Jose93z28

iTrader: (3)

So I recently changed my setup from a tc78 t4 to a S475 t6 on my car, I kept the hot side the same including the tial 38mm wastegate its located in the center merge section where both manifolds meet it has a horizontal pipe that connects to the wastegate then it dumps to the athmosfere my setup is stock 5.3 with 799 heads e85, with the old turbo it had a 3" downpipe thru a magnaflow and exhaust cutoff right in front of the axle, used to boost 10psi consistant on the spring only, with the s475 I have a 5" downpipe comming out of the bumper so no restriction, but its pushing north of 19psi I let go as soon as I see over 15psi, and feels like it will keep boosting if I dont let go, I changed the spring to a softer one to see if it made a difference but still pushing 18-19psi, not a spike but consistent boost, my question is has anyone here have a similar setup and has made the 38mm work? Or do I have to go with a 50mm wastegate? Let me knw thanks in advance.

yenkomike

iTrader: (2)

i have a 38 on my nova . s480/83/1.25 t4. i can run 7 psi with no creep. but it is on an outside bend at an angle so it flows very good. if yours comes out at a 90* to the pipe it will not flow enuff.

Jose93z28

iTrader: (3)

Do you have any pics of the location ?

autoaddictions

I have the same set up . I also had the same issue. boost creeping up with rpm. It was so bad that
id launch with 4 psi and have 16 in 3rd 6000 rpm. I ended up getting a 60mm gate and placed it at the merge. Inline with airflow. Now boost is rock solid.

Beanslsxnova

iTrader: (1)

The cheapest solution is to add a 2nd 38mm waste gate. I had the same problem your having on 2 different set ups I added a second gate and boost is perfect.

Jose93z28

iTrader: (3)

Thanks for the input guys I will consider either adding the second 38 or stepping up to a 50-60 see what happens cause this is out of control, when you added the second 38 do you use same springs on both wastegates? For example the green spring was giving me 10psi or so in the old setup, now if I add the second 38 would I use the same spring?