Excerpted from http://www.flashoffroad.com/Diesel/GM99Diesel/6_5LV8TurboDieselFeatures.htm


Turbocharging ­ - When GM set out to design the 6.5L V8 diesel engine, the goal was to build an engine that was reliable and durable, with unparalleled performance. From the start, the 6.5L was designed specifically for turbocharging. The secret weapon behind the 6.5L turbo diesel is the GM computer controlled wastegate. This wastegate allows the turbocharger rotor speed and boost to be electronically adjusted as altitude and engine speed change, and as torque is needed. The wastegate helps the engine work harder, but only when it needs help. When you need torque, it's there; when it's not required, the wastegate does not overwork the engine. The payoff is impressive fuel mileage, smooth, quiet operation and the necessary power to complete the job. This uniquely designed wastegate turbocharger delivers quick throttle response during acceleration and reduces turbo-boost pressure after obtaining maximum torque. The wastegate is designed to prolong turbo life and help manage the overall stress on internal engine components.

The question is: Many people pooh-pooh the GM computer-controlled system, saying it is not good, unreliable, produces poor boost, etc. It seems that the advantage is that it has a much greater flexibility, being controlled by the microcontroller. Would it not be better to go with reprogrammed chips/controllers to produce more boost with the stock system than to go to a mechanical wastegate controller?

Your opinion?

Sincerely,

Rob :)

If you're ok with keeping up with which part is failing in the vac controlled system, the stock set-up will do what is says and keep the boost at a moderate level. This is probably the way to go if you'd like to see 400,000 mi. on your engine.

The adjustable spring opens a big can of worms, how should the ECM be "fixed"?, flash resistors? how much can I run? and then there's the smilage factor. That stuffs addictive.

smooth and quiet???? maybe for a diesel, but I've found that it's actually smoother and slightly quieter with a little extra help from the turbo. It sounds like the engine is working lighter than with the stock ecm.

Well I think I'm on my 4th or 5th wastegate solenoid @ $35 each, and 2nd vacuum pump @ $125 for a total of around $400 so i guess thats not to bad for a truck with 215,000 miles on it. I guess that can be called reliable if you divide the cost over the miles I have, but not durable IMO. Once you get your boost gauge you'll see why they say reliable and durable since the gauge sit on 0psi most of the time. I'm not looking for ton's of boost just maybe a steady 9 to 11psi with a max of 15psi. But that just my thinking.

Whats the down side to the constant boost? I have the turbo master that I removed because on the road the motor always had boost, 6lbs on the highway under light throttle where with the stock system it would be 0-3 lbs.

Whats the down side to the constant boost? I have the turbo master that I removed because on the road the motor always had boost, 6lbs on the highway under light throttle where with the stock system it would be 0-3 lbs.

Was that with the light spring or the heavier one?

Not sure now.

Kennedy is a OEM waste gate control fan and as long as you want to again keep the system working then fine. On my truck the little plastic lines that the suction goes through got all cracked and broke and guess what the dealer parts department could NOT find a part number for is so Turbo Master to the rescue and off with the vaccum pump and now I have 1993 belt on it and NO more problems. With OEM PCM you can run about 9-10 PSI boost with out code problems.

Kennedy is a OEM waste gate control fan and as long as you want to again keep the system working then fine. On my truck the little plastic lines that the suction goes through got all cracked and broke and guess what the dealer parts department could NOT find a part number for is so Turbo Master to the rescue and off with the vaccum pump and now I have 1993 belt on it and NO more problems. With OEM PCM you can run about 9-10 PSI boost with out code problems.

On Heath's site, it sez: Not recommended for use with the factory computer programming.

Anyone know why?