I am about midway complete with full non-sequential conversion and I have a concern with the machine work done on my wastegate. I have read through numerous threads detailing the process and each one says to port the wastegate to 1.24 inch diameter. When I dropped the parts at the machine shop I asked that they take care to prevent any metal shavings from entering the assembly and to make sure the flapper still seats properly. Well... I got the parts back today and their work looks great but I am worried they "over-honed" the wastegate. It looks to be like a 1.40 inch diameter which means very little lip area on the flapper (which is 1.50 inch diameter... therefore it leaves a .05 inch margin). Of course, the flapper assembly has some give in it and I am afraid the area will be prone to leaking and that leaking would lead to slight erosion (and then increase the size of leak). Am I worrying over nothing? Is there any negative side effect to have such an enlarged wastegate? And finally, if there is any reason for concern, would it be feasible to replace flapper with an enlarged piece? Thanks for taking the time to read this and respond. I appreciate the help! I can attach some pics later if needed...

 

I don't think it would be much of a problem as far as erosion goes. The only thing I'd worry about is the wastegate flapper getting stuck in the wastegate hole itself which I don't think will happen with what you have described.
With an enlarged wastegate like that, there should theoretically be more turbo lag(the flapper opens earlier).. but I don't think it's significant and that can be fixed with a good boost controller(Ie non bleed type MBC)
As far as replacing the flapper, I have heard of people welding on a larger flapper.

 

Thanks for response! Yea, I think the only issue would be turbo lag... I am running Greddy Profec B 2 Boost Controller and I will see how it goes. Thanks again!

 

Garfinkle puts the prespool door in the waste gate position .It is 1/10 of an inch bigger than the wg door . On his car with the bigger BNR turbos he made a bigger door than the prespool door . His port hole is 1.380 in in dia with a good overlap .The better boost controllers will keep the lag down . The bigger port will not let it boost creep

 

so officially, what is the biggest port you can do if you want to keep the stock flap? i just traced around the flap and ported until there

 

.050"? That's kinda close, but I've heard of people doing it like that. Don't sweat it - at elevated boost it's not like the turbos are gonna last forever.

Dave