Turbocharging questions

[ubersonic]

Hope this is the right section, myself and a friend were discussing the way turbos work last night and you'll have to bear with me while I explain my line of thought, the CT12's on my 1jz spool up fast because they are small, but they are only fed by 3 cylinders each, if I had a single CT12 running of all six it would spool up ~twice as quick but make ~half the power at full boost.

This got me thinking, I had always assumed that it would be impossible for a single turbo to spool up as quick or faster than the twins and still make more power but Toyota managed to swap the CT12's for a CT15 and keep everything pretty much the same. So would it be possible to fit a big single that spooled up as fast or better yet faster than the CT12's but made more power? I know that the ceramic CT12s cannot handle as much boost as most turbos so I would assume you could get a single that spools fast and can reach high psi without dying?

Any idea what sounds good for that purpose? GT28? GT30? hybrid CT26? lol, Ideally I would like fast spool as I have an auto, and I would also like to be able to raise the boost over what CT12s can take (I can't see myself ever wanting over 400hp at the fly)

Thank you,

 

[bioskyline]

im not a turbo expert but i did do a search on this. a gt30 or gt40 seems to be what people are using for the 1j single, atleast in the JZX100 useres.

heres a post from a jzx fourms

As for a turbo, what sort of power do you want to make? I would HIGHLY recommend a GT35R, with a .58 T4 housing. With that, you can put down 500whp, and still be decently streetable. I;ve done a lot of research on them, I'm throwing one on my 1JZ this spring. They're a perfect match for the car. Alternatively, if you want a little less power, and more spool, look at a GT4082 with a midsize T3 housing (.68 should be good). You should be able to push close to 450whp, and have great spool characteristics.

If you're planning on anything over 400whp, upgrade the injectors. 2JZ 550cc injectors will drop right in with a resistor pack wired in, and will give you plenty of fuel. I would also recommend upgradnig your fuel pump too.

You WILL want some sort of engine management system, and a wideband O2.

Like was said before, you will need custom oil lines, downpipe, and intake pipes, but that's easy stuff.

If you're looking for some power, I would also highly recommend a new set of cams for the 1JZ. Stock cams are HEAVILY biased towards lowend power, that's why you have no turbo lag on the engine in stock form. A new set of cams will completely change the engine.

 

[Albert]

Look at my link. Doing ct12a upgrades with bigger compressor wheels, and a steel shaft. Close to came spool, but youll be able to boost 22+psi no problem

 

[IndigoMKII]

Look at my link. Doing ct12a upgrades with bigger compressor wheels, and a steel shaft. Close to came spool, but youll be able to boost 22+psi no problem

^x2

 

[te72]

If all you're wanting is 400hp at the flywheel, do a little headwork and call it a day. My mods are in my sig, and I dyno'd 320rwhp on 12psi on stock twins. For a single to make that kind of power, it would be beyond easy. Plus, there's always ball bearing turbos if you're looking for stupidly quick spooling characteristics...

Oh, and to answer your question of putting all 6 cylinders into a single CT12a, you'd be choking the engine even faster than normal... thing would feel like a lump above 3500 or so.

 

[destrux]

GT35 or GT40 are going to have a noticeable increase in lag above the stock twins, no matter what a/r or trim you go with.

I found a few people using mitsubishi 20G turbos (unsure about the lag, but it should be minimal on a 2.5L) and GT3071R and GT3076R turbos on the 1JZ that had fast spool and could support the kind of power you're talking about.

I went with a Holset HX35W on mine and you definitely notice more lag, even with the twin scroll turbine housing on a divided manifold (not fully divided though, using a shared WG). This turbo can support about 450hp.

You can also use a quick spool valve. I have no experience with them, but I hear positive results on the forums. It basically uses a twin scroll turbine housing on a non-divided manifold, with a flapper that closes one side of the turbine housing off at low load to increase flow velocity through the turbine.

 

[hvyman]

The only problem with upgraded stock twins is the exhaust housing is still going to get out flowed and flat line in high rpms.

You can use a small single like a t57 or something with a billet wheel and still get fast spool and more hp. Or a bigger turbo and quick spool valve.