wastegate spring swap (install pics)

[sTTanford]

ah, the last day of spring break. all in all, i got almost everything i wanted to do done. my new fuel rail will be done end of this week, but besides braided fuel lines, anodized fittings and a new front FPR, not much new.

wastegate: Tial hybrid (35mm bottom, 40mm top), anodized blue. Before, standard 0.9bar spring (big yellow), new, 1.1bar (big red) spring.

(I'm writing this after the rest of this post, because it might help for people who don't know how wastegates work)
Wastegates have two hoses, one coming from the boost controller (the N75, for stock cars), and one from manifold (vacuum line). The N75 dutycycles a solenoid to maintain a pressure difference across the WG's spring, which has some pressure rating (8 psi, for example). If both hoses going to the WG were coupled to the manifold, the WG is actuated purely by the spring, and will open up at its spring rating. if it is hooked up to a controller, the controller adds a force to the spring by increasing the pressure difference across the seal plate.

Diagnosis: basically, the boost controller was having problems controlling the wastegate at high boost (~21psi) at high RPMs (3, 4, 5th gear at 6+kRPM). The 0.9bar (14psi) spring actually opened up around 8psi on my setup, so to hold 21psi, the boost controller had to control 13+psi to keep the WG closed. solution: get a stiffer spring so the boost controller didn't have to work so hard.


me pointing to the dump flange. this bolts to the tube below, which bolts to the downpipe. the flange in my non-gloved right hand bolts on the underside of my exhaustmanifold.



this is where an N75 would plug into, if i used one. (for profec-B users, this is where the OUT port from the controller goes into. the hose on the side of the WG gets manifold vacuum).


WG springs are bigger than most people would guess. yellow = old, red = new. cig box for reference.


WG springs have many uses...


oh yah... careful, the used spring is a bit dirty!


i do not condone such behavior!

anyway, enough tomfoolery. finished up the fiberglass dash guage mount. got sick of sanding it down to prep for spray paint so just fabric'ed it. it'll do, for now.

guages to be mounted some time soon...

[downunder]

spend the same again on mods?? I must be in the wrong business!!

[sTTanford]