i completely understand how turbos work, compression and air/fuel ratios i think my main problem is goin to be with the tuning and turbo selection in general. im a carb guy and the computers and tuning are my main concerns but i will be doing alot of studying up and thanks for the link it looks very interesting

[NolimitZ32]

Most important of all learn to read compressor maps (if you don't know how) and understand how Volumetric Efficiency works, its all explained on that site. If you get a good understanding of these 2 subjects you will be able to pic a turbo based on your needs very easily, as for injector sizing, the general rule with the VG30DETT is 1.0HP=0.9CC so a set of 740s should be able to handle 700chp which is what the JWT700 is designed to output at its peak. Having said this, I personally being an engineer always, always allow a very good safety margin because if you run out of fuel on the top end at WOT and full boost, the amount of physical energy being produced is very high and if it turns volatile you could be replacing pistons and rods.

[C4ORCE]

yea i get the idea of Volumetric Efficiency but still have some stuff to learn about it and compressor maps baffle me at the moment lol thats what im trying to learn now. great info NolimitZ keep it coming

[NolimitZ32]

You my friend are in luck, I still have my worked compressor maps in my photobucket account.
TD04H15G - MHI Turbo, not commonly used on Z32 platform, comes in some Greddy kits

GT2860RS/Z1675RS - Awesome turbo with a slight bit of lag and great top end. (aka HKS 2530 which is what I have)

GT2560R/Z1600R - IMO Good turbo but considered by many to be a red-headed stepchild because its not as responsive as the smaller 25 series turbos and not as peaky as the 28 series.

GT2554/530BB - Very responsive turbo, compact size, BB, very good responce, no lag, not as peaky up top so really made for twisties more than wide open top speed runs.

TD0516G (small) - MHI turbo, run by many DSM guys all the time (being a MHI turbo) comes stock on some DSMs (IIRC 2G GS-T/GSX & Talons) Very peaky overall, flows slightly more than the GT28RS, not commonly used on the Z32 platform but available in a kit from Greddy

[addicted4life]

Good read, thanks nolimits

[C4ORCE]

wow NolimitZ thanks alot. i think i like the 2860 it seems to be what im looking for. what kinda boost and injectors are you running if you dont mind me asking