datsunan Posted February 24, 2005 Share Posted February 24, 2005 I'm in the process of changing to an external WG, I've been looking at the different WG's out there and they come with different spring ranges depending on what boost you want to run. I have an Apexi boost controller and usually run 14 psi. So, if I get a wg with a 10 psi spring that means it won't ever open untill it hits 10 psi regaurdless of my controller. If I use a 6psi spring then it would start opening somewhere around 6 and my controller would have to start working earlier than if I used the 10psi spring. So my question is, could I run out of control with my apexi if I use a light spring say 6psi and want to run 20psi boost? The controller would start bleeding off air at 6psi and have to increase bleed rate all the way up to 20 and then some. (if my turbo is capable of 20+)Would I get better control of high boost using a higher spring rate? Any input would be appriciated. Quote Link to comment Share on other sites More sharing options...
fl327 Posted February 24, 2005 Share Posted February 24, 2005 The more boost that you need to bypass, the bigger the wastegate you would need, depending on how low you need it to be. The bigger ones are better for lower boost, which is why you see a lot of 6psi honda motors going straight for an external. You may be able to get away with a smaller one, as the L series is down on exhaust flow. Quote Link to comment Share on other sites More sharing options...
datsunan Posted February 25, 2005 Author Share Posted February 25, 2005 I was'nt so concerned with the dumping of exhaust gas as I was of bleeding off the pressure to the wg that controls the opening and closing. But you bring up a good point. That adds even more questions to the proper sizing of the wg. I don't get stable boost even with a high tech controller. I'm willing to spend time and money one an external wg but I want it to work the first time. Any other suggestions? Quote Link to comment Share on other sites More sharing options...
awd92gsx Posted February 25, 2005 Share Posted February 25, 2005 If you are internally gated now you could probably port your internal gate to help with any boost creep you might have. The Apexi won't open it's solenoid until you hit your desired boost pressure, so, it really doesn't matter which spring pressure you use. Quote Link to comment Share on other sites More sharing options...
Doug71zt Posted February 25, 2005 Share Posted February 25, 2005 I run at Tial 38mm with a 12 lb spring, with a mechanical boost controller on the top port. It handles my output just fine. I would recommend Tial no matter what size, due to the quality of construction, and the fact that they are quite small, and easy to fit. I am running my same old 5 bolt turbine housing, with an adapter plate on the output side to mount the WG. Works worlds better than my old (extremely) ported internal gate. I'm sorry I waited so long to go external. As for the spring pressure, 10 psi would be as low as I'd go. What would you want 6 psi for? If I want less boost, I modulate the throttle. But seriously, the WG seems to work better with a bit higher spring pressure. My $0.02 anyway. Doug Quote Link to comment Share on other sites More sharing options...
datsunan Posted February 25, 2005 Author Share Posted February 25, 2005 Thanks Doug the just the kid of response I was looking for. I was actually looking at a Tia on ebay, I'm all about good quality. Is this like the one you have? http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&item=7955990067&rd=1&sspagename=STRK%3AMEWA%3AIT Is this the flang you used? http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&category=33742&item=7957610176&rd=1&ssPageName=WDVW Thanks for the reply Paul Quote Link to comment Share on other sites More sharing options...
Doug71zt Posted February 25, 2005 Share Posted February 25, 2005 I'm using a 38mm unit, with the 2 bolt flange. Same actuator head as that 40mm unit. It used to be known as the 38/40 hybrid, but I think that all 38mm units use that head now. The flange I am using looks similar to the one in the second picture of that ad, with the 1 inch WG hole. Mine is 3/8" waterjet cut 304 stainless, as is all the rest of the plumbing on my car. I just TIGed a elbow on the flange and ran it to my WG mounting flange. I'll have a look on some CD's to see if I can post a picture. I'm overseas right now, so not at my home computer. You may want to go to a 3" Vband adapter plate to ease the DP installation. I think that ATP turbo sells them. http://www.atpturbo.com Doug Quote Link to comment Share on other sites More sharing options...
datsunan Posted February 25, 2005 Author Share Posted February 25, 2005 Did you use any kind of flex joint in the waste pipe between the wg and exhaust pipe? If so where can I buy that? Quote Link to comment Share on other sites More sharing options...
Clifton Posted February 25, 2005 Share Posted February 25, 2005 A 6 psi spring won't hold 20 psi even with a boost controller. I had an 8 psi spring and it held up to 18 psi but anything more and I lost boost as the rpms went up. I went with a 18 psi spring and it holds steady to 24-25 psi, the most I have tried so far. I would run the stiffest spring you can. I will never run less than 18 so that's why I am using the 18 psi spring. I also ran a flex on the wastegate outlet. It makes exhaust installs and removal alot easier. I got it from an RV shop, it's really cheap. It's just flexable exhaust 1.5" Quote Link to comment Share on other sites More sharing options...
slownrusty Posted February 25, 2005 Share Posted February 25, 2005 I am running a 45mm TiAL (good to over 500hp apparently) wastegate which has the four bolt flange identical to the Porsche 944 Turbo....its an expensive unit, but its much lighter than the Porsche unit, plus its beautifully constructed and has a reputation that puts it at the fore front for all external WG units. I will be upgrading the spring soon to a 12psi soon. Should be fun. Please note the 944 Turbo was extremely reliable. Here it is next to my old 944 Turbo WG: Yasin Quote Link to comment Share on other sites More sharing options...
datsunan Posted February 25, 2005 Author Share Posted February 25, 2005 Thanks guys, Clifton I think thats my problem with my stock wastegate, I can hit about 17psi like a spike but it can't hold it there. Is that set up you have on a z? I see the oil filter hanging outon the same side as your exhaust. If it is a Z how is it handling the 18 psi? No problem? Are your mods similar to mine. Slowandrusty I'm sold on the Tial that is a nice unit. I just bought the one I posted above with a 1bar spring, so now at least I'll get 14psi steady all the time! Quote Link to comment Share on other sites More sharing options...
mtcookson Posted February 25, 2005 Share Posted February 25, 2005 i don't understand how having a softer spring could limit your upper boost levels considering all a boost controller is, is a device to block the air going to the wastegate... unless its just the pressure inside the manifold that is causing the valve to go up. is that what its doing? Quote Link to comment Share on other sites More sharing options...
yo2001 Posted February 25, 2005 Share Posted February 25, 2005 unless its just the pressure inside the manifold that is causing the valve to go up. is that what its doing? yap. The rule of thumb is to use the spring half of the desire max. boost. Anything more is going to be hard to control. So 14psi spring is good up to 28psi +/- 2psi. Also if you are internal WG running larger flapper, you are more likely to have the flapper blow open because the pressure applied to the flapper under boost square roots times the flapper diameter. Quote Link to comment Share on other sites More sharing options...
mtcookson Posted February 25, 2005 Share Posted February 25, 2005 hmm... i bet i could setup some odd valving to allow boost to go into the vacuum port on my wastegate to effectively handle more boost... time to go to the drawing board. Quote Link to comment Share on other sites More sharing options...
Clifton Posted February 25, 2005 Share Posted February 25, 2005 i don't understand how having a softer spring could limit your upper boost levels considering all a boost controller is, is a device to block the air going to the wastegate... unless its just the pressure inside the manifold that is causing the valve to go up. is that what its doing? The more boost the more turbine pressure it takes to make the boost. The extra back pressure will eventually overcome a soft spring and cause the wastegate to open. I run pressure to the top of the wastegate. It will still reach a point that it will loose boost with a too soft spring. The only way to avoid it is on an external wastegate. Use another spring to pull on the WG flapper. That will hold whatever you want. Guys that run 30+ with an external WG run a 20+ springs. No way around it. Larry at SP has completely removed the signal line from a few wastegates and let the turbo make as much as the spring would let it make on the dyno. datsunan......The pic is of the 7M 240. I run the same setup on the L28 Z but didn't have a handy pic. Quote Link to comment Share on other sites More sharing options...
Doug71zt Posted February 26, 2005 Share Posted February 26, 2005 I just used a double slip-joint in the outlet to the downpipe. I made it on the pipe-stretcher and welded it together. It doesn't leak at all. Doug Quote Link to comment Share on other sites More sharing options...
AnTmanS130T Posted February 26, 2005 Share Posted February 26, 2005 I am also planning on going external soon. Tial would be my choice of course. I understand the spring pressures / max boost fine, what I do not understand is what does a larger MM do? MM meaning the actual hole size on the external gate? A smaller one with the same spring pressure as a larger one does what? Quote Link to comment Share on other sites More sharing options...
yo2001 Posted February 26, 2005 Share Posted February 26, 2005 larger WG will allow better and faster boost control. I doubt anyone needs anything more than 38mm until you get to T series turbo or large GT. Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.