godzeerah Posted May 14, 2015 Share Posted May 14, 2015 So I turboed my Z and added an HX35W to the mix. I changed the actuator to the internal gate for a 5psi spring that I will later control with a boost pressure controller. Heres the deal.....the internal gate doesn't seem to do anything at all with my boost pressures. I can apply 5psi of compressed air and the flap opens with the actuator, but when I get it on the road, it just climbs like there is no wastegate at all. Its not creep, as I have heard that this internal wastegate will creep a little, because it doesn't even attempt to regulate the pressure. As in it won't even slow down at all. Just 0-12 in a blink of an eye, then I back off. The turbo is a twin scroll, and I am using the stock single scroll manifold. Looking at the wastegate hole in the turbo it seems like the hole only effects one side of the scroll.....anyone think this has anything to do with it? I have searched and found nothing so far.... Quote Link to comment Share on other sites More sharing options...
Leon Posted May 14, 2015 Share Posted May 14, 2015 Are you sure your downpipe is allowing full range of motion of the wastegate door? Remove the wastegate actuator arm from the wastegate and try to move it by hand. If you're not sure how much it's supposed to move, remove the downpipe and perform the same check. I've seen this happen more than once... Quote Link to comment Share on other sites More sharing options...
godzeerah Posted May 14, 2015 Author Share Posted May 14, 2015 (edited) Thats raises a great point Leon. However it is the stock downpipe flange that was on the turbo and the stock internal gate flapper. Yes the flap does open, however I did remove the dp flange and saw that the gasket was warped a little. For some reason they made the gasket the entire surface of the flange instead of just the outside. Im gunna try drilling out my hole, drilling a 1/2" hole to the other scroll side and cutting out that section of the gasket to allow the gate to open more. Im out of ideas if that doesnt fix it. Edited May 14, 2015 by godzeerah Quote Link to comment Share on other sites More sharing options...
jeffer949 Posted May 15, 2015 Share Posted May 15, 2015 DId you bore out the waste gate hole? Been 7-8 years but i remember that i had mine bored out till the flapper just covered it. I think my pinky would barely fit into it stock hole and it was bored out to around 1/2 or 3/4 Quote Link to comment Share on other sites More sharing options...
mtnickel Posted May 15, 2015 Share Posted May 15, 2015 Most holsets I've seen have TINY wastegate holes. Mainly since they regulate pressure usually around 25+psi which means it doesn't need to bleed off as much flow. Anyways, I experienced the same exact lack of control on my rb25 build. I had a 6psi actuator, 18g turbo and TD05 turbine (somewhat smallish turbine) and a slightly smaller than average wastegate port (maybe 22mm or so). Basically exhibited NO boost control. Once it reaches its' 5-6psi, there is already way too much gas to bypass and it just continues to rise (up to 20+ psi) Problem will be exacerbated if you have a really well flowing exhaust. I have 3" all the way back, no cat, straight through design resonator and muffler. I even disconnected the wastegate arm and wired it open to check. This results in the boost buildup to 6psi being a decent amount slower, but it still skyrocketed to the 15-20psi after that. Likely need to do what jeffer has said. Port as much of the flapper hole out as you can. You can hold port shut and spray paint in neon around it. That way when you open it up to port you can see how much clearance you have. There are also places you can order larger flapper disks. The DSM guys had to do this all the time. I've even resorted to welding a bead all the way around the stock flapper to enlarge it and then sand it flat again. (cheap mans enlarged flapper). Stainless filler recommended. Otherwise gotta go external wastegate. Thats the route I took. Good luck! Quote Link to comment Share on other sites More sharing options...
godzeerah Posted May 15, 2015 Author Share Posted May 15, 2015 I want to avoid an external setup if I can. I made a 1/2 inch hole between the scroll ports, and bored the wastegate hole a little bigger....No difference. So, I will try and bore it more, but I really just dont think the hole can be made big enough. I also have a bit higher compression, 9:1, so maybe thats contributing to that. Seems to climb to about 14 or 15psi now and stop. I guess thats an improvement. Thanks for the input guys, Im going to bore that hole a bit bigger if I can and see what that does. Quote Link to comment Share on other sites More sharing options...
Leon Posted May 15, 2015 Share Posted May 15, 2015 I had an amusing solution for a turbo Miata that had boost control issues, once I pulled the downpipe I noticed that the turbo-to-downpipe gasket completely blocked off the wastegate door! Your gasket doesn't block the door from opening, does it? Quote Link to comment Share on other sites More sharing options...
godzeerah Posted May 15, 2015 Author Share Posted May 15, 2015 It doesnt now, I cut the gasket out. I think it really is the size of the wastegate hole here... My goal is around 18psi...but to do that I will need injectors. Im going on the z31 turbo injectors at the moment. Quote Link to comment Share on other sites More sharing options...
lowrider Posted May 16, 2015 Share Posted May 16, 2015 When I was running the 12cm^2 factory Holset exhast housing, I was in the same boat. In an attempt to get enough flow from the wastegate I ended up removing the divider down to the wastegate hole, and replacing the wastegate flapper with a larger one / ported the crap out of the wastegate hole. It worked alright and would hold 10psi, creeping to 13psi at redline. Eventually I wanted a bit faster spool and changed exhaust housings and went external. I should have went external from the start. It controls the system pressure more accurately not to mention the time, money, and effort I spent trying to get the stock internally gated setup to work. Quote Link to comment Share on other sites More sharing options...
godzeerah Posted May 16, 2015 Author Share Posted May 16, 2015 Lowrider....can I see a picture of your external setup? Did you weld it to the exhaust manifold? Quote Link to comment Share on other sites More sharing options...
lowrider Posted May 16, 2015 Share Posted May 16, 2015 (edited) When I did the install I didn't snap any pictures, but it was fairly simple. I bought a v-band type wastegate from a vender on eBay after reading reviews of how quality they were (I don't remember the name). When I got it, I measured the V-band diameter and ordered a sc40 90 degree weld elbow from McMaster carr that matched od to od. Next I used a hole saw to make a hole directly under the turbo flange. I welded the V-band to one end of the weld-el and then the weld-el to the manifold with the V-band pointing rearward. It was a fairly simple process and only costed around $100 or so. Edited May 16, 2015 by lowrider Quote Link to comment Share on other sites More sharing options...
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