Superchargers or Turbochargers: The Debate

General Discussion
#21

[quote=""]
As I don’t have all day and my time zone is far away I’ll pre-empt any more nonsense by explaining what compressor efficiency actually is.

As you can (barely) see written on the Vortech map the efficiency lines on compressor maps are adiabatic efficiency.

Which is defined as: the ratio of work output for an ideal isentropic compression process to the work input to develop the required head.

In essence this is the relationship between the temperature of the compressor intake air and the temperature of the compressed discharge air. Relative to the IDEAL isentropic compression - the temperature increase created by the compression itself. In reality turbo or supercharger compressors add considerable heat to the air in the process. So efficiency is less than 100 percent. At 75 percent you could say the air coming out of the compressor is 25 percent warmer than it would be in an ideal compression. This is an oversimplification obviously but I think it gets the point across.

There is no “volume” anywhere in the map either. There is MASS flow in lb/min. To calculate volume you need temperature which isn’t a constant. The engine’s VE only comes into play when you want to select the proper compressor. Once you select a pressure ratio, estimated temperatures and estimated VE of the engine you can work out which engine rpm points hit which place on the compressor map.

#22

JC your just arguing semantics at this point.

Turbocharging is not the end all be all of power adders.
You can argue all day in saying that the exhaust restriction of a turbo is less important that the parasitic loss from a supercharger, but they we can talk about re gearing a centrifugal charger or the fact that they now have variable geared centrifugal a that are electronically controlled.

No one option is dominant, but from an installation and cost standpoint a supercharger almost always wins unless the car comes from the factory with snails hanging off of it.

#23

looking forward to the intake spacers discussion…

#24

Can we please split off the inaccurate part of this thread where JC comes in and just makes stuff up and rambles on. You can’t have a conversation woth an idiot and that’s all this JC guy ends to be here. This isn’t the foundation of this conversation.

Thanks swagger. Using a 15 year old supercharger map vs a new variable turbo just shows how desperate he is. Not only that but even that map shows how much efficient the supercharged app is. Look how more more boost is obtained at 1/2 the pressure ratio. Not only that but the turbo JC posted iis huge and would have incredibly terrible lag. If we are cheery picking compressor maps this one just dominates the argument and you can close up shop… you can run 78% from just under 300 CFM to over 1200 CFM all at less then 2 pressure ratio.

http://www.vortechsuperchargers.com/maps/X-Trim_Compressor_Map.jpg

It’s obvious to everyone what I was saying but JC is consistently wrong so he argues semantics. A supercharger looses less air and has larger islands for its efficiency. The VE for the air is better in supercharged apps adiabatic…is part of the map but it’s the over all map it’s range and adiabatic efficiency and the other factors that lead you to the VE. As the volume of air can carry a larger CFM before heat rise becomes an issue.

Also last point and such a simple argument. If turbos were better you wouldn’t need two of them to do the work of one supercharger. And no matter how you do it you can tailor the boost curve with a supercharger to make boost all through the Rev range.

Lag and pressure raise increase turbo Temps past those of supercharged apps. It’s not hard to see that a supercharger can make more CFM at a lower pressure ratio with better efficiency. Apparently JC posted compressor maps and didn’t even read them.

#25

Some observations:

Supercharging (and NA) are alive and well. You see it from Jaguar on the F-Type, Ford with the Mustang, and Chevy with the Z06. The power is more closely tied to the displacement. You’re not going to make huge numbers supercharging a 3.0L but you’ll blow everyone’s mind with a 5.0L. Personally, I feel the S4 has instant, linear throttle response throughout the rev range.

Among high horsepower cars, you’re finding about 5x more turbo motors than SC motors. There’s some reasons to be cautious. First, for many manufacturers this is their first attempt with turbo gasoline motors. BMW is still having trouble making a fuel pump that works 9 model years into it. Second, they generate a ton of heat so if you’re going to increase the power from factory you have to do surgery on the cooling.

On the M4 in particular, there’s a slight issue with MDM (M dynamic mode) and turbo lag. It cuts your power mid apex to save you from going into the wall, then it stutters on reapplication of power as the turbos spool. I’m not a good enough driver to pilot a 500 HP, front engine, RWD car with all of the nannies off. For this reason, I’d restrict my search to turbo cars that also have AWD. A 3.0L turbo RS5 would be welcome.

#26

Great post west. + member rating for you.
This entire thread is just about the inaccurate statement made by JC and the downward spiral that followed. The point is not one is superior to the other by default. They both have high abilities and shine in different configuration. In all a lost every post of his is his theory or thoughts as facts. He seems to do that often Maybe that’s why he has a negative members rating.

Again supercharged cars are alive and well. So are turbo cars.

#27

Justin,

I’ve always valued your write ups and posts. You contribute a lot to the Audi community. I am, however, in awe at some of the things you are spewing in this thread. I’m fine if people come off as ignorant as long as they have the knowledge to back up their argument. You are absolutely wrong with many of your arguments and accusing VC of being ignorant when he is technically much more correct than you are. I am 100% unbiased as I don’t know any of you.

I hate internet drama and avoid it at all costs (which is why I shouldn’t even look at Audi forums) but I hate false information even more. I guess I’ve gotten myself involved at this point so I’ll find some time in the near future to elaborate. My guess is you’re just going to attack me and tell me I’m an idiot like you did to VC but hey…I’m dumb enough that I’m going to try.

#28

Then I challenge you to defend what you wrote. And point out you jumped to an inaccurate conclusion.

Read the thread again

I have been assessing from the beginning that the blanket statement that turbos are better then Superchargers is false. I have been continuing to say that over and over. I continue to say they both have there bright spots and looking at a compressor map will show that. And clearly you can look at a compressor map and see that. Looking at a roots style map would continue to advance the debate in the favor of the supercharged app. It’s not to challenging to understand the bright points of each. The map argument is simple it isn’t the entire story but it’s one piece that destroyed the rest of JC and his argument.

From a technical aspect I do understand what your talking about. I used the term VE way too loose. This was ment to be derived from more of CFM efficiency or unit Efficiency. I used the term VE to collect all the parts of the map including the PR…AB% and CFM output given heat increase and drive loss. The AB % is without certian variables but when you look at the formula speed PR AB CFM that is the charge. And since the actual term for VE is the charge going into the motor and it’s use of that in efficiency. I loosely was using the label VE for the overall charge equation and all its inputs if everything was equal. While I understand the counter issue with this the overall vision i used VE for to explain seemed to be obvious to most as it was intended. I understand the inaccurate angle and have no issues with objections on that point.

JC once he completely looses an argument turns to semantic points one of witch you picked up on. The debate was about the blanket statement and my references (the maps) was an attempt to show him how his statement didn’t messessarly make sense. It was clear his other braud random thoughts as facts were dead he latched into the map verbiage. That’s fine he didn’t understand the first basic points I didn’t care much for the rest.

If were getting technical and this is your concern with you…look at the debate then I ask you to over look the complete incorrect posts of JC s feelings as facts. That’s more what I have been targeting. We just got off track.

To be clear I have wanted to have been saying that JC is wrong when he used his opinion as facts as they never stand. And that in the world of turbos and superchargers they each offer great results… to use a blanket statement to say over all one is better then the other is not only false but completely absent of the understanding of each. And again while the compressor maps don’t tell the entire story they do tell one that says there’s not room to say anything in a blanket statement.

#29

Stop. Please repeat after me:

The compressor map does not say diddly squat about the total efficiency of the supercharger or turbocharger. Do you see parasitic loss on that map? Do you see the turbine efficiency of the turbo? No you don’t.

I only posted it to illustrate that there is nothing inherently different in compressor maps. I compared entirely different compressor wheels. And the turbo isn’t variable at all, whatever you mean by that

[quote]Look how more more boost is obtained at 1/2 the pressure ratio.
[/quote]
Pressure ratio IS boost. What the hell are you on about? At every corner of this argument you demonstrate that you don’t have an actual clue of the subject matter. But keep downvoting my karma each time you get your nose rubbed in your own ignorance, why not.

[quote]Not only that but the turbo JC posted iis huge and would have incredibly terrible lag. If we are cheery picking compressor maps this one just dominates the argument and you can close up shop…
[/quote]
Serious question: do you think you could actually fit that supercharger to an RS4 to name one car? The garrett turbo I happened to link to (i just took something with similar flow rates to get the scale right anyway) is not inherently laggy, it always depends on the size of the engine you’re strapping it to.

[quote]you can run 78% from just under 300 CFM to over 1200 CFM all at less then 2 pressure ratio.
[/quote]
Yes, you can. How big does an engine need to be for the supercharger to do this, however?

Try and calculate how big an engine needs to be (let’s assume 100 percent VE) to consume 1200 CFM at 2.0 PR at maybe 7000 rpm? And keep in mind the surge line on the left.

[quote]JC is consistently wrong so he argues semantics.
[/quote]
The difference between volumetric efficiency and isentropic efficiency is semantics? ??? They’re completely different things! You’re the one who started arguing compressor maps and then proceeded to display his complete ignorance of them.

[quote]A supercharger looses less air
[/quote]
What?

[quote]and has larger islands for its efficiency.
[/quote]
No. And again you seem to think a compressor map is relevant to the whole of the supercharger.

[quote]The VE for the air
[/quote]
What? Zero meaning detected.

[quote]adiabatic…is part of the map but it’s the over all map it’s range and adiabatic efficiency and the other factors that lead you to the VE.
[/quote]
No, it doesn’t. In no way, shape or form is VOLUMETRIC efficiency related to the THERMAL efficiency of the compression process. No way. If you have an old physics schoolbook lying around somewhere please open it. You are talking absolute jibberish here.

[quote]As the volume of air can carry a larger CFM before heat rise becomes an issue.
[/quote]
You’re saying the same volume of air can carry more volume here.

Congrats.

You’ve now established that a supercharger not only has more boost at the same boost but also that it has more volume for the same volume. You might be up for a Nobel prize this year if you’re not careful.

[quote]If turbos were better you wouldn’t need two of them to do the work of one supercharger.
[/quote]
I’m starting to think I’m on Candid Camera. Tell me the truth is this a wind-up?

[quote]Lag and pressure raise increase turbo Temps past those of supercharged apps.
[/quote]
Mmmno. And how do you imagine lag affects temperatures anyway?

[quote]It’s not hard to see that a supercharger can make more CFM at a lower pressure ratio with better efficiency.
[/quote]
Sigh. No. Any difference that exists in compressor maps is purely the result of differently designed compressor wheels because of various reasons such as the shaft speeds of a supercharger typically being slower than turbos.

How often do I need to tell you that you are looking in the wrong place to find the difference between turbos and superchargers? The compressor maps DO NOT APPLY TO THE ENTIRE TURBO OR SUPERCHARGER.

#30

Ahhhh JC commits his loss of understanding again. This time it’s just simple to take down.

Again all I have said from the beginning is what we have seen with JC and that’s he makes up stuff and try to sell it as fact. I’ve continued to say turbos and superchargers are great and they each has its bright point. I keep saying the same thing over because that’s how you need to speak with JC because when he looses an entire argument he makes up more stuff. Let’s see.

1 everyone reading. I never at any point said anything about TOTAL efficiency. I keep making the statement about the compressor maps showing how the total statement of superior and more efficient is incorrect. In aspects that can be shown easily and measured this clearly disproves his case. And it does

2 other people knock down his karma due to them clearly seeing he is E fitting again. The boost comments were to explain that supercharger apps get more power while using less total over all pressure. In other words you see the PR of turbos in the measurement sheet is higher due to generally that being the case. It’s a general observation the sheet simply backs it.

  1. Here is turbo fact. 1 the turbo he listed would be laggy yes. 2. The turbo he posted made quite a bit less CFM then the supercharged map and 3. Apparently this is hard for JC to understand. If you want more CFM out of a turbo you need At some point to put in a bigger turbo. Simple a ko3 spools faster then a ko4 and a ko4 spools faster then a RS6. The bigger the CFM requirements the bigger the wheels need to be and thus more lag. That’s turbo 101 people. As you want more CFM you shift the tq curve further up the Rev range with a turbos. Just look at every b5 s4 that has bigger turbos and a slower then stock 0-60

4 yes you can was his answer. Conceding that the point I used the maps for made its point. This again is part of him seeing the maps have part of the answer to destroying his blanket statement. The rest is semantics. Remember I’m only saying that there isn’t a diffinitive turbos are better and more efficient blanket statement

5 I understand the point he is making and I explained my reasons for using a loose statement. Again all I’m saying is looking at the maps can disprove a blanket statement. I used loose terminology to make a point.

6 air quality. Due to superchargers actually running more efficient at delivery of CFM in SOME cases you loose less air quality

7 again I have said several times the maps are one part of the conversation. JC realizes the maps destroy his blanket statement and uses the over all comments. I never stated over all.

8 again explained.

9 again explained. Actually back to the semantics trick he does. I already explained the verbiage and why. No need to get off course again. I’m saying that JC posts his opinions as inaccurate facts. But when I do the same to have fun with him he points it out and carry on

10 semantics that is what I posted to explain what I was using the loose terminology for. Anyone that’s reading understands the point I’m making. More CFM less pressure means lower heat per lb of boost.

  1. Again easy to understand. If you want more boost it will come at the cost of more heat. As you request more boost to meet the abilities of the supercharger CFM you need to select a bigger turbo and with that turbo more lag and with the boost more heat.

12 again argument over for him. It takes two turbos to do the work of one supercharger CFM wise. Sure you can put one big turbo on but what everyone but JC understands is that just offsets the power curve by creating lag. To try and reduce the lag time of one big turbo you use smaller turbos. Simple to explain here. Take any turbo in this case a G garret gt2860…it’s roughly a 430 hp turbo the CFM output is only enough for that. Let’s say you want 530 hp and you step up to a larger GT3071…bugger wheels bigger flow paths and wait for it…more lag. But lest say you want more CFM out of a C fuge supercharger. Most of the superchargers flow a huge CFM that makes most of them a one size unit. But in several cases to get more CFM on some superchargers you just put on a lager inlet and if needed spin the blower faster. Now here is the cool part by spinning the blower faster your making more CFM SOONER so you actually widen the power curve.

13 easy to see. He admits there is a difference again and then continued on about making a point I was never talking about.

Again for the how many times. JC just keeps posting his thoughts as facts. There wrong. We all see it and when you make a good point and say just start with the map it kills your blanket statement he just keeps on with trying to defend being wrong.

Everything on supercharged apps are dead in automotive apps to turbos are by far superior and more efficient is an opinion and how this thread started. I appreciate TM…saying I got a little off course in my explanation I understand.

To be clear I have wanted to have been saying that JC is wrong when he used his opinion as facts as they never stand. And that in the world of turbos and superchargers they each offer great results… to use a blanket statement to say over all one is better then the other is not only false but completely absent of the understanding of each. And again while the compressor maps don’t tell the entire story they do tell one that says there’s not room to say anything in a blanket statement.

as more and more motors in the past year have come out with superchargers from several automakers this shows that there is a great need for superchargers and that they offer something great. Don’t tell JC this but Audi jag GM Ford and several other automakers used superchargers over turbos on there high performance cars. Shhhn…Apparently they know something JC doesn’t

#31

For the sake of a productive discussion, let’s assume that both turbocharging and supercharging goes full electric by 2020. Further assume that power comes from batteries and regenerative braking, so it really is “free”.

What does that do to Justin’s argument and the challenger’s argument?

#32

Justin, I would be very happy to take this to another place like physicsforums.com (the mechanical engineering subforum) where there is an audience which can weigh in constructively. Or if you have a place which is well educated in matter of forced induction I’ll be happy to go there as well.

It seems I can point out your basic mistakes and lack of understanding what is volume, mass and temperature indefinitely here and it’s getting us nowhere.

I could go ahead and quote another dozen things you just wrote which are not true in this universe at least but what’s the point if there’s no-one around to tell the difference between science and something which sounds only like science.

What I will say is that I never made the blanket statement “turbos are better at everything!” you suggested I did. And my very first post in fact says that for cars which weren’t turbocharged from the factory turbos are rarely the better option vs a supercharger.

So I’m somewhat confused how you got your panties in a bunch in the first place.

#33

Good question, thanks for joining in.

My reply would have to start with: would this device still be a turbocharger or a supercharger?

To answer my own question, no I don’t think so.

You’d have an electric motor spinning the charger. Not a turbine (hence turbo-charger) nor the engine itself (as is the case with a super-charger)

The compressor itself could be identical to the one fitted on a turbo or SC.

In reality I don’t think fully electric chargers are that great of an idea. They cannot deliver long sustained performance, only a short boost before they run out of stored electricity.

The kind of hybrid turbo you see in F1 is much more promising. It uses electricity to spin up when there isn’t enough exhaust flow but once there is the engine takes over and you’re left with a very efficient solution that has no perceptible lag. A SC has to be driven directly by the engine by design and any charger that isn’t would not really be a SC as we currently define it.

#34

I think this is a fair request. Everything being discussed is wayyy over my head. Kind of frustrating to be having this discussion with no objective person weighing in on the facts other than the people arguing. JC may have built up a bad reputation for some other shit, but I think it would be helpful if some others picked apart your arguments rather than refuting with blanket statements. But it’s easy for anyone with a technical background (such as JC) to obfuscate something by using scientific terminology or arguments that are misplaced.

It usually requires someone who’s an expert in the field to detect this kind of BS. In my opinion, resolving these arguments requires someone with at least an engineering background to weigh in. But maybe that is the engineering elitist in me. There are a few guys on AZ (obviously engineers) who think they can make complex automotive arguments simple by using some concept/modeling they learned in a sophomore level thermodynamics class. The more you learn/practice, the more you realize you don’t know shit.

#35

So let me see if I get what is being said. From JC at no point in time are supercharges more efficient. from Justin there are specific point where superchargers are more efficient and that is at critical points in the production of power. Then an argument about compression and heat where Justin is being general and JC specific. Ok so I am hearing lost of fact and figures where are these coming from site/ link resources I would love to be able to review. Check /read for myself not that I don’t believe either of you in the case of argument I am sure plenty are plenty of studies and reviews for both efficiencies’ where they are strong and weak. JC your argument that every going to turbo because its better doesn’t hold water companies typically go the path of least resistance meaning $$$ more often the almighty manufacturer is going for where they can make more $$$ how they can make strong machines that hold up well as quickly and cheaply as possible. The fact that they are going turbo could just mean its cheaper…

#36

Not only do manufacturers base their designs on cost to in an attempt to maintain profit margins but they also have to abide to ever more stringent environmental requirements (and many other variables including performance but not solely performance). We all know most of their MPG figures are BS because they’re not representative of real world driving and it’s a lot easier (referring to many new OEM turbo applications) to drive a turbo car below boost for miles and miles and show 10000 mpg lol. Those are factors and variables that need to be taken into account when one begins using car manufacturers as examples to back up one’s point.

In other words, stick to a vacuum (no pun intended) of strictly performance related arguments and keep "well, manufacturer does this and this and that and that) would be my suggestion. Who cares what they use, they have other considerations in addition to performance efficiencies.

#37

^^^ So true. ;D

#38

Completely agree with this. Keep in mind the EPA drive cycle for MPG is a fairly antiquated test that is in place to produce some kind of comparative standard metric. So not necessarily designed to be representative for actual driving. BUT auto makers are absolutely incentivised to provide engine calibrations that work well for EPA, but shit for actual drivability. There are even provisions which allow OEM’s to create EPA MPG scores for vehicles based completely on simulation data (since it becomes difficult to test every vehicle configuration within the production time-line), which resulted in some serious PR fiasco’s and giving a bunch of $$$ back to customers.

I would guess you are correct about the turbo applications, but I can’t back that up remotely to the technical level JC and Justin are debating lol :smiley:

#39

You’ll see that JC avoided this question. I’m sure you know why. If you look at shaft speeds you will see the supercharger shaft speeds at better then 1/2 those of the turbo shaft speeds.

#40

I appreciate you bowing out gracefully. Usually after you have had your points destroyed you keep going. Sooner or later i figured if you actually read what was being said you would see you didn’t have a leg to stand on. Under stand that there is no basic mistakes being made your constantly looking at the wrong picture. Since you don’t know enough your constantly looking at the wrong variables this isn’t the first time http://audirevolution.net/forum/index.php?topic=3352.msg96858#msg96858

Your painting a picture i never talked about.

Obviously there’s nothing left for you to “correct” as points have already been made but I understand that you make up stuff so your dozen example is what you need to make yourself feel better.

For anyone not sure why you shouldn’t listen to JC enjoy his other example of complete miss understanding of how something works I posted the link above.