Well I finally identified my turbo by matching some numbers on the badge and here it is http://www.turbobygarrett.com/turbobygarrett/catelog/Turbochargers/GT25/GT2554R_471171_3.htm

Now heres the question I was told it has a 6psi wastegate spring (Internal) I am going to want to run more than 6psi for sure (after motor break in of coarse) and I have heard different opinions some say that means I can run UP TO 6psi and I have also heard I can ONLY run 6psi AND UP. Now if I need a bigger spring where do I get one from?


Thanks in advance for any advice.

Sigh...

Read up on wastegates man.

The spring pressure on a WG means that is when the flapper/valve opens allowing exhaust gas to bypass the turbine wheel. So a 6 psi spring means the WG opens when boost pressure reaches 6 psi and additional exhaust pressure is bypassed.

Using a boost controller prevents boost pressure from reaching the WG actuator/valve until the pressure overcomes the controller and then opens the wastegate.

Originally posted by CODE4
Sigh... Read up on wastegates man. The spring pressure on a WG means that is when the flapper/valve opens allowing exhaust gas to bypass the turbine wheel. So a 6 psi spring means the WG opens when boost pressure reaches 6 psi and additional exhaust pressure is bypassed. Using a boost controller prevents boost pressure from reaching the WG actuator/valve until the pressure overcomes the controller and then opens the wastegate.

/ME feels like a BANME! now. That makes sense. Thats why you have to have that vacuum line attached to the wastegate without a boost controller so you dont spike.

Yea, Dave explained it well above.

Keep in mind that with low pressure internal wastegate springs like the one you have, even with the use of a boost controller it is common that you will not be able to increase boost much above the spring level. This is because exaust gas will literally force open the wastegate flapper prematurely.

This happened to me. I was running Hahns 8psi internal wastegate, and even with the use of a high quality MBC (Joe P Pro Z) I was not able to hold more than 10psi of boost through to redline.

Originally posted by Ebster1085
Yea, Dave explained it well above. Keep in mind that with low pressure internal wastegate springs like the one you have, even with the use of a boost controller it is common that you will not be able to increase boost much above the spring level. This is because exaust gas will literally force open the wastegate flapper prematurely. This happened to me. I was running Hahns 8psi internal wastegate, and even with the use of a high quality MBC (Joe P Pro Z) I was not able to hold more than 10psi of boost through to redline.

See and I keep getting answers like this. So should I just upgrade the spring?

Why not get it all bolted up and running first and see where you are at then. If you cant hold a desireable boost level with the wastegate you have and an MBC, then consider getting a new spring. Until then, dont jump to any conclusions. I was just giving you fair warning.

Originally posted by TuxdreamerxSee and I keep getting answers like this. So should I just upgrade the spring?

If you have an internal wastegate, you probably won't be able to change the spring. You'll simply have to purchase a new wastegate, if they're even available. I agree with Ebster, install the turbo as is and see where that gets you.

Paul is right. There are not many internal wastegates that allow you to change the spring. That is not to say you dont have one that does.

Personally, I went with Hahns Modular wastegate that has 8, 10, 15, and 20psi springs.

I used this turbo for 3 years with a manual boost control along with the internal wastegate and actuator that came with the turbo. I kept the manual boost controller set at 18psi and could hit it consistantly. Maybe I just had good luck but it worked for me without changing the actuator.

Originally posted by scorplon81
I used this turbo for 3 years with a manual boost control along with the internal wastegate and actuator that came with the turbo. I kept the manual boost controller set at 18psi and could hit it consistantly. Maybe I just had good luck but it worked for me without changing the actuator.

Cool, Eventually after break in and all I would like to take it up to the 18-20psi range. Just glad to hear someone elses experience with this turbo.

Use the turbo efficiency map to see what the best psi will be for that turbo. It looks no bigger than a t25.

Do not just run 20psi becuase you think it sounds cool. your only going to get 250-275 whp out of it. I would sell it.

Ya, running at 18psi on mine was way off the compressor map when plotted. Plus it spooled so fast I had no traction in lower gears, I had to back off the throttle a lot to keep from spinning tires. Ultimately thats why I ended up getting a new bigger turbo.