Wastegates (when open) divert exhaust gas away from the turbine and directly into the exhaust to prevent overboosting. When closed they allow all the exhaust energy to spin the turbine.

Wastegates are triggered by a pressure line that is sourced from (or just prior to) the intake manifold. When that pressure exceeds the pre-set spring pressure of the WG, it swings opens. The WG doesn't flip open instantly. It gradually opens. To avoid overshooting the boost target, stock WGs open before that boost target. This diverts some energy away from the turbine even though boost target has not been reached. This allows a slight loss of power.

The boost controller (manual or electronic) controls the signal going to the wastegate. So if you can get the WG to stay tightly closed until your boost target is acheived, you will have more energy going to the turbine up to that point. The end effect is seeing more boost at lower rpms. The trick is to get the WG to pop open instantly without overboosting.

 

So my question is for all of us here who have the EVO wg, how will we be able to realize seeing more boost at lower rpms without overtightening the actuator? Thanks for that response though, it was very thorough Roasterdoc

 

The EVO WG Actuators have a tighter spring which will provide early boost WITHOUT having to overtighten the WG actuator rod. Trust me, this mod is worth the money.

 

The idea is to "hide" the pressure from the wastegate actuator exactly until the boost hits a predetermined point. The easy way is to bleed off some of the pressure from the vaccum connections using a simple aquarium valve (really old-school), or a variable pressure industrial-style regulator. Using both of these in parallel (aquariums on each turbo with the regulator in the middle to the pressure source) will yield some pretty accurate results, but you'll still have a bit of lag.

I think the Hallman style valve has some sort of internal ball-bearing check valve inside that stays closed until the last minute, but I'll have to check with Marc to be sure.

I'll try to dig up my old plans and post them here.

 

Yes, the Hallman has a ceramic ball-bearing check valve to provide a more instantaneous action. I think it is one of the best functioning MBCs out there, and more importantly, the setting you dial in will remain and not wander.

I'd like to see your plans. I didn't consider using a regulator on a common pressure source. I was going to add a MBC inline on each WG line.

 

If you're interested, someone posted them up on their site here: http://www.unixfool.com/images/mcmbc2.jpg

My page is long ago dead, but Ron put together some pretty good schematics.

The only benefit this has over the Hallman is that it can be used inside the car (put in console for example).

Now to modify it for use on the TT. Looks like the sickness never went away, it was only dormant... this is gonna be fun...

 

when purchasing after market waste gates, do they come calibrated or do they need adjusting after they are installed?

Thanks

Sameer

 

If you buy them from a 996TT tuner (any sponser here), they will be ready to go.

 

NO

...and it depends which set up you have and where...be careful installing and you must have a boost gauge.

Ari has done it right I think:

Quote:

Originally Posted by ari

Pull off the boost hoses, connect a pump, and start pumping at 12 PSI you should see the rod start to move. If it doesn't, loosen it until it does.

but I hope someone could give a hand here and really confirm if this is right or/and which is the precise PSI that should be for every Stage to be calibrated (Ex: Stage 4 at 1.25 bar).

Thanks!

 

Do you have a K24 car?

 

Ari I have a K24 car and the wastegates are going on as I type. What's the best way to adjust them?

 

Get a boost gauge, some vac. hose, a "T" fitting, a hose nipple and a small bicycle pump to make a pressure tester.

Now, once installed, pressurize the actuators one at a time until they start to crack the WG open and note the PSI at which that happens. When properly adjusted, the WG should start to crack open at 12 psi. Adjust the tension on the actuator rod tighter/looser depending on which way you need to go to achieve the proper 12 psi setting. Do this for each side independently until they each start to open the WG at 12 psi, and you're done!

This adjustment will result in a steady 1.1 bar and an occasional 1.2 on a "flashed" car. It's much easier than it sounds. The drivers side is the easiest to reach and adjust, so do it last and you'll finish on a high note.

 

I have my stock wg adjusted to 1.1-1.2 what's the diff? what are you really gaining?

 

I have mine too but the EVO WG string is stiffer and will hold 1.2 to the red line.

Mine OEM was doing this:

On a fresh morning, sea level, 60-120 runs on 4th gear:

3,200 - 3,700 rpms: 0.6 bar
3,800 - 4,150 rpms: 1.0 bar
4,200 – 4,400 rpms: 1.2 bar
4,450 – 6,500 rpms: 1.1 bar

If you adjust the OEM WG will give you a good 1.2 bar spike and will fall.

 

funny mine holds to redline. maybe my stock springs are stiffer, or adjusted tighter. don't know?