should i have serperate exhaust pipe for the wastegate instead of the greddy down pipe where it merges into the the main pipe way up close to the turbo? i have a problem getting full boost on teh top end. i have to crank up the boost controller to a point i feel is too much just to make 15psi... on my avc-r i can set it at 43% to make 1kg/cm boost... but between 3500-5000rpm it only takes 38% to keep it spooled easy...maybe im just all wrong but i thought maybe reducing teh turbo backpressure by adding a seperate pipe for the wastegate might help some

 

not sure about your plumbing Q, but how is 40% "cranking up" your boost controller? I used 60% duty cycle to run 1 kg/cm3 and now have 66% to run 1.15kg/cm3. Isn't that what a boost controller is for? I think the avc-r will use only what it needs after it learns. I originally had it at 70%, but it spiked a bit. AFRs have stayed <=10.5.

 

just reread your post and I'm confused. Are you talking about having the waste gate dump tube plumbed back in? Mine is plumbed back downstream like right before the cat.

 

The Greddy design is fine. Weaklink is right, the duty cycles you are talking about are very low. In fact they are so low, you may have to go to alighter WG spring to prevent overshoot on really cold days. Carl Byck