Suprash Posted October 24, 2006 Author Share Posted October 24, 2006 This is all turning into a bit of moo point, I ask about this format not because I want to try and beat any single, to produce more low down power, or get greater torque then this or that. I love the sequential system, and wondered if there was an upgrade in which I could keep a sequential setup......irrespective of how it compares to T61 or other...... Quote Link to comment Share on other sites More sharing options...
Wez Posted October 24, 2006 Share Posted October 24, 2006 Basically if you have enough money then yes you could have a sequential system if you really wanted. Quote Link to comment Share on other sites More sharing options...
Gazboy Posted October 24, 2006 Share Posted October 24, 2006 Yes 1 will but then do you gain anything over the CT12b? That's what I'm trying to find out lol. Quote Link to comment Share on other sites More sharing options...
Suprash Posted October 24, 2006 Author Share Posted October 24, 2006 Basically if you have enough money then yes you could have a sequential system if you really wanted. So where the fuck was you when all this started, ROFL..... Quote Link to comment Share on other sites More sharing options...
Wez Posted October 24, 2006 Share Posted October 24, 2006 So where the fuck was you when all this started, ROFL..... Well if you have enough money you can get anything made, does not look like its an off the shelf jobby Quote Link to comment Share on other sites More sharing options...
Chiefgroover Posted October 24, 2006 Share Posted October 24, 2006 I was once very into this idea, but not anymore. Having a system that only kicks in @ 4000rpm means i get good fuel economy and easy town driving, anyway only your Granny races from 2000rpm. Running the engine most of the time below the power band of a big single can only increase engine life. Quote Link to comment Share on other sites More sharing options...
Gaz6002 Posted October 24, 2006 Share Posted October 24, 2006 I was once very into this idea, but not anymore. Having a system that only kicks in @ 4000rpm means i get good fuel economy and easy town driving, anyway only your Granny races from 2000rpm. Running the engine most of the time below the power band of a big single can only increase engine life. Quote Link to comment Share on other sites More sharing options...
Chiefgroover Posted October 24, 2006 Share Posted October 24, 2006 I found the Supra drives pretty nicely off boost, but only when it's airtight from the head to the end of the exhaust, and leaks whatsoever lost a load of torque. Quote Link to comment Share on other sites More sharing options...
Gazboy Posted October 24, 2006 Share Posted October 24, 2006 Just remembered I have a PM from the owner of the HKS car- one thing he did mention was that the HKSGT25/30's have no provision for #2 to prespool before coming online. Would I be correct thinking this would drastically shorten the lifespan of the blades & shaft because they'd be going from static to spinning at a high rate very very quickly? Quote Link to comment Share on other sites More sharing options...
Sharpie Posted November 15, 2006 Share Posted November 15, 2006 See here Ash - Looks like Nic has found one - 4th pic down. http://www.mkivsupra.net/vbb/showthread.php?t=89144 Quote Link to comment Share on other sites More sharing options...
JohnA Posted November 16, 2006 Share Posted November 16, 2006 OK, here goes: either you have a sequential setup, or you don't: If you DO then you are restricted in max power terms by the stock exh manifold, stock turbine housings and the prespool piping. These can only be marginally improved by a determined tuner. If you DON'T have a seq setup, then the world is your oyster (powerwise) but you may as well forget boost below 3500rpm, perhaps even 4Krpm and get on with it. Don't fall for the theory that two smaller turbos have less lag than a big one. This argument is flawed, and it usually comes from the same people who advocate that a big intercooler will increase lag. What two smaller turbos do for certain (on a supra setup at least)is add extra hot pipes under the bonnet and create packaging problems. To recoup: Once the sequential setup has been abandoned, forget low-down boost. Use different deciding factors for your evaluation. Quote Link to comment Share on other sites More sharing options...
Thorin Posted November 16, 2006 Share Posted November 16, 2006 OK, here goes: either you have a sequential setup, or you don't: If you DO then you are restricted in max power terms by the stock exh manifold, stock turbine housings and the prespool piping. These can only be marginally improved by a determined tuner. John, read the link posted by Peter, I've just posted the dodgyly translation info on the supposed "Big sequentials" at the end. Quote Link to comment Share on other sites More sharing options...
M4RK RZ Posted November 16, 2006 Share Posted November 16, 2006 OK, here goes: either you have a sequential setup, or you don't: Don't fall for the theory that two smaller turbos have less lag than a big one. This argument is flawed, and it usually comes from the same people who advocate that a big intercooler will increase lag. QUOTE] So your saying that by the time your sequential turbo set up has spun up turbo1 then changes to turbo2 - (both have had to spin up to speed)- this is accumaliative to the larger single unit? or is it how soon u get the power? or what? Its just in my world smaller turbo's spin up faster than larger ones, due to that pesky science thing - if your just talking about lag times that is? Quote Link to comment Share on other sites More sharing options...
Gazboy Posted November 16, 2006 Share Posted November 16, 2006 I know what you are saying John (6 into one vs 3 into 2), but then Porsche disagree with you. You could argue that that was a packaging issue but then Nissan also had two small parallels instead of one big turbo in the GTRs. Could you go more in depth regarding intercooler sizes? I was always under the impression that the bigger the volume, the longer it took to pressurise. Quote Link to comment Share on other sites More sharing options...
Wez Posted November 16, 2006 Share Posted November 16, 2006 Could you go more in depth regarding intercooler sizes? I was always under the impression that the bigger the volume, the longer it took to pressurise. Agreed Quote Link to comment Share on other sites More sharing options...
JohnA Posted November 16, 2006 Share Posted November 16, 2006 So your saying that by the time your sequential turbo set up has spun up turbo1 then changes to turbo2 - (both have had to spin up to speed)- this is accumaliative to the larger single unit? nope Quote Link to comment Share on other sites More sharing options...
JohnA Posted November 16, 2006 Share Posted November 16, 2006 ..Porsche disagree with you... Not at all. Their R&D is among the best, it is not likely that they'd make gross mistakes, is it? Which Porsche inline 6 are you referring to? Quote Link to comment Share on other sites More sharing options...
Gazboy Posted November 16, 2006 Share Posted November 16, 2006 Not at all. Their R&D is among the best, it is not likely that they'd make gross mistakes, is it? Which Porsche inline 6 are you referring to? They changed their 3.6 flat 6 with one big turbocharger, to two smaller turbochargers. RUF had been doing this for years before them though (CTR 'yellowbird') Quote Link to comment Share on other sites More sharing options...
JohnA Posted November 16, 2006 Share Posted November 16, 2006 A plumbing solution that is optimal for an inline 6 is not necessarily as good for a boxer or a V8. That is obvious, right? Porche actually *did* fit a sequential twin turbo to their flagship model, beating Toyota to it. Quote Link to comment Share on other sites More sharing options...
JohnA Posted November 16, 2006 Share Posted November 16, 2006 ... I was always under the impression that the bigger the volume, the longer it took to pressurise. You could calculate your engine's airflow under boost and then compare it to the internal volume of the biggest intercooler you can think of. We're talking milliseconds here. The falacy is thinking that lag is related to this volume - it isn't. Not to any significant degree, anyway. Quote Link to comment Share on other sites More sharing options...
M4RK RZ Posted November 16, 2006 Share Posted November 16, 2006 nope so.........can you explain to me why the argument is floored, because I think I may be missing something? Not taking into account the intercooler (big/small) argument - which is again easily solved with a little science as Gazboy points out quite rightly. Just a generic size will be fine. Quote Link to comment Share on other sites More sharing options...
Gazboy Posted November 16, 2006 Share Posted November 16, 2006 A plumbing solution that is optimal for an inline 6 is not necessarily as good for a boxer or a V8. That is obvious, right? Porche actually *did* fit a sequential twin turbo to their flagship model, beating Toyota to it. The plumbing situation wasn't what caused them to ditch the big single turbo for the smaller parrallels (which is what I initialy thought so I asked a Porsche tuner who corrected me), they found they could get the two spooling faster and more progresively than the single. If you just want to talk about straight 6's- the Skyline GTR- why does it have two when it should have used 1 big one? Quote Link to comment Share on other sites More sharing options...
Gazboy Posted November 16, 2006 Share Posted November 16, 2006 You could calculate your engine's airflow under boost and then compare it to the internal volume of the biggest intercooler you can think of. We're talking milliseconds here. The falacy is thinking that lag is related to this volume - it isn't. Not to any significant degree, anyway. It still take longer to presurise a huge fmic than the stock smic, like it would take longer to blow a paper ball out of the end of a 10foot hose than a 4 foot hose... Quote Link to comment Share on other sites More sharing options...
JohnA Posted November 16, 2006 Share Posted November 16, 2006 Gaz, this 2 vs 1 argument has been around for years. It is based on the incorrect assumption that the 'big' turbo will be twice as big as any of the 'small' ones. The argument goes that inertia forces in centrifugal assemblies tend to increase by the square/cube of diameter, so the 'big' turbo that is twice as big will have to overcome resistance that is 4/8 times as much, hence the disproportionately larger lag. In real life it ain't so because other manufacturing parameters get in the equation. Also a turbo that is twice as big will flow a lot more than the two 'half' turbos, so the comparison is flawed anyway;) Quote Link to comment Share on other sites More sharing options...
JohnA Posted November 16, 2006 Share Posted November 16, 2006 It still take longer to presurise a huge fmic than the stock smic, like it would take longer to blow a paper ball out of the end of a 10foot hose than a 4 foot hose... Blowing the paper ball is not very comparable, is it? Also remember that lag is only measured over the boost threshold. Quote Link to comment Share on other sites More sharing options...
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