VGT turbo controller ideas?????

[swank]

well, figure about 130,000 rpms.

the other input i forgot is:

throttle position


that way your not driving down the road with 25 psi of boost, at all times.

[Begle1]

That'd be nice and would save tons of wear on the turbo, but it wouldn't be necessary for operation.

What would be necessary for operation?

{
If Shaft_Speed < Max_Speed Then decrease Exhaust_Housing_Size;
If Shaft_Speed > Max_Speed Then increase Exhaust_Housing_Size;
}

To prevent the constant exhaust braking and wear that would cause...

{
If TPS < Half_Throttle Then do not decrease Exhaust_Housing_Size;
}

I think it all hinges on whether or not you can read the shaft senser and how you are controlling the exhaust housing size...

[Fnschlaud4620]

KTA says there is a shaft speed sensor in the turbo.

All you need is a controller to read TPS for engine Load and RPM, IN the simplest form.

That way when you let off the Throttle your RPM is still high but the load is gone you can keep the housing big.

The problem with using boost is it is only load sensitive. When you are at 3500 RPMS and you let go of the throttle the load is gone and a mechanical actuator will Think MAKE HOUSING SMALL and will overspeed the shaft and SNAP. Alot like Turbo bark.

Granted you can build as elaborate of a system as you want, But I think all you need is load and RPM.

Using a Box such as a MegaSquirt EFI controller which is like $150.00 used will give you a 16 by 32 map. that should be enough.

NO this is not Rocket Science.

This is along the same idea as Electronic Fuel injection. Not that hard.

[Begle1]

If you did it according to TPS and RPM, then you'd have to reprogram your map every time you changed the amount of fuel that you gave it.

A truck with just a little amount of fuel will be able to keep the housing small until a higher RPM under a given throttle position. But if you give that truck more fuel and keep it's TPS/RPM map, it'll overboost the turbo a lot faster than it would've before.

If you controlled the exhaust housing size according to shaft speed, you'd never have to reprogram anything. The only variable would be what you consider the maximum shaft speed.

I think that a TPS signal would only be so that it doesn't exhaust brake itself to death when you let off the fuel at 40 PSI. And that same circuit could be used to control an electric blow off valve.

[swank]

i was just told about this megasquit thing this weekend. i'm very interested in finding out about it. are you familiar with the set up? my brother told me you can have them program it for you and what not?

by a 16 by 32 map, do you mean an x,y type thing?

like i said, i'm all for the development of this. i wasn't trying to discourage the process or anything.

you say you would only need a controller to read tps and rpm, i think you at least need to add the shaft speed in there too.

i think that just running it off shaft speed alone would definitely be the easiest, but i don't think it would be very efficient, which is why i want to run one of these things (or maybe two). can't forget the override switch too, that way you can have a bichin e brake.

[Fnschlaud4620]

There are different types of megasquirts. Do a search there is a ton of info.

Yes, they have x,y maps in 8x8, 16x16, and I think 16x32 I may be wrong though, anyway it depends on what version you get.

I have to work on this, I am thinking about making it a senior design project!

I think you would have to manually monitor shaft speed or it becomes a 3D map.

I think you would have to watch shaft speed and run the engine on a dyno at various RPM and LOAD and if it is too slow shaft speed you input a number that closes the housing, too fast and you enter a number that opens it.

I agree shaft speed alone would be ideal but it is along the same lines as using a boost actuator.

I don't think there will be any type of exhaust breaking without over speeding the shaft and breaking the turbo.

[swank]

there is a switch on the dash of the 6.7's that just keeps the turbo at it's rpm limit, i would think. those new trucks don't have a flapper type brake. don't forget that without any fuel, the turbo isn't going to want to spin.

manually monitor shaft speed? my eyes don't turn that fast.

[Fnschlaud4620]

there is a switch on the dash of the 6.7's that just keeps the turbo at it's rpm limit, i would think. those new trucks don't have a flapper type brake. don't forget that without any fuel, the turbo isn't going to want to spin.

manually monitor shaft speed? my eyes don't turn that fast.

I was unaware that the 6.7s had a switch.

When I say manually monitor shaft speed, I mean just for the initial base map

like when you tune and engine you look at the a/f ratio, power, knock and tune accordingly.

My brain hurts, been thinking too hard

[Begle1]

I think you would have to manually monitor shaft speed or it becomes a 3D map.

I think you would have to watch shaft speed and run the engine on a dyno at various RPM and LOAD and if it is too slow shaft speed you input a number that closes the housing, too fast and you enter a number that opens it.

I agree shaft speed alone would be ideal but it is along the same lines as using a boost actuator.

I don't think there will be any type of exhaust breaking without over speeding the shaft and breaking the turbo.

Running with your insistence-on-a-graph idea...
Instead of using engine RPM in your RPM/ TPS map, use the turbo shaft RPM.

If the shaft is spinning above 120,000 RPM, increase the housing size.
If the shaft is spinning below 120,000 RPM and exhaust brake is "on", reduce housing size.
If the shaft is spinning below 120,000 RPM and exhaust brake is "off", do not reduce housing size until throttle is pressed.

You want the output of the graph to control the size of the turbo. So you probably want it to output a 0-5 voltage that can go to a PWM that can go to an electric servo.

If the shaft RPM is 121,000, then increase the housing size a little. If it is 123,000 RPM, increase it a lot. If it is 129,000 RPM increase it as much as possible.

If the shaft RPM is 100,000 RPM, decrease the size of the housing a little. If it is 50,000 RPM, decrease the size of the housing a lot. If it's 20,000 RPM, decrease it even more.

If the "Exhaust Brake Off" switch is turned on, the housing will not decrease in size no matter what the shaft RPM is. If the throttle is pressed, the "Exhaust Brake Off" switch will turn off automatically.

The TPS/ "Exhaust Brake Off" circuit will just interrupt the map's input to the turbocharger, so it isn't going to impact the values on the map at all. I don't see a reason for the TPS or switch position to be separate dimensions on the map.

The million dollar question is how to get the shaft speed value imported into your graph.

Depending on what the shaft speed signal is, it might even be possible to not play around with variable opening and shutting rates and just use an analog circuit that either opens or shuts at a constant rate. Or one that has a dynamic rate that increases automatically the faster the shaft is spinning over a predefined speed.

[swank]

ok. can you write that code?

[Fnschlaud4620]

I am not trying to insist on anything, That is just the only way that I understand it.

I am a Fabricator, Give me a tig welder and I can make anything, NOT a programming engineer.

I see what you are saying with your program. I just dont have that good of an understanding of computer programming.

Ok so if you can write a program, HOW do you suggest we make it move the turbo?

[Begle1]

ok. can you write that code?

If you can get the tach input into a fuel injection or water injection box then there is no code.

If you wanted to condense everything into a plug-and-play black box that would let the turbocharger work on any vehicle, then you would need code.

That black box would take at least a 4th or 5th semester control systems engineer to make. I'm only a 2nd semester control systems engineer, so I need to start with a programmable black box...

[Begle1]

Ok so if you can write a program, HOW do you suggest we make it move the turbo?

How much force does it take to move the turbo? Could an electric servo out of a big RC car do it? Or do we need some kind of hydraulic/ pneumatic set-up?

[cummins king]

a hd servo would do it

[flashgordon]

All of this is way cool !!!

I haven't done any mapping and can only grasp it in theary.......So I won't baffle yeah with my bowl He Hee

The 6.7 exhaust brake is use by this vary actuator in the turbo, that is being discuss.
If it sees any throttle reading it open up to stop the ext brake affect.........under deceleration, it kick out at 20 mph..........They really work much better then the old air blade or Valve in the exhaust.


One question here. Is this turbo a 6.7 turbo or what did it come on originally

Flash