slownrusty Posted July 27, 2006 Share Posted July 27, 2006 Guys - what do you think..."Yes" or "No" What are most of you guys running for external WG sizes? Yasin Quote Link to comment Share on other sites More sharing options...
240hoke Posted July 27, 2006 Share Posted July 27, 2006 Keep in mind the more boost you run the smaller a wastegate you need. And yes 38mm is plenty big. Quote Link to comment Share on other sites More sharing options...
Lunar240z Posted July 27, 2006 Share Posted July 27, 2006 what if you wanted to run very little boost? say for a daily driver econo type situation. Quote Link to comment Share on other sites More sharing options...
slownrusty Posted July 27, 2006 Author Share Posted July 27, 2006 Keep in mind the more boost you run the smaller a wastegate you need. And yes 38mm is plenty big. OK thats what I thought....I wanted to make sure. Thanks Austin. Lunar - for little boost I would stick with an internally gate Turbo. Quote Link to comment Share on other sites More sharing options...
Lunar240z Posted July 27, 2006 Share Posted July 27, 2006 big boost and little boost. most EBC's let you use two settings Quote Link to comment Share on other sites More sharing options...
turbo_fb Posted July 27, 2006 Share Posted July 27, 2006 More boost, smaller wg? more boost = more exhaust? I dont understand why...but I guess it's correct since there is a 1400 hp bmw here in Norway running one single 60mm wg. Quote Link to comment Share on other sites More sharing options...
Thumper Posted July 27, 2006 Share Posted July 27, 2006 More boost' date=' smaller wg? more boost = more exhaust? I dont understand why...but I guess it's correct since there is a 1400 hp bmw here in Norway running one single 60mm wg. [/quote'] Think of it this way. Lets say you have a fairly large turbo. And you are driving along and you have the boost set at 10psi. Now the exhaust gases are turning the exhaust turbine and thus turning the intake side. Since you have such a large turbo you need to spin the exhaust much slower so you have to bypass lots of air around the exhaust turbine. When you are running 20psi you need the turbine to spin alot more so the exhaust needed to spin the turbine is alot more. Although you do have alittle more exhaust gases being spent out not nearly the double amount of exhaust gases need to turn the turbine at 20psi vs 10psi. So you need to expel less exhaust gases at 20psi vs 10psi. Did I make sense? Probably not:rolleyesg Quote Link to comment Share on other sites More sharing options...
thehelix112 Posted July 27, 2006 Share Posted July 27, 2006 Thumper, that is true, but you are ignoring the fact that when you run more boost, you produce more exhaust gases, so therefore have more to bypass. I am sure its more complicated than just big boost = small w/g, as with all things. Try the 38mm and see, I think it'll be fine. Dave Quote Link to comment Share on other sites More sharing options...
Kennysgreen280zt Posted July 27, 2006 Share Posted July 27, 2006 My friend made 409 whp with no boost creep on a 38mm tial. Quote Link to comment Share on other sites More sharing options...
slownrusty Posted July 27, 2006 Author Share Posted July 27, 2006 My friend made 409 whp with no boost creep on a 38mm tial. Wow..music to my ears! Quote Link to comment Share on other sites More sharing options...
TimZ Posted July 27, 2006 Share Posted July 27, 2006 Thumper' date=' that is true, but you are ignoring the fact that when you run more boost, you produce more exhaust gases, so therefore have more to bypass. I am sure its more complicated than just big boost = small w/g, as with all things. Try the 38mm and see, I think it'll be fine. Dave[/quote'] As usual, I'm with thehelix - flow through the engine increases exponentially with boost. The more boost/smaller wastegate notion assumes that everything is linear, which it decidedly is not. As a counter example if it takes less wastegate to manage higher boost, why is it generally necessary to port an internal wastegate when higher boost is run? If the high boost/small wastegate idea were correct, then that would imply that the stock internal wastegate could never have worked properly at any boost level. That said, 38mm is probably okay for the power levels you want, but I wouldn't recommend going any smaller. Quote Link to comment Share on other sites More sharing options...
JustinOlson Posted July 27, 2006 Share Posted July 27, 2006 Its all based on the size of your turbine wheel and the pressure differential across the turbine. If it is very easy for exhaust gases to pass through the turbine,(example: larger turbine wheel, large exhaust), it will be harder to get exhaust gases to go through the wastegate.(edited for a brain fart) The lower the boost(the more exhaust you are bypassing around the turbine wheel, and not turning the compressor wheel) the smaller the wastegate you will need for a given turbo. Regards, Justin As usual' date=' I'm with thehelix - flow through the engine increases exponentially with boost. The more boost/smaller wastegate notion assumes that everything is linear, which it decidedly is not. As a counter example if it takes less wastegate to manage higher boost, why is it generally necessary to port an internal wastegate when higher boost is run? If the high boost/small wastegate idea were correct, then that would imply that the stock internal wastegate could never have worked properly at any boost level. That said, 38mm is probably okay for the power levels you want, but I wouldn't recommend going any smaller.[/quote'] Quote Link to comment Share on other sites More sharing options...
thehelix112 Posted July 27, 2006 Share Posted July 27, 2006 Justin, Can you please re-read what you wrote to make sure thats what you meant? Just want to check before I respond. Dave Quote Link to comment Share on other sites More sharing options...
dapiper Posted July 28, 2006 Share Posted July 28, 2006 Small wg will cause boost creep, predominately at low boost. I ran a 1" Turbonetics deltagate for years at over 400 hp with a 5 psi spring, but when turned down, boost easily crept up to 7 psi. A smaller wg will control better, less pressure fluctuations. Need biggest diaphragm you can get to provide "gain" for proportional action. Now using Tial 38 mm with no discernable creep, but lap those flanges true and use gasket with integral firering. Quote Link to comment Share on other sites More sharing options...
Thumper Posted July 28, 2006 Share Posted July 28, 2006 From my personal experience with my holset. I had the internal wastegate ported very very much to the max. I would have more boost creep at 12psi almost to 15psi. But when I ran it at 20psi I had no boost creep. So that tells me that the wastegate wasn't big enough at low boost but was at high boost. Any thoughts on this? Quote Link to comment Share on other sites More sharing options...
thehelix112 Posted July 28, 2006 Share Posted July 28, 2006 Thumper, dapiper is on the money and made me think of the reason (as Justin very briefly mentioned), the pressure differential between the exhaust manifold and the wastegate dumppipe is important. At a high pressure differential you don't require as large a hole to reduce the pressure because more flows air flows out for a given open time. Or something like that. A good reason for running a screamer pipe to me, keep that w/g backpressure down. Dave Quote Link to comment Share on other sites More sharing options...
JustinOlson Posted July 28, 2006 Share Posted July 28, 2006 Small wg will cause boost creep' date=' predominately at low boost. I ran a 1" Turbonetics deltagate for years at over 400 hp with a 5 psi spring, but when turned down, boost easily crept up to 7 psi. A smaller wg will control better, less pressure fluctuations. Need biggest diaphragm you can get to provide "gain" for proportional action. Now using Tial 38 mm with no discernable creep, but lap those flanges true and use gasket with integral firering.[/quote'] This is very true, the larger the wastegate you use, the less resolution you will have to control boost with. I'm going to be building a header for my L28 this summer with dual tial 38mm gates and a divided T3 turbine housing. I will be looking at using a GT3071R with a .78 a/r divided turbing housing. Regards, Justin Quote Link to comment Share on other sites More sharing options...
Clifton Posted July 28, 2006 Share Posted July 28, 2006 I've seen first hand boost creep with a 38mm WG at 10 psi pushing up to 12 at redline were at 18 psi it was dead steady. The car made 320 rwhp at 10-12 psi. The higher the boost the higher turbine pressure will be. To get the higher pressure you don't need to bleed off as much exhaust. At 25 psi I was around 35 psi pre turbo with a P trim. It was almost 10psi higher with an O trim. Quote Link to comment Share on other sites More sharing options...
240hoke Posted July 29, 2006 Share Posted July 29, 2006 Hehe I guess I spurred lots of talk here with my inccorect answer, sorry guys. I will chime in with my expirience, Im running a 38mm on a l28 running 15 psi on a 60-1 turbo and I have SOLID boost controll. Ive taken her to 20psi and its still rock solid. I think a 38mm will be plenty for 350-400 hp on a l28. I am runnign a open dump pipie on my 38 mm so there is no restriction whatsoever and Im running a profecb with it. Quote Link to comment Share on other sites More sharing options...
turbo_fb Posted July 30, 2006 Share Posted July 30, 2006 When running open downpipe from wg, do you smell lotsa exhaust in the car when driving? I am not sure if I am gonna merge the engine exhaust with the wg or run another piping from wg and out behind the car. Gonna take up lotsa space with that.. but then again there is this sound the wg makes when it screams straight out Here are some pics from a swedish site www.savarturbo.se Lots of good info if you know swedish Quote Link to comment Share on other sites More sharing options...
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