I am trying to see how big I have ported my wastegate so far and can only really compare it to coins. Anyone know how big(or can measure for me) a penny is? How about a nickel? In millimeters would be great. TIA.

 

Diameter, right?

penny = 19mm
nickel = 21mm
quarter = 24mm

 

Don't worry about how big the hole is, worry about how close to the edge of the flapper it is

 

I've heard that the hole can be bigger than the flapper. This is correct, right? Something like the flapper has to cover 75% of the hole, right?

Oh and the stock S4 WG is 12mm, right? Right now I am at about 18 then, how big do you think I need to keep boost down to 10psi or lower? Thansk alot for the help.

 

If you make the hole wider than the flapper, make sure the flapper can't get caught on any of the edges.

 

please read this thread

https://www.rx7club.com/forum/showth...hreadid=155100

 

I did do a search in case anyone is wondering. I found that thread, but theres no way I'm going to that much trouble. Just wanted to be sure how far I can go. Is it safe to go bigger than the flapper? I mean, will it make it harder to boost? Or any negative effects by making the whole larger than the flapper? Thanks again.

 

EDIT: sorry, stupid internet connection

 

Bump for those questions up there. PLUS, I was wondering what size WG everyone thought was needed to control boost with my turbo(TO4B compressor housing/wheel, P-trim turbine wheel, 360 degree thrust bearing on an S4 turbo)? Like how many millimeters. I know that a standard external wastegate is alot of times 35mm, so what should I shoot for with my WG? Like 25mm?

 

stock the wastegate is 15mm the door is 20mm i ported to mine to 22m. the door now covers 86% of the hole i think. i still have to see how it works.

 

you can get bigger flappers, you know. That's how BNR ports stock wastegates to ~35mm.

 

Are you sure the stock WG is 15mm? I heard it was 12? Either way, I got mine to 21mm and the flapper barely covers the entire hole I think. Plus I grinded down inside it to make it a smoother flow out the wastegate.

 

i measured the hole with a telescoping gauge and micrometer throughout the process. im pretty sure it was 15mm. either way its bigger now . i did the math and the door covers 83% of the hole at 22mm. im soo tempted to go that little bit bigger. if i make it 23mm the door covers 76% but it would probably lag a lot more.

 

Yeah but you have to mill the turbine housing to have room for the flapper.