The turbo i'm getting for my 1641 will require an external wastegate. so I need to now all there is. Also boost controllers although I'm not going to go electronic but a simple ball and seat type.

I cant give much info on the turbo yet as I won't have it till early next week but it will boost between (so i'm told)2500 and 6000 rpm.
I plan on starting out small (5-6psi) and going to 9-10psi if my setup allows.
From what i've read i'm thinking a 38mm wastegate (please tell me if i'm wrong) and this is based on the hp and the exhaust size. I did read however that on low boost applications a bigger wastegate is recommended to help prevent wastegate creep. I'm lead to believe the boost controller will also help this.
Although it won't be a daily driver but more something for the track, I would like to be able to drive it there so I will plumb the wastegate outlet into the muffler so I don't scare small children.
Anyway I guess this is only a minor part of it so please let me know your thoughts.
Also what size exhaust 11/2 or 15/8 I have 4 into 1 extractors and will come out of the merged flange.

Cheers

M8, you have answered most of your own questions.
Dont get to bent out of shape about boost creep. it just isnt that much of an issue at the very mild setup you are looking at.
Have fun
L8tr
E

Even smaller than 1.5" would be better I understand.

Is that to do with the increased velocity of the gas through the smaller ID exhaust? If it is makes sense.

If I go smaller than 1 1/2 will i need a smaller wastegate than 38mm?

Hi Stanley

38 mm wastegate should work fine- even if you go with smaller than 1 1/2 exhaust.
With your size engine, you should try to keep the exhaust as short as possable to get the turbo to make boost at low rpm.
You want the exhaust gasses to reach the turbo before it loses too much of its heat.
Are you going suck-through, if so, dont go too big on your intake T-section.

L8R
Hermann

You should be fine with 1 1/2", however (and correct me anybody if I'm wrong as I have never tried to run such low boost) external gates only start working at 7psi, I have never seen a spring set lower than this.

As for what to go for, this all depends on how close to edge you want to go. If you have a relatively high CR (assuming you are running a medium tuned engine), then an accurate gate is a must... CHEAP GATES STICK AT HIGH TEMPS. So go with an Ultra Gate or Tial, I havent used the Tials but am told they are all good. If you have a low CR well to be honest, 7psi wont be much of a rush, but a cheap chinese copy will do the job.

if you post more about your combo Im sure you will get more help...

and as for small children, well they shouldnt be playing on the road anyway!

Go Australian... Turbosmart and leave it as a screamer!
T54

hi name is brad and i have played with a few turbo set up's on all diferent kinds of cars.
with such low boost needed you realy need to go with one of the more expensive waste gates or go for a turbo with an internal set up, due to to the fact that little charlie chan in china doesn't always put the 7 psi spring in when he is told to ,he only get,s paid $1 a week and doesn't realy care .
i have had a few problems with the cheap wastegates.
they creep realy bad .
placement of the gate is also important.