Why would you want to put the A Team Turbo on your 6.5 and replace a 'working' turbo? What else do I need to get the most out of the A Team Turbo? Can I pass Emissions with an A Team Turbo?
Notice I said "Working" turbo when referring to the factory turbo, not 'perfectly working'. Lets take a moment to think about "pumping losses" on a engine. The more suction an engine has to overcome from a plugged air filter or the more exhaust back pressure it has to overcome from a small exhaust pipe, chambered muffler, plugged kitty etc. all take away from power that could turn the wheels. The less exhaust back pressure you have by changing the exhaust to a larger size and using a straight through muffler can gain you 1 MPG in some cases because the engine doesn't have to push the exhaust out as hard. (2002 1500 5.3L V8 long bed results.)
Now we add a turbo. Turbo's unlike belt driven superchargers are supposed to work off exhaust heat not engine power. This is why a turbo is more efficient than a belt driven supercharger because it doesn't use engine power to drive the compressor - it uses waste heat from the exhaust.
Unless you are GM and throw a turbo on that is way too small for the engine. Then the turbo generates boost with no exhaust heat. Adding a boost gauge and watching the turbo generate 6 PSI of boost at 2000 RPM with no throttle. This is referred to as a turbo exhaust brake. Vacuum systems will open the waste gate to reduce this parasitic exhaust back pressure. That is still a pretty darn small hole to shove 6.5L of air through. So the factory turbo is really acting like a parasitic belt driven supercharger.
The Turbo Master is similar to the "spring can" on mechanical injection 6.5's. It is a pretty strong spring and this means high exhaust back pressure before the waste gate opens. This back pressure is what is spinning the turbo to 6PSI of boost with zero heat 'throttle' applied.
If your engine NEVER goes over 2000 RPM (say you are plowing snow?) then the factory turbo is your best choice. The 6.5/6.2 is called a high speed diesel for a reason. Low end is great but will only get you so far before you need the higher speed end for power.
As the engine RPM increases on a belt driven supercharger the airflow and boost increase. On a small turbocharger more heat and RPM blow the waste gate open further and result in extreme back pressure to hold that spring open. Your engine can't breathe and has 30 PSI of exhaust in the cylinder when the intake valve opens having only 20PSI behind it. You reach a point where boost does not increase with RPM or throttle because the waste gate is open. Around 2200 RPM the waste gate is open and you are not going to get anymore boost out of a GM turbo rather, you will just be forcing more exhaust through that small waste gate.
Buddy says the back pressure of the turbo's is as follows:
ATT
To 5PSI of boost 1:1.1
To 30PSI of Boost 1.1.2
GM4
up to 3PSI of boost: 1:1.1
8-16PSI 1:1.4
(GMx choke point is said to be about 14 PSI of boost.)
16-30PSI 1:1.6
I think Buddy's boost experiments is one piece of the puzzle many have been looking for when figuring out why the GMx turbo's are so bad and literally kill power over 2200 RPM. Using the above numbers: The A Team Turbo generates 14 PSI of boost (16.8psi exhaust) with less back pressure than a GM3 (19.6psi exhaust). The A Team then generates more boost, in my case 17 PSI (20.4 exhaust), GMx 17 PSI (27.2) after passing the GMx's choke point of 14 PSI. The choke point of a turbo generates extreme intake air heating with little additional boost as the turbo is being oversped.
Air Intake temperature.
Did I mention when pulling 6%+ grades with a trailer at WOT I was boiling off 1 quart of oil every 500 Miles? Wire looms or anything that got close to the intake was turned into melted goo.
The ATT was giving me around 270 degrees IAT at 17PSI. Compare this, well you can't compare to a turbo in the choke range. But 300+ degrees isn't uncommon for a GMx esp on a mechanical injection unit that doesn't care... Overspeeding the turbo merely takes altitude with a turbo master set to the edge of 14PSI at low elevation.
But wait! The GMx turbo only went to around 6PSI on the mechanical injection trucks. Exactly. We all know what 6PSI doesn't get us. Near 6.2 NA performance with nearly 5MPG less. We are waking up our 6.5's and delivering enough boost to use the fuel the factory injection system is capable of.
What about MPG? The harder you work your truck the lower your MPG will be. However, this is where you can get the most out of a larger turbo. I went from 7MPG to 10.4MPG towing a trailer up 6% grades to Payson. Other owners do report MPG gains. When the turbo isn't spooling up from exhaust flow alone you are going to gain MPG from reduced exhaust back pressure - like for the folks that don't have the mountain passes...
How does an ATT feel? "I have power over 2200 RPM all the way to redline. The engine doesn't choke and loose power like it did with a GM3." The GM3 made me hate automatics as I would loose speed faster above 2200 RPM than below it. Now I have more power to play with above 2200 RPM where I need it.
What else do I need to get the most out of the A Team Turbo?
The ATT comes as a bolt on kit. You supply 2 intake clamps and 2 oil drain hose clamps. You make 2 cuts, one to the intake, upper, and the other to the oil drain tube. The exhaust down pipe connection is easier than the factory turbo to put the clamp on...
I recommend you have an engine and injection system in good shape. This means known injector miles and condition. Clean fuel system like tank sock and all other screens, FFM last ditch, and IP screens clean.
The factory exhaust needs to go. You want a 4" exhaust with an aftermarket down pipe. Inspect the crossover for internal collapse and replace if needed.
Fender snorkels need to go and fender restrictions on the air box need to be cut out as applies to your year. K47 air cleaner boxes with the smaller element are recommended.
A tune will let you get the most out of your Turbo Upgrade.
I recommend a Turbo blanket and header wrap. Wrap the down pipe and crossover. Wrap the headers if you can. Keep the heat down and keep the heat in the exhaust to help drive the turbo.
Can I pass emissions?
Yes.
I have mounted a 4" Duramax converter on my 1995 Surburban and passed emissions. The Converter causes the turbo to make a little more noise, but, we have not seen any performance difference at 17PSI the 6.2 makes. I am not going to bother taking it back off as it would be a waste of time. Forget the ~3" restrictive ceramic POS the factory gave you. The Duramax unit is a spun metal converter with more room between elements so the engine can breathe. Aftermarket makes a 4" spun metal converter you can use. In CA you have to be creative and deal with converter replacement laws...
Notice I said "Working" turbo when referring to the factory turbo, not 'perfectly working'. Lets take a moment to think about "pumping losses" on a engine. The more suction an engine has to overcome from a plugged air filter or the more exhaust back pressure it has to overcome from a small exhaust pipe, chambered muffler, plugged kitty etc. all take away from power that could turn the wheels. The less exhaust back pressure you have by changing the exhaust to a larger size and using a straight through muffler can gain you 1 MPG in some cases because the engine doesn't have to push the exhaust out as hard. (2002 1500 5.3L V8 long bed results.)
Now we add a turbo. Turbo's unlike belt driven superchargers are supposed to work off exhaust heat not engine power. This is why a turbo is more efficient than a belt driven supercharger because it doesn't use engine power to drive the compressor - it uses waste heat from the exhaust.
Unless you are GM and throw a turbo on that is way too small for the engine. Then the turbo generates boost with no exhaust heat. Adding a boost gauge and watching the turbo generate 6 PSI of boost at 2000 RPM with no throttle. This is referred to as a turbo exhaust brake. Vacuum systems will open the waste gate to reduce this parasitic exhaust back pressure. That is still a pretty darn small hole to shove 6.5L of air through. So the factory turbo is really acting like a parasitic belt driven supercharger.
The Turbo Master is similar to the "spring can" on mechanical injection 6.5's. It is a pretty strong spring and this means high exhaust back pressure before the waste gate opens. This back pressure is what is spinning the turbo to 6PSI of boost with zero heat 'throttle' applied.
If your engine NEVER goes over 2000 RPM (say you are plowing snow?) then the factory turbo is your best choice. The 6.5/6.2 is called a high speed diesel for a reason. Low end is great but will only get you so far before you need the higher speed end for power.
As the engine RPM increases on a belt driven supercharger the airflow and boost increase. On a small turbocharger more heat and RPM blow the waste gate open further and result in extreme back pressure to hold that spring open. Your engine can't breathe and has 30 PSI of exhaust in the cylinder when the intake valve opens having only 20PSI behind it. You reach a point where boost does not increase with RPM or throttle because the waste gate is open. Around 2200 RPM the waste gate is open and you are not going to get anymore boost out of a GM turbo rather, you will just be forcing more exhaust through that small waste gate.
Buddy says the back pressure of the turbo's is as follows:
ATT
To 5PSI of boost 1:1.1
To 30PSI of Boost 1.1.2
GM4
up to 3PSI of boost: 1:1.1
8-16PSI 1:1.4
(GMx choke point is said to be about 14 PSI of boost.)
16-30PSI 1:1.6
I think Buddy's boost experiments is one piece of the puzzle many have been looking for when figuring out why the GMx turbo's are so bad and literally kill power over 2200 RPM. Using the above numbers: The A Team Turbo generates 14 PSI of boost (16.8psi exhaust) with less back pressure than a GM3 (19.6psi exhaust). The A Team then generates more boost, in my case 17 PSI (20.4 exhaust), GMx 17 PSI (27.2) after passing the GMx's choke point of 14 PSI. The choke point of a turbo generates extreme intake air heating with little additional boost as the turbo is being oversped.
Air Intake temperature.
Did I mention when pulling 6%+ grades with a trailer at WOT I was boiling off 1 quart of oil every 500 Miles? Wire looms or anything that got close to the intake was turned into melted goo.
The ATT was giving me around 270 degrees IAT at 17PSI. Compare this, well you can't compare to a turbo in the choke range. But 300+ degrees isn't uncommon for a GMx esp on a mechanical injection unit that doesn't care... Overspeeding the turbo merely takes altitude with a turbo master set to the edge of 14PSI at low elevation.
But wait! The GMx turbo only went to around 6PSI on the mechanical injection trucks. Exactly. We all know what 6PSI doesn't get us. Near 6.2 NA performance with nearly 5MPG less. We are waking up our 6.5's and delivering enough boost to use the fuel the factory injection system is capable of.
What about MPG? The harder you work your truck the lower your MPG will be. However, this is where you can get the most out of a larger turbo. I went from 7MPG to 10.4MPG towing a trailer up 6% grades to Payson. Other owners do report MPG gains. When the turbo isn't spooling up from exhaust flow alone you are going to gain MPG from reduced exhaust back pressure - like for the folks that don't have the mountain passes...
How does an ATT feel? "I have power over 2200 RPM all the way to redline. The engine doesn't choke and loose power like it did with a GM3." The GM3 made me hate automatics as I would loose speed faster above 2200 RPM than below it. Now I have more power to play with above 2200 RPM where I need it.
What else do I need to get the most out of the A Team Turbo?
The ATT comes as a bolt on kit. You supply 2 intake clamps and 2 oil drain hose clamps. You make 2 cuts, one to the intake, upper, and the other to the oil drain tube. The exhaust down pipe connection is easier than the factory turbo to put the clamp on...
I recommend you have an engine and injection system in good shape. This means known injector miles and condition. Clean fuel system like tank sock and all other screens, FFM last ditch, and IP screens clean.
The factory exhaust needs to go. You want a 4" exhaust with an aftermarket down pipe. Inspect the crossover for internal collapse and replace if needed.
Fender snorkels need to go and fender restrictions on the air box need to be cut out as applies to your year. K47 air cleaner boxes with the smaller element are recommended.
A tune will let you get the most out of your Turbo Upgrade.
I recommend a Turbo blanket and header wrap. Wrap the down pipe and crossover. Wrap the headers if you can. Keep the heat down and keep the heat in the exhaust to help drive the turbo.
Can I pass emissions?
Yes.
I have mounted a 4" Duramax converter on my 1995 Surburban and passed emissions. The Converter causes the turbo to make a little more noise, but, we have not seen any performance difference at 17PSI the 6.2 makes. I am not going to bother taking it back off as it would be a waste of time. Forget the ~3" restrictive ceramic POS the factory gave you. The Duramax unit is a spun metal converter with more room between elements so the engine can breathe. Aftermarket makes a 4" spun metal converter you can use. In CA you have to be creative and deal with converter replacement laws...
