Heat = Power?

[Gollum]

Ok, I wanted to reply to the "how to tune for less turbo lag" but I would have been entirely off topic. To understand why I'm posting this, go read that thred.

 

Ok, I'll prove simple physics with a simple 4th grade science project.

 

For this you'll need

 

1. A glass jar

 

2. A Latex glove

 

3. A popsicle stick

 

4. A rubber band.

 

5. Simple scotch tape

 

Cover the opening of the jar with the letx glove and wrap the rubber band around the end so the surface of the latex is flat and tight. Then tape the stick to the top with one end in the middle of the jar opening then going directly out. It's good to extend at least a good 2" off the edge to get a good readout.

 

Now put the jar in the fridge/freezer. Then check on it in a couple of hours. If the seal around the edge was good you'll notice a slight concave in the surface and the stick will be pointing up. Now take the car and put it in direct sunlight, or even better, a black car. Once you've given enough time check on it again, you'll have a convex bubbleing out with the stick pointing down.

 

This simple little test shows that hot air requires more space for the same mass. The molucule count hasn't changed (to a noticable degree) but the space taken has changed considerable.

 

If you wanted to pass the mass in the jar through a given nossle you'd have to propell the hot air faster to get it all though in the same amount of time as the colder air. Anyone with some firm physics grounding should now be able to understand why heat is GOOD for turbos. In the test we're talking a difference of 100F degrees at most (depending on where you live) but the temps between exhast at the muffler tip and the exhast manifold are MUCH more different. So difference are much more dramatic.

 

Now, with turbos it's still air that's turning the turbo, but for STS to try to sell people on the fact that thiers is more "eficciant" is BS. Sure thier system creates power and it's very reliable, but I'd never use it in any serious engine simpley because the same parts can make more power with more heat.

[johnc]

http://en.wikipedia.org/wiki/Thermodynamics

[tannji]

I read the other thread as well.... moving your static system example here was a good idea. What I dont like about that example is that it implies that that heat is the most necessary component, when it is a by-product of combustion that turbo system engineers have very cleverly compensated for, and even turned into a mostly positive factor. What is important is velocity... no matter how you look at any of the popular equations. (which are almost universally intended for describing static systems, not dynamic.) The change in size between inlet and outlet nozzle create more velocity, and if the extra volume from heat becomes too great, you have to use a larger outlet, to avoid back-pressure. STS systems use that same adjustment in reverse, going to a smaller outlet to increase velocity, without much concern over excessive back-pressure, because they have a cooler, denser charge. You get pressure in either system, because the engine is pumping volume.

Either system has it's pros and cons. Conventional Turbo kits will usually be slightly more expensive and complicated. (mechanicals and plumbing) They are hotter, and while that can be used productively, it is also a concern that has to be planned around, at some expense. STS system kits are slightly cheaper on average, much easier to install on average, are much easier on the degradeable materials under your hood, and much easier to revert from. Either system, in an all-out race car where you are trying to max your performance, becomes expensive and requires similar funding and tuning. Both systems have disadvantages that have to be compensated for.

Bottom line, they are intended (by Squires) for different customers than conventional systems. I have read about them as much as anyone else here is likely to have done, and never come across a claim (by Squires) that they were more efficient. I have seen one statement that could be mis-construed as such a claim, and that was that their turbo handled the cooler, denser exhaust more efficiently, but they also noted that their turbo would not be appropriate in a conventional location.

Both systems work.... I just cant figure out what the fixation on STS being inferior is all about. There are well engineered cars out there runing 9 and 10 second passes on STS systems. There are fanboys that think because it is new and easy to install, it must be better. There are other fanboys that have to bash, because it is unconventional. The bashers miss two important facts; It works well, and it was not intended, nor does Squires market it as either more efficient, or better suited for competitive race setups than a conventional mount.

 

Your final point was: "Sure thier system creates power and it's very reliable, but I'd never use it in any serious engine simpley because the same parts can make more power with more heat."

 

First, I imagine your definition of a "Serious Engine" is similar to mine, and that is not who Squires is targeting. Second, we are not talking the same parts here. The turbo certainly is designed with a different outlet, and the average STS user probably doesnt have a IC. FWD is not better than RWD, Diesel is not better than gasoline, and more precisely, Apples are not better than Oranges, if that's not too fine of a point.

[dr_hunt]

Well, John C, summed it all up without saying a word, I think it was a hint.

[zguy36]

I don't really see the problem with having a hot turbocharger under the hood of your car. With proper placement and shielding, it isn't going to cause harm to anything. The STS system is a good system, for those who cannot seem to fit a turbo under their hood. It is however, a less efficient system. Read my post again on the "how to tune for less lag" post and you can see why. There is a given amount of energy in the fuel you burn given off as heat. If you choose to let that heat out without using it, then that is a energy loss. Read up on that thermodynamics link. It is good stuff.

 

-jeremy-

[MatMan]

I don't really see the problem with having a hot turbocharger under the hood of your car. With proper placement and shielding' date=' it isn't going to cause harm to anything. The STS system is a good system, for those who cannot seem to fit a turbo under their hood. It is however, a less efficient system. Read my post again on the "how to tune for less lag" post and you can see why. There is a given amount of energy in the fuel you burn given off as heat. If you choose to let that heat out without using it, then that is a energy loss. Read up on that thermodynamics link. It is good stuff.

 

-jeremy-[/quote']

Yes, Thermodynamics is good stuff.

I had a stint as a materials engineer doing failure analysis of turbochargers for AlliedSignal/Garrett before Honeywell bought them out. A lot of heat is NOT good for any turbocharger, oil/liquid cooled/lubed or air lubed.

 

An engine is a heat pump, more or less. The whole idea behind an intercooler is so that hot expanded air coming off the hot turbo will cool and compress itself, so to speak, before entering the combustion chamber.

 

The specific equation fails me, but the efficiency of any given engine is proportional to the difference in the temperature of the air before and after leaving the combustion chamber. And I believe the efficiency of any/all internal combustion engines (due to its design) peaks somewhere around 0.70. So that no matter how you charge the combustion chamber and at any temperature, you will lose 30% of the total energy available to heat, sound, friction (mechanical losses), etc.

 

Moral of the story, hot turbo = hot air = not good, or to answer the title of this thread:

delta heat = more power

[zguy36]

Most of the heat in the intake is from compressing the air, not from transfer from the exhaust side. In the exhaust, heat makes the air expand. The more volume you run through your turbo.... blah blah, I've said it all before.

[MatMan]

Most of the heat in the intake is from compressing the air, not from transfer from the exhaust side. In the exhaust, heat makes the air expand. The more volume you run through your turbo.... blah blah, I've said it all before.

True, making compressed air mechanically does introduce more heat into the system than the radiant or convected heat from the exhaust side of the turbo. Where the heat comes from isn't the issue, I think, as much as how to get rid of it, because of the efficiency/work problems associated with the high temperatures.

[zguy36]

On the compressor side, it doesn't matter where you mount your turbo. You are still going to get hot air due to the fact you are compressing air.

[MatMan]

Yes, it doesn't matter physically where the turbo is located, or where the compressor is located. My point was this:

 

you will get higher efficiency, from any motor, with the greatest difference in air temperature before compared with after.

ie. if your intake air was, say, 280 degrees, and your exhaust temp was 600, you would not have as much thermal efficiency as if your intake temp was 100.

 

The greater the difference in temperature = greater thermal efficiency.

 

You do not want high air temperatures on the intake side of the motor, only on the exhaust. You will never be able to use the evergy available in the hot exhaust gasses, because you have already used the energy in the process of changing the temperature in the combustion chamber, exchanging the energy of combustion (chemical) to rotational (mechanical) energy. I know, "the energy of the hot gasses is spinning the turbo." NO. The pressure differential between the exhaust strokes in the combustion chambers and the ambient air pressure outside the motor is causing the turbo to spin. The heat is inconsequencial and due to the rapid expansion (oxidation of the fuel) of gasses and friction.

[zguy36]

I am getting kinda tired of trying to explain all of this to you guys. It really is a simple concept of balancing energy going in and energy going out. Believe what you want to believe, but I want you to know that you are dead wrong. Heat is not a mear byproduct that is inconsequential. Also, you are wrong in your efficiency. Higher efficiency is not obtained with the highest temperature differential, but with the lowest. Heat=energy. If you expel heat from your exhaust, that is lost energy. If an engine were 100% efficient, the exhaust would be the same temperature as it went in. All the heat energy would be converted to mechanical energy. In the sense of a turbocharged engine, the exhaust temperature is decreased as it travels through the turbo. This is energy transferred from heat energy to mechanical energy. It is not as simple as saying, put your turbo in an oven and watch it spin. Yes, the turbo will not spin in an oven and it is sad that you all think that is equivalent to what I am saying. Heat causes changes in volume, and those changes in volume are causing the turbo to spin. Please read up more on your thermodyamic theory before you post erroneous knowledge on a forum.

[MatMan]

I am getting kinda tired of trying to explain all of this to you guys. It really is a simple concept of balancing energy going in and energy going out. Believe what you want to believe, but I want you to know that you are dead wrong. Heat is not a mear byproduct that is inconsequential. Also, you are wrong in your efficiency. Higher efficiency is not obtained with the highest temperature differential, but with the lowest. Heat=energy. If you expel heat from your exhaust, that is lost energy. If an engine were 100% efficient, the exhaust would be the same temperature as it went in. All the heat energy would be converted to mechanical energy. In the sense of a turbocharged engine, the exhaust temperature is decreased as it travels through the turbo. This is energy transferred from heat energy to mechanical energy. It is not as simple as saying, put your turbo in an oven and watch it spin. Yes, the turbo will not spin in an oven and it is sad that you all think that is equivalent to what I am saying. Heat causes changes in volume, and those changes in volume are causing the turbo to spin. Please read up more on your thermodyamic theory before you post erroneous knowledge on a forum.

All I can do is shake my head.

In layman's terms, the change in internal energy is equal to the change in temperature, minus the change in work done by the system

At constant temperature, there is no energy differential, and there is no work.

There is energy in heat, but you cannot harness it unless you can change the temperature.

[zguy36]

Your temperature differential you speak of occurs in the engine. Cold air comes in mixed with fuel and ignites. This burns making a hot mixture. The piston moves down and the hot combustion gasses expand and cool. This is the transfer of heat energy to mechanical energy. The more transfer of energy you have, the cooler the exhaust resulting. Shake you head all you want, but maybe put your nose back in that book.

[MatMan]

It really is a simple concept of balancing energy going in and energy going out.

Most of the energy in this system is held in the fuel, not the air.

 

Higher efficiency is not obtained with the highest temperature differential, but with the lowest. Heat=energy.

I am afraid you have is bass ackwards. Heat is just one form of energy.

 

If you expel heat from your exhaust, that is lost energy. If an engine were 100% efficient, the exhaust would be the same temperature as it went in. All the heat energy would be converted to mechanical energy.

It's not the heat energy that is being converted. It's the chemical energy.

 

In the sense of a turbocharged engine, the exhaust temperature is decreased as it travels through the turbo.

You said yourself that the heat energy was caused by the compression of air, not from the heat of the turbo...

 

Heat causes changes in volume, and those changes in volume are causing the turbo to spin.

Only one part is true. Heat will cause a change in volume in an ideal gas, with pressure and the amount of gas molecules being constant. It is the pressure differential between the exhaust strokes on all cylinders pushing the exhaust gasses to the ambient air pressure outside that drives the turbo.

 

Please read up more on your thermodyamic theory before you post erroneous knowledge on a forum.

How quaint. I don't thik I should have to post my resume in order for my point to be made.

[thehelix112]

You two can stop anytime.

 

 

FWIW, zguy36 is making a lot more sense to me.

 

Dave

[tannji]

I am getting kinda tired of trying to explain all of this to you guys. It really is a simple concept of balancing energy going in and energy going out. Believe what you want to believe, but I want you to know that you are dead wrong. Heat is not a mear byproduct that is inconsequential. Also, you are wrong in your efficiency. Higher efficiency is not obtained with the highest temperature differential, but with the lowest. Heat=energy. If you expel heat from your exhaust, that is lost energy. If an engine were 100% efficient, the exhaust would be the same temperature as it went in. All the heat energy would be converted to mechanical energy. In the sense of a turbocharged engine, the exhaust temperature is decreased as it travels through the turbo. This is energy transferred from heat energy to mechanical energy. It is not as simple as saying, put your turbo in an oven and watch it spin. Yes, the turbo will not spin in an oven and it is sad that you all think that is equivalent to what I am saying. Heat causes changes in volume, and those changes in volume are causing the turbo to spin. Please read up more on your thermodyamic theory before you post erroneous knowledge on a forum.

 

If you are getting tired, take a rest. The turbo would spin if we manually rotated the engine with no spark whatsoever. The Turbo is spinning whether or not you are taking advantage of some of the heat by-product or not. A system that sizes the nozzle to use the volumetric increase in exhaust gasses is scavenging extra power, and is more efficient than one that does not, in the same situation. The change of volume from heat is not what spins the turbo.... but it does with the proper outlet spin the turbo better. Just as a remote mount, with the proper outlet, spins the turbo better than it would with a larger outlet.

Its two different systems, in different locations, with different variables... and intended for different applications. STS makes an otherwise stock car go faster, as does a front mount. STS does it a little easier for some people. If you have a front mount, you try to manage the heat by-product efficiently. If you rear mount, you try to manage a denser charge efficiently. Who cares which is more efficient? Ya, in some ways the front mount is more efficient. Who cares? For some people the rear mount is more practical. Religeous and Political discussions are banned here now, and this is why. People insist on comparing apples and oranges.... My apple and I dont care if your orange has more vitamin C.... I like apples, and they both qualify as a healthy snack.

 

Heat is a byproduct..... and ya, it IS consequential.... but a turbo that is rear mounted compensates for lost heat and volume by efficiently using whats left to it: a cooler dense exhaust. If the STS system were worthy of the @#$%-storm over how inefficient it was.... it wouldnt be selling and performing very well.... and there would be countless posts from disgruntled users, many of whom are previous owners of either front mount turbos or super chargers. They are happy with their change.... and they dont typically run around trying to tell everyone they have a superior product, but they will generally tell you how happy they are with its performance, and thats all that really matters.

[Gollum]

First' date=' I imagine your definition of a "Serious Engine" is similar to mine, and that is not who Squires is targeting[/quote']

 

And that's why I hate them. I'll admit, it's not THEM I hate so much, but rather thier "elite" fans that swear by them as the holy grail.

 

If it weren't for those tpye of people I'd actualy consider them an option

 

But I'll admit I don't hate the idea, just all the myth caught up in it. (created 100% by consumers, no retailers)

 

As you said they use a small outlet to increase the pressure. In my mind they're just trying to be as efficient as possible for the reduced heat difference. It's not to say you can't make power that way, but think about this, the only difference is air temp (thus volume as well as we all know) and they have to reduce the outlet to increase the pressure again. Now you're creating backpressure via exhast size instead of backpressure from heat. The valves might not react the same to the different pressure systems.

 

Again, I don't think they're bad, just not the "best thing since sliced bread" that all these people make it out to be.

 

=======================

 

The internal combustion engine IS NOT a heat pump. Heat is a byproduct and the internal combustion engine is a air pump. Heat is apparent in any internal combustion engine but it would rather be avoidable by engineers.

 

Turbos take advantage of this "flaw" so-to-speak (as previously stated) and transfer as much of this energy as possible. I believe even without heat you could get considerable amounts of boost on a turbo, but I'd like to see some research on how much more pressure it would take in the exhast system to create 30PSI boost at room temp and 30PSI boost at normal exhast temps.

 

 

And as someone wonderfully noted, heat in exhast = BAD... well, I didn't think anyone would assume from my first post that we were even talking about intake temps to begine with. Maybe I should have started this as "turbo + heat = power?" That would have been closer to the topic I was after. But yes, lower intake temps increase power dramatically. Ever dynoed a car with ice packs on the intercooler? Amazing how easy it is to gain 10 on even a low hp setup 8)

 

===============================

 

I think I'm just going to state some closing comments and leave this thred for others.

 

If you take an engine with a fixed volumetric efficiency and compare two different readings of intake and exhast temps, with one spread being farther than the other...

 

example

 

test 1 intake temp: 100F exhast temp:800 volumetric efficiency = 30%

 

test 2 intake temp: 100F exhast temp:1000 volumetric efficiency = 30%

 

Test two should indicated more power was created. Thus if you're measuring efficiency from temp difference you have to know the given HP as well.

 

A rough equation would be

 

TD = temperature difference

 

E * TD = HP

 

Efficiency multiplied by Temperature Difference = Horse Power

 

Granted that's a very generalised formula, it's still the idea behind it that i'm trying to get across. Real motors vary in efficieny across the power band (usually similar curves to tourqe) and have many other influences on heat, such as load.

 

oOo, i just thought of something. If you're in nutral, and you rev your turbo'd motor, you're not going to get a full boost read out until upper rpm correct? This could be atributed to the fact that they're no load on the engine, thus lower exhast temps. Once you're actually in say, 3rd gear you'll get full boost at much lower RPMS becuase you'll have much more load and thus more heat created, thus more volume wich creates more pressure ect...

 

Just a good example for anyone who wants to argue the fact that heat doesn't create power... (like in the other thred...)

[cygnusx1]

I'll say it again. Heat (from burning fuel) expands the gasses. Heat does NOT spin the turbo. The expanded gasses moving between two states spin the turbo. The spinning of the turbo is purely mechanical in the form of vectors on the blades.

 

Yes, I studied thermo, in fact it was my strongest subject.

 

Here is a fun question that a professor asked to demonstrate that we understood a closed system.

 

If you have a fridge in a room and you leave the fridge door open, does the room get warmer, colder, or stay the same? Why?

[tannji]

Oooo... I know the answer...! I even know part of why, lol. I'll let someone else venture first tho.

 

My main problem with the people that hate STS so much is the fact that they seem to think that heat is the only thing going on, and we must therefore treat heat as the Holy Grail, as the turbo wont work properly if it is dealing with exhaust gasses that are several hundred degrees cooler. Even when you get them to admit, as Gollum finally did, that STS makes no claims to being a better or more efficient system, they lay the claim on the users, but I havent actually seen a discussion anywhere, let alone here, that claimed STS was better than anything else specifically. In my opinion, the "heat" of the arguement comes from people attacking STS systems, and getting too generalized in their criticism, and then taking offense when someone defends the system. I find it most amusing that the people who have the fastest STS-powered cars quite frequently happen to be people who got tired of all the criticism and definitive statements by people (who almost without exception have never driven or owned a STS system) and decided to take their own money and effort and see where it would take them. 11 and 12 second trucks and 9 and 10 second F-bodies based on non-radical STS setups says this: your front mount is more efficient, and your internet postings are more strident.... and STS owners dont care.

[johnc]

http://en.wikipedia.org/wiki/Mechanics

http://en.wikipedia.org/wiki/Thermodynamics

 

You guys are confused because an engine/turbo SYSTEM combines both mechanics and thermodynamics. Evaluating the system from only one of these paradigms is incomplete.