# turbo heat wrap



## mtcookson (Jul 16, 2003)

what are your guys opinions on turbo heat wrap? i've heard the stuff is both bad and good but never heard any reasons for either. any input would be appreciated.


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## javierb14 (Jul 9, 2002)




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## Engloid (Jul 7, 2002)

It makes sense to me that one of the purposes in the exhaust system is to carry heat away from the engine. The best way to do this is by NOT allowing much of it to escape through the pipes.

The problem with the wrap on the turbo is that it's large and is a thick metal...so it absorbs a lot of heat. Therefore I think you'd shorten the life of the turbo to wrap it (turbine side)


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## javierb14 (Jul 9, 2002)




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## 1fastser (Sep 30, 2002)

If you wrap it you should seal it with the spray that's made for the wrap (forgot the name of it)...that way moisture doesn't get underneath it...


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## mtcookson (Jul 16, 2003)

i may just leave it unwrapped for now and see how hot it gets under there. if i start seeing signs of melting i'll wrap it.


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## Engloid (Jul 7, 2002)

I notice you don't mention the lifespan of the turbo seals.

You also don’t address the fact that the hotter the turbine side is, the hotter the compressor side will be…and the hotter the intake air will be.

Thermal expansion is NOT the biggest factor in creating energy in the turbo. FLOW is the biggest factor. If you disagree, try this:
Get a turbo on a bench and put on an intake pipe and a downpipe. Then heat the turbine with a torch to the point it glows red….and see if the turbine will even turn one time on its own. Flow is most important, not heat.

You will gain much more energy by worrying about keeping intake temps lower than you will by worrying about thermal expansion. And to keep intake temps low as possible, you need to keep the exhaust heat in the exhaust gasses…and send them through the pipes, out of the area.


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## king_johnthegreat (Apr 6, 2003)

Technically, thermal energy is a bigger contributor to the complete equation. The flaw in that "bench" test is that with no flow, it will not work at all. The engine will always flow something, though, as long as it is running. It also produces a great deal of heat. Coating piston decks, valve faces, and wrapping primary tubes helps to deliver more of that energy to the turbine, as opposed to heat soaking engine components. Flow is a big part of the end result, but heat enery is bigger. Try flowwing huge air through your turbo using tight primaries and placing it several feet further away. Without insulating that heat, you'll hardly get the turbo to spool. Even if you corrected the pipe size to reduce pressure drop over distance, it still wouldn't do the trick. Heat energy drives the turbo hardest. Wrapping will enhance performance, but it may distress parts more, leading to shorter service life. Pick your poison.
John


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## Engloid (Jul 7, 2002)

I dunno if you missed the point or not…

The example I gave above was to show that the thermal expansion of air inside the engine, turbo and piping will NOT turn the turbo at all. It is the flow of air through the turbo that turns it. 

If we claim thermal expansion is the energy that turns the turbo then it must be that the air in the combustion chambers becomes hotter as it gets into the turbo and expands, creating more pressure to turn the turbo. Is this your side of this theory?

I don’t know if you’ve read Maximum Boost, but I don’t see ANY mention of a turbo getting its energy from thermal expansion…but I do see mention of turbo inlet pressure and flow rates.


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## king_johnthegreat (Apr 6, 2003)

I never said thermal expansion; I said thermal energy. Heat is the contributing factor, not gaseous expansion. I do have the book; as well many other books. It makes mention of thermal energy and its contribution to enhanced turbine efficiency. Apart from the heat issue in the turbine side, the compressor side of the turbo does not suffer from heat soaking all that much. An intercooler is the key to pulling the added heat of compression out of the charge air, as is using a cold air intake to pull in the coolest air possible, anyhow. The air in the compressor side is there only long enough to absorb a small amount of heat from the surrounding surface; the heat it does possess is a function of the air molecules friction with one another due to the great amount of work performed on it. These are all very elementary physics and thermodynamics concepts that any other engineer could validate. Added heat on the turbine wheel means added work on the turbine wheel. The more work put on the turbine, the more work performed by the compressor; period. The torch on the undriven turbo is just plain out of left field. Try driving it with a given volume of gas with given specific gravity, then do the same thing with the same turbo, but with the gas at 400 degrees higher than previously. Nitrous doesn't just do a great job of spooling big turbos because of the added combustion pressures, but also (more so) because of the added combustion temps. 
John


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## javierb14 (Jul 9, 2002)




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## Engloid (Jul 7, 2002)

king_johnthegreat said:


> *I never said thermal expansion; I said thermal energy. Heat is the contributing factor, not gaseous expansion. *


 

Ok, then explain to me how heat energy, without flow or expansion, will turn the turbo.



king_johnthegreat said:


> *I do have the book; as well many other books. It makes mention of thermal energy and its contribution to enhanced turbine efficiency.
> *


 

Page number?? 




king_johnthegreat said:


> * Apart from the heat issue in the turbine side, the compressor side of the turbo does not suffer from heat soaking all that much.
> *


 
So you’re saying that the compressor side gets too hot to touch just simply because it’s a compressor? Do you really think that a compressor making 7psi will generate that much heat.




king_johnthegreat said:


> * An intercooler is the key to pulling the added heat of compression out of the charge air
> *


 

That’s after the fact that the compressor side of the turbo puts heat into it. And that heat is primarily generated from the exhaust side of the turbo.




king_johnthegreat said:


> *Added heat on the turbine wheel means added work on the turbine wheel. The more work put on the turbine, the more work performed by the compressor; period.
> *


 
So if you have a car on a dyno and boosting, then put a torch onto the turbine housing, you will be making the turbine work more, therefore making the compressor side work more? 



king_johnthegreat said:


> *The torch on the undriven turbo is just plain out of left field.
> *



The point is that heat, without flow, will not turn the turbo. PERIOD!!!


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## Engloid (Jul 7, 2002)

javierb14 said:


> *a well designed turbo exhaust manifold will optimize everything that gives a turbo better performance.....heat, pressure, and flow. to say flow is the biggest contributor isnt correct. if this were true then "log manifolds" and the poor flowing cast OEM manifolds wouldnt work that well
> *


They don’t, compared to a better header type of setup.



javierb14 said:


> *u should read the introduction of corky bells book....
> "a turbocharger is a simple device. it is nothing more than an air pump driven by energy remaining in the exhaust gases as they exit an engine.of the energy released in the combustion process, approximately 1/3 goes into the cooling system, 1/3 becomes power down the crankshaft, and 1/3 is dumped out the tailpipe as heat. It is the last third that we can use to power the turbo. *


*

So you ignore the word dumped in that paragraph? Dump is a verb. I won’t resort to defining this as a way to insult your intelligence, as I do not mean to in any way. Anyway, it takes energy to dump the heat. 

In short, as I’ve heard before, energy cannot be be created or destroyed. The fact is that the turbo is not a heat exchanger.


javierb14 said:



basically, optimize the energy transfer (heat, pressure, and flow) to the turbine and u will get better performance. 

Click to expand...

Transferring heat to the turbo is important to get it away from the engine, but likewise, you need to get it through the turbo as efficiently as possible also. I do notice you say optimize, rather than reduce or increase…I agree with you on that point.



javierb14 said:



i like a good flow.....thats why we use a real merger collector in our manifolds.

Click to expand...

I agree here also…I feel that flow is most important, as that’s what turns the turbo.

About your pics…they look pretty nice compared to most I’ve seen. However, if you want to see some welds on the that look even better, send me the parts for one and I’ll work it up for you J 

I can see that the fit is nice prior to welding. Why don’t you just purge the inside and put a full penetration weld on it?*


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## mtcookson (Jul 16, 2003)

hey javierb14, i would take engloid's offer on this! he does some awesome work and fabricating. i've seen some pictures of some intake manifold work he's done for the vg30et on the earlier 300zx's and it is top notch.


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## king_johnthegreat (Apr 6, 2003)

The few lines of mine you didn't quote stated in no fewwer words that the turbo will not turn over most efficiently (In terms of generating boost) without either flow or heat. I never said heat would turn the wheel by itself. I said that it would make the greatest contribution to making the turbo more efficient and responsive. You ask where in Maximum Boost this mentioned; here you go: Pages 117, 119, and 129, just to name a few.
You quoted someone else who paraphrased a passage from Corky Bell, trying to correct them for saying that exhaust heat is a portion of raw energy dumped out the lait pipe; I ask you: how much energy it takes to exhail? None is the answer, you relax to let the gas out. The engine does not work to allow gas to escape, the exhaust system operates off of residual rotational motion from the crank, and reciprocating motion of the rods/pistons. Heat energy is much easier to lose than maintain, as well, so the fact that exhaust exiting the tail pipe is still warm means that there is more energy left over that the turbo could possibly have made better use of. He (Corky) also states boldly that heat energy works to eliminate a large portion of the lag a turbocharger encounters while spooling to create viable boost pressures. Without the heat (As I tried to explain with my bench test), you would suffer from horendous lag. Again, you tried to use the torch for a testing tool; not smart. Let's just stop with the pyromania. That whole energy cannot be created nor destroyed thing; that's actually a quote about matter. Matter can neither be created nor destroyed. Energy has no mass, so you don't really create it; you generate it, expend it, transfer it, store it, lose it, or gain it. It can be conducted, inducted, insulated, shared, so on and so forth. 
Yes, the compressor side gets very hot to the touch because even without using hot exhaust gases to drive the comp wheel, compressing air generates a great deal of heat. The less efficient the compressor wheel, or the more pressure you ask it to generate, the hotter it will get. 400 degrees is possible from a T04E wheel generating 30 psi. My T04E 50 trim can make 248 degrees at 18 psi. You think that might burn your hand? That is from an electrical shaft drive for flow testing, too, not because of the turbine side. The bearing housing has oil and water running through it on many turbos, do you think the oil would withstand coking if the turbine side could heat the compressor side to that temperature? Not likely. Try sticking your hand on the valve cover after a long drive, and then blame it on the exhaust gases in your crank case when you burn your hand. 
I could start using equations to explain my points further, but you'd probably try to use a torch to solve them. The point is, unless you can pay someone to agree with you, anyone with half an engineer's whit would likely not. Thanks, though.
John


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## javierb14 (Jul 9, 2002)

*Thermodynamics 101*


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## pschurr (Jul 21, 2003)

You blokes are smarter than I, so you all know very well that flow is the game, and heat is a major conbritutor to flow. Keep the heat in the gas, and you maintain more of the velocity. Let the heat soak off thru the pipework, and it slows down. 

So kiss and make-up, and agree that wrapping the dump pipe post-turbo is a good thing for evacuating gas away from the turbine.

Yeah?
peter


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## FFgeoff (Nov 2, 2002)

mtcookson said:


> *i would take engloid's offer on this! he does some awesome work and fabricating. i've seen some pictures of some intake manifold work he's done for the vg30et on the earlier 300zx's and it is top notch. *


post the pics. Ive seen some people make really nice stuff and who had no idea what was really going on... case in point. Javier and I are both mechanical engineers, (no offense here, just asking) is engloid? If so he may want to go over some thermo topics...

Also the material we use would be very very difficult to weld at our level. I would be seriously impressed if you can weld better, not that its not possible, but i would love to see. Maybe you can teach us a thing or two! We can teach each other some things  

BTW the guy who called everyone blokes, why would we agree it is a good idea, if it is not a good idea?


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## pschurr (Jul 21, 2003)

Sorry Geoff, that's the Australian influence. I'll use the term 'guys' then, ok?

If it's not a good idea, I wouldn't suggest that people agree to it. 
Fact of the matter is... you stuff a lot of very hot gas into a confined space and want to to flow through there as quickly as possible?? one of the impactors is maintainence of the gas temperature. Keep the pressure up by keeping the temp up, and the gas will flow faster through the confined space - driving the turbine (if that's the requirement). 

yeah? No?
peter


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## javierb14 (Jul 9, 2002)




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## pschurr (Jul 21, 2003)

I give up. I wrote a diatribe, but deleted it. 

Love your work Javier. 
But that statement is just kooky. 

Heat in gas = fast flow
fast flow AWAY from turbine = better turbine response
better turbine response = good 
good = keep post-turbine gas hot and flowing.


peter


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## FFgeoff (Nov 2, 2002)

pschurr, i appreciate your argument, but you are incorrect. If the post turbine wheel exhaust system is suitable (big enough with low enough pressure) it does not need to move fast. We are not at all concerned about velccity at this point, we are only concerned with pressures. While it would be bad for the gasses to have a reallllllllly slow velocity, the differences are minimal. If you wanted high exhaust gas velocity you could put a 1.5" stock SE-R exhaust on a high power sr20 and make power.

Javier and I have two classes before we are mechanical engineers. We really understand this stuff. I do hope you dont perceive this as us being dicks!


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## 240ZT (May 9, 2003)

Great discussion. Makes sense that pressure is a bigger concern than flow velocity. Any high pressure area after the down pipe will reduce flow and it seems if the pressure differential is large enough flow can be backed up into the turbo slowing its rotation. I know overall gas velocity is not very important but isn't the mass flow rate important? Bigger cross sectional area will move more gas at the same velocity.


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## pschurr (Jul 21, 2003)

That's cool man. Everyone is different, hence the adventure of life.

I had a 3" dump-pipe off the ass of a HKS GT2530 on my GTIR. I swapped out the 3" for a twin dump pipe... 2" runner for straight off the turbine, and 1.5" for the wastegate flow. The flange has a separator plate that splits the turbine housing chamber into two to completey separate turbine and wastegate flows. 

As a consequence, the turbine sees a pure 2" pipe snaking away down to the 3" flange under the block. It maintains pressure/temp/flow away from the turbine (through the bends) better than the 3" 'plenum'. Torque is up, hp is up, boost is earlier... because the speed of the gas flowing away from the turbine is greater. It delivers reduced pressure pre-turbine, which delivers improved evacuation during the exhaust stroke... etc...

Pics are here, and I love it. 
http://gtiroz.onthenet.com.au/gallery/albun43
When the wrap went on, it delivered boost about 200rpm earlier. That's my experience anyway.


peace out
peter


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## javierb14 (Jul 9, 2002)




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## Engloid (Jul 7, 2002)

king_johnthegreat said:


> * You ask where in Maximum Boost this mentioned; here you go: Pages 117, 119, and 129, just to name a few.*


P.117 Pretty much only says that you don't want much heat to escape through the exhaust manifold walls...as I have said before, this is because if it soaks into the manifold, it will soak elsewhere... and one of the reasons to have a manifold is to move the heat away from the engine.

P.119 did have a point of interest in this topic.
"It is generally not feasable to directly wrap the exhaust manifold with an insulating material, as the manifold material itself will overheat to the point of structural failure."

I guess that is more directly towards the origination of this topic. But it really says nothing about the turbo getting energy from heat.

P.129 also mentions thermal retention, but does not say that the turbo is more efficient when this is done, or that is is powered by thermal energy.

Sure, the intro you mentioned says that the last 1/3 of the energy released in combustion is funneled through the exhaust....but the importance is that it's not so much the heat energy, it's the movement of molecules. Movement is energy, and in this case, it's the flow that turns the turbo.


king_johnthegreat said:


> *You quoted someone else who paraphrased a passage from Corky Bell, trying to correct them for saying that exhaust heat is a portion of raw energy dumped out the lait pipe; *


I don't know what you're talking about here. I believe everything I quoted was directly out of the book.


king_johnthegreat said:


> *I ask you: how much energy it takes to exhail? None is the answer, you relax to let the gas out. *


No, this is not correct. By using your muscles to expand your lungs, you use energy. Well, actually use isn't the best word, since, as mentioned before, you cannot create or destroy energy. You can only alter it's form or direction. By inhaling, you store energy in your body in your muscles. When the muscles are released, the energy is released. It's the old kinetic energy and potential energy theories in motion.


king_johnthegreat said:


> *The engine does not work to allow gas to escape, the exhaust system operates off of residual rotational motion from the crank, and reciprocating motion of the rods/pistons. *


If this was true, you'd not gain anything by reducing backpressure in the exhaust system. 


king_johnthegreat said:


> * Heat energy is much easier to lose than maintain, as well, so the fact that exhaust exiting the tail pipe is still warm means that there is more energy left over that the turbo could possibly have made better use of. He (Corky) also states boldly that heat energy works to eliminate a large portion of the lag a turbocharger encounters while spooling to create viable boost pressures.*


Quote from the book: "The more heat that can be retained inside the manifold, the less the thermal-lag portion of the total turbo lag."

This is because as the exhaust gasses cool, they become more dense...and flow rate would likely be less. I don't see where it says anything at all about what you call a "large portion."


king_johnthegreat said:


> * Energy has no mass, so you don't really create it; you generate it, expend it, transfer it, store it, lose it, or gain it. It can be conducted, inducted, insulated, shared, so on and so forth.
> *


Here's a quote:
"Physicists define energy as the capacity to do work. They have learned that energy cannot be created out of nothing; it must be obtained from somewhere else. This insight has led to one of the most fundamental principles in science — the first law of thermodynamics, which states:
"The total amount of energy in the universe remains constant. More energy cannot be created; existing energy cannot be destroyed. It can only be converted from one form to another."" (Suzuki 1997, p.106)

It was found HERE 




king_johnthegreat said:


> * Yes, the compressor side gets very hot to the touch because even without using hot exhaust gases to drive the comp wheel, compressing air generates a great deal of heat.*


Again, I will return to asking why it is that my compressor in the garage can create 130psi and never get that hot, but a turbo compressing 12psi can get so hot.



king_johnthegreat said:


> * The bearing housing has oil and water running through it on many turbos, do you think the oil would withstand coking if the turbine side could heat the compressor side to that temperature? Not likely.*


the oil and water are reasons that the compressor side doesn't get nearly as hot as the turbine side. 



king_johnthegreat said:


> * Try sticking your hand on the valve cover after a long drive, and then blame it on the exhaust gases in your crank case when you burn your hand. *


If you could keep all the heat from combustion inside the exhaust gasses and then flush it out of the engine in the exhaust ports, you'd greatly reduce that heat found there. You'd only have the heat of friction to deal with.



king_johnthegreat said:


> * I could start using equations to explain my points further, but you'd probably try to use a torch to solve them. The point is, unless you can pay someone to agree with you, anyone with half an engineer's whit would likely not. Thanks, though.
> John *


Sorry, bro...but that gets you nowhere with me. Personal attacks do nothing but reduce your credibility in my eyes.

The fact remains that you still havn't proven your theory that heat energy is more important than flow.


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## Engloid (Jul 7, 2002)

*Re: Thermodynamics 101*



javierb14 said:


> *for example:
> have u ever seen those candle powered fans or ornaments? it looks like a little fan or whirly bird type thing on a stand that is free to rotate. u place a lit candle underneath it, and it alone powers the fan. *


The issue here is that the heat creates and upward flow of air that creates the movement. In a turbo, an upward flow is not going to help you.


javierb14 said:


> *thanks for the compliment. we usually dont purge the inside of collector since it is TIG'd both inside and out.*


If you putrge the inside, weld outside, then weld inside, you don't have to burn out the oxidation on the inside that would otherwise be created by not purging. You may find it so much easier (and prettier) that you would rather spend a couple minutes and a couple dollars purging it.

Those are some nice pics you posted. Good work, definitely.
You may want to consider (if you havn't) a turntable and using a pulser on some parts. It can make even the most average welder put down welds that look like a machine did them.

Here's a page I put up with a few pics from places I've worked:
LINK 
The copper nickel coupling was selded by hand on a turntable, but not pulsed. Copper nickel welds best when "dabbing" wire into the puddle.

Here's a page I made showing an intake I make for the Z31. Keep in mind that it is cast aluminum, which doesn't weld very well at all. Many welders will tell you that cast aluminum can't be welded...that's BS. I have only found one piece of cast metal I couldn't weld, and it was a rear diff housing for a Ford truck. It was absolutely the nastiest metal I've ever seen. It was like trying to weld up a piece of steel wool.

LINK 
A couple pics don't work now, but I'll try and fix that.


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## king_johnthegreat (Apr 6, 2003)

I'm not sure you're really understanding the exact properties of heat and energy here. Heat IS energy. If the heat remains within the gases going through the turbine housing, the turbo's efficiency will be higher. Corky Bell says this in no fewer words, as do do most text books in regards to thermodynamics. Insulating the system to deliver as much of the combustion temps all the way to the turbo is far more than simply a function of moving the heat away from the engine. If there is heat, any at all, left in the exhaust gases that exit the tail pipe, that energy has gone to waste. 
I was not making a personal attack on you with the torching comment; it just strikes me as ignorant, for lack of a better term, that you interpreted several posts as claiming that raw heat is a force than can drive a shaft to rotate. If heat was so insignificant, why would powerplants use steam to drive turbines, as opposed to just using "compressed air" under the same pressure? I'm sure they would waste all their money superheating that large volume of water to create vapor, just because the steam looks cooler leaving the stacks. Ever burn yourself real bad? Hot water, hurts, steam hurts WAY MORE; you know why- it has a whole lot more energy in it. If added heat creates more power in a powerplant, and can do more work on the surface of your skin, why wouldn't it play a large role in doing more work in a turbo system?
Yes, a great deal of the heat in a turbocharger does get soaked away by the water and oil, but if you think your turbo's compressor doesn't generate a great deal of heat because your air compressor doesn't in your garage, then somethin' ain't right. My 18 gallon air compressor is very average for a garage mechanic, and I actually melted through the power cord simply because the cord was touching the pipe that carried the compressed air into the cylinder. If I use the tools while it is compressing, the hoses get so hot, I can't even touch them. Compressing air creates a great deal of heat, even when done efficiently. Pick up a SCUBA tank right after filling it, it'll burn your hand. Open the valve all the way, and the tank will freeze to the point where your hand would stick to it. Energy in means heat, enegy out means freeze. Real basic. 
Apart from the fact that you have missed several references in Max Boost to thermal energy and how it aids turbine efficiency, you just don't seem to get it. You might be able to weld really well, and I'm sure you know more than enough to make a fast car faster; I'm not disputing that, though. I simply represent the efforts to put correct information with regards to the way things truely work out there for others. There are more important things than simply taking heat out of the engine; one of those is making use of that heat before disposing of it. A turbo car can make great use of this energy, and that is why it is most important to get the heat to the turbo. I'm not argueing that flow is unimportant, but to say that heat doesn't matter is just plain wrong, as is denying that heat plays no part in elevating efficiency of the turbo system.
John


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## UnderDog (Jul 14, 2002)

pschurr has the right idea, but nobody listened to him.

Ideal gas law, people.

Heated air expands, and in an enclosed area, increases pressure. High pressure tends to migrate to low pressure. The higher the pressure difference between two regions of air, the faster and harder the high pressure air will move to the low pressure air. Keeping the manifold as hot as possible keeps the exhaust gasses from cooling down, contracting and lowering pressure. The hotter the exhaust gasses, the faster and harder it wants to get out of the block and down the pipes, meaning, the faster and harder it presses against the exhaust turbine, turning the compressor turbine. The difference isn't much, but the difference is there.

So, class...

Flow is the major contributor to powering a turbo. Heat is not. They don't work in a vacuum, you know.

However, heat alters the energy in the flowing air, either in a positive or negative manner.

That wasn't hard, and it didn't take two pages to explain, either...


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## pschurr (Jul 21, 2003)

My last post.... to Javier (even though I sent a pm to geoff errantly). 

Yep, the separator is part of the dump pipe flange and extends into the housing to separate wg and turbine gases. But this is only effective when the wg is opened... which is only at peak boost, so from zero-boost to hero-boost, we're only talking about turbine gas here - and the wg is not part of the equation. 

To allow turbine gas to expand out into an open area immediately post-turbine creates turbulence and heat-loss through the walls of that area, and slows down the ultimate exit rate of that gas through the exhaust system. It acts like an inlet plenum (only in reverse).... or pressure buffer. 

Have fun
peter


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## javierb14 (Jul 9, 2002)




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## javierb14 (Jul 9, 2002)




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## James (Apr 29, 2002)

I hate when I miss discussions like this... now I don't even know what everyone said cuz I'm too lazy to read through it all...


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## UnderDog (Jul 14, 2002)

I didn't say create boost, I just said "operate the turbo." Moving air spins the turbine. That's the end all and be all. Whether or not it creates boost was not part of the point of my post. My point was to explain how someone said a few pages before that heat meant nothing flow meant everything.

I don't think I was clear in what I said. I apologize.



javierb14 said:


> *NO
> if this were true, then u would be able to create boost with the car in nuetral just increasing engine rpms=which increases flow through teh turbine. go try and get the boost gauge to read past 0 by doing so..... it wont happen! a very easy to understand example of how heat plays a role in turbine performance is by reviewing how an "anti-lag" or "2-step" system works.
> 
> http://www.rallycars.com/Cars/bangbang.html
> ...


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## javierb14 (Jul 9, 2002)




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## James (Apr 29, 2002)

UnderDog said:


> *I didn't say create boost, I just said "operate the turbo." Moving air spins the turbine. That's the end all and be all. Whether or not it creates boost was not part of the point of my post. My point was to explain how someone said a few pages before that heat meant nothing flow meant everything.
> 
> I don't think I was clear in what I said. I apologize. *


Flow does not mean anything then on the turbine side if you want address it like that. Javier is right, you cannot count on flow to produce boost, if it could then the electric turbo would be a great idea!


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## king_johnthegreat (Apr 6, 2003)

> you cannot count on flow to produce boost, if it could then the electric turbo would be a great idea!


 EXCELLENT point, James. The idea that has been misunderstood from my side, I think, is that people think that us believers in heat want to replace the idea entirely that flow really isn't important. I don't believe that, though, and don't want others to, either. Flow is highly important. Flow, however, is a variable factor that can affect efficiency possitively even when the flow is restricted.
Let me explain the above idea: If you cannot create boost at lower RPM due to a very large turbo, but yet you do not reach it's full potential in the upper limits of its efficiency, you could effectively reduce the manifold primary inside diameter (Restricting flow, but creating higher pressures), and generate the same compressor efficiency earlier in the RPM band. This does negatively affect the flow at high RPM, but as stated before, you never met the upper limit before, so you really don't have much to loose. By reducing the ID, you increase gas velocity, and retain more of the gas temperature from combustion. Flow is something that can be increased or decreased for positive effects, because of the behavior it imparts on the system. Heat, on the other hand, is always good to retain within the gases.
So long as the engine is properly tuned to the correct A/F ratio, the more heat you can lock into the exhaust gases all the way to the turbine, the better it will function. As I said before, nitrous is one way racers greately increase the combustion temps, thereby also increasing the exhaust gas temps. It far more than simply increasing combustion pressures... Flow is very important, but without the heat it is merely a function of blowing through a steel straw. More heat equals more gas velocity, more velocity equals higher efficiency, THAT is the end all, be all. If you say more flow equals more efficiency, you'll have to prove how a little T28 could generate low end boost response with gigantic, long, straight primaries... Cause it probably wouldn't even match the flow efficiency through the turbine housing using a stock SR S15 manifold! Yes, it would flow more gas, but not to the requirements of the tiny turbo.
John


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## UnderDog (Jul 14, 2002)

javierb14 said:


> *teh turbine and teh compressor are connected...they must rotate at the same speed. in order to create positive pressure or boost, u must rotate the turbine and compressor at relatively high speeds. upwards of 100K rpm's. it takes a great deal of energy to power teh turbine to these speeds.....flow will not do it alone!
> 
> 
> 
> then what is teh point of having this power adder if it doesnt add power? *


Someone a few pages back said flow was not as important as heat, and someone countered that heat actually is important. On with the two page argument about it.

Of course flow won't do it alone, but what if there was no flow at all? It won't spin. But I believe I said that already...


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