Controlling a vnt with wastegate?
Controlling a vnt with wastegate?
Thinking of a regular pneumatic actuator connected to the vanes. And an additional wasegate. Using a fairly small turbo.
-Have a microswitch connected to throttle pedal. Below a certain engine load (cruisemode) the wastegate will regulate intakemanifold boost to 5 psi. Vanes fully closed position.
-When throttle is advanced beyond cruisemode an electric valve will close the boostline to the wastegate. Wastegate closes.
-manifold- and exhaustboost builds up. VNT actuator opens and will travel to its mechanical stop. Let`s say 15psi.
-Exhaust pressure and temp will further increase as exhaustflow exeeds the small turbo designlimits.
-Now is my golden thought. Have the WG open at a certain EGP. Have a pressureline directly from exhaustmanifold to wastegate diaphragm. 25 psi EGP maybe? Maybe a "exhastgas intercooler" is needed in exhastpressureline to avoid frying the WG diaphragm..?
-This setup will require a pressureline "T" cross, two one-way valves and a pressure regulator(orifice) making 25egp psi become 5psi on the wategateclock.
With this setup the manifoldboost will only be controlled at bottom and far end of the pressurescale. Unlike FI`s 0-5-10-15psi thoughts.
Any thoughts or comments? SHOOT!
I have also been hired to work on a bosch electro-diesel workshop the rest of this year. Good times
I am finally a happy MB owner. 1988 190e 2,5td
Thinking of a regular pneumatic actuator connected to the vanes. And an additional wasegate. Using a fairly small turbo.
-Have a microswitch connected to throttle pedal. Below a certain engine load (cruisemode) the wastegate will regulate intakemanifold boost to 5 psi. Vanes fully closed position.
-When throttle is advanced beyond cruisemode an electric valve will close the boostline to the wastegate. Wastegate closes.
-manifold- and exhaustboost builds up. VNT actuator opens and will travel to its mechanical stop. Let`s say 15psi.
-Exhaust pressure and temp will further increase as exhaustflow exeeds the small turbo designlimits.
-Now is my golden thought. Have the WG open at a certain EGP. Have a pressureline directly from exhaustmanifold to wastegate diaphragm. 25 psi EGP maybe? Maybe a "exhastgas intercooler" is needed in exhastpressureline to avoid frying the WG diaphragm..?
-This setup will require a pressureline "T" cross, two one-way valves and a pressure regulator(orifice) making 25egp psi become 5psi on the wategateclock.
With this setup the manifoldboost will only be controlled at bottom and far end of the pressurescale. Unlike FI`s 0-5-10-15psi thoughts.
Any thoughts or comments? SHOOT!
I have also been hired to work on a bosch electro-diesel workshop the rest of this year. Good times
ForcedInduction
11-13-2009, 12:35 PM
#2
It sounds pretty much the same as what I'm doing but with pressure instead vacuum.
In situations where the exhaust manifold pressure is highest, you need boost the most. For example accelerating with a cold exhaust manifold and turbo (from a standing start) and high rpm full load is where you need boost. An exhaust manifold actuated wastegate will drop boost in these situations and lead to excessive EGT's.
Opening wastegates or vanes based on exhaust manifold pressure won't work.
In situations where the exhaust manifold pressure is highest, you need boost the most. For example accelerating with a cold exhaust manifold and turbo (from a standing start) and high rpm full load is where you need boost. An exhaust manifold actuated wastegate will drop boost in these situations and lead to excessive EGT's.
Would it then maybe be wiser to have the wastegate open at ~2psi intakemanifold pressure more than the vnt actuator -and in that way controlling the bypass for the turbo to avoid high emp and egt? I am thinking of start to look for a stock 110hp vw tdi vnt. They can afaik easily push 130+hp. Perfect for a stock fuelpump 602?? Is this idea already doomed?
Oki, see. Learn things every day.
Would it then maybe be wiser to have the wastegate open at ~2psi intakemanifold pressure more than the vnt actuator -and in that way controlling the bypass for the turbo to avoid high emp and egt? I am thinking of start to look for a stock 110hp vw tdi vnt. They can afaik easily push 130+hp. Perfect for a stock fuelpump 602?? Is this idea already doomed?
(11-14-2009, 08:54 AM)lars I am thinking of start to look for a stock 110hp vw tdi vnt. They can afaik easily push 130+hp. Perfect for a stock fuelpump 602?? Is this idea already doomed?
A VNT 15 or 17 would be way too small. A GT2052V would be the smallest I'd look for.
ForcedInduction
11-14-2009, 12:48 PM
#5
(11-14-2009, 08:54 AM)lars I am thinking of start to look for a stock 110hp vw tdi vnt. They can afaik easily push 130+hp. Perfect for a stock fuelpump 602?? Is this idea already doomed?
A VNT 15 or 17 would be way too small. A GT2052V would be the smallest I'd look for.
(11-14-2009, 08:54 AM)lars Oki, see. Learn things every day.
Would it then maybe be wiser to have the wastegate open at ~2psi intakemanifold pressure more than the vnt actuator -and in that way controlling the bypass for the turbo to avoid high emp and egt? I am thinking of start to look for a stock 110hp vw tdi vnt. They can afaik easily push 130+hp. Perfect for a stock fuelpump 602?? Is this idea already doomed?
High EMP does not create high EGT on a turbocharged engine. I think this myth started with petrol engines and plugged exhausts.
EGT rises with pressure in tune with the ideal gas law. You need a massive increase in pressure to give any meaningful increase in temp. Further, the higher your EMP and EGT's are the more energy is extracted by the turbo and the more boost you get.
You should only be using the vanes and wastegates to control boost based on what you need or what your engine can stand. Attempting to control other outputs will compromise the original goals (i.e. boost control).
(11-14-2009, 08:54 AM)lars Oki, see. Learn things every day.
Would it then maybe be wiser to have the wastegate open at ~2psi intakemanifold pressure more than the vnt actuator -and in that way controlling the bypass for the turbo to avoid high emp and egt? I am thinking of start to look for a stock 110hp vw tdi vnt. They can afaik easily push 130+hp. Perfect for a stock fuelpump 602?? Is this idea already doomed?
High EMP does not create high EGT on a turbocharged engine. I think this myth started with petrol engines and plugged exhausts.
EGT rises with pressure in tune with the ideal gas law. You need a massive increase in pressure to give any meaningful increase in temp. Further, the higher your EMP and EGT's are the more energy is extracted by the turbo and the more boost you get.
You should only be using the vanes and wastegates to control boost based on what you need or what your engine can stand. Attempting to control other outputs will compromise the original goals (i.e. boost control).
ForcedInduction
11-14-2009, 03:55 PM
#7
I'm not aware of any manufacturer that controls pre-turbo backpressure for anything besides EGR function/flow.
. But too high egp screws up fuel efficiency, right? Googled gt2052v and it looks like it is mounted on quite a few german 2-2,5 diesels from late 1990s and on and should be easily available. All seems to be controlled with a actuator. goodgood.
Thanks. EGP as controlinput is scrapped. But too high egp screws up fuel efficiency, right?
Googled gt2052v and it looks like it is mounted on quite a few german 2-2,5 diesels from late 1990s and on and should be easily available. All seems to be controlled with a actuator. goodgood.
(11-14-2009, 04:24 PM)lars But too high egp screws up fuel efficiency, right?You should only see high exhaust pressures during hard acceleration.
ForcedInduction
11-14-2009, 04:34 PM
#9
(11-14-2009, 04:24 PM)lars But too high egp screws up fuel efficiency, right?You should only see high exhaust pressures during hard acceleration.
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