Thread: How important is boost source?

Is it worth it to tap the compressor housing for a boost source or should I just keep getting a source for my wastegate from the stock DET boost source location on the intake manifold? How important is a source close to the turbo?

-G

For practical purposes, the source is not really important. The only major difference is this; if you source from the turbo the wastegate will open at a lower intake pressure than if you source from the intake manifold. The difference in the intake pressure will be equal to the pressure drop across your intake system.

If you want to get to OCD levels of nit-picky you let me know.

Reason I ask is because I'm going to have the turbo off again and was wondering if I should take the time to do this or if it's really not worth it.

If your running a boost controller, I really wouldn't bother. Even if your not, like Ben said, it'll rob you of power anyway since your turbo is seeing a higher boost level than your motor actually is thus your wastegate sees (for example) 7psi while at the intake manifold, you'll only read ~5-6psi.

I would not do it. Personally, I do not like boost sources at the compressor. They make sense if you're trying to make that vacuum hose as short as possible for aesthetics or weight (distance from compressor port to internal wastegate actuator is usually extremely short). They also make sense if you're trying to run the absolute lowest possible boost you can, or try to combat very minor boost creep. In those instances it can also make sense.

For me, I like my boost source from right before the throttle body plate (usually a port ON the throttle body itself). That means the wastegate and MAP sensor (if you have one) and boost gauge (if you have one) are all getting the same signal, and are all getting the most important pressure info in my opinion, which is what the intake manifold is seeing, not what anything else is seeing closer to the turbo.

Keep in mind, you don't want vacuum on the wastegate line. Not only will it shorten the life of a diaphragm type wastegate, more importantly it can also force the turbo to over-spin on a regular basis and can cause really extreme on/off throttle behavior.

Currently I'm running it right outside of the compressor housing for simplicity/ease sake.


Once I actually build my own intercooler piping I plan on welding a nipple on the piping right outside of the throttle body for more accurate readings like Ben has mentioned.

So if you have it done right already, don't bother doing any more changes. If you need a quick and dirty way to get some pressure to the wastegate then it's fine.

On another note, my GTiR WG is giving me 7 psi now, from what I'm told that is the WG pressure since GTiR's have WG solenoids to increase their boost to 10.5 psi. That means pressure drop in my system is very low



Over-spin part is news to me, is this an issue if you run a boost control too?

Vadim, the GTi-R wastegate spring is 8 psi I'm almost positive. Yes, they have a boost controller that takes it up to 10.5 psi.

Vadim I know we talked about the diaphragm wear issue. It may have been exactly what killed my wastegate diaphragm, or it could have been age. That issue was not enough for me to reroute my vacuum lines.

I had a conversation with someone who pointed out the bigger issue (to me) with having the wastegate see vacuum. And now that I'm going to a piston wastegate, I'm still going to route boost only to the wastegate because of this issue.

I'll describe the issue in the appropriate thread and link it in a second. The issue may no longer exist depending on which boost control method you're using.

Edit: I described the problem here in post #15.

1 PSI pressure drop is not bad then, on my B14 I had 2-3 psi drop, but I also didn't have a compressor to properly test the intercooler piping.



Yup that's where I was getting at, but it's been a few years since we talked about it and I am please to see you have new information. Will be looking towards your thread then

I am running an EBC.



Since the boost source IS from the IM after the TB(Nissan engineered) and since it's going to the boost control selenoid first, I wonder if it'll be OK?

::EDIT:: Actually, Upon looking at the bluebird/avenir vacuum diagram it apperears the stock wastegate source is on the intercooler piping..hmmm.

-G

Continuing with my last post..is there a boost source before throttle plate on the stock motor? Perhaps I should just tap my charge pipe for a source and JB weld it in.