JohnA Posted June 14, 2005 Share Posted June 14, 2005 First of all let me clear up that I am familiar with whatever has been posted on mkiv.com or in this forum (or supraforums) I've been experimenting with a manual boost controller, (as you do ) We know that there is only one wastegate, and that is at turbo #1. This wastegate has one entry and one 'exit', both on the same side of the diaphragm. The 'entry' is permanently connected to the pressurised side of the intake, while the 'exit' is hooked up to a VSV, so the ECU decides when to allow the back of the actuator to become pressurised (thereby pushing the actuator rod open). Nice'n'simple until now, right? Suppose now that a MBC (ball&spring) is hooked up to this 'entry' hose, set up to give way at 1 bar. This means that until boost pressure has reached ~1 bar the back of the actuator won't see jack, so it doesn't really matter if the actuator VSV is open or closed, there is no pressure until then. IF my understanding of the sequential 'symphony' is correct, then I see no reason for a boost 'cap' below 4Krpm. Until 3.5K rpm all exhaust gases from all 6 cylinders go through turbo #1, so at some point around 3-3.5Krpm it should be able to boost up to 1 bar or thereabouts. But it doesn't --- it still goes up to 10-11psi, just like it would have done without the MBC. This to me indicates one of two things: 1. there are no more exhaust gases until 4Krpm anyway OR 2. something else is happening and the gases bypass #1. I'd expect a small amount of gases to start redirecting to #2 from 3.5K upwards, but why would the boost controller affect that flow? In a nutshell, I don't understand why with the MBC I can see 1 bar+ over 4Krpm, but below that it's strictly std boost. Anybody got any ideas? Link to comment Share on other sites More sharing options...
eyefi Posted June 14, 2005 Share Posted June 14, 2005 exhaust gas control valve Link to comment Share on other sites More sharing options...
Pete Posted June 14, 2005 Share Posted June 14, 2005 The diagrams on these pages explain this I think.. Turbo 1 only state: http://www.mkiv.com/specifications/ncf/ncf93/ncf093.jpg Turbo 2 state: http://www.mkiv.com/specifications/ncf/ncf93/ncf094.jpg On the second diag you can see that there is still a passage for exhaust gasses to follow via turbo 1. I can't see how they wouldn't? The Exhaust By Pass valve? Explained on the first page. Link to comment Share on other sites More sharing options...
JohnA Posted June 14, 2005 Author Share Posted June 14, 2005 exhaust gas control valve What about it? Are you saying that it might be malfunctioning? Like not being shut below 3.5K rpm? The impression I've got from various forums, is that what I experience is normal behaviour. Do you think that's the case, or should I try and check the hoses around the EGCV? (well-hidden are they?) Link to comment Share on other sites More sharing options...
eyefi Posted June 15, 2005 Share Posted June 15, 2005 Are you saying that it might be malfunctioning? no, well it might be but that's not what i'm saying. look here Link to comment Share on other sites More sharing options...
Aerotop Dave Posted June 15, 2005 Share Posted June 15, 2005 omg, is that the fabled 'blue spaghetti' post?! I've read so many references to it but that's the first time I've actually seen it! Link to comment Share on other sites More sharing options...
JohnA Posted June 15, 2005 Author Share Posted June 15, 2005 This thread moves on nicely We've now questioned whether boost under 3.5Krpm (maybe even 4K rpm) is only controlled by the 'main' wastegate, but speculated that the EGBV might be involved as well. These two hoses (side by side, in the spagetti pic) go to the EGBV, right? One is 'pressure in' other is 'pressure out' according to the 'twin turbo identification' doc found in the FAQ. The EGBV is meant to crack open at 3.500rpm to prespool turbo #2, right? We wouldn't want to interfere with that or else we'd be compromising the smooth blending of #2, I'd think. This raises another question though Why do the 'spagetti' mods on that page show both pipes being intercepted by the MBC? And in any case, if we were to use a similar hookup as with the 'main' actuator, then surely we'd want to fit the MBC at the pipe connecting the pressure tank with the EGBV actuator, wouldn't we? Another question might be: how would the IACV feel with this change of balance? Questions, questions.... Link to comment Share on other sites More sharing options...
JohnA Posted June 15, 2005 Author Share Posted June 15, 2005 After staring at the diagram for a while, my first choice would be a ball'n'spring valve set at just below 1 bar on the line connecting the pressure tank to the EGBV actuator. That doesn't look very easy to access though, so my next best solution would be a bleed valve between the EGBV actuator and the EGBV VSV. If we can't stop that actuator from filling with boost prematurely (well...) let's bleed some of that air off. I'm hoping that this will end up in quicker spooling at low revs and a bit more boost (at low revs again) without upsetting the 'symphony' too much. The EGBV is used for both boost control at low revs and prespooling of #2 so maybe this balance might be a bit tricky. Any comments on this one? Link to comment Share on other sites More sharing options...
_Rob_ Posted August 22, 2006 Share Posted August 22, 2006 bit of a thread resurection, but hey.. John, ive been doing some reading about the differing methods of increasing the boost to turbo 1. The method done by Ian C in his blue spaghetti thread is one which i am assuming is not the most favourable. According to Ian, he stopped using the MBC on turbo 1 due to varying boost pressures and dramatic boost drop off. Have you had any problems similar to Ians with your set up? Is there any onther kind of supporting mods required for this boost increase at low revs? I know you're running water / meth injection so det isnt going to be a problem for you, but what about us mere mortals? Link to comment Share on other sites More sharing options...
INDYPWR Posted August 23, 2006 Share Posted August 23, 2006 sup guys, i just want to share my experience with the manual boost controller i have. i just recently took out my greddy profec b and installed a manual (ball and spring) boost controller. i hooked it up between the actuator and the turbo and capped some of the hoses off. right now, i can hit 1.2 bar if i like but i am boosting 1.0 consistently. no more boost creep and i am very happy with the results. Link to comment Share on other sites More sharing options...
JohnA Posted August 23, 2006 Author Share Posted August 23, 2006 ..Have you had any problems similar to Ians with your set up?. No, it's more safe because it is closer to the way Toyota designed it to work. Even the VSV remains operational, especially useful when moving down the rev-range. It is a bit more involved to start though, as you need to disconnect a couple of hoses near the bulkhead (no big deal once you've removed the two hoses on top though) This way, you can get a few extra psi on turbo #1 without compromising pre-spool of #2. But if you push it too far, then you will be compromising it and getting the 'dip' at changeover. But it's easy to readjust, as the MBC for turbo #1 will now be in an accessible location. Link to comment Share on other sites More sharing options...
_Rob_ Posted August 23, 2006 Share Posted August 23, 2006 This way, you can get a few extra psi on turbo #1 without compromising pre-spool of #2. But if you push it too far, then you will be compromising it and getting the 'dip' at changeover. Exactly what im after. I was thinking of around 11psi. What are you running on turbo 1 John? are you using an MBC for control of full boost, over 4k rpm? Link to comment Share on other sites More sharing options...
JohnA Posted August 23, 2006 Author Share Posted August 23, 2006 I've settled to around 1 bar from turbo #1, available from 2.2Krpm For turbo #2 I used to have an MBC, but now I use nothing but the atmosphere... Link to comment Share on other sites More sharing options...
Mcgoo Posted August 23, 2006 Share Posted August 23, 2006 sup guys, i just want to share my experience with the manual boost controller i have. i just recently took out my greddy profec b and installed a manual (ball and spring) boost controller. i hooked it up between the actuator and the turbo and capped some of the hoses off. right now, i can hit 1.2 bar if i like but i am boosting 1.0 consistently. no more boost creep and i am very happy with the results. This is just what i'm after. Have you seen any big 'spikes' ? What hoses have you capped off? I havent heard of anyone capping any before. Link to comment Share on other sites More sharing options...
_Rob_ Posted August 23, 2006 Share Posted August 23, 2006 For turbo #2 I used to have an MBC, but now I use nothing but the atmosphere... Are you still holding 1.5 bar over 4k? Link to comment Share on other sites More sharing options...
JohnA Posted August 23, 2006 Author Share Posted August 23, 2006 Bit more, depending on the weather. Link to comment Share on other sites More sharing options...
_Rob_ Posted August 23, 2006 Share Posted August 23, 2006 nice.. how are you holding the boost at 1.5 bar John? Link to comment Share on other sites More sharing options...
JohnA Posted August 23, 2006 Author Share Posted August 23, 2006 It's not like it's manual labour. I don't have to lift anything, do I? Link to comment Share on other sites More sharing options...
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