I am getting tired of the crazy drive pressure on my stock turbo, and thats with stock or mild fueling enhancements.

So here is what I am thinking, let me know if I am off in left field.

The electronic solenoid defaults open, and with 12V its closed. So if I unplug the solenoid it will be open all the time, and a resistor in the plug on the wiring harness side keeps the ECM happy.

So now I essentially have a fixed boost elbow. The WG will open about 24-28 psi (different sources) without modification, but if I shorten the WG rod I should get more pressure out of it, hopefully the 35ish I am looking for, with reasonable DP. (Honestly I wouldn't be surprised if EGT's drop when the WG opens even if the boost drops since the DP will drop)

Then if I need to go back to stock all I do is unplug the resistor and plug in the solenoid and if I get an overboost code i'll turn the actuator rod back out.

Does anything sound wrong with that idea? If I can't get the boost I want out of the OEM WG I can always upgrade or add a manual boost controller inline.

Thoughts?

 

I am confused. In your opening statement you say you have "crazy drive pressure". Then you want to push your turbo harder? That takes even more drive pressure to do so.

So first question: what is your drive pressure at 24-28psi?

The only issue I have with the thinking is that somehow a wastegate mod and higher boost will alleviate excessive DP.

That being said, with reasonable egts, DP with the stock turbo can be a fair amount higher than boost and still be ok.

 

I want to push the turbo as hard as I do now with less drive pressure. Now I peak at about 35 psi and 55psi of drive. If I can get 33 psi of boost and 40 psi of drive I am sitting better.

My truck runs about 1:1.3ish below 2500 then as high as 1:2 above 2500.

I am not looking for more boost, just less DP.

Smarty Jr tuning disables the WG, and I've never agreed with that 100%, based solely on DP.

 

Just add a boost elbow to the boost reference line and tune it to where you want it. Reducing the boost is going to raise EGT's but if you don't have that much fuel its probably not a problem. Not sure how much adjustment there is the WG actuator but its a larger pain to deal with than the elbow.

If you want more reduction that would take working the housing over to promote better flow. Keeping the rpms under 2500 and the late event from firing is about the only way to control the DP without more drastic measures.

Removing the TQ management, cam change, and bigger injectors usually gains more power in the lower rpms and negates the need to wind the motor out. The Jr may not allow enough tuning to make that happen though so your stuck looking for different options.

 

You can also drill the the holes under the wastegate pucks. This will help eleviate some drive pressure from better flow. Dont quote me on this but think I recall reading that they can be opened up to 15/16".

 

The only way to lower drive pressure is to either Buy a upgraded turbo or install an external wastegate and weld the turbo's gate shut.

 

I'm curious about the drive pressure reading. Is it 2:1 or higher than that?

I believe the correct way to deal with high drive pressure (other than dropping the boost level) is to install a larger turbo exhaust housing.

MikeyB

 

Just as boost is really a measurement of restriction, so is drive pressure, or back pressure. The main causes of the restriction are the exhaust housing AND size of the turbine. Since both are small on the stock turbo, what is being reported is actually quite normal.

With that turbo, and considering you already have a proper cam, there is not much you can do to maintain current boost level yet drop DP. At this point is where most folks upgrade. Yes, a wastegate mod helps lower DP by opening, but heck it only opens long after you have reached the level of DP you are trying to fix.

 

I realize the primary reason the DP is so high is the small housing and the turbine wheel, mostly the latter. Yes the housing is 9cm, but the housing isn't divided and thus flows about the same as a divided 12cm.

I realized external gates flow more than internal, but if the internal isn't even being used there is room for improvement.

Looking at how the DP runs on a stock truck I don't think it will be all that hard to adjust it to open when I want and keep DP a little lower, but it will all be an experiment. A larger turbo will happen some day, but for now I'm going to tinker with the cheaper option.