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  1. #51
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    No flame. I just don't want the trade off personally. I don't see the added complexity as significant, but it is easy to say that before doing it.

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    Click here to enlarge Originally Posted by rudypoochris Click here to enlarge
    No flame. I just don't want the trade off personally. I don't see the added complexity as significant, but it is easy to say that before doing it.
    When making big horsepower there are always a trade offs. ALWAYS. If you don't want trade offs, you have to stay below a certain level. Its just how it is.

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    Click here to enlarge Originally Posted by VargasTurboTech Click here to enlarge
    When making big horsepower there are always a trade offs. ALWAYS. If you don't want trade offs, you have to stay below a certain level. Its just how it is.
    Of course. In this case, the trade off would be added complexity for a quicker spool. I guess my point was that that trade off is worth it for me. Most certainly I can say that now, but it may be a nightmare later. If I ever upgrade these turbos, I guess we'll see. Click here to enlarge

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    Click here to enlarge Originally Posted by rudypoochris Click here to enlarge
    Of course. In this case, the trade off would be added complexity for a quicker spool. I guess my point was that that trade off is worth it for me. Most certainly I can say that now, but it may be a nightmare later. If I ever upgrade these turbos, I guess we'll see. Click here to enlarge
    Sounds like we will leave it to you to build a sequential system then...Click here to enlarge

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    Click here to enlarge Originally Posted by VargasTurboTech Click here to enlarge
    Sounds like we will leave it to you to build a sequential system then...Click here to enlarge
    Not any time soon. But maybe eventually. Click here to enlarge

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    If i win lotto in any of the big ones til new years, consider me an n54 Experimental FI system bankroll hahaha

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    Smile

    Click here to enlarge Originally Posted by Sered Click here to enlarge
    Not true. Check out the comparisons between Supras running stock turbos in parallel mode versus the sequential mode. The stock TT Supra has a very wide powerband because of the sequential system.

    The complexity came from attempting to smooth out the powerband so that when the 2nd turbo came online, it wasn't some abrupt power increase.

    True, definitely true for a supra

    but when you consider the n54 has 10.2:1 static compression for power off boost (and slightly better spool)... The supra has 8.5:1, so it needs a load of boost early, and a smaller turbo to get there

    Of course if you went a BIG 800hp twin setup, it would feel like stock down low with the massive peak still like has been said.. But the supra doesn't exactly quite have that stock lol

    it wouldn't be 100% the same results, less drastic... Unless you went for said BIG sequential setup, and with the big, comes the cost and complexity..

    as much as the n54 is sometimes called a modern day euro 2j, they are so far apart in so many ways.

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    Personally, my car is my DD and I live in the torque band. For the price, duals are what I want. Now if a single was price competative, then I'd consider it just as much, but with the current available setups and the amount of supporting mods required, its not on my personal horizon just yet. Just my .02

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    2 out of 3 members liked this post. Yes Reputation No
    My opinion:

    1) Stock sequentials always get ditched for some reason. My guess is they're not all they're cracked up to be...

    2) No point in going twin-charged by using a roots/screw/Lysholm supercharger unless you can disengage the supercharger using an electromagnetic clutch once the turbo has spooled (superchargers suck up 50+ HP on the top end due to parasitic loss). However, there's already a great compromise between the two that was invented way before twin-charging; it's called a centrifigul supercharger. Not as much potential down low as a roots (but more than a turbo) and sick top end.

    3) Still not fully convinced that a 70 lb/hr single turbo will take any longer to spool up than two 35 lb/hr turbos, assuming similar exhaust restrictions. However, being able to stick with the stock wastegate and lambda sensor configuration has its advantages.

    4) Let's be honest, lag is really only a factor in 1st gear. Once you get going, you can keep RPM's high enough to stay in boost by being in the "right" gear. That being said, I prefer less lag; but would sacrafice for more power in the mid-higher RPM's. Luckily, with a 10.2:1 compression ratio, you can still pull out quickly in traffic and not have to worry. These cars are not slugs off of boost.

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    Click here to enlarge Originally Posted by Eleventeen Click here to enlarge
    My opinion:

    1) Stock sequentials always get ditched for some reason. My guess is they're not all they're cracked up to be...

    2) No point in going twin-charged by using a roots/screw/Lysholm supercharger unless you can disengage the supercharger using an electromagnetic clutch once the turbo has spooled (superchargers suck up 50+ HP on the top end due to parasitic loss). However, there's already a great compromise between the two that was invented way before twin-charging; it's called a centrifigul supercharger. Not as much potential down low as a roots (but more than a turbo) and sick top end.

    3) Still not fully convinced that a 70 lb/hr single turbo will take any longer to spool up than two 35 lb/hr turbos, assuming similar exhaust restrictions. However, being able to stick with the stock wastegate and lambda sensor configuration has its advantages.

    4) Let's be honest, lag is really only a factor in 1st gear. Once you get going, you can keep RPM's high enough to stay in boost by being in the "right" gear. That being said, I prefer less lag; but would sacrafice for more power in the mid-higher RPM's. Luckily, with a 10.2:1 compression ratio, you can still pull out quickly in traffic and not have to worry. These cars are not slugs off of boost.
    2) not how it works.. compound twincharging means that you don't need the complexity of a clutched system, as the compressed air from the turbo feeds into the supercharger compressor, this means incredibly high boost pressure potential, not just 20-30psi at all.

    centrifugal superchargers are a terrible compromise unless you're building a big motor that revs high and don't feel like a turbo setup, i've seen shootouts on same engine's between all 3 types, it has less efficiency than the turbocharger, less peak power, barely more peak power than a roots/screw, and far FAR less down low than either.. it's like sacrificing both low and top end for an ok midrange lol.. it works better than a sequential twin in an identical setup (compressor>compressor).. and instead of being said 50hp loss, it's a massive MASSIVE gain.

    4) lag in a setup like this is a huge factor on strip/circuit.. and even more so for the guys that autocross, constantly on and off throttle/partial throttle, having an instant spooling turbo with 100hp less could lead to several tenths off times.

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    Click here to enlarge Originally Posted by Flinchy Click here to enlarge
    True, definitely true for a supra

    but when you consider the n54 has 10.2:1 static compression for power off boost (and slightly better spool)... The supra has 8.5:1, so it needs a load of boost early, and a smaller turbo to get there

    Of course if you went a BIG 800hp twin setup, it would feel like stock down low with the massive peak still like has been said.. But the supra doesn't exactly quite have that stock lol

    it wouldn't be 100% the same results, less drastic... Unless you went for said BIG sequential setup, and with the big, comes the cost and complexity..

    as much as the n54 is sometimes called a modern day euro 2j, they are so far apart in so many ways.
    Actually, they're pretty close considering the eras they were released. Coil-on-plug ignition and sequential turbos were the DI of the 90s Click here to enlarge They do share head-flow characteristics, too; and they are built very strong from the factory (though we do not know the limits of the N54 really quite yet).

    And the Supra turbos flow more than the N54 turbos, don't forget. I've seen Supras making 500whp on stock turbos before, with the 8.5:1 CR, older electronics, and everything.

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    Click here to enlarge Originally Posted by Flinchy Click here to enlarge
    4) lag in a setup like this is a huge factor on strip/circuit.. and even more so for the guys that autocross, constantly on and off throttle/partial throttle, having an instant spooling turbo with 100hp less could lead to several tenths off times.
    Agreed. I don't mind lag too much, but I do mind response; and what most people call 'lag' is really response and it will kill you on a track. Even if you're in the powerband, punching it on a large turbo still causes a significant delay.

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    Click here to enlarge Originally Posted by Eleventeen Click here to enlarge
    My opinion:

    1) Stock sequentials always get ditched for some reason. My guess is they're not all they're cracked up to be...

    2) No point in going twin-charged by using a roots/screw/Lysholm supercharger unless you can disengage the supercharger using an electromagnetic clutch once the turbo has spooled (superchargers suck up 50+ HP on the top end due to parasitic loss). However, there's already a great compromise between the two that was invented way before twin-charging; it's called a centrifigul supercharger. Not as much potential down low as a roots (but more than a turbo) and sick top end.

    3) Still not fully convinced that a 70 lb/hr single turbo will take any longer to spool up than two 35 lb/hr turbos, assuming similar exhaust restrictions. However, being able to stick with the stock wastegate and lambda sensor configuration has its advantages.

    4) Let's be honest, lag is really only a factor in 1st gear. Once you get going, you can keep RPM's high enough to stay in boost by being in the "right" gear. That being said, I prefer less lag; but would sacrafice for more power in the mid-higher RPM's. Luckily, with a 10.2:1 compression ratio, you can still pull out quickly in traffic and not have to worry. These cars are not slugs off of boost.
    1. They are expensive and complex. Most people shooting for 250hp/liter dont give a $#@! about drivability.

    2. If you're trying to increase low end or go for huge boost a centrifugal supercharger doesn't make as much sense as a positive displacement supercharger.

    3. The MOI on the equivalent flowing single is larger. It will spool a bit slower all things considered.

    4. I disagree 100%. Go from vacuum to full boost in 3rd. There is almost a 1 second delay. On a dyno you won't see this, but you do in any transient heavy activity (around down, road corse, etc). Drive an equivalent 500hp NA car such as the Z06 and you will see what I mean instantly.
    Last edited by rudypoochris; 12-18-2012 at 12:03 PM.

  14. #64
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    Click here to enlarge Originally Posted by Flinchy Click here to enlarge
    centrifugal superchargers are a terrible compromise unless you're building a big motor that revs high and don't feel like a turbo setup, i've seen shootouts on same engine's between all 3 types, it has less efficiency than the turbocharger, less peak power, barely more peak power than a roots/screw, and far FAR less down low than either.. it's like sacrificing both low and top end for an ok midrange lol.. it works better than a sequential twin in an identical setup (compressor>compressor).. and instead of being said 50hp loss, it's a massive MASSIVE gain.
    They really aren't that bad and very efficient at high rpm. They pair best with a high rpm and efficient motor, obviously. Plus the power delivery is linear and they are fairly easy to tune for.

    I mean the M3 shows just how potent they can be. In a roll on race good luck.

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    Click here to enlarge Originally Posted by Flinchy Click here to enlarge
    2) not how it works.. compound twincharging means that you don't need the complexity of a clutched system, as the compressed air from the turbo feeds into the supercharger compressor, this means incredibly high boost pressure potential, not just 20-30psi at all.

    centrifugal superchargers are a terrible compromise unless you're building a big motor that revs high and don't feel like a turbo setup, i've seen shootouts on same engine's between all 3 types, it has less efficiency than the turbocharger, less peak power, barely more peak power than a roots/screw, and far FAR less down low than either.. it's like sacrificing both low and top end for an ok midrange lol.. it works better than a sequential twin in an identical setup (compressor>compressor).. and instead of being said 50hp loss, it's a massive MASSIVE gain.

    4) lag in a setup like this is a huge factor on strip/circuit.. and even more so for the guys that autocross, constantly on and off throttle/partial throttle, having an instant spooling turbo with 100hp less could lead to several tenths off times.
    I think you are better off transitioning boost supply over to the turbo once you can get it to spool (via clutching device). Superchargers have a lot of parasitic loss, so what's the point of running both at higher RPM's when you can just use a large turbo to supply the boost? The real advantage of twin-charging is to have boost down low AND up top. Once the turbo is spooled, the supercharger isn't needed.

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    Click here to enlarge Originally Posted by Sticky Click here to enlarge
    They really aren't that bad and very efficient at high rpm. They pair best with a high rpm and efficient motor, obviously. Plus the power delivery is linear and they are fairly easy to tune for.

    I mean the M3 shows just how potent they can be. In a roll on race good luck.
    yeah
    , sorry, i didn't mean centrifugal superchargers were terrible, of course they're not, they can be much more practical to install than a turbo, if you have a high revving motor, they're better than a roots, just like for the s65, a centri accentuates factory characteristics.

    how are they linear though, as the boost builds exponentially due to the centrifuge?.. I mean, i know the blown m3 dynos are dead straight.. Just a question lol

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    Click here to enlarge Originally Posted by Eleventeen Click here to enlarge
    I think you are better off transitioning boost supply over to the turbo once you can get it to spool (via clutching device). Superchargers have a lot of parasitic loss, so what's the point of running both at higher RPM's when you can just use a large turbo to supply the boost? The real advantage of twin-charging is to have boost down low AND up top. Once the turbo is spooled, the supercharger isn't needed.
    Well, check out some of the crazy setups on google sometime... Say you have a Nice biiig turbo that can supply 40psi... Awesome.. But what if your setup can take more boost than that? Then you'll make more power with the blower still running..or what if you go hey, that's a horrible idea as the turbo is still too big and i want it sooner.... Wait lets go a smaller (but still big) turbo that can make a bit less than 40psi, but itself spools and peaks hundreds lower.. but that's irrelevant because the blower compensates for that.. And you get an even fatter power band

    it's not about a need, it's a want Click here to enlarge haha

    it's also less complex to setup, more reliable

    plus, if you want to turn it off.. Circuit and drag racing would mean it's dead weight still..

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    Click here to enlarge Originally Posted by Sered Click here to enlarge
    Actually, they're pretty close considering the eras they were released. Coil-on-plug ignition and sequential turbos were the DI of the 90s Click here to enlarge They do share head-flow characteristics, too; and they are built very strong from the factory (though we do not know the limits of the N54 really quite yet).

    And the Supra turbos flow more than the N54 turbos, don't forget. I've seen Supras making 500whp on stock turbos before, with the 8.5:1 CR, older electronics, and everything.
    That's true. I mean in the way that the n54 has much newer tech, in time it could have the same potential as a 2j with a bit less fuel used hahahah

    i've always read that the supra turbos have a short life past about 450whp, anything more and you're lucky to keep it likethat for years (which of course has happened)

    at it's basics, they're both 3.0 turbos with average heads at best, both have VVT, the only MAJOR difference is the n54 has DI which has it's own benefits.. Though if we have to go PI for huge numbers, that's at least partially negated :/... Ann d the 2j has a shorter stroke no? They seem to be a bit more rev happy?

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    Click here to enlarge Originally Posted by Flinchy Click here to enlarge
    how are they linear though, as the boost builds exponentially due to the centrifuge?.. I mean, i know the blown m3 dynos are dead straight.. Just a question lol
    Boost builds at the same rate by RPM, in that sense. You don't suddenly experience a large boost surge at a certain point rpm it builds progressively. Directly proportional to the RPM.

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    Click here to enlarge Originally Posted by Sticky Click here to enlarge
    Boost builds at the same rate by RPM, in that sense. You don't suddenly experience a large boost surge at a certain point rpm it builds progressively. Directly proportional to the RPM.
    but.. going by https://www.google.com.au/search?q=c...HeSQiAeSrIDwCQ

    i always thought it was: roots makes a roughly set amount of boost at any RPM, and simply increases the airflow linearly... where a centrifugal builds boost similar to a turbo, though not QUITE as drastically (instad of a massive ramp, it's a gentle exponent)?

    if it's a perfectly (or near) linear 'curve', that's pretty cool, but not sure how it'd be better than a roots that makes stable boost from near idle? (efficiency aside)

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    Click here to enlarge Originally Posted by Flinchy Click here to enlarge
    i always thought it was: roots makes a roughly set amount of boost at any RPM, and simply increases the airflow linearly... where a centrifugal builds boost similar to a turbo, though not QUITE as drastically (instad of a massive ramp, it's a gentle exponent)?

    if it's a perfectly (or near) linear 'curve', that's pretty cool, but not sure how it'd be better than a roots that makes stable boost from near idle? (efficiency aside)
    Centrifugal uses an impeller like a turbo but doesn't build boost like it, as stated, with rpm in a linear fashion.

    The roots or positive displacement is just about always the same boost.

    One isn't necessarily better the centrifugal tending to be known for top end and the positive displacement for down low. You will see something like a roots die up top the higher it revs and also get diminishing returns past a certain level of boost. Newer models are better in this regard like the Eaton TVS series but still, they will start to lose potency up top. Much better response though.

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    Click here to enlarge Originally Posted by Sticky Click here to enlarge
    Centrifugal uses an impeller like a turbo but doesn't build boost like it, as stated, with rpm in a linear fashion.

    The roots or positive displacement is just about always the same boost.

    One isn't necessarily better the centrifugal tending to be known for top end and the positive displacement for down low. You will see something like a roots die up top the higher it revs and also get diminishing returns past a certain level of boost. Newer models are better in this regard like the Eaton TVS series but still, they will start to lose potency up top. Much better response though.
    fair enough.

    it's pretty hard to find solid info on this specific subject, doesn't seem like centrifugals are commonly spoken about as much as turbos or positive displacement

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    Click here to enlarge Originally Posted by Flinchy Click here to enlarge
    doesn't seem like centrifugals are commonly spoken about as much as turbos or positive displacement
    Actually, they kind of are. If you check out yellowbullet or just do a general google search you may be surprised. Lot's of drag classes based around them as well.

    Centrifugals can be beastly when done right:


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    Click here to enlarge Originally Posted by Sticky Click here to enlarge
    Actually, they kind of are. If you check out yellowbullet or just do a general google search you may be surprised. Lot's of drag classes based around them as well.

    Centrifugals are can be beastly when done right:

    http://www.youtube.com/watch?v=tDIVNv08wKQ
    i'm always amazed at how much power they somehow make on 91 (95~? RON) over there... it's hard enough to make it on E85 or 98 or something, no idea how the motors don't ping themselves to death..

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    Click here to enlarge Originally Posted by Flinchy Click here to enlarge
    at it's basics, they're both 3.0 turbos with average heads at best, both have VVT, the only MAJOR difference is the n54 has DI which has it's own benefits.. Though if we have to go PI for huge numbers, that's at least partially negated :/... Ann d the 2j has a shorter stroke no? They seem to be a bit more rev happy?
    The 2jz is a square motor; 86mmx86mm IIRC. The 2jz has a longer stroke than the 1jz (which came first); so maybe that's what you're thinking.

    Not too many 2jzs in the states ever had VVT (Toyota calls it VVTI). It wasn't available until 1998, the last year. The 1jz was never available in the states, but it also got VVTI in 1998, along with a single turbo instead of parallel twins.

    The two biggest differences is variable timing and DI. The electronics in the 2jz are also old school; the Toyota ECU runs a Japanese/Taiwanese copy of the Motorola 68000 cpu (the same CPU in the Sega Genesis to put it in perspective lol)

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