I've never messed with a turbo before and am wondering how much I should port my wastegate. I want to be able to make it as large as possible but was wondering what happens if I made it larger than the flapper? I don't want to lose boost or make it boost slower or anything. Thanks

 

the consensus is that the door should cover at leat 75% of the wg hole....you can try porting it larger and welding a new flapper on there. its been done.

 

Assuming an S4 here, Ryde.

Go ahead and port it larger, the flapper does not even need to be air tight. If you do port it larger than the flapper door, amke sure you actuualy do so... you don't want it to get caught and stuck in the closed position. You can weld a new flapper on their as while, but you might not need to.

 

Well the turbo is an upgraded S4.

If I go larger than the flapper, will it take longer to spool the turbo? Any negative effects? I just want to be able to keep boost down to 8-10psi which I shouldn't really have a problem since with the stock turbo(and wastegate) I could keep it to 7.5psi.

 

Here are some pics of mine here::

https://www.rx7club.com/forum/showth...5&pagenumber=2

 

Hardly any negative effects on spool. If you are concerned with spool-up time, considering wrapping your downpipe and put a cover over your exhaust side.

 

Id port it to 30mm and weld a larger flapper on there.

 

So even with a ported wastegate do you generaly still creep?

Ive got an HKS intake and a 3" Dual turbo back... im in the process or taking my turbo off to port it.... should i expect to have to make a new flapper door so i dont creep at all?

 

http://www.aaroncake.net/rx-7/s4wastegate.htm

I'm GUESSING it'll creep a bit with the three inch exaust. Don't KNOW. Guessing.

I ported my series four wastegate last week with a rotary file. Put some paint on the area the flap rests on and scribed a line around the flap. Gutted the interior of the holw and made the hole itself larger. Made it where there is maybe a 1/32 inch of material left for the flap to rest on.

Sorry. I only run a 2 1/2 inch exaust and have no visible creep at 10psi (boost controlled up to 10psi). I think your 3 inch exaust is going to make it creep a bit. GUESSING.

 

I ported mine to 31mm and welded on a washer. I was surprised that I could only get 7psi on cold nights and about 5.5-6psi otherwise. Also, I have a complete RB exhaust and cone filter.

 

I shoulda welded a washer while I was there and gutted it even bigger. Oh well. Next time It have it off.............

 

mines a series 5 thought... what is the stock boost level for a s5 8psi ish??

 

You realise this thread is over four years old right...? I don't think any of the original posters are still around...
Those guys are talking about the S4's small round wastegate flap. There's not much point in trying to replace the S5's large oval flap. Just enlarge the two ports to suit it. Don't port too close to the edge, but leave ~1mm (0.04") or so for it to seal on. A leaking wastage will cause the turbo to spool slower (i.e. increased turbo lag) because exhaust is bypassing the turbine when it shouldn't be.

Yep, 8.3psi to be FSM-exact. But a 15-20yo modified FC could be running anything from 1psi to 20psi depending on how modified and/or how broken it is.

 

So this is why you wrap the exhaust? So all the air gets to the turbo?

 

no, you wrap the exhaust from the engine ports to the turbo to keep heat in... after all, heat is energy, hotter gasses are at a higher pressure, and the higher pressure can spin the turbine more quickly, imparting more energy to the compressor. Some people also wrap the exhaust to keep the engine bay temperatures down, but this for engine cooling, not to make the turbo work more efficiently

Also, why would you make the port for the wastegate larger than the flapper? Then it will never close fully and you'll always have air pushing its way past the wastegate, preventing you from building much boost. Sure, it wont creep, but because it doesnt exist in the first place. If you have access to a dremel, port out the housing to about a millimeter from the flapper (make sure to check how much play is in the flapper, so that you wont grind away enough so taht the flapper could fall and leave a bit exposed). If you have access to a dremel and welder, go to town, carve out not only the port, but the wall around flapper, and the plate that bolts down over the whole thing to help guide gas flow and to allow the flapper to open higher. Then weld a washer onto the flapper that will cover your newly enlarged port. You may also want to weld the joint that allows the washer to pivot around the flapper arm to prevent it from wedging against the wall and getting stuck. Have fun with it!

 

At least people are searching

 

good call