a98pmalcolm Posted October 5, 2011 Share Posted October 5, 2011 Hay all. Am I correct in saying this With the Twin Turbo system on the supra's work as follows: At low revs on one of the turbos wastegate is shut off while the other one is open to allow 1 turbo to be used at the low end of revs. But as the revs build up to about 3500ish that wastgate will close up while the other turbo wastegate opens up until the set peak boost level is hit and then the closed wastegate will open to prevent more boost? Thanks Paul Quote Link to comment Share on other sites More sharing options...
mellonman Posted October 5, 2011 Share Posted October 5, 2011 yeah pritty much have alook here http://www.mkivsupra.net/vbb/showthread.php?35926-The-sequential-system Quote Link to comment Share on other sites More sharing options...
Swampy442 Posted October 5, 2011 Share Posted October 5, 2011 Theres only 1 wastegate though. Quote Link to comment Share on other sites More sharing options...
mellonman Posted October 5, 2011 Share Posted October 5, 2011 (edited) both turbos have a waste gate, if not why would it have 2 acuators to try and prevent over boost. the ebgv just lets the second come on line not set its boost level. (if that what you was on about?) have a lok here http://www.mkivsupra.net/vbb/showthread.php?254364-Opinions-on-these-Used-Turbos-Updated-with-another-set-for-sale/page2 Edited October 5, 2011 by mellonman (see edit history) Quote Link to comment Share on other sites More sharing options...
a98pmalcolm Posted October 5, 2011 Author Share Posted October 5, 2011 Ok thanks for the replays. What im looking at doing is have both wastegates closed until the set boost levels open them up. Kind of like the true twin turbo conversion but instead of having them open at low revs have them closed.. Thanks Paul Quote Link to comment Share on other sites More sharing options...
Scott Posted October 5, 2011 Share Posted October 5, 2011 There's only actually 1 wastegate. The actuator on tubby 2 is to control the pre-spool of it and the maximum boost of the 1st turbo. It's called the exhaust gas bypass. Quote Link to comment Share on other sites More sharing options...
Scott Posted October 5, 2011 Share Posted October 5, 2011 Ok thanks for the replays. What im looking at doing is have both wastegates closed until the set boost levels open them up. Kind of like the true twin turbo conversion but instead of having them open at low revs have them closed.. Thanks Paul Why? It won't do anything different. Quote Link to comment Share on other sites More sharing options...
Supranature Posted October 5, 2011 Share Posted October 5, 2011 Ok thanks for the replays. What im looking at doing is have both wastegates closed until the set boost levels open them up. Kind of like the true twin turbo conversion but instead of having them open at low revs have them closed.. Thanks Paul Read this http://www.max-boost.co.uk/max-boost/supra/turbo.htm It explains the workings of the system very well. Go to the bottom of the page, click "Boosting the Beast", and it will explain that there are 2 wastgates, and how to do what you require with a MBC and EBC together. It tells you how to keep pre-spool on turbo2. which is often not happening with the fitting of a "boost controller" Read it a few times. Quote Link to comment Share on other sites More sharing options...
a98pmalcolm Posted October 6, 2011 Author Share Posted October 6, 2011 The reason for me asking is I believe I have a problem (that improves the cars feel) Now and again 45% of the time I suddenly get a flutter noise with my BOV being very loud, the car also feels so much smoother and quicker. My only explanation for this is a fault occurs in the VSV system or which ever controls the 2nd turbo's wastegate and rather than the wastgate being open at low revs its closed. So with both wastgates closed ALL unused boost is firing out the BOV coursing it to be louder and some going back into the turbo causing the flutter. If the 2nds turbo wastegate was open alot of unused boost can escape that way. So by having both wastegates closes until it hits 1.2 bar when the boost controller opens them up I will get this great feeling and sound out of my Supra. Quote Link to comment Share on other sites More sharing options...
Scott Posted October 6, 2011 Share Posted October 6, 2011 There's only one wastegate though Quote Link to comment Share on other sites More sharing options...
Mario Posted October 6, 2011 Share Posted October 6, 2011 Scott is right, here is the article (turbosupras.com) Below you will find the detailed specifications and facts on the JDM JZA80 CT20 ceramic turbochargers along with known limitations of these turbochargers. The CT20 turbocharger is found in pairs on the 2JZ-GTE, which is commonly found in the JZA80 Supra and the JZS147 Aristo. There is the misconception that the JDM turbochargers are CT12B's - this is incorrect and I will explain why below. The CT12B series of turbochargers use a 7.5mm turbine shaft while the CT20 series use a 10mm turbine shaft. The dimensions on the turbine wheel are identical to that of other CT20's found on such vehicles as the LJ70 Series Landcruiser (2LT - 2.4ltr Turbo Diesel), LN60/61 Hiace & LH51 Hilux which run a CT20 with identical turbine wheel dimensions, shaft diameter and blade count. The CT20 utilises an aluminium compressor wheel and a ceramic turbine wheel and uses bronze bushing bearings and carbon seals. The turbo itself generates around 10lbs in standard form on the 2JZ-GTE and they have been known to successfully run around 18lbs and above, however the general consensus is that 18lbs is the absolute limit for this turbocharger if you want any form of reliability from them and even then it's a gamble, for ultimate reliability 14.7lbs (1 bar) is the number to run them at. The A/R of the exhaust housing on CT20 is .35 while the compressor housing runs an A/R of .36, although this is a small A/R Toyota has done this so the turbochargers offer minimal lag and maximum response. The turbine housings are of high nickel content and utilise a 3 stud inlet flange and a 5 stud outlet flange. The turbochargers themselves are identical in size with the exception being the rear turbochargers exhaust housing which is 23.7mm longer and does not contain a wastegate, instead it contains an exhaust bypass valve which is used in the sequential operation to transition this turbocharger online with the primary (#1) turbocharger so both turbochargers are producing equal amounts of pressure and flow. It is to note that the secondary turbocharger has a slightly larger outlet pipe (4.8mm larger) in the cast elbow however this slight gain in diameter is offset by the restriction of the EGCV located further down the dump pipe. If you feel this is information is in any way incorrect or you can provide further information please do not hesitate to sign up on the forums and provide some useful feedback so I can make this article as accurate and detailed as possible. Manufacturer Toyota (Hitachi) Type CT-20 (PN: 17201-46020 (Front), 17208-46020 (Rear) Turbine size (Outlet diameter) 48mm Turbine size (Inlet diameter) 59.8mm Turbine blade count 10 Turbine material Ceramic Turbine Housing Inlet (ID) 36mm Turbine Housing Outlet (ID) 50.1mm Turbine Shaft Diameter 10mm Turbine housing A/R .35 Compressor size (Inlet diameter) 37mm Compressor size (Outlet diameter) 62mm Compressor blade count 10 Compressor material Aluminium Compressor Housing Inlet (ID) 49.8mm Compressor Housing Outlet (ID) 32.4mm Compressor housing A/R .36 Bearing ID 10.05mm Bearing OD 15.9mm Bearing Width 8.96mm Bearing material Bronze Bearing oiling holes (per bearing) 6 *Wastegate size (ID) 26mm **Maximum Wbastegate size (ID) 28mm Actuator spring rate 10lbs *Secondary turbocharger does not utilise a wastegate, it is an exhaust bypass valve used to match compressor speeds with the primary turbo prior to the second turbocharger being brought online. **This is the maximum allowable ID before the wastegate flap itself needs be replaced with a larger item. The viability of doing this would be only beneficial if you were doing this modification yourself and even then the gains are negligible Turbine outlet (Cast dump) #1 turbocharger (OD) 47.8mm Turbine outlet (Cast dump) #2 turbocharger (OD) 52.6mm EGCV outlet housing - outlet for #1 turbocharger (OD) 46mm EGCV outlet housing - outlet for #2 turbocharger (OD) 50.3mm EGCV outlet housing OD 56.3mm O sensor hole (OD) 15.5mm Quote Link to comment Share on other sites More sharing options...
Swampy442 Posted October 6, 2011 Share Posted October 6, 2011 There's only one wastegate though Hang on, didnt I state this in post 3? Quote Link to comment Share on other sites More sharing options...
mellonman Posted October 6, 2011 Share Posted October 6, 2011 i think i might of confused it all with my 2 waste gate comment, the turbos them selves have a lets say a valve gate each but only the on the first turbo its used as a waste gate. i only said that from when i took mine off i see gates in both but after a look at the system drawing i see my misstake. Quote Link to comment Share on other sites More sharing options...
Scott Posted October 6, 2011 Share Posted October 6, 2011 Hang on, didnt I state this in post 3? Yeah but nobody paid attention so I backed you up..... So they paid no attention again.... So I decided to reiterate it lol. Quote Link to comment Share on other sites More sharing options...
Guest Standard Posted May 18, 2014 Share Posted May 18, 2014 (edited) This is probably the best place to discuss this. On a ride along today in an auto JDM TT, it made a constant flicking/fluttering sound when you manually drove it in 1st or 2nd. It happened under acceleration and wind down. It was most prevalent beyond 3-4k rpm (It's NOT the high pitched whipple/ turky gobble sound you get when air goes back into the turbos without a BOV fitted). I found it odd this occurred, particularly during acceleration. Is this auto box specific? Extreme compressor surge? Tension spring getting old? Faulty actuators? Or could it be the recirculation bypass system? Edited May 18, 2014 by Standard (see edit history) Quote Link to comment Share on other sites More sharing options...
Swampy442 Posted May 18, 2014 Share Posted May 18, 2014 Recirc valve operation. Im guessing the car has a cone filter fitted? Quote Link to comment Share on other sites More sharing options...
Guest Standard Posted May 19, 2014 Share Posted May 19, 2014 (edited) Recirc valve operation. Im guessing the car has a cone filter fitted? Hey Swampy, First let me say that I was mistaken, it's only noticeable in 1st above about 2500 rpms. In second if it's happening we cannot hear it. Second, no cone, it's using standard box filter. Everything on the car is stock sans the sports exhaust. Having said that, the car has developed a twitching/clicking noise from the left side today - sounds like someone rapidly flipping a light switch on and off. I hear it most when passing by solid walls where the sound reverberates. It only becomes audible about about 10 or 15 mph. It is probably not related to the TT system, I guess it could be loose lug nut, something with the caliper or the air conditioning unit is getting low(even though it's not on). Edited May 19, 2014 by Standard (see edit history) Quote Link to comment Share on other sites More sharing options...
Havard Posted May 19, 2014 Share Posted May 19, 2014 Hang on, didnt I state this in post 3? Yeah but nobody paid attention so I backed you up..... So they paid no attention again.... So I decided to reiterate it lol. I can sense Scott going out of his mind over the internet..!! Quote Link to comment Share on other sites More sharing options...
2soops Posted May 19, 2014 Share Posted May 19, 2014 Hey Swampy, First let me say that I was mistaken, it's only noticeable in 1st above about 2500 rpms. In second if it's happening we cannot hear it. Second, no cone, it's using standard box filter. Everything on the car is stock sans the sports exhaust. Having said that, the car has developed a twitching/clicking noise from the left side today - sounds like someone rapidly flipping a light switch on and off. I hear it most when passing by solid walls where the sound reverberates. It only becomes audible about about 10 or 15 mph. It is probably not related to the TT system, I guess it could be loose lug nut, something with the caliper or the air conditioning unit is getting low(even though it's not on). Stone or something similar in the tyre!!! Quote Link to comment Share on other sites More sharing options...
Scott Posted May 19, 2014 Share Posted May 19, 2014 I can sense Scott going out of his mind over the internet..!! I believe this was around the time I wrote the "does noone read past the title" type thread. Quote Link to comment Share on other sites More sharing options...
Havard Posted May 19, 2014 Share Posted May 19, 2014 I believe this was around the time I wrote the "does noone read past the title" type thread. Lol. There are very few members on here, where even though the response is polite, you can sense the upset, through the words. Keep going Scott..!! Quote Link to comment Share on other sites More sharing options...
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