Turbo Project ( A Satoh Beaver with teeth)

[Renze]

As a rule of thumb, any Diesel needs a waste gate when you want more than 25-30% torque backup. Which means most commercial engines currently produced, have them.

As for the Detroit 2 stroke diesels, i believe they arent really known for their low end torque...


Both my previous Volvo 440 1.9 TD (which is now in the buggy) and my daily driver (Volvo 850 2.5 TDI) have a waste gate that opens when the intake manifold pressure overcomes the resistance of a spring loaded valve.
The 850 has a mechanical Bosch VE rotary pump, but does have electronic throttle. The 440 buggy motor has a French CAV pump which is purely mechanical.

 

[rock2610D]

"Both my previous Volvo 440 1.9 TD (which is now in the buggy) and my daily driver (Volvo 850 2.5 TDI) have a waste gate that opens when the intake manifold pressure overcomes the resistance of a spring loaded valve."

Could you be a little more specific on the above statement? I do understand the theroy behind a wastegate and assume (maybe incorrectly) that a waste gate will open a exhaust valve type gadget in the exhaust side of turbo and actually reduce the speed of the tubine. How can you get "torque backup" with a turbine that actually is spinning slower?

I do understand that a BOV on a gas engine will releave intake pressure and turbine will keep spinning at a high RPM, but anything that reduces exhaust pressure on the turbine will slow the turbine and thus reduce torque???

I have a wastegate on my turbo and have it disconnected. Are you saying I will get better performance with the wastegate hooked up???

 

[Renze]

How can you get "torque backup" with a turbine that actually is spinning slower?

I have a wastegate on my turbo and have it disconnected. Are you saying I will get better performance with the wastegate hooked up???

You dont just add a waste gate to a turbo: When a waste gate is added to the same engine, a more effective turbo is used, capable of higher boost levels and spooling up at lower engine RPM. To limit the boost on this "hotter" turbo, the waste gate limits the boost when the engine gets into higher rpm.

This means, the turbo picks up at lower RPM, allowing for more torque if the fuel injection is adjusted the same way. At higher rpm where the turbo might harm the engine, the waste gate opens.


When the same engine is used with, and without a waste gate, the waste gated engine will use a different turbo capable of much more boost. The full capacity isnt used at higher rpm due to the waste gate blowing it off, its just the better performance at low and mid rpm is what the engine developer was seeking.


locking a waste gate wont get less performance, unless you change for a turbo that achieves the same max. turbo pressure as the original WITH the waste gate. The latter would have turbo lag and poor low end performance.

 

[ripplefct]

OK now your loosing me. All I know is, I have some extra power to play with now, and it sounds really neat to hear it spool up. My smoke problem is not so noticeable. In fact when the governor kicks in when under load the turbo keeps right up with it. Boost jumps emediatly. So I must have chosen pretty close for what I wanted it to do. We will see how it operates this winter with the colder air. Didn't get to use it this weekend... to much rain and snow. But No its time to move onto my next project. I bought a Ford 1210 4x4 with a hydrostatic trans. its an no runner. I have my hands full with this one. I'm going to do a full restore on this one. So I will probably start a new thread on this one.

Rip

 

[Savagepike]

Good information, I wish I had the kahonies to install a turbo on my mahindra. I love my turbo car, and would love a matching turbo'd tractor
I actually tried contacting some turbo manufacturers with the specs of my engine to get a properly sized unit, but when they learned it was for a tractor I was not taken seriously. Oh well, maybe I'll get around to installing one someday, I'd love the extra power.

 

[Renze]

ripplefct, just think of it like cultivating with a small tractor and a big tractor.
Small tractor uses, lets say, 10 liters of diesel per hour.
The bigger tractor's fuel pump has a limiting device that prohibits the fuel consumption to go above 10 liters per hour. So, both the big and small tractor are limited in using 10 liter of fuel per hour, the small tractor by the max capacity of the injection pump, the big tractor by this limiting device, even though the fuel pump could inject a lot more than 10 liters per hour.

When we go to work, the small tractor would only reach max power, and the max 10 liters per hour fuel consumption, at high rpm where it reaches max. power.
The bigger tractor would already reach the same power, and the same fuel consumption, at lets say 1500 rpm. Because the total fuel consumption is limited, and the limit is reached at 1500 rpm, the engine will have about a constant power level from 1500-2200 rpm where the smaller tractor can only get to that power and fuel consumption at 2000 rpm.


A turbo with a waste gate, is the SMALL tractor with the ENGINE of the BIG TRACTOR, capable of overloading the entire drivetrain. The limiting device on the motor, makes sure you can use the mid and low end performance of the bigger motor in that small tractor, without overloading it with its peak power.


So, when an engine maker adds a waste gate to an existing turbo engine, they dont just add the waste gate because the turbo wouldnt create enough boost to open that waste gate anyways.

If the manufacurer chooses to use a waste gated turbo instead of a stock turbo without the waste gate, he would allways use a more powerful turbocharger and use the waste gate to limit the maximum boost, to reduce overboost and overstrain.

Turbines work by converting gas speed into pressure. They do nothing at low rpm. They need to spin at a certain speed before they actually start making pressure. Then the pressure increases exponentially with the speed increase. (within reasonable limits)

Because of this characteristic, a turbo without waste gate would pump in way more air than necessary at high rpm. if it would keep up with the natural torque characteristics of a non-turbocharged engine.

If you have a strong engine that just has a gentle boost to get 20% more power, its not really a problem.
But if you have a modern 4 cylinder tractor engine of 4 to 4.5 liter, putting out 75 hp without turbo, and 150 hp with the full turbo package, (which means double the amount of air is pushed in) this turbo characteristic would result in outrageously and harmful overboost at 2000 rpm if the turbo had to be sized to keep up with the air requirement of the engine at 1500 rpm.

.... i hope you're with us again ??

 

[schmism]

something i read in a diesel tuning artical for 4x trucks....

"you cant run a diesel to lean"

just cram more air in there

 

[rock2610D]

Just want to clarify that the turbo used in this thread is a turbo with a wastegate incorperated into the exhaust housing like the one I have. Not an aftermarket add on.

Please do not forget about elevation. Not sure what ripplefct's elevation is but I am at 8000 feet. Turbo makes tractor breathe better. Activating my wastegate would limit my boost to 4-6 psi instead of 8 psi. Up here that means I am only boosting an equivalant 4 psi with out wastegate hooked up. Given there are density and temps to comply with.

Reguardless, I can "feel" the difference with the turbo and tractor seems to like it. It is possible however that a wastegate activating at say 6 psi "could" be benificial, I tend to think it would be because of the reduction of exhaust backpressure due to wastegate opening at higher rpms. It is my belief that if I have enough boost to burn all fuel at 6 psi that is all I need. Right now I have no way other than smoke to determine if all fuel is being burnt at 6 psi..

What it boils down to is at 8000 feet a turbo ,in my mind, is needed to bring tractor back to MFG recommended air flows. I added a little because I believe my tractor runs rich and extra O2 helps it run more efficiant.

 

[xlr82v2]

Rock,

You are correct. at 8000 feet, your first 2-3 lbs of boost are used up just bringing the pressure in the intake manifold back down to sea level. So, in effect, running 8 lbs of boost at 8000 MSL is the same as a guy at sea level running 5lbs of boost. You are both going to make the same horsepower.

 

[rock2610D]

My air pressure here is about 11 psi. Sea level I think is 14.7 ish so I believe turbos do help in high elevation situations.

Just a note here. I believe that a turbo that produces around 8 psi at high elevations will produce MUCH more boost at lower elevations due to the increased density of the air. It is very possible that I would have to use a wastegate at sea level. I would bet that my turbo would produce over 12 psi at sea level.

This is another reason that I belive many "newer" diesels have wastegates. Wastegates will allow a vehicle to go over mountains and thru valleys and always have the same boost pressures. And not hurt the engine with overboost situations. Like I typed, my tractor at sea level would definately over boost and create a situation that I do not want. IE 12 or more psi....