strudel

The 911 turbo manual doesn't show where the 2 waste gate hoses connect. Does the hose at the back of the wastegate (control line opening) go to the intercooler? And the hose at the front of the waste gate go to what looks like the intake manifold?
I've disconnected the 2 hoses that run to the boost ****.
Don't know if I have a factory wastgate.
By waste gate spring do you mean the stock turbo boost spring, or is there another spring in the wastegate.

38D

Take a picture and post it...much easier.

Kevin

Well, the port closest to the exhaust section of the wastegate is your control pressure. The top connection is your vent port (which is further away from your exhaust inlet and outlet pipes)..

Inside of your wastegate there is a spring that keeps the valve on exhaust seat. Once the threshold of boost pressure overcomes the spring value the valve opens and dumps exhaust gas pressure which slows the turbine wheel down thus limiting boost. This spring can have different values.. ie the stock boost .7-.8 bars, 1bar and 1.2bar

strudel

Got it. I can try a stock spring and see what I get.
So, does the hose from the wastegate control pressure side go to the intercooler. And does the hose from the vent port side go to the, what appears to be the intake manifold?

911rudy

The top line is just a vent to the outside air. It should not be attached to anything. Most are routed back up into the engine bay to keep road dirt out of the end.

strudel

That still leaves me with a hose that comes from the manifold(?) to the intercooler, but not sure where it goes.

Kevin

Cap it for now.

strudel

To recap this:
The wastegate control line goes to the intercooler (Andial).
The vent line goes to air.
The line from the manifold gets capped.
The boost **** is bypassed.
Put a stock spring in the wastegate.
Could the hose that ran from the wastegate vent fitting to the manifold have had an effect on the boost. Or is the boost only controlled by the spring?

Kevin

When you install a valve to regulate the boost, you are controlling the diaphram on the vent side of the wastegate. With your system you have to many variables. With the installation of a stock spring you will be able to get a baseline to control your boost and work from that point. If you want to run a 1 bar boost level, I'd just install a 1bar spring. If you want to vary your boost settings or run higher boost levels (at risk to your engine) you can install your regulator.

nathanUK '81 930 G50

Let us know what happens Strudel.

Going over 1 bar is not recommended without arp hardware etc etc...

PorschePhD

I like EVCs much better. They are smart and use technology that watches and adjust for any change in control. The old ball and valve will not do that. One day it will be ok, the next it will be low, the next high. This is why we call it dial a death!

strudel

I did everything mentioned above except replace the spring. I hit 1.4 bar. I took the w/g off today and removed the spring and it matches a 1 bar spring I borrowed from my mechanic. I will try a .7 bar spring and see what I get. I will also get the gauge checked.
This is an Andial twin plug motor, Gruppe B cams, Andial fuel enrichment box, intercooler, K27 turbo, stock w/g, stock heat exchangers, DP muffler. It also seems to have a controler on the vent side of the w/g which is suppose to keep the diaphram from opeining early.
Not sure if any other mods were done to the engine.
Harold
'79 930/DP935

Sameer

Harold,
I hear that some haders do increase the boost pressures. Have you changed your headers?

WERK-I

nathanUK '81 930 G50

You could try fitting a larger diameter exhaust pipe from the wastegate to the atmosphere. My wastegate had a small silencer/muffler on it.
I am replacing it all anyway with a Tial wastegate and a curved SS exit pipe.

You can see my SS exit pipe in the very left of the picture.

It is straight through with no restricting silencer/muffler, the stock muffler had a very small diameter approx 1"

GHL Headers & K27HFS