What turbos to get?

[Boyce18]

Wanted to know best options on turbos

1993 300zx TT
850cc injetors/300degree rails
SZ tune
3"down and test pipes
Greddy evo2 exhuast
Dual filters and dual MAF
Z1 58mm throttle body's machined to 61mm
Ash 2.5 piping with massive IC

Stock engine 60,000 miles
I'm running 17 psi with stock turbos
I'm goin to build an engine just not right now

Which leads me to my next question, how much PSI can a stock engine take?

[NolimitZ32]

The question is not how much PSI but how much air/fuel and produced HP and TQ can an engine take, the same HP numbers can be achieved at different pressures on different turbos and with different intercoolers/piping. Pressure in actuality is the resistance of flow and running higher PSI on a smaller turbo is less efficient than running lower PSI on a larger turbo (without going too big). The 2860R (disco potato) is the most efficient turbo for most VG30DETT setups unless you are chasing a specific point such as high peak HP for Drag racing or minimum lag for a AutoX application.

BTW running 17psi on stack turbos is inefficient to the point of borderline detonation, I imagine the only thing saving you from pinging are those ash massives.

[Boyce18]

Ok so I was looking on the Z1 web site
Would the gtx2860r be a good kit to get?
Would it work good on a stock engine with my mods and be good for a built engine later?

And just to keep things clear I don't drive this car very offten might take it out 1 nite a week and put 20 miles on it. And as it is now I always run VP110 fuel

[NolimitZ32]

The GTX2860Rs are capable of well over what your stock engine can handle. They are great all around turbos, basically the disco potato brought into the 21st century with Billet wheel IIRC. You do realize that you can't just strap the suckers on and go, you MUST get a tune for whatever turbos or injectors you install. Most other mods don't really require a tune but for turbos and injectors it's an absolute must.

[Boyce18]

Can I put them on and run the same boost that I am now? My car is tuned for the the 850cc and everything eles I have.
My plan was to get the turbos done then get that ECU map selector from SZ and run E85

[trandana]

I use JWT 530 Ball bearing turbos. They spool up very fast and are capable of 530 hp. They great for stock internals. I have run 17psi
but i think anything over 16 psi is not really getting much benefit with my setup.

[NolimitZ32]

OP. In short NO you cannot just bolt on bigger turbos and not tune. There are many intricacies to this and some tolerance but in general its a NO, you will blow up your engine.

[Boyce18]

Ordered the gtx2863 + bde motor mounts + MSP manifolds, Z1 said I would not have to retune with turbos just run lowered boost with these until I build engine

[evildky]

Actually you can just bolt on bigger turbo's that's the beauty of a metered air system. If the ecu were map based you would have to tune for a larger turbo as it measures only pressure which is a function of turbospeed and engine efficiency, whereas the Z32 uses a metered air system so that when you bolt on a larger turbo that flows twice the lbs/min at the same psi the ecu knows that the amount of air has doubled even if the psi remains the same. That being said, you will at some point max out the MAS, fuel pump, and intercoolers. Your big injectors are good for around 800 hp ish on gas, well in excess of what the pistons, intercooler, fuel pump and MAS are capable of. Your injectors on E85 should be good for 550hp, so the JWT530's would be a good fit. Your intercoolers will be a restriction at that point and it's pretty much the max of the fuel pump and MAS. anything at this level is it certainly well advised to have it actually tuned even though it should in theory work you are nearing the limits of many parts and it would be easy to scatter the pistons.

[NolimitZ32]

In comparison to a set of upgraded turbos an OTS EPROM is nothing. I would strongly recommend AGAINST running the bigger units without tuning and setting a boost limit (by the tuner). Your injectors are plenty large enough to handle the power that the 2860s would make and after spending this kind of money I just don't understand why you wouldn't tune.

Did Z1 tell you what boost limit to set?

[Boyce18]

Actually you can just bolt on bigger turbo's that's the beauty of a metered air system. If the ecu were map based you would have to tune for a larger turbo as it measures only pressure which is a function of turbospeed and engine efficiency, whereas the Z32 uses a metered air system so that when you bolt on a larger turbo that flows twice the lbs/min at the same psi the ecu knows that the amount of air has doubled even if the psi remains the same. That being said, you will at some point max out the MAS, fuel pump, and intercoolers. Your big injectors are good for around 800 hp ish on gas, well in excess of what the pistons, intercooler, fuel pump and MAS are capable of. Your injectors on E85 should be good for 550hp, so the JWT530's would be a good fit. Your intercoolers will be a restriction at that point and it's pretty much the max of the fuel pump and MAS. anything at this level is it certainly well advised to have it actually tuned even though it should in theory work you are nearing the limits of many parts and it would be easy to scatter the pistons.

I do have the ash massive intercoolers and dual mass air flows my understanding was that they be good for 800HP

[Boyce18]

In comparison to a set of upgraded turbos an OTS EPROM is nothing. I would strongly recommend AGAINST running the bigger units without tuning and setting a boost limit (by the tuner). Your injectors are plenty large enough to handle the power that the 2860s would make and after spending this kind of money I just don't understand why you wouldn't tune.

Did Z1 tell you what boost limit to set?

They told me to start at 12psi, they said that should be around the same as the 17psi on the stock turbos I'm running now. And I did not want to have tuned until I get the engine done.

That being said I know these turbos are much more then my engine can handle and I'm thinking now I might just buy a stage 3 short block from z1+cams and put my stock heads on it. What do you think?

[NolimitZ32]

You're talking about dropping $$$$ I can't in my right conscience be responsible for giving you advice on stuff like that. I built my engine by hand, I built my car because I enjoyed building it, I was never chasing any number HP or 1/4 mile or otherwise, I didn't build it to compete, I just did my research figured out what I wanted and built it (with a huge safety margin in the bottom end). Now as for 800hp on 2860s that would be on race gas and at the crank. I've never heard of those kind of whp numbers on any 2xxx turbo. Now if you are asking me specifically about the block's ability to handle the power then yes, that collection of parts is built to handle some serious numbers but again your ability to make power and do it safely will depend more on your tune than anything else. Lastly, I have a question, if you are not changing the CR of the pistons why would you choose to tune after a bottom end build rather than before. Ideally you will be maintaining OEM compression and volumes so the change in physical quantities of your mixture, your combustion parameters and so on would remain relatively the same, other than perhaps pushing your limiter higher.

[Boyce18]

I was not saying I was trying to get 800hp, just that I thought the dual mass air flows and intercoolers where capable of if as the other person said they where not. And I was not planing on tuning until after because there really are not any place near me that I trust. I was planing on bringing the car done to SZ and having it done after I do everything.

And just to be clear this is just a car that I take out maybe 4 times a month and only drive on the road. Once and awhile someone gets next to me and I just like to be faster, I don't compete

[NolimitZ32]

Ok, I was under the impression that you were trying for 800hp, I must've misread. The tune I am referring to is an EPROM swap which can be OTS (off the shelf) as your setup is fairly common, or you could even do logs and a couple chip swaps to get it more aligned with your car. Dyno tuning will run a pretty penny and I don't blame you for wanting to hold off, what I am talking about is far less involved and much cheaper than dyno time.