Recommendations for a new Turbo?

[pf85]

My current setup is running around 590bhp running a really old T4 turbo with an autobox but I am planning to go 6 speed next year. Before then I am replacing the turbo and want some recommendations from people with knowledge and experience. 

Current manifold: Tubular divided T4

60mm HKS GT external wastegate 

I am aiming for somewhere in the region 650-750+bhp once the new gearbox is installed running on 97 octane setup for the fastest spool within reason as it will be mostly street use with some rolling pulls.

My tuner has recommended a Garrett G30-900 .83AR (V band) - this will require a change to the manifold and there is also a waiting period to get these turbos in too it seems however now that it's coming into Autumn/Winter I can put up with that as it will be going off the road. The other suggestion was a Xona Rotor but I dont know anything about this brand and dont know anyone else running one.

 

Edited September 5, 2022 by pf85
Add wastegate (see edit history)

[Krimi]

As your tuner said, new G series from garrett are the way to go. G35-900 its an awesome option.

[AC93]

See what your tuner recommends and what he's experienced with. 

I have a Borg Warner and it's been absolutely solid, 64mm 0.88 single scroll, making 700hp (forged with cams) 

[Mike2JZ]

If you are wanting to go down the garrett route with G series, I'd recomend the G40-900. Its also a 62mm but can be specced with a T4 Divided housing so you dont have to change manifold. Personally I'd go with a 0.95 or 1.06 housing, anything smaller usually creates a restriction at higher rpm. 

If you do go G35-900, then go with a 1.x housing. 

[pf85]

Going with a larger AR will definitely give some room for higher bhp at the top end but surely that would shift the useable power curve to the right and introduce lots lag? 

There doesn't seem to be many divided turbo housings these days are they not much advantage over open? 

Also does anyone run a quick spool valve or are they not reliable?

[Mike2JZ]

No it won't, trust me im a doctor. 2JZ needs a decent size A/R or you will choke it, I see it all the time. 

I wouldnt bother with a quick spool valve due to reliability issues with them. 

If you haven't already seen this video, maybe you should watch

 

[pf85]

Thanks for the help, I didn't bother looking at anything above the G30 as I thought there would be too much lag but having looked at that video above and the specs of the G40-900 it seems a perfect fit in the sense that it will work with a T4 divided and an external wastegate. I can't seem to find much info in terms of dyno charts on a 2JZ though - it would be nice to know how early the boost comes on at and what the curve would look like.

[Mike2JZ]

G40 900 will be laggier than a G35-900 as the exhaust wheel is bigger. How much laggier I cant say as I dont have any data on our dyno with these turbos yet. If I had to hazard a guess, on a non vvti setup G35 will come on strong at 4k, G40 will come on at 4.5k

[pf85]

Ok yes its hard to know without seeing some dynos but that might be a bit too much lag for what I'm after. I'll keep doing more research but it seems my options are super limited unless I get some fabrication work done or else change the manifold

[Mike2JZ]

Although the G series are more efficient, more response etc they are new versions to previous garrett turbos.

GTX4088 is essentially a G40-900 and a GTX3582R is close to a G35-900. You should be able to find dyno sheets online for those on a 2J as they have been out for years now. Should give you a rough idea on the differences to expect in the wheel differences/sizing. 

Edited September 7, 2022 by Mike2JZ (see edit history)

[pf85]

Ok I think I'm going to go towards the smaller side of things for now with the G30-900 until I have the gearbox installed and maybe new cams and see where things are at come then.

Im torn between the 0.83AR (tuners recommendation), 1.01AR (recommendation from the dyno video above) or there is another option of a divided 1.06AR. Would the divided housing be enough to offset some of that lag or will it be worse?

Edited September 8, 2022 by pf85 (see edit history)

[Mike2JZ]

If you are stock engine with stock cams 0.84 will be a good fit. If you plan on doing cams then I’d go 1.X as you will be able to rev out better on the larger housing. Realistically on boost you will never be below 4000rpm 

[pf85]

I've got a forged bottom end with supporting mods but havent done any head work to it yet. I did find an SRD business card in it when I bought the car so it must have been with you guys at some point but Im not sure what work was carried out

Edited September 8, 2022 by pf85 (see edit history)

[Pudsey]

Really interesting watch that, and I must say the red Supra looked great.

Certainly a well worth while watch if your thinking of going single turbo.

Maybe one day.

[pf85]

I ended up after a lot of thought and indecisiveness going for the Garrett G30-900 1.06AR divided T4 - reason being that it will be a direct bolt on to my HKS T4 manifold which I don't want to change and I'm hoping it will be relatively fast spooling but still have plenty of overhead to push some more power when I'm ready to do so.

There is a 3 month delivery date so I've got some time to work out a couple of other mods - I'm planning on:
1. Rerouting the PCV lines into an oil catch can
2. New exhaust - either Blitz Nur spec R or else HKS Carbon Ti
3. New CAMS and valves & springs

What sort of power is the stock intake manifold good for?

Edited September 13, 2022 by pf85 (see edit history)

[Thunder2J]

Great thread, am trying to decide between g30 or g35 myself.

What results did you end getting? Do you have a chart?

[pf85]

As a very rough guide I would say If you're aiming for upto 700bhp at the flywheel then the g30-900 is epic and spools super fast. If you want to go more a bit more then you'll need a g35-900 and if you're aiming for 850+ then dont go smaller than a g35-1050. AR size I'd say 1.01+ but talk to your tuner to get more precise guidance.