external wastegate woes......
 

Hey guys, i just have a quick question and would like a sensible answer.

The other day while driving my car, i ran through the gears quite vigorously, and everything was fine(11.4afr <14psi) and i was getting a steady .8 bar of boost.

I had come to a stop and when i decided to take off and get the gears moving again, the boost had jumped to 1.25 bar!!!(Hks cast manifold, std hks 50mm w/g, 3"d/p). I decided to go easy and didnt boost the car again. When i got home, i looked under the hood and the vacuum going to the gate was burned off by the heat. I decided to go back out and datalog it at this new found level of boost.......and it was like night and day.

Long story short, does the wastegate have to have a vacuum line running to it, or would it be fine operating on "spring pressure"?? It hasn't dropped below that level yet, and everything seems to be fine.

Help?

Yes. the vacuum line has to be there, otherwise the gate will not open. Think of it this way, with out the vacuum line, you will not get the boost to push on the spring ("diaphragm" if you want to be technical ) and open your gate. Not having any boost pressure to your gate leads to a shut gate and a bunch of over boost.

you NEED to run stainless steel hoses to your wastegate!!!!!!!

the absolute cheapest way to do it this way: buy 3 feet of 4AN hose, which is approximately 3/16" inner diamater. Install a 1/8 NPT -- > 3/16" (1/4" barb won't work, it's too big) hose barb on the lower fitting of your wastegate. Then slide the 4AN line over it, and connect the other side to whatever pressure source you plan to use. Then use hose clamps on each end. Obviously the better way is to buy all the screw on fittings but this will solve your problem of lines melting and blowing off.

Hey i ordered a few goodies from you before.....when will you be making a manifold for the fc3s. I like the one from turblown, but i wont be able to eat for like a year :Kill2: ........I would be pretty angry.......I have the cast hks one, but the turbine housing is almost touching the frame rail....it has already melted my paint!!!!!!!!

Not to stray away from the topic at hand and everything :)

Actually we are currently working on our divided turbo manifolds. From single wastegates or dual wastegates. PM me for details..

wont allow me to pm

You're a little confused...

An HKS standard wastegate is 40mm.
Only the HKS SS Race and GT wastegates come in a true 50mm.

"Spring pressure" requires the single vacuum line.


-Ted

You didn't think you were going to come here in my thread and leave only 5 cents worth of bullshit????????

I require at least a dollar worth from you :)