Queen,
The statement in the article clearly says "more turbo boost". If the waste gate is set to open at 8 psi, then there is nothing that can be done with fuel, temperature, or other variables to get more than 8 psi boost without changing the waste gate.

The waste gate opens to PREVENT any higher pressure to save the motor. That has nothing to do with fuel, turbine speed, temperature, or phase of the moon.

 

Davchr,
As a friendly hypothetical discussion.
We are assuming that with lower combustion fuel the pressure was reaching 8psi.
What if it was only reaching 7.5psi. Which is the more likely scenario.

 

Every turbo car I have been in pops the waste gate when you get on it.

 

Yes, but a point does it open. That's where the higher BTU fuels work. They make more temp / pressure / power lower in the RPM curve. As said above, with the octane you can dial the boost timing master back and gain some more HP with the timing bump.

In spite of Mikey's constant nay saying retailers do put different supplements in different grades of fuels, either at the hub tanks or in the trucks before delivery. That's how they get the different octane ratings. Of course he's an EXPERT in everything so I'll be wrong, again...

 

That's nice.

Here's my original statement:

'Fuel octane has nothing to do with quantity or quality of additives.'

Which is true. Please find somewhere else to pick your nits instead confusing the OP even more.

 

Not quite.
A turbine or "turbo" operates on flow which is created when you have a DIFFERENCE in pressure.

Heat is not pressure. Heat is a measure of energy flow with units of joule or BTU. Pressure is measured in units like psi or bar. (If heat is pressure what is the conversion factor from BTU to psi?)

Temperature IS RELATED to pressure by PV=nRT (Boyles Law)
P= pressure
V= volume
n= number of moles
R= gas constant
T= temperature

I'm done with this topic. I spent 40 years dealing with this crap as an engineer. I am retired now and would like to forget it all - i probably will need to get Alzheimers for that to happen though.

 

 

Yes and No. Using your own statement: A turbo operates on pressure created by expanding hot gasses. All else is secondary and incidental.

If you restrict the flow of the exhaust by using it to drive something else- you lose power. In other words you gain nothing. In fact the flow is undisturbed, it comes right out the tailpipe with the same velocity. It has to!. What is captured is the heat.

by all means have the last word. I just did not want you to have the misapprehension that the flow of the exhaust is in any way utilized. it simply cant be by laws of physics. You cant use a water hose to drive a pump and still have the same flow at the end of the pipe.

 

An essential simplification.
If you measure the flow pre-turbo and post-turbo, it will show that the flow is entirely unused.

An engine is an air pump- you cant restrict to flow to increase the intake.
Thats like trying to pick yourself up by standing in a bucket

 

I hear ya. At one point I thought the internet was invented for underage kids to watch ****. I later learned that it was for sharing pictures of kitties or to futilely argue with strangers.

 

One more point.... so if you apply heat to a turbocharger but have zero flow, you will still gain turbine velocity? All my childhood pinwheels say that if flow is introduced to blades, the blades turn. The wind that blew the blades never dissipated, but merely lost velocity for a microsecond.


I call this picture "The Day All Wind Stopped":

 

Change that to constant flow and increasing heat nets more turbine speed. That's how a diesel turbo works. There's no throttle plate so RPM is based solely on fuel input (well, injection timing too). Diesel at 1700rpm low fuel load, no boost. More fuel, more boost and power at a constant RPM load.

I guess it's hidden somewhere in DAVCHR's description of Boyle's law but I suck at mathematical engineering. Hopefully he'll give some more input on that subject.

My empirical education is from a '83 Mercury Capri with a twin turbo blown through carb'd 351w setup and now my 1st gen Cummins powered '71 F-350. I ported the turbine housing where the gas is induced to the turbine wheel on the Cummins and turned it into a dog. Took a lot of fuel to get it to spin and then drop a little throttle and the pressure in the plumbing to the intake would blow back through the turbo giving a nasty turbo bark.

I then MIG welded the housing followed by turning it on my lathe to get a couple thousandths radial clearance to the turbine and used a whiz wheel to cut a new inducer slot that was the same port size as the exhaust manifold at the ID of the turbine housing. It was a sketchy layout with the cut off wheel hose clamped to the lathe carriage but it worked out really well. I run really low EGT's with near instant off idle boost and a very happy engine. The H1C is supposed to run out of steam at 21 psi but mine will turn up to 28 if I push it hard. I seldom do because it doesn't need pushed that hard.

I enjoy learning about this stuff and applying it where I can.

 

Aaaaand hijack is complete. Initiate argue phase.

 

Perhaps you should go troll elsewhere...

 

 

You are describing how a jet turbine is started.

 

Forget all that, you are beyond Boyle. You nailed it when you said Turbos run on heat and not air flow. It was succinct and brilliant.

If you could take air flow energy from an exhaust and make more energy than you put in- You would create a SuperMachine. They would give you the Nobel prize for the next decade because you would solve mankind's energy problem.

Bottomline: if you drove the turbo or any accessory for that matter with exhaust airflow- it would rob more power than it put out. An internal combustion engine has zero airflow it can spare. It has copious amounts of heat energy, in fact 2/3rds of the energy put into it is lost to heat.

 

Yes- it would be called a Stirling Engine. Note air is entirely sealed.

 

Contained high temperature air FLOWS into a contained low temperature area because of the increased volume of the heated area and lower volume of the cold area.
In speaking of HEAT making the actual turbine spin, it is the HOT gasses which MUST go SOMEWHERE, and the ONLY way out is through the blades and out the exhaust system. Of COURSE hotter "air" (gasses, whatever) make turbines spin more and faster, there is More Flow because of MUCH More Volume.
Heat increases the flow because there is more TO flow.

Yes, I know all about Stirlings, but open the closed system but leave the heat on..... then see what happens. MY exhaust isn't a closed system.
Same with turbojets, the increased VOLUME from the much hotter gasses spins the blades...... with FLOW.

 

This is a great discussion.

The flow cannot be reduced by driving a fan from it.
Every % decrease in air flow will give you a corresponding decrease in engine performance- you know this because the engine is nothing more than an air pump.

If you could drive the turbo by flow- they would just put the turbo at the other end of the tailpipe. They would solve many problems that way. Reducing turbo heat, and cooling the air that goes to the engine.

A turbo is in many ways identical to a Stirling engine. It is a closed system till the hot air is turned to cooler air in the next chamber.

One final proof, a turbo engine loses little air flow at the tailpipe. It should lose a great deal if that energy was being used to push a turbo compressor. Guess what it does lose compared to a non-turbo, heat.