A turbo logic session

[Wheel House Motorsports]

I just want to pose a really simple question to get some concepts I feel are being missed out there.

How do you spool a turbo, what is the order of events? spare no details.

 

[Silber]

I just want to pose a really simple question to get some concepts I feel are being missed out there.

How do you spool a turbo, what is the order of events? spare no details.

Restricted compressor outlet is the best way.

 

[Hardass]

That's it?

 

[Wheel House Motorsports]

That's it?

Justin must have had a slow night!!!

but seriously. nobody has anything to say?? nobody knows??

 

[tdbaugha]

I am by no means an expert but I have taken a few high level engineering courses in fluid dynamics and compressible flow. I'd like to learn from all you guys that have hands on experience with this.

I mean obviously to spool a turbo you need the exhaust heat energy to be converted to mechanical energy on the turbine/compressor. One common misconception is that the "flow energy" if you will is what is doing the work.. In all actuality, heat is where the majority of your energy comes from.

 

[Boyko]

There is really a turbo god that has control oven you turbo and it is up to that entity to spool your turbo, It is as simple as that

1st event would be a increase or decrease of air pressure at the compressor wheel, depending on if there is o BOV that is active

2nd event would be a increase in exhaust pressure

Am I on the right track

I just make this stuff up so it is wrong

 

[Spaarky]

The exhaust turbine is connected to an air pump that compresses atmospheric air before it enters the combustion chamber. This action works off the rpm of your engine and the load that the engine is under. The higher the load on the engine, the more exhaust gas available to spin the turbine, the more power that can be obtained.

The power needed to spin the centrifugal compressor is derived from the kinetic energy of the engine's exhaust gases.

 

[Wheel House Motorsports]

you guys are all on the right track, but damn, outlaw, boyko, i know you guys already are way ahead of the curve!!! hahah. your cheating.

So we need exhaust energy to create exhaust pressure, driving the turbine wheel, thus spool.

BUT, we got a few steps beforehand we need to adress, is exhaust energy magic? where does it come from?

 

[Boyko]

Ah Ha there is a turbo god,


I seen it was riding with you on that e-tec!

 

[Boyko]

There is a misconception that turbos don’t rob power from you engine to make boost, nothing is free in this aspect! Your engine has to act like a compressor to get that turbo to make boost by raising your exhaust pressure. I think a good system on a 800 the turbo is stealing 12 hp to make 10psi, number is just a guess it could be over 20hp.

This is a simulation from a nitro @ 18 psi max, the turbo needs 32hp to make that boost

 

[Boyko]

Wonder why you don't see the loss of hp the turbo took on a dyno sheet? when you just do the math to figure out how much hp ya got with boost it is close to the dyno numbers?

Dynos measuring boost provide BS numbers, I have yet to see a correction factor that takes into account boost. At sea level yes you can get some good data if it is uncorrected. The problem is there are several SAE correction formulas for standard hp output, because boost is added air pressure above normal atmosphere it should not receive the correction factor. So essentially you end up with a higher hp number after the SAE correction is done.

 

[Spaarky]

you guys are all on the right track, but damn, outlaw, boyko, i know you guys already are way ahead of the curve!!! hahah. your cheating.

Rule #1 - Cheaters always prosper.

Sorry, I think, I know where you are trying to go with this, but I cant put it in mechanical engineer terms.

 

[Wheel House Motorsports]

oh im thinking in very plain terms.

we need a fire to power the turbo, whats needed for a fire? we can easily add all the fuel we need via ECU mods, controllers, etc. whats left?

 

[Iceman56]

Don't fall into the BS of all these "Internet know it all's".... There is a hampster on a wheel in the center section of the turbo. There is an electric prod stuck up its a$$ that is hooked to the TPS.. The more throttle you give it the more voltage the hampster gets up his butt the harder he runs turning the compressor wheel faster.

This is the truth don't let anyone tell you otherwise

 

[tdbaugha]

The power needed to spin the centrifugal compressor is derived from the kinetic energy of the engine's exhaust gases.

Sorry but energy is derived from the heat energy in the exhaust. The work done on the turbine shaft is equal to the change in enthalpy across the turbine multiplied by the mass flow rate. It has nothing to do with the kinetic energy of the flow.

Yes, the faster the exhaust gasses travel across the turbine, the higher the mass flow rate and thus more energy is transfered - but that doesn't have anything to do with kinetic energy.

 

[wrang]

oh im thinking in very plain terms.

we need a fire to power the turbo, whats needed for a fire? we can easily add all the fuel we need via ECU mods, controllers, etc. whats left?

Ignition

 

[Iceman56]

Anyways what are you trying to get out of this thread Ski Dooin it?? You gonna educate everyone on how there running to small of turbos?

 

[TheBreeze]

Once you have a running motor, off boost, you are creating vacuume as your motor is essentially "sucking" air through the compressor wheel. I would assume "boost" is being created when there is enough heat/air pressure in the exhaust that it spins the turbine and thus the compressor wheel with enough speed that it transitions into boost.

I will defer to tdbaugha on all technical terminology from here on out... I am just a dumazz salesman

 

[Wheel House Motorsports]

Anyways what are you trying to get out of this thread Ski Dooin it?? You gonna educate everyone on how there running to small of turbos?

haha, well, if they come to that conclusion on there own, so be it, there are a lot of things that affect airflow to the motor... its not some A+B=C equation to make power. im trying to bring some simple overlooked concepts to light and help people think more about whats going on. a more educated clientele results in demand for higher quality more functional turbo systems. knowledge is power, dont be stuck powerless. not everyone has the time and money to test and try everything on there own, and learn for themselves, thats the beauty of a forum, we can all work together and evolve our sport.

 

[tdbaugha]

im trying to bring some simple overlooked concepts to light and help people think more about whats going on.

I think we're all interested to hear your opinion on things... in detail with explanations if you wouldn't mind.