Ok, I've got the burning question, In the case of the Supra, what is better, a single or twin turbo setup? For example, which has more possibility, the 2JZ motor (single) or the 1JZ motor (twin), Is 1 big turbo more efficient than 2 smaller ones? If you guys had to recommend a motor swap for a Supra, assuming that the car is N/A (7MGE) or something, what would it be? And why!
most high horsepower cars ive seen have one single huge turbo.. but with that im sure comes some lag. if you could build a nice sequential setup with one medium turbo and a bigger one that might work..but idk
thats what you would think, 2 smaller would be more efficient and less brutal than 1, making the power at lower RPM and building more stedily. I've got a friend thats running 300 horse in a 97 civic running a huge garret ball bearing turbo at 19-21 PSI. When you rip it, it revs to 5000 rpm and then explodes all the way to his cutoff. Its sick, but practically undrivable!
What do you guys think of a 1JZ in an MKII? make for a nice project?
The generally accepted rule of thumb, without getting all technical on you, is that if there were a perfectly comparable single and parallel twin pair, according to the physics of it: the twins spool up faster, delivering the grunt more quickly, but suffer losses in efficiency at the top end limiting peak power. That said, these differences are fairly small, and the hardest part is finding this mythical comparable turbo arrangement to experiment with. Singles quite frankly, are cheaper to do, require less complexity and take up less space. Twins are more complex, cost more, take more effort to get working right, but have a certain coolness IMO.
1j MKII, not the first one, but a cool little setup. An ideal chassis weight for the 1j
I would say most cars that are built to run fast have 1 huge turbo because they launch the car at a high rpm and don't care about turbo lag. For twin turbo cars one turbo is smaller to boost up and make power at a lower rpm and the other kicks in and runs for the high rpm. I like the twin turbo set up because the lag is quicker compensated for. Even if you do a single turbo it can work great if you do the research you don't want something to big and have a hard time on the road with spooling up.Check with some supra gurus and even look into the manufactures problems, like the 93-96 Rx7 had problems with the twin turbo set up and many have gone to the single turbo.
I think the twin is the best way to go, for a street car. I personally like to see power made at low RPM, which is what you would usually use on the street. I have a friend with a stock 1JZ in a 1991 JDM Supra, it does the trick.
If this motor makes about 280 horsepower stock, what are some of the tuning options with the 1JZ, how much can you get out of a reletively stock setup? Also, is that 280 horsepower made at the wheels or the crank?
Twins don't mean one big one small. There are 2 types of twin setups: parallel, and sequential. Sequential (RX7, MKIV) are equal sized, with a mechanical system diverting more exhaust to one of the pair to get positive boost faster, which shuts off after the boost gets going so both turbos work more equally at the high end. As with mechanical systems, make it mroe complex, and failures are more common. Hence the MKIV blows up turbo #2 more frequently...it's the one that gets the larger low rpm exhaust flow, so it's working harder. Almost noone makes sequentials for the aftermarket. They are almost always parallel, meaning 2 snails getting half the exhaust flow each at all times. Much easier to implement, easier to set up and tune and you still get the advantage of the smaller impeller and compressor. That mass being closer to the centreline of the shaft is what gives it the physical advantage over a single at the low end. That is also the reason the singles are more efficient at the top end (single shaft to induce friction versus 2 of them, and the inertia of the larger wheel makes them more boost stable and holds more speed while shifting...and that's as deep into the physics as I'll get here).
Can a sequential system be done with different sizes, yes. It becomes even more complex than a same sized system with backflow from the large to the little and vice versa being a consideration that has to be mechanically emiminated. It is so complex and error prone that off the top of my head, I can't think of anyone that does it.
For a street car there are 2 things that you will want.
First, you will want as much displacement as possible.
Second, you will want the fastest spooling turbo possible.
The reason for this is that both will help produce low end power. In a street driven car very little time is spent high up in the power band (over 3500 RPM). You will want to make as much low end power as possible for all that arroud town and rush hour driving. A finickey race motor with its power band way up in the rev range is the last thing you will want on the street.
Don't forget the other complex way to do twins. You can run them in series plumbing the outlet of one turbo into the inlet of the second (I have only seen it on a big diesel). The idea being to compress the already compressed air. This is the methodolgy used in compound systems that use a blower and a turbo. Like sequential systems this method should be left alone.
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Don't you SAS me boy.
Please wheel responsibly.
Don't forget the other complex way to do twins. You can run them in series plumbing the outlet of one turbo into the inlet of the second (I have only seen it on a big diesel). The idea being to compress the already compressed air. This is the methodolgy used in compound systems that use a blower and a turbo. Like sequential systems this method should be left alone.
Yes, but diesels can do sequential boost setups because they don't have to worry about detonation.
As for the turbos, One is often done because you can direct all your exhaust flow through one larger turbine and flow more air into the engine with a larger single turbo. Twins are often done to have power across the entire band, or to smooth it out so there's not just a big HIT at 3K rpm. There's lots of ideas behind turbo methodology.
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1988 Mk3 Turbo Targa - 17.5psi, 486hp, 494tq.
[img]http://www.**********s.com/supra/rsw_sig_stupidTN.jpg[/img]
Who came up with this 500px wide BS?
one big ass snail all the way no matter wat ur doin i think u should jus boost the 7m they respond good to boost but if ur doin a swap jus go all out and single 2j it man
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