[toohighpsi]

With the recent posting of the new TVS R2650 information being posted I saw a couple comments which kind of made me believe that we don’t all fully understand the difference between Supercharger and Turbochargers, especially around the area of power to drive the boosting devices. Sorry if I’m a bit winded here but there’s clearly more mis-information out there than accurate info so I though I'd start this as a separate post.

Input power of a compressor/blower is based off 4 items:
Mass Flow
Pressure Ratio
Thermal Efficiency
Mechanical Efficiency

Every compressor (PD, Turbo, Centri) will require the exact same amount of drive power under the same conditions - YES even the turbo. There is not any "completely free" drive power, it is either provided by a belt or the turbine (we all must be careful not to drink too much of the FORD commercial kool-aid).

With Superchargers, all this information is easily found on the map, with a Turbocharger it’s not quilt so easy. The turbocharger compressor map contains mass flow, pressure ratio and adiabatic efficiency. What about mechanical efficiency? You can’t calculate the total power needed to drive the compressor without that – well that’s baked into the turbine maps which are normally not readily available for public consumption.

This is where the confusion comes in - to say the SC requires 100HP at the belt to make 1000HP at 20PSI is easy to understand and read from a map, but to say that there is 100HP required by the turbine - well that might be a bit more difficult to get across in a 30 second commercial, so calling it "free exhaust temperature" is easy and since most people won't understand or have the background knowledge to argue, so they can get away with it.

To get a feeling of what this means, we need to start with a bit of thermodynamics. A turbine is driven by the “enthalpy” or the measure internal energy in the exhaust stream, the amount of enthalpy the exhaust flow is determined by:
Exhaust Temperature (the free part)
Exhaust Pressure (the part that’s the belt)

The combination of these inputs need to be enough for our turbine to drive our turbo compressor – in our example above we need 100HP. While the power can be provided by temp and pressure, with a turbocharger we really want it to be provided by the temperature as much as possible. We have a known value of HP that we want to achieve (100HP), the more temperature that we have – the LESS exhaust pressure (from the engine) that we need.

In a turbocharged engine, the exhaust pressure is your belt. It’s not easily seen, but it’s there. Hence the reason that Rear Mount turbo systems are not a good idea. It’s not that they won’t work (they do) but the high temperature exhaust is what gives turbo systems their efficiency. In most cases the back pressure required to run a low temperature rear mount turbo system requires much more power from the engine than a belt on any supercharger because most of the turbine power is created by pressure, not temperature (the energy was lost traveling to the turbo).

So, we want a close exhaust mounted turbo to get the most out of our system, we will normally see about a 300F to 400F temperature drop across the turbine. This is the amount of energy available from temperature and the remainder must be scrounged from pressure. If you have designed a good race turbo system, you’ll probably fall into the pressure category of making turbine inlet pressure pretty close to your intake pressure, there are ways to make it even less, but they normally require a very narrow operating range, forfeiture of a waste-gate, and limited street drivability. The split between the two (pressure and temp) can be calculated but let’s just say for this example on a race car it’s about 60/40. (the free part being the exhaust temperature). FYI - If we were to look at an OEM designed turbo system (like the ECO boost) it would be closer to 80/20.

That’s looking pretty good, the turbo vs supercharger in this example is costing 100 HP for the belt supercharger and 60HP for the turbine on the turbocharger, but we’re not quite done yet. We have to look at how each system interacts with the engine.

Turbocharged Engine – operates quite closely to a NA condition at WOT and full boost (20psi intake and 20psi exhaust). Exhaust pressure will be slightly lower than intake pressure (if everything in the exhaust is hot) up until the waste-gate opens at which point the “wasted energy” will cause the exhaust pressure to rise higher than the intake pressure for the remainder of the operating range. Since pressure is quilt similar to a naturally aspirated engine (same pressure intake and exhaust) the engine builds are similar (camshaft, ports etc). If we were to look at the P-V diagram for this scenario we would find a positive “power loop A” and a near neutral “pumping loop B” up to the point where the waste-gate starts to open and which point the “pumping loop” would shift negative compared to the P-V diagram shown. The total sum of these two areas are the provide thee amount of power that the engine is producing.


Supercharged Engine – bit of a different story here, under WOT we now have 20psi of boost it the intake, but our exhaust is still at atmospheric pressure creating a positive pressure differential on the engine. If we were to look at the P-V diagram for this WOT scenario we would find a positive “power loop A” and a positive “pumping loop B” (it flips to positive when compared to a turbo) which returns belt losses, in this case about 25HP of the 100 we were using to run the SC resulting in 75 HP needed for the SC at a 1000HP. When you build a SC engine your goal should be to make sure you are utilizing the most efficient exhaust, good flowing exhaust ports, and longer exhaust cam profiles in an attempt to get the combustion chamber as close as possible to atmospheric pressure at the end of the exhaust stroke.

So, I’m not saying that the scenarios are the same, but they are much closer than one might think (or at least have been lead to believe) when it comes to the comparison of SC drive power to TC drive power. The turbocharger system will always have a slight peak power advantage with higher cost and increased complexity when compared to the positive displacement SC systems. Its these tradeoffs that one should consider when trying to best choose the best system for their car.

[Atomic Ed]

Again, thanks for taking time to share your insight. I would love to come spend a week or two with you at your "shop".

[sub_ETCS_ret]

I love this place! Thanks for sharing.

Sent from my SM-G920V using Tapatalk

[AGP Turbo]

Stretching really far there trying to deny what everybody else has known to be true for 30yrs. Turbos are run by waste energy and that is proven by how much more power they make at the same boost levels. As turbos have gotten easier and easier to drive and approached no lag, superchargers have made almost no advancements.
Turbos are used 100+:1 in OEM applications to superchargers for the reason of efficiency. They are the flip phones in a smart phone world.

[bpang1234]

Originally Posted by AGP Turbo

Stretching really far there trying to deny what everybody else has known to be true for 30yrs. Turbos are run by waste energy and that is proven by how much more power they make at the same boost levels. As turbos have gotten easier and easier to drive and approached no lag, superchargers have made almost no advancements.
Turbos are used 100+:1 in OEM applications to superchargers for the reason of efficiency. They are the flip phones in a smart phone world.

Yeah unfortunately that is the case...I still like how current superchargers feel in terms of throttle response versus the lag in most turbocharged cars I have owned. However, they are getting closer and closer to getting rid of turbo lag...maybe one or two more generations and lag will only be a big turbo / tuner car issue.

AGP is right, turbos are employed SO MUCH more than superchargers by the OEMs, that is why they are getting WAY MORE R&D which is helping to even the gap in throttle response. Hell, my last car (22015 Audi S4) may be one of the last mass produced cars with a supercharger from the factory.

[jessrayo]

Originally Posted by toohighpsi

With the recent posting of the new TVS R2650 information being posted I saw a couple comments which kind of made me believe that we don’t all fully understand the difference between Supercharger and Turbochargers, especially around the area of power to drive the boosting devices. Sorry if I’m a bit winded here but there’s clearly more mis-information out there than accurate info so I though I'd start this as a separate post.

Input power of a compressor/blower is based off 4 items:
Mass Flow
Pressure Ratio
Thermal Efficiency
Mechanical Efficiency

Every compressor (PD, Turbo, Centri) will require the exact same amount of drive power under the same conditions - YES even the turbo. There is not any "completely free" drive power, it is either provided by a belt or the turbine (we all must be careful not to drink too much of the FORD commercial kool-aid).

With Superchargers, all this information is easily found on the map, with a Turbocharger it’s not quilt so easy. The turbocharger compressor map contains mass flow, pressure ratio and adiabatic efficiency. What about mechanical efficiency? You can’t calculate the total power needed to drive the compressor without that – well that’s baked into the turbine maps which are normally not readily available for public consumption.

This is where the confusion comes in - to say the SC requires 100HP at the belt to make 1000HP at 20PSI is easy to understand and read from a map, but to say that there is 100HP required by the turbine - well that might be a bit more difficult to get across in a 30 second commercial, so calling it "free exhaust temperature" is easy and since most people won't understand or have the background knowledge to argue, so they can get away with it.

To get a feeling of what this means, we need to start with a bit of thermodynamics. A turbine is driven by the “enthalpy” or the measure internal energy in the exhaust stream, the amount of enthalpy the exhaust flow is determined by:
Exhaust Temperature (the free part)
Exhaust Pressure (the part that’s the belt)

The combination of these inputs need to be enough for our turbine to drive our turbo compressor – in our example above we need 100HP. While the power can be provided by temp and pressure, with a turbocharger we really want it to be provided by the temperature as much as possible. We have a known value of HP that we want to achieve (100HP), the more temperature that we have – the LESS exhaust pressure (from the engine) that we need.

In a turbocharged engine, the exhaust pressure is your belt. It’s not easily seen, but it’s there. Hence the reason that Rear Mount turbo systems are not a good idea. It’s not that they won’t work (they do) but the high temperature exhaust is what gives turbo systems their efficiency. In most cases the back pressure required to run a low temperature rear mount turbo system requires much more power from the engine than a belt on any supercharger because most of the turbine power is created by pressure, not temperature (the energy was lost traveling to the turbo).

So, we want a close exhaust mounted turbo to get the most out of our system, we will normally see about a 300F to 400F temperature drop across the turbine. This is the amount of energy available from temperature and the remainder must be scrounged from pressure. If you have designed a good race turbo system, you’ll probably fall into the pressure category of making turbine inlet pressure pretty close to your intake pressure, there are ways to make it even less, but they normally require a very narrow operating range, forfeiture of a waste-gate, and limited street drivability. The split between the two (pressure and temp) can be calculated but let’s just say for this example on a race car it’s about 60/40. (the free part being the exhaust temperature). FYI - If we were to look at an OEM designed turbo system (like the ECO boost) it would be closer to 80/20.

That’s looking pretty good, the turbo vs supercharger in this example is costing 100 HP for the belt supercharger and 60HP for the turbine on the turbocharger, but we’re not quite done yet. We have to look at how each system interacts with the engine.

Turbocharged Engine – operates quite closely to a NA condition at WOT and full boost (20psi intake and 20psi exhaust). Exhaust pressure will be slightly lower than intake pressure (if everything in the exhaust is hot) up until the waste-gate opens at which point the “wasted energy” will cause the exhaust pressure to rise higher than the intake pressure for the remainder of the operating range. Since pressure is quilt similar to a naturally aspirated engine (same pressure intake and exhaust) the engine builds are similar (camshaft, ports etc). If we were to look at the P-V diagram for this scenario we would find a positive “power loop A” and a near neutral “pumping loop B” up to the point where the waste-gate starts to open and which point the “pumping loop” would shift negative compared to the P-V diagram shown. The total sum of these two areas are the provide thee amount of power that the engine is producing.


Supercharged Engine – bit of a different story here, under WOT we now have 20psi of boost it the intake, but our exhaust is still at atmospheric pressure creating a positive pressure differential on the engine. If we were to look at the P-V diagram for this WOT scenario we would find a positive “power loop A” and a positive “pumping loop B” (it flips to positive when compared to a turbo) which returns belt losses, in this case about 25HP of the 100 we were using to run the SC resulting in 75 HP needed for the SC at a 1000HP. When you build a SC engine your goal should be to make sure you are utilizing the most efficient exhaust, good flowing exhaust ports, and longer exhaust cam profiles in an attempt to get the combustion chamber as close as possible to atmospheric pressure at the end of the exhaust stroke.

So, I’m not saying that the scenarios are the same, but they are much closer than one might think (or at least have been lead to believe) when it comes to the comparison of SC drive power to TC drive power. The turbocharger system will always have a slight peak power advantage with higher cost and increased complexity when compared to the positive displacement SC systems. Its these tradeoffs that one should consider when trying to best choose the best system for their car.

Hmm, I don't know if you clarified anything here or not. I could propose several tests to show how much more efficient turbos are than superchargers but I would go out on a line and say they have much less than half the demand on the engine to operate than the supercharger does.

I agree 100% that for a turbo to make say 10 pounds of boost it will take the exact same mathematical amount of horsepower to generate the boost as the supercharged engine. What you do correctly point out is that the turbo is driven from the enthalpy of the exhaust. And there is energy here obviously driving the invisible "belt". The thing of it is, the supercharged engine also has enthalpy in its exhaust. You could calculate the energy lost in the supercharged engine exhaust also. The big difference is the enthalpy in the supercharged car is truly lost, wasted and vented to the atmosphere and the enthalpy in the turbo car is used to spin the turbine. The only true "cost" to the turbo system is whatever power it takes to drive the exhaust stroke through the increased back pressure.... And that is not even close to the real power it takes to crank those steel supercharger rotors at 18,000 rpm against resistance.

So I'm going to pull a number out of my a$$ based on my own experiences trying to get the most power out of forced induction systems and say that about 80% of the enthalpy used to drive the turbos really has absolutely no effect on the car and only about 20% is caused by additional backpressure that would not be there without the turbo. I'm open to discuss it though...

Oh, and unless you are running open straight pipes on a drag car you never have atmospheric pressure on the exhaust side of a supercharged car, if you have cats, pipes and mufflers you have plenty of back pressure.

[LibertyHill]

Originally Posted by toohighpsi

When you build a SC engine your goal should be to make sure you are utilizing the most efficient exhaust, good flowing exhaust ports, and longer exhaust cam profiles in an attempt to get the combustion chamber as close as possible to atmospheric pressure at the end of the exhaust stroke.

So the most free-flowing exhaust possible is highly recommended for a PD SC? And the back-pressure requirements that may or may not exist in NA applications definitely go away?

[toohighpsi]

Originally Posted by AGP Turbo

Stretching really far there trying to deny what everybody else has known to be true for 30yrs. Turbos are run by waste energy and that is proven by how much more power they make at the same boost levels. As turbos have gotten easier and easier to drive and approached no lag, superchargers have made almost no advancements.
Turbos are used 100+:1 in OEM applications to superchargers for the reason of efficiency. They are the flip phones in a smart phone world.

Turbochargers do offer fuel economy benefits at WOT, but normally no real benefit under the drive cycle when compared with SCs which can pull taller gearing and lower RPM thanks to their quick response (downspeeding). So, if you're lucky enough to live near the Autobahn then you'll probably see a MPG benefit for your commute. (Especially on the eastern side of Germany where traffic isn't too bad - I recommend Berlin to Dresden on the A13 )

The OEM selection process is primarily based on cost. Turbochargers in the OEM world are a commodity. There are several manufactures out there all battling each other for their portion of the market driving the cost down - and in that OEM world, turbochargers are really cheap.

[Atomic Ed]

I'll throw this out here. I went back and checked my old notes on my Audi TT turbo setup. Exhaust manifold pressure was around 55psi at 26 psi boost and roughly 900*F EGT.

I know these numbers don't mean much without a lot of other info for context, but it does point out that at 55 psi in the exhaust manifold, pre-turbo, the engine itself has to supply extra energy to become the driving compressor to spin the turbine side of the turbo.

[JANNETTYRACING]

Originally Posted by toohighpsi

With the recent posting of the new TVS R2650 information being posted I saw a couple comments which kind of made me believe that we don’t all fully understand the difference between Supercharger and Turbochargers, especially around the area of power to drive the boosting devices. Sorry if I’m a bit winded here but there’s clearly more mis-information out there than accurate info so I though I'd start this as a separate post.

Input power of a compressor/blower is based off 4 items:
Mass Flow
Pressure Ratio
Thermal Efficiency
Mechanical Efficiency

Every compressor (PD, Turbo, Centri) will require the exact same amount of drive power under the same conditions - YES even the turbo. There is not any "completely free" drive power, it is either provided by a belt or the turbine (we all must be careful not to drink too much of the FORD commercial kool-aid).

With Superchargers, all this information is easily found on the map, with a Turbocharger it’s not quilt so easy. The turbocharger compressor map contains mass flow, pressure ratio and adiabatic efficiency. What about mechanical efficiency? You can’t calculate the total power needed to drive the compressor without that – well that’s baked into the turbine maps which are normally not readily available for public consumption.

This is where the confusion comes in - to say the SC requires 100HP at the belt to make 1000HP at 20PSI is easy to understand and read from a map, but to say that there is 100HP required by the turbine - well that might be a bit more difficult to get across in a 30 second commercial, so calling it "free exhaust temperature" is easy and since most people won't understand or have the background knowledge to argue, so they can get away with it.

To get a feeling of what this means, we need to start with a bit of thermodynamics. A turbine is driven by the “enthalpy” or the measure internal energy in the exhaust stream, the amount of enthalpy the exhaust flow is determined by:
Exhaust Temperature (the free part)
Exhaust Pressure (the part that’s the belt)

The combination of these inputs need to be enough for our turbine to drive our turbo compressor – in our example above we need 100HP. While the power can be provided by temp and pressure, with a turbocharger we really want it to be provided by the temperature as much as possible. We have a known value of HP that we want to achieve (100HP), the more temperature that we have – the LESS exhaust pressure (from the engine) that we need.

In a turbocharged engine, the exhaust pressure is your belt. It’s not easily seen, but it’s there. Hence the reason that Rear Mount turbo systems are not a good idea. It’s not that they won’t work (they do) but the high temperature exhaust is what gives turbo systems their efficiency. In most cases the back pressure required to run a low temperature rear mount turbo system requires much more power from the engine than a belt on any supercharger because most of the turbine power is created by pressure, not temperature (the energy was lost traveling to the turbo).

So, we want a close exhaust mounted turbo to get the most out of our system, we will normally see about a 300F to 400F temperature drop across the turbine. This is the amount of energy available from temperature and the remainder must be scrounged from pressure. If you have designed a good race turbo system, you’ll probably fall into the pressure category of making turbine inlet pressure pretty close to your intake pressure, there are ways to make it even less, but they normally require a very narrow operating range, forfeiture of a waste-gate, and limited street drivability. The split between the two (pressure and temp) can be calculated but let’s just say for this example on a race car it’s about 60/40. (the free part being the exhaust temperature). FYI - If we were to look at an OEM designed turbo system (like the ECO boost) it would be closer to 80/20.

That’s looking pretty good, the turbo vs supercharger in this example is costing 100 HP for the belt supercharger and 60HP for the turbine on the turbocharger, but we’re not quite done yet. We have to look at how each system interacts with the engine.

Turbocharged Engine – operates quite closely to a NA condition at WOT and full boost (20psi intake and 20psi exhaust). Exhaust pressure will be slightly lower than intake pressure (if everything in the exhaust is hot) up until the waste-gate opens at which point the “wasted energy” will cause the exhaust pressure to rise higher than the intake pressure for the remainder of the operating range. Since pressure is quilt similar to a naturally aspirated engine (same pressure intake and exhaust) the engine builds are similar (camshaft, ports etc). If we were to look at the P-V diagram for this scenario we would find a positive “power loop A” and a near neutral “pumping loop B” up to the point where the waste-gate starts to open and which point the “pumping loop” would shift negative compared to the P-V diagram shown. The total sum of these two areas are the provide thee amount of power that the engine is producing.


Supercharged Engine – bit of a different story here, under WOT we now have 20psi of boost it the intake, but our exhaust is still at atmospheric pressure creating a positive pressure differential on the engine. If we were to look at the P-V diagram for this WOT scenario we would find a positive “power loop A” and a positive “pumping loop B” (it flips to positive when compared to a turbo) which returns belt losses, in this case about 25HP of the 100 we were using to run the SC resulting in 75 HP needed for the SC at a 1000HP. When you build a SC engine your goal should be to make sure you are utilizing the most efficient exhaust, good flowing exhaust ports, and longer exhaust cam profiles in an attempt to get the combustion chamber as close as possible to atmospheric pressure at the end of the exhaust stroke.

So, I’m not saying that the scenarios are the same, but they are much closer than one might think (or at least have been lead to believe) when it comes to the comparison of SC drive power to TC drive power. The turbocharger system will always have a slight peak power advantage with higher cost and increased complexity when compared to the positive displacement SC systems. Its these tradeoffs that one should consider when trying to best choose the best system for their car.

A very well written article that brings to light in layman terms some of the real world facts.

In the end The turbo guys will wave their flag and the supercharger guys will wave their flag.

Both are making big improvements in efficiency, this is where all the R&D is focused on both fronts.

It is no longer just a discussion about which Forced induction you should bolt on your N/A engine.

Engines are now built from the ground up to optimize the choice of forced induction in an OEM package.

You really can't compare an add on forced induction with what the OEMs are choosing for this very reason.

[Spulbus2013]

Yeaahh... Nothing confusing about it here. Simply put the LT1/LT4 can surly use the extra power with the same amount of fueling turbos can and do provide.

[ProCharger]

Originally Posted by AGP Turbo

Stretching really far there trying to deny what everybody else has known to be true for 30yrs. Turbos are run by waste energy and that is proven by how much more power they make at the same boost levels. As turbos have gotten easier and easier to drive and approached no lag, superchargers have made almost no advancements.
Turbos are used 100+:1 in OEM applications to superchargers for the reason of efficiency. They are the flip phones in a smart phone world.

To be devil's advocate...

If what you say is true...
Then why do ProCharger powered GM's hold all these track records?

Fastest 6th Gen Camaro
Fastest Corvette C7
Fastest LT4 Corvette Z06
Fastest IRS C5 Corvette
Fastest IRS C6 Corvette Stick
Fastest IRS GTO
Fastest Chevy SS Sedan
Fastest LT GM Truck

and I am sure plenty that I don't even know about....


Just saying that turbo guys seem to dog on blower cars all the time. Yet the blower cars are the ones at the track every weekend, setting records and enjoying the boost.

[parish8]

I hope to be taking fastest 6th gen Camaro from you. I just need a little more time(by time I mean money). It is all about the money.

[ProCharger]

Originally Posted by parish8

I hope to be taking fastest 6th gen Camaro from you. I just need a little more time(by time I mean money). It is all about the money.

Jim you know I love your effort... and have nothing buy respect for ya.

But, its just funny that for years and years and years I have to listen to the "turbo guys" tell me about how blowers suck.

Yet, I get to watch all of our amazing customers out there setting records.
I just had to make a post that was throwing a little back