Turbo crapping out, time to get a new one

[SoCalRyder7]

So it seems alot of people are satisfied with their GT28rs and am thinking about going that route. I'm on http://***********************

and on the disco potato turbo it has a selector for a .64A/R and a .8A/R. The website recommends .64 but i have no idea what it means.

[SeR_Cyclops]

Do you have forged internals? if not then go back with the GT25RS

[zuku26]

I'm running a GT28RS with NON-forged internals and No aftermarket ECM or tuning at this moment. I do have a split second that has yet to be installed. I can tell you without hesitation that you will be much happier with GT28RS as long as you keep the boost low like 6 psi low!!! but at 6 psi it still much bigger balls then the T25 and is still safe on the engine!!!
Once we install and tune the split second I should be able to run 9 psi safely

I've been running this set-up and really beating up on this car every day, without any issues for several months

[Outlawstar98]

A GT28 is a nice turbo upgrade if u dont want to go "balla"


But I also dont know what the different trims mean :(

[SeR_Cyclops]

It means the the Turbo Engineers are smarter than we are! lol

[slo03.5msp]

It's the exhaust housing a/r. You want the .64 or else your spool will be slower .

[SoCalRyder7]

I'm running a GT28RS with NON-forged internals and No aftermarket ECM or tuning at this moment. I do have a split second that has yet to be installed. I can tell you without hesitation that you will be much happier with GT28RS as long as you keep the boost low like 6 psi low!!! but at 6 psi it still much bigger balls then the T25 and is still safe on the engine!!!
Once we install and tune the split second I should be able to run 9 psi safely

I've been running this set-up and really beating up on this car every day, without any issues for several months

What is a split second? Also, i read on here that some guy couldnt put his boost lower than 9psi. Is your boost at 6psi?

And thanks for the info slo03.5. Lets say the spool is slower, wont it boost harder and spool longer?

Oh, and is a WGA short for wastegate?

[slo03.5msp]

Yes in theory however with the boost levels you are talking about running you would rather be fully spooled by 2800/3000 rpm then 3500/4000 and not have it tail. Again though at the levels you plan on running a stock replacement is more than enough. Get a 28rs a/ a .64.

[zuku26]

What is a split second? Also, i read on here that some guy couldnt put his boost lower than 9psi. Is your boost at 6psi?

And thanks for the info slo03.5. Lets say the spool is slower, wont it boost harder and spool longer?

Oh, and is a WGA short for wastegate?
A split second is a device used to tune the car, piggy back system. It helps recalibrate the Air Fuel mixture and timing of the ECM. It's not a full stand alone ECM unit.
I am running the Forge WGA, with the green spring which is rated from 5-10 psi, I have it sett almost all the way down. So I'm only rinning 6 psi. I actually tend to spike at 9-10 but it settles at 6 PSI, at least when my Knock-off SSQV isn't leaking all that boost out

[Ricktalife]

i wouldn't order the 28rs until you decide what your power goal is. for example i'd be satisfied with about 200whp. the gt25r is more than enough to reach that goal, and more than enough to blow my engine. slapping a 28rs on there with no tune and no forged internals like this guy ^^....kinda risky.

[zuku26]

The only way it's risky is if you get greedy and turn up the boost. at 6 PSI the motor is well within it's limits running a GT28RS, and to top it off it's flows better and is producing more power then the stock T25. What I'm saying is that if you have to replace the Turbo anyway, get a gt28RS. There are several members that I talked to that even ran the GT28rs at 10-11 PSI without forged internal, I'm too cautious for that.
When I first started researching about this bigger turbo, I PM'd everyone that I could find on here running it, They all said basically the same thing.

[Ricktalife]

There are several members that I talked to that even ran the GT28rs at 10-11 PSI without forged internal, I'm too cautious for that.

whoa that's asking for trouble.

[JDM Sam]

http://www.turbobygarrett.com/turbobygarrett/tech_center/turbo_tech102.html

Turbine A/R - Turbine performance is greatly affected by changing the A/R of the housing, as it is used to adjust the flow capacity of the turbine. Using a smaller A/R will increase the exhaust gas velocity into the turbine wheel. This provides increased turbine power at lower engine speeds, resulting in a quicker boost rise. However, a small A/R also causes the flow to enter the wheel more tangentially, which reduces the ultimate flow capacity of the turbine wheel. This will tend to increase exhaust backpressure and hence reduce the engine's ability to "breathe" effectively at high RPM, adversely affecting peak engine power.

Conversely, using a larger A/R will lower exhaust gas velocity, and delay boost rise. The flow in a larger A/R housing enters the wheel in a more radial fashion, increasing the wheel's effective flow capacity, resulting in lower backpressure and better power at higher engine speeds.

When deciding between A/R options, be realistic with the intended vehicle use and use the A/R to bias the performance toward the desired powerband characteristic.
Here's a simplistic look at comparing turbine housing geometry with different applications. By comparing different turbine housing A/R, it is often possible to determine the intended use of the system.
Imagine two 3.5L engines both using GT30R turbochargers. The only difference between the two engines is a different turbine housing A/R; otherwise the two engines are identical:
1. Engine #1 has turbine housing with an A/R of 0.63
2. Engine #2 has a turbine housing with an A/R of 1.06.
What can we infer about the intended use and the turbocharger matching for each engine?
Engine#1: This engine is using a smaller A/R turbine housing (0.63) thus biased more towards low-end torque and optimal boost response. Many would describe this as being more "fun" to drive on the street, as normal daily driving habits tend to favor transient response. However, at higher engine speeds, this smaller A/R housing will result in high backpressure, which can result in a loss of top end power. This type of engine performance is desirable for street applications where the low speed boost response and transient conditions are more important than top end power.
Engine #2: This engine is using a larger A/R turbine housing (1.06) and is biased towards peak horsepower, while sacrificing transient response and torque at very low engine speeds. The larger A/R turbine housing will continue to minimize backpressure at high rpm, to the benefit of engine peak power. On the other hand, this will also raise the engine speed at which the turbo can provide boost, increasing time to boost. The performance of Engine #2 is more desirable for racing applications than Engine #1 where the engine will be operating at high engine speeds most of the time.

[JDM Sam]

In short, stick with .64.

[MANDO]

Wow. Very well said! Makes perfect sense to me.

[zuku26]

whoa that's asking for trouble.

With a solid tune that is still just under the line of pushing it.
I'll up the boost to 9 once I get all tuned and dialed in. I'm super anal and cautious with this car. I work in an ER and can get called in at a moments notice, To have to call them back and tell them I blew my motor on the way in because I pushed the envelope on my motor to far could mean someone's life!!! So I did months and months of Homework before I even went this route and talked to so many Good folks on here to see how there cars were running and FOR HOW LONG!!! With the info I gathered I'm more then comfortable with a 9 PSI tuned set-up. You have to keep in mind that other facts fall into play to keep that set-up safe. condition of motor and car, what oil, plugs and wires your running. What your doing for cooling of motor and the air going into it...and air going out of it for that matter. The bigger you go as far as exhaust goes the easier that turbo will spool..ect. So upping the turbo also require upgradeing the supporting mods. When we first installed it. the rest of my upgardes were still pending. So for about a month, I was running stock plastic pipeswith teh Stock SMIC and stock exhaust. It ran, but you could tell the turbo wasn't happy and needed to breath better, once I got my parts on, she felt much happier