Im thinking about getting the 2.1 for my s4 t2 n333 ecu got a large streetport stock injectors three inch intake and exhaust will this be good for my set-up let me know.

 

How much boost do you plan to run?

 

If it's stock turbo then absolutely BUT you have an issue with your setup.

You need bigger injectors. Don't chance running out of injector. Get some 720 secondaries and be in the clear. The street port may max out the stock 550's.

10psi is the acknowledged limit on a stock port motor. Street port would make it less psi.

 

^ Why would the port size determine how much boost you should safely run? A street port will naturally decrease the amount of top-end boost the turbo is able to make by taking it further out of its efficiency range, but there's no reason to think that running 11+ psi on stock ports is somehow damaging. The turbo's efficiency, the turbo's bearings, and the intercooler setup all play a role in what is safe for the turbo and engine, but port size isn't related. The general consensus is that about 12psi is the max you should run on the stock turbo, since intake air temps skyrocket soon after that level.

 

Yeah im wanting to run about 10 to 12 psi nothing to big

 

And also is the 1.7 just plug in and go im kinda nervouse about this hole ecu thing i dont wana screw anything up if someone could give me any tips i would apprciate it alot thanks guys.

 

Since it's a larger port, the motor is going to need more fuel. More air in engine = more fuel needed....

I'm talking injector duty cycle danger. It's always better to under drive bigger injectors versus running smaller near 90% duty cycle.

Injector size, duty cycle, porting, turbo, and psi are all related for fuel demands.

I personally run 10psi but ran 14 for a long time. I snapped the center shaft at 15psi after 8 months. 14psi is usable with a good enough IC. The TMIC sucks ***** over stock psi.
Don't expect the turbo to last long at those speeds though.

I'm running an Atkins 3mm stock port, Rtek 1.7, 720 secondaries, NPR fmic, Aeromotive FPR, Walbro, and S5 tubo at 10psi. It's a dead reliable setup.

 

I do have a walbro255 but i do need a fpr what is a good one to get and the 1.7 is a plug and go right

 

On a non-turbo engine, this would be true. But on a turbo engine, the turbo will be the limitation on airflow. You could run a p-port, stock turbo and stock fuel, and the mixture would still be ok (at the boost level that was safe with stock ports). The stock turbo wouldn't be able to flow near enough for the large ports, so it would just end up spooling late & choking on the top end. It's the same thing with a streetport engine; just to a much lesser degree. The same turbo at the same psi will supply the same amount of air. The guys that build 6-port turbos and use the stock turbo run into the same problem. Khanartist's 6-port turbo is only able to make 2-3 psi to redline due to the port size not matching the turbo size.

As far as fuel, upgraded secondaries are always a good thing if raising boost past stock levels. No question about it. But the primaries can also max out before the injector staging point. I've logged mine maxing out by about 3500 RPM (the Rtek 1.7 staging point), so I have it moved down to about 3100 RPM. My primaries now peak at about 70-80% before the secondaries come online. This is all on 11-12 psi max with a ball-and-spring MBC keeping the wastegate completely shut until peak boost is reached (faster spool).

The thing with the stock turbo is you can only make above ~10 psi (on stock ports) for about 2000 RPMs before pressure starts to decline anyway. This brief window of higher boost doesn't seem to have a huge effect on IATs (even with the TMIC), so the main reason I see to keep the pressures below a set level is to protect the bearings (or shaft in your case). Brian at BNR upgrades the thrust bearing in most of the hybrids he builds so they're better able to handle boost around 1 BAR (14.7 psi).

 

I wana thank you guys a bunch for all the info so i will get some 720 primary and secondary injectors and prob get the 1.8 if anyone has any objections let me know.

 

I will 100% disagree with this. Any port, even a mild street port, changes the way the efficiency of how an engine breathes and therefore changes fuel requirements. I've seen it plenty of times with guys running lean on a ported but otherwise stock engine, and they end up needing to step up to the stage 2.

 

Turbo or NA engines? I ran slightly lean with the Rtek 1.7, 720cc secondaries, FD fuel pump and stock ports on my TII engine. I moved to the 2.1 so I would be able to correct this. I don't think the conclusion can be drawn that porting was the source of the problem unless compared before and after with identical fuel/fuel control setups.

The AFM measures air volume & the MAP sensor measures pressure, are you saying the ECU does some calculation using volumetric efficiency? As far as I've seen/read, this is not the case. If it were, TIIs with free-flowing exhaust/intake would need a programmable EMS like FDs with the same modifications (no AFM on FDs). The incoming air volume and pressure should give the ECU all the airflow information it needs to maintain appropriate mixture. As long as the injectors aren't topping out & the fuel pump is flowing enough to maintain fuel pressure, all should be fine.

Porting absolutely changes the way the engine breathes, but that also changes how the turbo will spool. The stock turbo is already inefficient at boost levels above stock & high RPMs, so if you increase the airflow of the engine, you're just moving it into an even less efficient area of the compressor map.

If PV = nRT (Ideal Gas Law), then n = PV/RT.

P = absolute pressure
V = volume
n = # air molecules
R = gas constant
T = absolute temperature

Lower efficiency means increased temperature (T), less pressure (P) and therefore fewer air molecules (n) in the fixed volume of the intake manifold. n decreases with increased T and decreased P. If the amount of air is lower, and it is under less pressure, how could the mixture become lean?

Here is a compressor map for a turbo similar in size to the stock HT-18 (Garret T3 50-trim). The red lines mark the 30-40 lbs. of air/min. lines, and the green lines mark the ~7 to 15 psi range. Stock ports would flow around 30 lbs./min. and anything larger would approach 40 lbs./min. (or possibly more). It's obvious that anywhere near redline (max airflow), the turbo's extremely inefficient & well outside the 65% efficiency ring. The further out you go with the airflow, the less efficient it becomes still. At lower RPMs (somewhere between 0 and max airflow), the turbo is more efficient (and thus able to make 15-20+ psi), but changing the port size still shifts it to a lower efficiency range on the whole.