What Drives the Turbo?

[Doc Tinker]

OK guys, I want to know what drives the turbo.

Is it:

Exhaust Gas Pressure
or
Exhaust Gas Heat
or
None of the above

 

[C-Series-Man]

Technically it is "exhaust gas velocity pressure". Basically that is a combination of pressure and temperature. It takes into account that the same volume of gas at a higher temperature will drive the turbo faster and vise versa. It is the pressure that is generated from the velocity of the exhaust being pushed through the exhaust manifold and trying to go through the turbo. Basically yes, it's the pressure just keep in mind that temperature plays a roll in it. Clear as mud?

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95 Ford F-350 4x4 Ext Cab, Cummins 6CTAA 8. 3, Fuller 9 Speed, Big Rig Heart in a Pick-up Truck

 

[jwgary]

The kinetic and potential energy of the exhaust drives the turbo. It is stored in several ways, pressure, velocity, and heat. The pressure differential across the turbo determines how fast the exhaust can flow through. The molecules transfer their energy to the turbine by coliding with it. Since the exhaust stream is giving up energy, there will be a drastic temperature drop (up to 500*) fro pre- to post-turbo.

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B I G O R A N G E AMBER-FIRE (BURNT ORANGE) / BRITE SILVER 2001(. 5), 2500, SLT, Q-CAB 4x4, SWB, AUTO, 3. 55, LSD, TOWING PACKAGE
ADD-ON'S: LINE-X, 1/4" STEEL LONGHORN HITCH COVER, WESTIN NERF BARS, YELLOW-TOP OPTIMAS

 

[Papa Joe]

Ever hose off the lawn mower and get a wheel spinning with the water stream from the nozzle?
The momentum of the gas and differntial pressure from the turbo inlet to the turbo outlet drives the turbo. Temperature is a factor. This explains why the veins that carry the exhaust gas get smaller along the path (cooler gases occupy less space) to the outlet from the turbo.
Answer: Pressure.
#ad
Joe

 

[illflem]

Gee, and I always thought it was the boost pressure from the turbo making a circle from the intake to the exhaust that spun it #ad

 

[Papa Joe]

Hoof and mouth disease... ... ... ... ..... #ad

 

[HDH]

OK guys, I want to know what drives the turbo.

Is it:

Exhaust Gas Pressure
or
Exhaust Gas Heat
or
None of the above


Its Both (All Of the Above).
Doug.

 

[CannonBall]

Yeah, what he said, or something like that.

 

[JyRO]

Maybe that's what drives the turbo on your engines, but I popped my hood the other day when it was idling, and looked around in the turbo area and noticed a gerbil (sp?) on a little wheel. Poor little gerbil was sweatin' like a ***** in church. But he can make a hell of a boost. I read in my owners manual that the increase in noise (acceleration) scares him and makes him run faster. The time it takes him to actually get scared and react from the noise was originally called, "gerbil lag. " But in an effort to deter protests by animal activists (who know nothing about engines), they decided to blame it on the turbo and call it, "turbo lag. " Thus the whole animal activist scenario was avoided.

Ram Ahead! (Gerbil Powered, my gerbil can kick a PSD's gerbil's a$$)

- JyRO

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Y2K 2500 Cummins ETC/DEE, SLT+, 4X4, Quad, LB, Intense Blue Sport, 3. 54 LSD, rear aux. springs (camper special), sliding rear window, all options except cab clearance lights including agate leather, totally stock engine, silencer ring removed, "stealth," mod to run fogs with high beam. (20. 8 mpg @ 70 mph) Since everybody else listed their toys, I will too.

2000 Toyota 4Runner SR5 4X4, 5-speed, 3. 4L V6 (25. 5 mpg @ 65 mph)
1995 Kawasaki ZX6-R, 97 H. P. @ Rr tire, 6-speed, . 6L I-4, 410 lbs. wet
- (60+ mpg @ 65 mph, but who can do that?) (For Sale)-[SOLD]
1990 Toyota Celica STX, FWD, 5-speed, 1. 6L I4 (36+ mpg @ 65 mph)
1983 Mazda RX-7 GSL Limited Edition RWD, 5-speed, 1. 1L Wankel (For sale)
No auto trannies in my home! Just say, "No!" to auto trannies.

 

[Doc Tinker]

And here I thought you had another use for that gerbil. #ad

 

[Doc Tinker]

Does more RPM = more exhaust pressure?

If so... why does my boost pressure drop after I reach cruising speed (2100 rpm) and why does it rise when I'm pouring it on at lower RPMs?

Maybe tempurature plays a BIG part?

Doc

 

[MCummings]

When you get on the gas,, the diesel fuel that is put in the combustion chamber expands and makes MORE Air than originally went into the engine.
When cruising the engine has a set amount of air that enters the engine, and a set amount of air that exits the engine.
When you pour on the fuel, instantly more air starts coming out of the engine than is going in.
The air going out of the engine starts spooling up the turbo, and in turn, makes more boost.

Diesel, When burned Expands. So,,More diesel fuel, more "Expansion" (aka "Exhaust Gas)=more Boost

When you are cruising, your Throttle is at 50%, which means your engine is getting "XX" amount of fuel, which will make "X" pounds of boost.

When giving the engine lots of gas at low RPM's. The Throttle is at 100%. Which means the engine is getting "XXX" amount of fuel, which will make "XX" pounds of boost.

Hope this Kinda Helps,, I know there are alot of Mathematical ways to figure this out, But I am not so good at math.

Merrick N. Cummings Jr.


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1998. 5 Dodge 3500, 2wd
5-Speed, Light Driftwood
Replaced the Resonator and Muffler with 6ft of 3" Aluminized pipe.

 

[NVR FNSH]

Bomber_101,
You're gonna have to try this one again... . "it makes more air"?

Brian

 

[Dennis Garrett]

the short answer is "hot, expanding gasses"

 

[Power Wagon]

Ok... follow this carefully:

Cold air is inducted into the cylinder, compressed to make it hot, and then fuel is injected. That air rises from 90 degrees, to over 1200 degree in the process of getting from the air filter to the exhaust valve. Heating air (or anything else) causes it to expand, which is what drives the piston down in the cylinder, losing some of that heat as it expands. Yet, the volume those gasses occupy is MUCH greater than that which entered the engine. So, now you take that (still) expanding exhaust and nozzle it down, point it at a spinning turbine wheel, and that very fash rush of gas past that wheel makes it spin. The rush of the piston coming back up and the open exhaust valve will generate quite a bit of force. Piers measured 75PSI on a hot (bombed) engine with a 12CM exhaust housing.

Why do you lose boost at cruise or when you let off the pedal? Simple, you're burning WAY less diesel, which makes less heat, so therefore the volume of gas forced past the turbine wheel is far less.

Of course, engine rpm influences the boost, but the amount of fuel burned does as well.

 

[MCummings]

^^What Power wagon Said^^

"Makes More Air" um,, "Air Expands",,is what I meant to say.

I'm not the brightest Bulb on the Block... . #ad


Merrick N. Cummings Jr.



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1998. 5 Dodge 3500, 2wd
5-Speed, Light Driftwood
Replaced the Resonator and Muffler with 6ft of 3" Aluminized pipe.
3. 55 rear-end
A. R. E. Camper
Michelin 245/75/16's

 

[Papa Joe]

As I said... ... ... ... ... ... ... pressure (pounds exerted per square inch of surface area of turbine blade). Love you guys #ad


PS No flames, had a bad day #ad

 

[Bill Lins]

Turbos are driven by the same thing that drives this forum- HOT AIR! #ad


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Bill Lins Wharton, TX 98 2500 QC SLT,12 (the CORRECT # of)valves,NV4500,3. 54 LSD,Manik grille guard,Semi-Psychotty Air,Amsoil everywhere, Reading aluminum utility body and bumper,Optima yellow tops- silencer ring & muffler stolen.

 

[Andy Perreault]

Hey, all I know is that it works, so let's not mess it up by questioning it!

Here's a quote for you:
"You're better off not knowing how laws and sausages are made. "

What I'd like to know is:

What happens if you get scared half-to-death twice?

How is it that coincidences always manage happen at the same time?

Why is "bra" singular and "panties" plural?

 

[JyRO]

Bill and Andy - If we could just harness the hot air we put out to boost our daily performance. Man! I'd like to improve my output! How can we do it? #ad


If you scared yourself half to death twice, you'd be only 1/4 alive. Theoretically you could continually scare yourself half to death, cause in doing so you'd never scare yourself completely to death. #ad


Now about the bra being singular, panties being plural. Oooooh, that's deep, I don't have anything for that. I'll ask my wife about it, she knows everthing.

Am I really the only one who's turbo is propeled by a easily frightened gerbil?

- JyRO