Muffleman Posted March 30, 2007 Share Posted March 30, 2007 Check out picture four on this link http://www.nissanperformancemag.com/march06/nerds/ Seems like a damn good idea to me, has anyone manufactured anything like this yet ? Quote Link to comment Share on other sites More sharing options...
Kranz Posted March 30, 2007 Share Posted March 30, 2007 Yes, for years in diesels. Known as VNT (variable Nozzle Turbine) or VGT (Variable Geomtry Turbine) turbos. Get one off ebay.... if youy can find one big enough Other option is a pair! Quote Link to comment Share on other sites More sharing options...
Lucifer Posted March 30, 2007 Share Posted March 30, 2007 Good luck mapping them! Quote Link to comment Share on other sites More sharing options...
JustGav Posted March 30, 2007 Share Posted March 30, 2007 You can't map them using the convential units available at the moment, as the variable vanes need some sort of map just for themselves, similar to the way VVTi is done. Quote Link to comment Share on other sites More sharing options...
Kranz Posted March 30, 2007 Share Posted March 30, 2007 I think this pic further down is just as interesting. http://www.nissanperformancemag.com/march06/nerds/images/8.jpg I mean.... WTF??? Using the intake air to cool the intercooler?? An interheater??? Quote Link to comment Share on other sites More sharing options...
Gaz6002 Posted March 30, 2007 Share Posted March 30, 2007 I spoke to Borg Warners UK disti for these and you could get one. the single unit price for a suitable one would be above £5000 just for the turbo. Quote Link to comment Share on other sites More sharing options...
Kranz Posted March 30, 2007 Share Posted March 30, 2007 Good luck mapping them! Used to do it for a living Quote Link to comment Share on other sites More sharing options...
Lucifer Posted March 30, 2007 Share Posted March 30, 2007 Used to do it for a living Wow, all teh people ive spoken to say its whey to difficult on large High BHP applications. Know any different? Surely the way forward if it can be done. Quote Link to comment Share on other sites More sharing options...
Kranz Posted March 30, 2007 Share Posted March 30, 2007 It can be done, but the control required is much more then used in current gasoline calibration. Normal requirements are: PID control with mappable P, I and D terms and limited control authority for each Base boost demand map Base duty cycle map Transient duty cycle map interpolated from the base map by rate of change of speed or load Transient boost demand map interpolated from the base map by rate of change of speed or load Altitude compensation duty cycle map Altitude compensation boost demand map Turbo overspeed compensation map Temperature (both air & engine) correction duty cycle compensation map Others I can't remember!! Its possible but you need instrumented turbos, a good rolling road dyno, ideally an engine dyno, software capable of controling this..... and lots of money Quote Link to comment Share on other sites More sharing options...
RedM Posted March 30, 2007 Share Posted March 30, 2007 Are these the same sort that are used in the 911 Turbo? Quote Link to comment Share on other sites More sharing options...
Gaz6002 Posted March 30, 2007 Share Posted March 30, 2007 Are these the same sort that are used in the 911 Turbo? yep same idea Quote Link to comment Share on other sites More sharing options...
Kranz Posted April 3, 2007 Share Posted April 3, 2007 Thread resurrection time! I've been looking into this, and other than the Porsche with the VNT turbo, there has only been one other gasoline VNT .... the Garrett VNT25. Chrysler was the first to put a variable nozzle turbo into a production gasoline vehicle in 1990 (it was also used in the 1989 Shelby CSX). It was fitted to the LeBaron, the Shadow, and the Daytona and although 1700 were planned, only 500 cars were built with VNT turbos. The other 1200 turbos were sold off, for various uses These VNT's were fitted with simple diaphragm type actuators, with both pressure and vacuum ports to enable control by boost pressure and vacuum (to fully open the vanes at idle and reduce back pressure). Although quite small, rated up to 220 hp on a gasoline engine, these turbos are near identical to the Garrett T25 turbo, and bigger T28 compressor wheels were a good method of increasing the output. A VNT25 modified in this way was capable of supplying 20 psi to a 2.0 engine (std was 15 psi max) while spooling up at 1500 rpm!!! Sounds interesting? How about a pair of these??? Quote Link to comment Share on other sites More sharing options...
Wez Posted April 3, 2007 Share Posted April 3, 2007 Interesting Quote Link to comment Share on other sites More sharing options...
Kranz Posted April 4, 2007 Share Posted April 4, 2007 And now I've gone and got myself a pair of these babys!! Oh yeah Garrett VNT28's Quote Link to comment Share on other sites More sharing options...
Muffleman Posted April 4, 2007 Author Share Posted April 4, 2007 So what's the plan mate ? Quote Link to comment Share on other sites More sharing options...
Kranz Posted April 4, 2007 Share Posted April 4, 2007 So what's the plan mate ? First, check out what they can do! The biggest restriction will be the turbines which are normally quite small in comparison to 'normal' sized medium power twins. The compressor wheel is bigger than the VNT25, so hopefully that will be able to supply a resaonable amount of boost. I'll need to make up some adaptors for the stock manifold (spare manifold anyone???) and probably incorporate a wastegate (or 2) to bleed off some of the exhaust gas to prevent the turbos over spinning and going off the efficiency map. The turbos themselves are controlled by boost pressure (and vacuum at idle to open them up) and as such are controllable with a good aftermarket boost controller The wastegate(s) will serve to limit the turbos when they have opened fully and can't move anymore to drop boost. Needs some figuring out but should work! None of this fancy controller stuff, just plain & simple mechanical set up (to start with ). Quote Link to comment Share on other sites More sharing options...
Muffleman Posted April 4, 2007 Author Share Posted April 4, 2007 Interested in seeing how you get on mate, keep us up-to-date How big are they compared to stock tubbies ? Quote Link to comment Share on other sites More sharing options...
uk-rich Posted April 4, 2007 Share Posted April 4, 2007 looks like a good project, good luck with it Quote Link to comment Share on other sites More sharing options...
Kranz Posted April 4, 2007 Share Posted April 4, 2007 How big are they compared to stock tubbies ? Compressor is about 47mm minor, and a guess at 60mm major, 62 trim (from T28) and .42 A/R. Turbine is approx 55mm minor, major not known. A/R is .64. Will know for sure when I pick them up. These sizes don't seem too bad Quote Link to comment Share on other sites More sharing options...
Chiefgroover Posted April 4, 2007 Share Posted April 4, 2007 The whole idea behind these turbos is great. However after 1/2 an hour at the wheel of a 997T i started to think it was something I'd personally never want. Reasons are, it takes and age to kick in @ 2.5K in 6th, drop your big tub supra in 2nd and be outta sight by the time the long 6th gear started to pull. Secondly, I like the low power revs, great for traction on shitty greasy roads. Thirdly the fuel economy is pretty good when in the laggy area. Anyway, only granny would try and race from 2K rpm. It will be great for Tdi golfs etc, but Supras, hhmmm if they ever make one and I get a spin in it, I might get converted, but I'm in the "its a gimmick" camp for now. Quote Link to comment Share on other sites More sharing options...
Kranz Posted April 4, 2007 Share Posted April 4, 2007 Well, I'm aiming for full throttle boost from sub 2000rpm. How it actually performs we'll have to wait and see. If there are driveability gains by getting on boost lower in the rev range then its a bonus, but for the moment this will purely be a feasibility study. I have no intention in aiming for the power that big singles achieve, just a better response that pulls from low down and just keeps on pulling If you've driven the VW Toureg (Toe rag??) V10 twin VNT turbo diesel then you'll know what I mean by a seamless and constant power delivery Quote Link to comment Share on other sites More sharing options...
Chiefgroover Posted April 4, 2007 Share Posted April 4, 2007 I got the impression that the turbos pulled from lower revs in higher gears in the 997T Quote Link to comment Share on other sites More sharing options...
Kranz Posted April 4, 2007 Share Posted April 4, 2007 I guess with the control systems they are running then they can make them boost at whatever revs they want. Handfulls of boost at low revs in the lower gears would mean excessive wheelspin all the time I had diesel engines producing positive boost at idle. It just depends on what you want to do. That's the beauty of it I guess.... boost exactly where you want it! Quote Link to comment Share on other sites More sharing options...
bolarbag Posted April 4, 2007 Share Posted April 4, 2007 This could be interesting... are you expecting more power and response from these turbos in a hybrid twin setup? How can you control them mate? This could be the perfect street setup! Quote Link to comment Share on other sites More sharing options...
Gaz6002 Posted April 5, 2007 Share Posted April 5, 2007 that must have cost stupid money! I was quoted £5k+ per turbo Quote Link to comment Share on other sites More sharing options...
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