Weird question about turbos???

[89accordlxi]

I was just wondering how fast are exhaust gases moving in order to spin a turbo? In terms of psi, at what pressure do exhaust gases exit the combustion chamber?

I know this might be a stupid idea and not very practical or efficient, but lets say instead of using our exhaust to turn the turbo, could we not find an alternative way of spinning the turbo. Compressed air, leaf blower, vacuum? I just want to know what kind of pressures are we talking about in order to spin a turbo to produce lets say 5 psi..

I realize that this is a very stupid question but I am just curious, and a little ignorant on how turbos work..

Thanks for any insight into this matter..

peace..

[NXRacer]

i imagine you'll need a lot more then a leaf blower to turn the turbine and get consistant power out of it. If you wanna go that way, why not just connect the leaf blower directly to the intake manifold.........

[89accordlxi]

Originally posted by NXRacer
why not just connect the leaf blower directly to the intake manifold.........

Well, that's sort of why I'm asking. I don't think a leaf blower alone would produce enough pressure to be benificial. I don't know what the effeciency ratio of a turbo is. Is it pressure out = pressure in, or is it pressure out = 1/2 pressure in , or pressure out = 2x pressure in? I don't know.. I don't know if the turbo is creating any sort of mechanical advantage to increase the pressure coming out from what is going in, or does it lose energy from what is going in. My thoughts are that the exhaust is exiting the combustion chamber at a pretty high velocity. And instead of wasting that energy, turbos are designed to take that wasted energy and turn it into useful energy to benifit the engine. Right???
So maybe the exhaust is turning the turbo with 20-30 psi of energy, but the turbo only produces 5-10 psi. Or does the turbines of the turbo produce some sort of mechanical advantage where it actually increases the psi of what is coming out of the engine????? if that were true, then that is why I'm asking if a leaf blower could work. Lets say the leaf blower can only produce .5 psi. Use that to spin the turbine of a light weight turbine to produce say 2-3 psi. But if that isn't how a turbo works than this procedure would not work.

Anybody else have any comments or insights..

[NXRacer]

you can change the effinciency of turbo turbines by doing hybrid turbo setups. You can have a larger exhaust turbine and a smaller impeller ( i think thats what they call it). Like the t3/t4's. With a bigger exhaust turbine, the turbo will spool up faster thereby creating more boost faster. I'm not sure what the ratios are though, but i've heard there is a good book to get that has TONS of info on everything you'd ever want to know about turbos, turbo systems, and installing turbo systems on your car.

I havent had a chance to look at it yet, but i read the first few pages on amazon and it looked pretty damn good to me.

Maximim Boost: Designing, Testing & Installing Turbocharger Systems by Corky Bell

Hope that helps a little.

[BootMachine]

I hooked a leaf blower to my intake once...I noticed a VERY SMALL amt of bottom end.....top end lacked because the engine was sucking air faster than the leaf blower could put out.

The exhaust gas commout out of the engine is very fast and can build VERY high pressure. One time I put my hand over my intake to try and stall my car....not smart...the suction was so strong I almost broke my hand.

The turbine of a turbo spins at 160 000 RPM...a Dremel tool at full tilt only spins at 30 000 RPM....this is why the turbo is so expensive. The turbine must be 100% true or it would fly apart. In order to provide the engine with positive pressure you gotta move A LOT of air.

ALSO..the turbo puts in MORE air than the engine puts out. The exhaust side of the turbo is smaller and has a diff shape than the compressor side. You can tune the way your turbo works by using diff size compressor wheels and exhaust turbines!

The best way to build big PSI fast is

a) Stage your turbos....small turbo dumps into a larger turbo which dumps into a HUGE MONSTER turbo for 5th gear redline!

b) have a very light weight turbine/compressor. Garett has some made out of ceramic. BIG BUCKS THOUGH!

[A20A1]

The exhasut pulses move at the speed of sound, I think I read that some where.... though the exhaust gases may travel slower then the pressure wave.

[89LxiAg]

According to many of my aerodynamics texts, the turbo functions much like a gas turbine engine EXCEPT no fuel is added inside the turbo housing.

The rotor, or exhaust turbine, is spun by exhaust gases through a momentum exchange - not necessarily a pressure difference. Thus the use of exhaust gases is perfect since they are already moving very quickly. The impeller, spun on the same shaft as the rotor, utilizes a centrifugal design to pull air in and compress it in a radial direction. Blah Blah.

My point is this: in order to extract any benefit from the turbo, you have to make it as self-sufficient as possible. Any extra equipment adds weight (leaf-blowers, air tanks). Also, these devices have their own inefficiencies that compound upon the inefficiencies of the turbo. Even though it may seem like you can get something for nothing with a leaf-blower, you have to expend more energy to power it than you will gain from the increased intake velocity.

I think that in order to gain more power, you have to use lighter stronger materials for the car and engine; cool the incoming air charge more; increase the pressure of the intake air; relieve exhaust pressure quicker; and use a more energy-dense fuel than gasoline (i.e. rocket fuel or alcohol).

Ok, I've said enough.

[89accordlxi]

That's some good info peeps. I knew you guys had it in ya.

Keep em coming...

[smufguy]

like mentioned the turbo spins at around 30,000 to 35000 rpm on avg. And to attain this much amount of rotational speed is uncanny unless u have a powerful motor to spin it. Also u have to know that the turbo spins at different speed at different rpms and this means that it packs different amount of Air into the cylinders (with no boost control). But this is why we have boost control. To have an external device to spin the turbo or to say an external device to pack certain volume of air is a bit to hard of a task but can be done and this would lead to a constant amount of pressure or volume of air at any given engine speed. If anyone can do this mechanism right, then say bye bye to ur wastegate and ur boostcontroller cause baby ur saving a fuck load of money on these fancy electrical gadgets.

[BootMachine]

Originally posted by smufguy
like mentioned the turbo spins at around 30,000 to 35000 rpm on avg. And to attain this much amount of rotational speed is uncanny unless u have a powerful motor to spin it. Also u have to know that the turbo spins at different speed at different rpms and this means that it packs different amount of Air into the cylinders (with no boost control). But this is why we have boost control. To have an external device to spin the turbo or to say an external device to pack certain volume of air is a bit to hard of a task but can be done and this would lead to a constant amount of pressure or volume of air at any given engine speed. If anyone can do this mechanism right, then say bye bye to ur wastegate and ur boostcontroller cause baby ur saving a fuck load of money on these fancy electrical gadgets.

you forgot a 1 (one)

A turbo spins at 130 000 RPM...not 30 000 RPM....

well...for the most part....I'm sure some are faster and some are slower!

[johndej]

yeah, if your really interested in all of this, go get the june 2003 sport compact car mag (titled "crazy boost on any budget") and they got a whole shit load of graphs, charts, turbo matching guide, and other shit that can be really infomative on the topic. oh yeah, turbos can reach up to 165000 rpms at the top end. more revs = more exhaust = more boost build up.

[PogiLXI]

hmmm. I think hes asking, how much power does it take from the Exaust to make one PSI of boost?????

[AccordEpicenter]

depends on the turbo, exaust velocity and volume, how much air the engine needs etc... tons of variables

[PogiLXI]

hmmm, very true. Well I think to answer the Leaf blower question. Thats just PUSHING the air faster. a Turbo COMPRESSES the air. The air in a leaf blower doesnt compress the air anywhere NEER a Turbo.

[89accordlxi]

Originally posted by PogiLXI
hmmm. I think hes asking, how much power does it take from the Exaust to make one PSI of boost?????

Or in general, how much power from any source would it take to produce 1 psi of boost?


Originally posted by PogiLXI
Well I think to answer the Leaf blower question. Thats just PUSHING the air faster. a Turbo COMPRESSES the air. The air in a leaf blower doesnt compress the air anywhere NEER a Turbo.


So I guess the next question then, is what is the difference between a blower and a compressor? Is a compressor the same as a blower but much faster? Or does a turbo act more like a pump that can move large quantities of air. Because yeah, a standard air compressor can produce up to 150 psi, but it can't move enough air to supply an engine, and a blower can move a lot of air but not at high pressures.
Or is it the design of the impellers that helps them to compress air at high volumes.. I just don't know. This whole topic is starting to make my head hurt.

Changing topics now. Ok, It seems every body agrees that turbos can spin in the 130,000 rpm range and up. On an average turbo at that speed, what is the max psi that the tubo is putting out? I'm sure it is probably a lot that is why the wastegate was invented so that turbos can be tuned to limit the amount of boost coming from the turbo. So lets just say, for argument sake, that a certain turbo puts out 9psi at 120,000 rpm. Is it save then to say that if you only wanted 3 psi, the turbo would only have to spin at 40,000 rpm? Or is that logic not correct???


Anybody have anything else to add?????

[smufguy]

different kinda turbo needs to spin at different rpm to produce 1psi of gas pressure. This is the reason a lot of people go with Hybrid turbos, the cold side and the hot side from two different turbos. So if u want to know about one single turbo, then u gotta be specific like a T1 or a T3 or something like that.

NOTE: I aint a turbo god or anything, but i know something very basic about em. I aint technical on turbos :(

[BootMachine]

Originally posted by 89accordlxi
Or in general, how much power from any source would it take to produce 1 psi of boost?




So I guess the next question then, is what is the difference between a blower and a compressor? Is a compressor the same as a blower but much faster? Or does a turbo act more like a pump that can move large quantities of air. Because yeah, a standard air compressor can produce up to 150 psi, but it can't move enough air to supply an engine, and a blower can move a lot of air but not at high pressures.
Or is it the design of the impellers that helps them to compress air at high volumes.. I just don't know. This whole topic is starting to make my head hurt.

Changing topics now. Ok, It seems every body agrees that turbos can spin in the 130,000 rpm range and up. On an average turbo at that speed, what is the max psi that the tubo is putting out? I'm sure it is probably a lot that is why the wastegate was invented so that turbos can be tuned to limit the amount of boost coming from the turbo. So lets just say, for argument sake, that a certain turbo puts out 9psi at 120,000 rpm. Is it save then to say that if you only wanted 3 psi, the turbo would only have to spin at 40,000 rpm? Or is that logic not correct???


Anybody have anything else to add?????

The turbo works the SAME as a leaf blower. BUT....instead of using an electric motor to spin a compressor a turbo uses another turbine wheel with exhaust spinning it. The leaf blower turbine and the turbo turbine look a lot like the same thing...just a few diff shapes and one is plastic and the other is metal/ceramic!

The leaf blower can produce prob about 3-4 PSI of boost if you have a nice one but can not keep up with the volume of air required by the engine. The turbo's turbine is designed to push a lot of air when its spinning VERY fast so it can keep 3-4 (or even more) psi of pressure at high engine rpm.

Its all in the design of the turbine and the housing. Changing the shape of the housing/turbine even a little bit changes the way the specific turbo will work.

You will get to a point when the turbo is spinning so fast it "cavitates" in the air and just causes it to get hot....no compression just heat. This kills the turbo very fast. Same with a prop in the water...you spin it TOO fast and you dont go anywhere...you just get froth!

The only reason the turbo "compresses" the air is because its shooting out so much. Think of a house fan....it can produce like 0.1psi of pressure if you fired the air down a pipe and measured it. A turbo just shoots out A LOT more air and because the air has nowhere to go (inside the intake) it compresses!

You know on big trucks on the highway you can hear the turbos! That sound thats like a camera flash charging up...a VERY high pitch whistle thats gets louder. Thats from the turbine blades spinning so fast!

Every turbo is diff in shape and design..the dynamics of a turbo all depend on the shape/size of the compressor wheels and housing!

[BootMachine]

If you want to know even MORE about tubos you can go and check this out!

CLICK HERE FOR TURBO INFO (http://auto.howstuffworks.com/turbo.htm)

Flip through the pages and learn brotha!

[PogiLXI]

k, so heres the conclusion. A Turbo is like a leaf blower, but a Turbo can spin MUCH MUCH faster then a Leaf Blower, Thats why the PSI is so Great.

One more Question, Ever see those Drag imports? They have some SERRIOUS Custom Exaust. The exaust isnt like just some wicked headers. the headers are Long!!! and on the exaust theres a Huge Pill looking shape Right before the Turbo. WHAT IN THE HELL is that? Ive seen it before. but on dirt Bikes, and Go-Peds.

[BootMachine]

its an expansion chamber.

Go to the web site I posted about turbos and you can learn about those too!

[PogiLXI]

ahhhhh, I see. Expansion Chamber, In any motor the Valves over lap, so there is some Air and Gas being pulled out so when the Exaust hits the expansion chamber it pushes it back in. KINDA like a turbo charger. but with out any moving parts, KOOOOOOO. I wonder why any street turbo car dont have these. hm..........