i just got my full turbo bak exhaust for my 88 TII and want to port the wastegate to prevent boost creep when i install my exhaust. i dont have a boost gauge right now so i want to be able to keep it safe. does any body have a write up on how to properly port the wastegate

 

its not difficult...after getting the turbo off the car find a dremel (sorta a last resort) or somthin similar that can properly do the job and what i did was cut the material to edge of the surface where the flap comes in contact to the surface...then i found a washer and welded it to the flap...a miachine shop could also do the job...

 

i was looking for some specific dimensions for porting the WG if any body had them. did you get a creep with that porting job?

 

no boost creep...its got high comp. rotors also

 

Hey, got a question, how big should the new flap be? I was going to prolly do a 40mm port but did not know how big my flap should be.... Also on the flap, do I just weld a mild steel washer onto the exsisting flap?

Thanks guys

 

becarful with the mild steel. I had one disintigrate on me, but i've also had success with one as well.. just pick your washer wisly. . lol nothing too thin pretty much

 

yep, i had 2 steel washers go MIA and even the hardened steel one i believe is starting to go out as well. either port as large as the stock flapper will allow while paying close attention to the beveling or use an exhaust valve welded to the flapper arm rather than the stock flapper to increase the surface area.

 

https://www.rx7club.com/2nd-gen-archive-72/serious-s4-wastegate-porting%85-352816/
i think theres also one of a guy modding a honda exhaust valve to work as the flapper and do a massive port job... Is your new exhuast free flowing, or do you have cats. You might now need a massive port job if you still have some backpressure

 

Dont know about the other guy, but my exhaust will be straight free flow 3". So I am thinkin 40mm and using an exhaust valve. Any one know if the valve used as a flap will be enough to cover a 40mm port?

 

i have the ssauto single out turbo bak. its gotta a 3 in down pipe racing cat and i think it tappers down to 2.5 after that. i was thinking about porting the WG to about 35 mm?? and does any one know how much the honda exhaust flange costs?

 

ford big valves, you can probably get them from summit racing. i dunno if you can only get one though. but you can cut the head off the valve at the neck and rig that up.

 

You can also file off the back side of the door to give more clearance behind it.

 

If you are worried about mild steel, go to the fastener store and buy some thick stainless washers. Or the local metal store and root around in their offcuts bin until you can find some stainless rod of the proper diameter, then cut a disc. Unless you have a supply of piston valves handy then using an valve is more trouble then it is worth.

 

Great idea about the steel rod, thanks aaron! So If I do a 35-40mm port, what would be sufficient for a new flap? Or I guess I should ask, how many mm should the flap be bigger than your port?

 

The flap needs to be about 2MM or so larger then the port so it doesn't get stuck. None of this is really critical engineering. Just make sure the flapper moves freely and doesn't bind up anywhere, doesn't get stuck in the hole, and won't melt.

 

Isn't 35mm about the largest you can port the wastegate?

 

You can get damn near 40MM if you are willing to compromise the wall of the discharge housing...

 

i still dont see a stocker ever needing more than a 30mm port, we are talking about a stock turbo here... they can only blow so much air.