Effects of undivided ext. gate spacer on divided manifold & turbine housing

[PASSENGER]

I must volunteer that it's possible the reduction in under the hood temps is responsible for this although I think it's the heat retained by the blanket. IN my experience egt's are slower to drop with the use of the blanket.

Regarding the comments about tractor pullers some of these guys are spending $5000-$10000 per turbo. I'm pretty sure if they were gaining anything with a header they'd be running them.

Underhood temps can make a huge difference. I know with some the high performance gasser stuff I've worked on, especially when getting up there with race gas its not uncommon to see some big losses with a closed hood on the dyno vs open.

EGts would most definitely be slower to drop with a blanket because the material is heat soaked, and cannot radiate the as quickly as it can without any surface barriers.

I would be really surprised to learn that no tractor pullers are running tubular style manifolds. IS this really true?

I am saying the heat is something that needs to be maintained all the way to the turbocharger. Take a tire air it to 80lbs in a 80* room, then heat it up to 1400*, see how much psi it has then, it will gain psi with heat. That is the theory that I am referring to when I say heat drives a turbo, not heat alone bug it is a big enough factor worth discussing.

So, how much heat is lost with a equal length header, that is really long therefore giving the exhaust gas more time to cool and contract before it hits the turbine wheel? Is it alot, a little, or none? Heat is why we run turbo blankets, to keep the heat IN, and the drive pressure UP, to utilize the air we have to drive the turbine faster, and not just let that energy dissipate.

The tire analogy does not hold any merit. Heat in an exhaust pulse is a function of the air and fuel burned in the cylinder, the engine speed, and how effectively that pulse is evacuated.
The confusion about heat loss in tubular vs. log is that the log manifold itself is actually creating heat, like I explained earlier. A tubular manifold doesn't create any heat.

 

[PASSENGER]

So now your trying to tell us gas temperature has no effect on on velocity through the turbine?

Yes. Its the other way around, velocity has the effect on temperature.

 

[GOT-Torque]

This is a great question. I have seen both. The rare V8s (Perkins in the Masseys) I have only seen individual tube headers on. The the I-6 engines, I have seen both. Which is more popular, I have no idea....fill us in.

I couldn't find many pics real quick, but Hypermax sells plain old log style.

If you were hypermax, would you build one that took 20 hrs to build that you would sell 100/yr or one that took 60 hrs to build that you would sell 10 per year? (just an example) I would bet that most of the top performing tractors aren't running alot of parts you could just call up a shop and order with a credit card. The big dogs are running the tubular style...

I had an old friend who often said "one experiment is worth a thousand expert opinions."

very good words indeed...

Regarding the comments about tractor pullers some of these guys are spending $5000-$10000 per turbo. I'm pretty sure if they were gaining anything with a header they'd be running them.

exactly

I've run SPEEDSHIFT's t4 header and a PDI t4 header back to back on a turbonetics t66. The PDI piece was a ton better to drive making boost from 0-10 psi much much faster. After 10psi SPEEDSHIFT's t4 header worked a little better and provided less exhaust gas temps. The header used a t4 divided flange just like the pdi t4 manifold. The difference noted on 0 to 10 psi with the manifold was far greater than the difference after 10 psi with the header.

that's real world data right there that shows each different design supports a different end use application. pdi = great for spool and street and tubular = great for max rpm flow and egt drop (oh yea, and stainless tubular = good for cracking :bang )

 

[PASSENGER]

If you were hypermax, would you build one that took 20 hrs to build that you would sell 100/yr or one that took 60 hrs to build that you would sell 10 per year? (just an example) I would bet that most of the top performing tractors aren't running alot of parts you could just call up a shop and order with a credit card. The big dogs are running the tubular style...

that's real world data right there that shows each different design supports a different end use application. pdi = great for spool and street and tubular = great for max rpm flow and egt drop (oh yea, and stainless tubular = good for cracking :bang )

Good points. Most designs out there are more about ease of manufacture and cost than performance.

Does anyone have pictures of this tubular manifold?

And yeah I would agree that stainless tube headers (particularly ones for turbo applications) are less than ideal.

 

[Turbo Performance]

So now your trying to tell us gas temperature has no effect on on velocity through the turbine?

Yes. Its the other way around, velocity has the effect on temperature.

So what happens when you increase exhaust temperature and the air inside the manifold expands? (We all agree that air expands as it gets hot right?)

 

[dvst8r]

So what happens when you increase exhaust temperature and the air inside the manifold expands? (We all agree that air expands as it gets hot right?)

Just so I am following this correctly, the only way we could do this is by releasing more heat from the cylinder (ie add fuel), or by running a torch under the manifold????

Or did I miss interpret the explanation above?


I do not have the answer to your question only those questions.

 

[Turbo Performance]

Just so I am following this correctly, the only way we could do this is by releasing more heat from the cylinder (ie add fuel), or by running a torch under the manifold????

Or did I miss interpret the explanation above?


I do not have the answer to your question only those questions.

Sure, to add heat to the exhaust stream, that would be a couple options. I wasn't trying to explain anything, just asking Passenger what happens when exhaust temp rises, either by adding more fuel or by controlling what you have. Doesn't matter how it rises, just asking what happens when it does and what effect it has on driving the turbine. In his opinion, that is.

 

[PASSENGER]

So what happens when you increase exhaust temperature and the air inside the manifold expands? (We all agree that air expands as it gets hot right?)

You don't just increase the heat.
Heat is only a byproduct of the air and fuel mixture, and how efficiently it is evacuated. If you have a fixed volume (cylinder) and you increase the amount of fuel and air to burn, you will generate more heat, the level of potential heat this burn has is a function of its capabilities to dissipate.

To make it more simple, if you have increased your egts it is because you have added more fuel to your burn cycle, creating a more dense and expansive exhaust pulse, if you keep the volume it travels to escape the same, and especially if you restrict it (slow the gas down) your heat increases at an exponential level.

 

[PASSENGER]

Sure, to add heat to the exhaust stream, that would be a couple options. I wasn't trying to explain anything, just asking Passenger what happens when exhaust temp rises, either by adding more fuel or by controlling what you have. Doesn't matter how it rises, just asking what happens when it does and what effect it has on driving the turbine.

Its simple the heat has nothing to do with it, the only way you will get more heat is by creating more energy, either by increasing rpm (gas speed) or adding fuel (gas density). Those are the things that drive your turbine, heat is merely a by product.

 

[SPEEDSHIFT]

Its simple the heat has nothing to do with it, the only way you will get more heat is by creating more energy, either by increasing rpm (gas speed) or adding fuel (gas density). Those are the things that drive your turbine, heat is merely a by product.

I'm sorry man, but that is not true. Heat needs to be maintained all the way to the turbine wheel. If it is not, you loose drive pressure, therefore not getting the full potential out of the energy.

 

[Turbo Performance]

Its simple the heat has nothing to do with it, the only way you will get more heat is by creating more energy, either by increasing rpm (gas speed) or adding fuel (gas density). Those are the things that drive your turbine, heat is merely a by product.

So if heat is just a byproduct, putting a blanket on or having cool air move over the manifold shouldn't change spool?

 

[PASSENGER]

I'm sorry man, but that is not true. Heat needs to be maintained all the way to the turbine wheel. If it is not, you loose drive pressure, therefore not getting the full potential out of the energy.

So if heat is just a byproduct, putting a blanket on or having cool air move over the manifold shouldn't change spool?

Ok I think we need to clarify something here, what kind of temperature swing are we talking about here? Within 200*? Or going from 1400* to freezing?

 

[SPEEDSHIFT]

I am not sure, that was one of my questions. How much of a temp drop did you have from the head port to the turbine? Every little bit counts. Is there some type of formula that can tell us temp drop vs pressure drop?

 

[PASSENGER]

I'm sorry man, but that is not true. Heat needs to be maintained all the way to the turbine wheel. If it is not, you loose drive pressure, therefore not getting the full potential out of the energy.

Pressure doesn't drive the turbine.

So if heat is just a byproduct, putting a blanket on or having cool air move over the manifold shouldn't change spool?

With really incomplete combustion you could see spool gains from heating up a manifold via an external source.

I wonder if I can find pictures of some of the water cooled exhaust manifolds I've built.

This has gotten a good ways off from the point I was trying to make earlier, a log manifold creates heat, by being restrictive. A tubular manifold does not. I've bolted on tubular manifolds and without tuning seen a drop of 200* and have lost zero response or spool up.

 

[PASSENGER]

I am not sure, that was one of my questions. How much of a temp drop did you have from the head port to the turbine? Every little bit counts. Is there some type of formula that can tell us temp drop vs pressure drop?

I've never lost more than 50* from port to turbine. However bolting a tubular in place of a log I've measured 200* drop/difference at the port, same tuning...

Temp drop vs pressure drop has a lot of variables, and I doubt it could be accurately used for a variety of setups.

*edit*

I should mention this is under moderate load, not idle, not wot.

 

[Turbo Performance]

I am not sure, that was one of my questions. How much of a temp drop did you have from the head port to the turbine? Every little bit counts. Is there some type of formula that can tell us temp drop vs pressure drop?

Pressure doesn't drive the turbine.



With really incomplete combustion you could see spool gains from heating up a manifold via an external source.

I wonder if I can find pictures of some of the water cooled exhaust manifolds I've built.

This has gotten a good ways off from the point I was trying to make earlier, a log manifold creates heat, by being restrictive. A tubular manifold does not. I've bolted on tubular manifolds and without tuning seen a drop of 200* and have lost zero response or spool up.

You're right. I understand what you've been saying, I was just looking for clarification on some of your points. Two different manifolds, same flow characteristics, same spool, drop 200* heat from one, keep it in the other. Your thoughts on which will spool better or will they be the same?

 

[SPEEDSHIFT]

PASS, I see what you are saying about restriction causing heat, I understand seeing a EGT drop because of better flow, but what I am getting at is, we do not want the cool the air, we want to keep it the same temp all the way to the turbo. Its a battle of keeping the velocity up and the heat constant. If either is lost, you are not getting the full potential.

 

[PASSENGER]

You're right. I understand what you've been saying, I was just looking for clarification on some of your points. Two different manifolds, same flow characteristics, same spool, drop 200* heat from one, keep it in the other. Your thoughts on which will spool better or will they be the same?

Well the only way you could accomplish this would be externally heating the manifold. My guess as far as power is concerned within a range of 200* you would see no useable difference. Measuring psi and hp to tenths, yes I believe you would find gains from the manifold being hotter. IF we got into a range of 400 or more I do think you would see more useable gains, especially if you have unburnt fuel. If we are at all talking about unburnt exhaust gasses what I have been saying goes out the window.

PASS, I see what you are saying about restriction causing heat, I understand seeing a EGT drop because of better flow, but what I am getting at is, we do not want the cool the air, we want to keep it the same temp all the way to the turbo. Its a battle of keeping the velocity up and the heat constant. If either is lost, you are not getting the full potential.

Same temperature as when it leaves the cylinder? Sure I am with you on that. I'm not suggesting we radiate the exhaust, but rather understand what heat is, and why it is there, the heat generated from a restriction or turbulence (the whole reason I started this derail) is that it is unuseable for our application.

 

[Joesixpack]

Oh wow now were actively cooling the exaust gas. Were's that spare charge air cooler........

 

[PASSENGER]

Oh wow now were actively cooling the exaust gas. Were's that spare charge air cooler........

You must have misunderstood something.