Jump to content
The mkiv Supra Owners Club

External Wastegate sizing


bluedrag

Recommended Posts

hey guys just after some opinions on what size wastegate i should be using for my NA-T build, only wanting to run 8-10 psi at most and currently im overboosting to 15psi at 5000rpm any ideas or suggestions? im currently running a 38mm external gate but do you think that is big enough?

 

any help is appreciated =)

Link to comment
Share on other sites

Is it a hks copy? as I had one and mine was also overboosting! I only found out mine was doing it the day before I was due for mapping so I had to miss that day and I orded a pw46 46mm precision wastegate and its perfect! It's not the size it's the cheap copy stick slightly! I took the piston out of mine to inspect and clean and I noticed the shaft was ever so slightly bent. Not sure if it was a manufacture fault or weather the cheep metal couldn't take the heat?

 

But up to now I'm the only person that has seem to have that problem, but if you do do then this makes 2 of us.

 

Good luck and I hope you get sorted dude :)

Link to comment
Share on other sites

How did you go about fitting it Fosta? Did you buy a 4 bolt to V Band adapter?

 

What I done was take the 4bolt plate that has the seal for the wastegate piston top and welded a v-band to that. So it just bolted to the manifold like before and then the clamp when on the v-band.

 

image

Link to comment
Share on other sites

i will try with a friends wastegate maybe then and see if the beter gate makes a difference as it is more than likely some cheap ass chinese copy (no offence to any chinese people) if that wokrs ill either have to buy his spare or fork out for a decent one myself, thanks for the help guys will keep you posted

Link to comment
Share on other sites

okay then, only a couple of things it can be ,

have you checked the vac pipes for splits ? what boost controler do you have ? if you do plumb the waste gate straight to boost referance to make sure its not the boost controler .

there are a couple of ways to add a boost controler to a wastegate try another way if bypassing the boost controler works .

last of all get a new waste gate :D

Link to comment
Share on other sites

38mm should be fine.. but I'd also look at the flow to the gate as well.. How does the turn to the wastegate look like? In some china manifolds there's a lot of material you can remove to make the exhaust flow better.

 

Also like above, first run just the boost source to the bottom of the wastegate and see if you still over boost to make sure it's not the boost controller. Then test with some compressed air with a gauge to see where the waste gate really opens so that you dont have a stiff spring in there and make sure the travel of the valve is good and it's not sticking.. If those do not help, you might have to fit a bigger 44-46mm wastegate and at the same time port the manifold.

Edited by Krister (see edit history)
Link to comment
Share on other sites

ok well ive tried running vac lines to both top and side of wastegate and neither made any difference and i also tried with the boost controller out of the vac lines altogether, someone suggested that i try restricting the exhaust and hoping the the resulting back pressure slows the turbine because it cant get the waste out fast enough?

any thoughts on this idea?

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.

Guest
Reply to this topic...

×   Pasted as rich text.   Restore formatting

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

×
×
  • Create New...

Important Information

We have placed cookies on your device to help make this website better. You can adjust your cookie settings, otherwise we'll assume you're okay to continue. You might also be interested in our Guidelines, Privacy Policy and Terms of Use.