It all depends in the tuning. I think what people are telling you with the larger injectors is safer but In spending lots of time at large Rotary shops here in Japan they all get 420-430 hp with 4x800cc injectors. I have a TD-O6H20G and I am gonna use 720ccX2 and 800ccX2. I asked the same question about if I upgraded turbines or wanted more power say like 450 would those injectors be good enough and they said yes.

I can show you a dyno of a FC using 550's and 800's to produce 380hp. I have dynoed 362 with 550's and 720's but it is a little on the lean side at full boost high rpm and Injector duty is about 90%.

Stateside thinking and Japan thinking are different and with the lack of places to get real tuning maybe larger injectors will give you a saftey margin that you need.

Personally I think there is something to proper injector staging and using fewer larger injectors VS more small ones. Mazda has stuck with 550's in the primaries I think for emissions and mileage reasons as well as they are big enough to handle the first part of the powerband in most situations. Now on the RX8 they have went with 3 injectors per rotor..... Just something to think about .

it would be nice if u could send me those dyno sheet is that turbo comparable to a 60-1 so you think i would be good with 4x800cc and i won;t lean out up top? and what psi are u making that power?

Ok I am using a TD06H-20g running 720's in the primaries and 800's in the secondaries. I have not dynoed yet but am hoping to this week. My injector percentage does run in th 95-96% range. Rmagic assures me that because I am just tuning using the commander that he can exhibit more control on the injectors and lower that % While maintaining power.

This Dyno graph is from Rmagic homepage. The FC has a high flo turbine, and 800cc inj. in the secondaries

I made 380rwhp on 1 bar on my E6k and 60-1 with 550/1600 combo. on 20 psi i saw as high as 78% duty cycle with a 11.5:1 afr (race gas).

Spend some extra $$ on a fuel system, and it'll be one less thing you need when you decide you want more power. BTW, 850cc primarys will still keep a smooth idle. I'm running a 850/1300 combo, with a Groundzero (Or Xcessive) motorsports fuel pump with no problems at 400+rwhp. Idle is flawless and smooth. CJ

I had, 1680 x 4 w/ T60-1...but one of the 1680 prims were dropping out, so I replaced them with 1000x 2 and 1680 x 2.... Getting 4 x 1680 took some time to dial in

Definitely go w/ 720 and 1600 or MORE. This is not overkill, it is insurance. I mean, what if you do a lot of optimizing your set-up and accidently end up w/ 450HP+?

I have my 720/1600 and Walbro 255HP hitting 100% duty cycle by 7,500rpm @ 15psi on my BNR Stage IV (hybrid w/ 60-1 hi fi compressor)- it definitely can be leaned out when I dyno, but it pulls through the rich mix easy.

I would recommend a more serious fuel set-up than just an intank Walbro as well.

Don't cheap out when it comes to fuel it can end up costing more...

What kind of pressure are you running? It's either way too rich or you have a problem somewhere else, that is a shit load of fuel!
If you haven't already check out Max Coopers excellent website for fuel calculation.
Here
While fuel setup is not something you want to skimp on, you want to go with something that will provided the best combination of power needs, tuning ease, price, and reliability.

Base pressure is 45psi it is 1:1 rise w/ boost. It has been suggested to me to turn the base pressure down since the Walbro loses flow at high pressures, but the 1600s stages smoother w/ the higher base pressure.

It is running rich.

GEEZ i guess, thats crazy. way too much fuel. Im runnin stock fpr and walbro, 550/1600, and even at 10.5:1 at 7600 it was around 88%