This can be possible yes. But it can be completely eliminated by using an isolated tension system. Much like on the factory S4 and likes the Jhm unit has.
Great posts, Justin. I’m enjoying the debate.
Sadly it can’t even be a debate. I keep trying to be nice but when someone doesn’t even get the most primitive basic starting point. And then says it’s I that don’t get it. It just turned into a hey dumb ass post. I don’t think JV…understood anything that compresses air has a compressor chart for VE and if he actually looked he would see supercharged VE rates are higher and cover a extremely large area in comparison to turbos. Superchargers can run in the 80% VE range turbos can’t. Also in supercharged apps consideration of draw to draw is constant. It’s delivery system is the crank. Turbo apps don’t but put the calculation in like you had perfect manifolds.
I was trying to be nice but when this was said
That’s wrong. And hey just look at a compressor map and you can see that. I went back and read where in nicely said that several times. Not only are turbos not more efficient they are not more salable per unit per VE. You can take 1 supercharger that can flow 1000 CFM and scale your CFM to just about whatever rpm you want. Just adjust the step up ratio and pulley. Sure you can strap on a turbo that makes 1000 CFM but it will be huge and if you want it to actually flow 1000 CFM it will take a good amount of time to spool. You can kill the AR ratio on the turbo to make more CFM down low but then it will never make 1000 CFM because it will choke up top
. And if the turbos were so great why did audi pass them over in favor for the supercharged unit for the S4. the fastest S4 to date keeping the majority of its OEM parts. If were talking scale. You can scale a b8 S4 into the 11s on the stock head unit. That’s not possible with the b5 turbos.
They each have a good place in making power. They both have pints where they shine. Understanding this helps make for a better understanding
Interesting. I guess I don’t knows what this is.
Have you ever taken part in any Dunning-Kruger research?
[quote]In what case can you put the same wheel from a turbo on a supercharger and in that case they would still share the same VE
[/quote]
What VE? Volumetric efficiency? That’s not actually a metric that is normally used for compressors. Engines or anything else with pistons, sure. Compressor blades…not really.
[quote]Looking at roots and c fuge maps you will see they carry a higher VE then conventional
Turbo maps. Turbos can get into the low to mid 70s in VE but there range of CFM and speeds at that point are limited. While the Cfuge or roots style carry a VE in some ranges in the 80% VE. If you knew what you were talking about you would have known this.
[/quote]
The efficiency of compressors is not measured in VE. Not at all.
Before you try to educate anyone you really should know what you’re talking about.
And compressor maps apply to the compressor itself only. Not to the unit (unit being the turbocharger or supercharger)
There is no inherent difference between compressor maps for centrifugal compressors whether they are mounted on a turbo or supercharger so your initial point (which you are straying away from slowly but surely) that the “clue” to what is the difference between SC and TC is invalid
Just for reference a Vortech map vs a Garrett map. There’s more efficiency lines on the latter but that doesn’t really matter.
http://www.greenringer.net/shoot/maps.jpg
So your point was?
[quote]It takes 2 turbos to do the work of 1 supercharger… win supercharger.
Sure you can use one big turbo but the lag and efficiency will be terrible.
[/quote]
If you’re talking about V engines then it is more convenient to use one turbocharger per bank, yes. Not really the point of the argument though is it. A single turbo is not more laggy or less efficient, au contraire, it would get twice the exhaust flow of 2 small ones but manifold design and space requirements favour the twin setup on V engines.
[quote]You can run boost at super low loads and tailor a boost curve of all supercharger apps getting close to 80+% efficiency.
[/quote]
And then you add parasitic loss to it. Compressor efficiency (which rarely if ever hits 80 percent by the way) is one small part of a larger equation. Superchargers have a lot of parasitic loss and turbochargers do not.
[quote]Hey genius did you know to recycle exhaust energy you need to create a restriction and to get that restricted path costs you a ton of energy and you loose even more VE.
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Yes but the overall loss is a lot less than superchargers. Automotive knowledge 101 really. Overall efficiency turbochargers are simply better and to argue this point is like arguing the sky is green.
[quote]when you ACTUALLY READ A COMPRESSOR MAP for each you can see supercharged apps offer a much larger range for VE. So while the compressor map isn’t going to be the entire story it will be the start of the story. Since you don’t know that you don’t even know what your talking about.
[/quote]
- The efficiency lines on compressor maps are not VE. There is no frigging VE on a compressor map. Capiche?
- The compressor itself on a SC or turbo has similar efficiency and mid-70s are about as good as it gets.
- At the same boost level the VE of the ENGINE is better with a supercharger but this is offset by large parasitic losses.
- the last line applies entirely to yourself as I have just demonstrated.
Stay tuned as next week I might be on the side of the argument that intake manifold spacers are a complete waste of money.
Without wishing to detract from the hilarity of the RS4TT fail, you know as well as anyone that comparing numbers from completely different dynos is not really possible with any degree of accuracy.
The power gain vs intake manifold pressure is probably way off here because didn’t they have the MAF in the hot side piping? If he’s losing air out of the IC the MAF will be measuring a LOT of air that never makes it into the engine. AFR and timing would be pretty far off.
Not sure if they realized that themselves. I would hesitate to do pulls at all with that big of an issue.
[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.
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.
looking forward to the intake spacers discussion…
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.
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.
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.
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.
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.
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.
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.
- 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.
- 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
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?
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.
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.
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.