Got the idea from the SRT4 guys, with the SRT it's common practice to move the vacuum tube from the compressor itself to just after the intercooler, so that the turbo will make up for any pressure loss across the core. Any Miata people tried this?

 

I run mine off the back of the intake manifold now. Seems much smoother and haven't hit any problems yet.

 

How does it make any difference? You're setting it by the boost gauge, which is at the manifold, so....

 

Haven't proven it out yet, but I think at high boost and high cfm, controlling the setting at the compressor can dump the wastegate at a time where it is not maintaining the pressure at the manifold. I think this is why I lost boost at the dyno in the higher rpm's.

 

Just so I'm clear, I'm talking about the signal to the wastegate actuator from the turbo. On my Greddy the signal tube is about 8" long and comes directly from a fitting on the turbo itself. The idea is to get the signal further downstream to trick the turbo into spooling faster and producing a little more boost.

 

Yeah, I know what you mean. I guess it might help it spool a little faster since it'll start bleeding the boost off a little later. Never thought of it like that. But it still will only make as much boost as you set it for any loss through the IC is already made up for since you are setting the boost level post IC anyway.

 

it would be almost like a "crack pressure" adjustment on an electronic boost controller...

It delays the wastegate's acquisition of the boost signal..... based on distance rather than duty cycle..... and lets the turbo spool a bit more before the wastegate opens up to regulate the boost.....

 

I even ran with no boost signal to my WG talk about delayed WG deployment hit 20 psi that was fun

 

As I will shortly cover in another post, I just moved my WG source from about 8" of hose (through MBC) directly off the compressor housing to a 5foot piece of hose off the manifold. Still have the exact same overshoot problem. No change whatsoever in response or spool.

 

realy moving the Mbc over to the manifold with a short peice of line helped me.

 

mine is run from the intake manifold, works fine

 

I've had great success with the intake manifold. At first, I was running my wastegate signal off the turbo compressor and experienced minor boost spiking. I've tested my wastegate signal in various locations and the intake manifold held the most consistent readings.

 

I've done both, for the sake of not having as much crap under the hood, I run it off the compressor with no problems.

 

sourcing your gauge off the manifold and you see exactly what the engine sees...just up the boost a tad to make up for pressure loss then.

 

MAP sensor for boost controller runs off intake manifold, here.