wastegate positioning and injector question

[pyrex]

I have spent a lot of time researching and collecting information to help me decide how I am going to build a 99 gsx.

So my first question is . . .

I have noticed that some turbo setups flange an external wastegate to the port that contains the internal wastegate flapper.

I can't think of any reason why this would path would we taken over an external wastegate flanged to the exhaust manifold, especially if one was upgrading the turbine and exhaust manifold.

My second question is . . .

To get power you need air and fuel. In the pursuit of great power, many people go with really large injectors (greater than 800cc). Does this affect the quality and fuel efficiency of idle and due to the injectors not being able to squirt a small enough amount of fuel.

The other option instead of the really large injector is to use an ems like the motec m48, two fuel rail, two intank fuel pumps as i saw in the extreme tech page and two sets of 550cc injectors(which would require another set of injectors boss or a custom intake manifold).

I would like to follow the second path . . .

I am looking foward to your responces and opinions.

 

[PaleDSM]

There are 2 main ways to mount an external wastegate as you have seen. I dont know of any negative consequences of running the wg off of the O2 housing after opening up the wg passage.

I have never run an external off of the manifold but the theory is that it isn't optimal because it is pulling exhaust from only one manifold running to control boost.

In the real world I dont' think there are any noticable differences between the two.



As to injectors. With proper tuning idle quality is still quite good even with large injectors. Especially with newer systems like DSMLink that allow for dead time adjustment as well as a global fuel adjustment. Even on a Safc and 660s my car had near stock idle quality.