My s/c vs. turbo paper

[grey5.0beast]

lucky, my teacher grades hard as hell.

 

[spiff]

Its okay, I found that you spent too much time elaborating on the way that the devices work. You also put in a lot of information that isn't relevant to the argument. Do "we" need to know about a roots, twin screw, and centrifugal supercharger when you just discuss superchargers generally? The part where you discuss how the headers or manifolds are reversed towards the front of the car is confusing, and isn't always the case anyways. You could just simply state it is driven off of the exhaust gases expelled by the motor, rather than off of the fan belt. You should justify the part about where the longevity of the kit is at risk, that is a good part, but if you just leave it at that it is going to weaken your argument. Also, you should paraphrase the part about engine RPM and parasitic drag as it is difficult to understand. I'm assuming that you've corrected most of the spelling errors and grammatical errors within the paper since you wrote this. However, your tone is sufficient, but you could sound a bit more persuasive with your argument.

Otherwise you've got a good start.

 

[bluevenom867]

Ugh,is it me,or did you just focus totally on after-market type parts?

There are reason for using a S/C over a turbo on some factory cars (and trucks).Plus the way the power is made is a bit differant,like if I was towing I would want a big roots blower on a big block,so I could have like 650ft-lbs. @ 2300rpm's or so even if the turbo made more peak torque.Also,your assuming its a "kit" with all the modern turbo control devices,blow off's,waste gates,boost controle,ect. How about old turbo design's were the factory just threw one on with nothing to control it and hoped it free spooled alright.

Also,that "test".....lol what a joke. They were showing how much power could be made on a stock Cobra like that,try putting 24psi on a stock GT and see what you get .Plus it was against the factory blower,should have put it up against a Kenne Bell making equal amount of boost at (now this is important) peak rpm.Root blowers do tend to fall off a few psi in the upper range,but you make up for that by spinning the blower faster witch also results in more boost down low.

 

[Nibblesworth]

No mention of 14.7psi of natural atmospheric pressure, and how an s/c or turbo increases that. No mention of traditional uses of forced induction, which is to use tiny motors and not sacrifice power. No mention of hot chicks in wicked weasel bikinis (do a google search, you'll thank me). No pron.

D+

 

[ms93gt]

TURBO FOR TEH WIN

 

[25thmustang]

Interesting paper, good info but like stated above not the most relevent stuff. Makes me wish I could write those kinds of papers.

Im stuck with 6 pagers every week (12 pagers for the mid term and final) in an AUC (all university classes) class that means NOTHING to my major other than having to take 4 of them over the course of college. Mine was about certain historical times and how it affected things.

 

[grey5.0beast]

Like I said, I didn't go into why using a supercharger is better in some cases cause it wouldn't be as persuasive. If Ihad listed that superchargers can be just as good as turbos, he would have said that I was indecisive and I need to sway thepaper, so a first time reader who has no idea what I was talking about, would pick the turbo. The point of a persuasive paper

 

[millhouse]

Ugh,is it me,or did you just focus totally on after-market type parts?

There are reason for using a S/C over a turbo on some factory cars (and trucks).Plus the way the power is made is a bit differant,like if I was towing I would want a big roots blower on a big block,so I could have like 650ft-lbs. @ 2300rpm's or so even if the turbo made more peak torque.Also,your assuming its a "kit" with all the modern turbo control devices,blow off's,waste gates,boost controle,ect. How about old turbo design's were the factory just threw one on with nothing to control it and hoped it free spooled alright.

Also,that "test".....lol what a joke. They were showing how much power could be made on a stock Cobra like that,try putting 24psi on a stock GT and see what you get .Plus it was against the factory blower,should have put it up against a Kenne Bell making equal amount of boost at (now this is important) peak rpm.Root blowers do tend to fall off a few psi in the upper range,but you make up for that by spinning the blower faster witch also results in more boost down low.

Yes, there area reasons for choosing superchargers over turbo's on factory cars/trucks….but towing is not one of them. Turbochargers are by far the preferred method of adding power for towing applications. I'd venture to say those reasons are more along the lines of cost and packaging issues than anything else.

 

[ms93gt]

Like I said, I didn't go into why using a supercharger is better in some cases cause it wouldn't be as persuasive. If Ihad listed that superchargers can be just as good as turbos, he would have said that I was indecisive and I need to sway thepaper, so a first time reader who has no idea what I was talking about, would pick the turbo. The point of a persuasive paper

Hope thats not towards me....

 

[grey5.0beast]

no, at blue venom.

I had to make turboes appealing to my paper's audience(my teacher) and I did that by making it a onesided paper.

 

[bluevenom867]

Yes, there area reasons for choosing turbochargers over turbo on factory cars/trucks….but towing is not one of them. Turbochargers are by far the preferred method of adding power for towing applications. I'd venture to say those reasons are more along the lines of cost and packaging issues than anything else.

Did you mean to say supercharger in the first line?

And towing....I dont think so. You realized I was talking gas motors right? Not big rig diesels. Oh,and I have a book with some dyno sheets to prove it. It was on mod motors,but the same power curve should result in larger motors. Basicly,the roots/twin screws would out torque and power the turbo (twin turbo's in some cases) to about 3500rpm.

 

[bluevenom867]

no, at blue venom.

I had to make turboes appealing to my paper's audience(my teacher) and I did that by making it a onesided paper.

Hey,I wasnt saying you should add this to your paper...I was thinking of way I could shoot your reasoning out of the sky .

It was a arguementive paper right? LOL

 

[millhouse]

Did you mean to say supercharger in the first line?

And towing....I dont think so. You realized I was talking gas motors right? Not big rig diesels. Oh,and I have a book with some dyno sheets to prove it. It was on mod motors,but the same power curve should result in larger motors. Basicly,the roots/twin screws would out torque and power the turbo (twin turbo's in some cases) to about 3500rpm.

Oops, fixed.

You know...either way, it shouldn't matter. Turbo's don't work differently on a gas powered engine than a diesel. You do realize that turbo's operate off of load. As such, while towing (with any turbo'd engine) load is almost always there…meaning so is boost. Do you have the dyno sheets with a simulated towing load on them? I thought not….as I stated, towing is a turbo's forte'. To really compare apples to apples, you would have to take two identical vehicles….one supercharged the other turbo. You then would have to throw the same amount of boost at them….put a simulated towing load on both vehicles and dyno them side by side.

 

[bluevenom867]

Oops, fixed.

You know...either way, it shouldn't matter. Turbo's don't work differently on a gas powered engine than a diesel. You do realize that turbo's operate off of load. As such, while towing (with any turbo'd engine) load is almost always there…meaning so is boost. Do you have the dyno sheets with a simulated towing load on them? I thought not….as I stated, towing is a turbo's forte'. To really compare apples to apples, you would have to take two identical vehicles….one supercharged the other turbo. You then would have to throw the same amount of boost at them….put a simulated towing load on both vehicles and dyno them side by side.

It does matter,diesels have a lot more static compression,and I bet if you measured the actualy exhaust pressure between the head port and the turbo housing/impeller it would be much higher than that of a gas engine,let alone you can run some crazy amounts of boost witch would cause the exhaust to be under pressure if you had the slightest amount of overlap.Thats another thing too,the restriction,no matter how effcient a turbo is,it will still at some point become too much of an exhaust restriction and you loose power.

And I agree,I would like to see a dyno test like that be done,however I think it would be hard to simulate "towing" a load,it is alot differant than just throwing some weigth on the back end.

That brings up another question,under low/part throttle witch one would make more power? My guess would be the blower/supercharged car because part thottle 2k rpm's,or full throttle 2k rpm's,ithe supercharger is turning the same speed. And if the factory put on alot of vacuum operated devices,I think the vacuum would be higher on a blown motor if the throttle body is befor the blower inlet and there is a manifold to connect things to (like on a Lightning).

 

[millhouse]

It does matter,diesels have a lot more static compression,and I bet if you measured the actualy exhaust pressure between the head port and the turbo housing/impeller it would be much higher than that of a gas engine,let alone you can run some crazy amounts of boost witch would cause the exhaust to be under pressure if you had the slightest amount of overlap.Thats another thing too,the restriction,no matter how effcient a turbo is,it will still at some point become too much of an exhaust restriction and you loose power.

And I agree,I would like to see a dyno test like that be done,however I think it would be hard to simulate "towing" a load,it is alot differant than just throwing some weigth on the back end.

That brings up another question,under low/part throttle witch one would make more power? My guess would be the blower/supercharged car because part thottle 2k rpm's,or full throttle 2k rpm's,ithe supercharger is turning the same speed. And if the factory put on alot of vacuum operated devices,I think the vacuum would be higher on a blown motor if the throttle body is befor the blower inlet and there is a manifold to connect things to (like on a Lightning).

Exhaust pressure is not what spools a turbo…but rather the heat exchanged over the turbine. Large amounts of exhaust back pressure is only beneficial for quicker spool time. With today's tubo's, variable vane technology allows the turbo to do just that. Yes, I realize that the static compression is greater in diesel applications….but the turbo's work the same regardless. All your proving is that diesels are better for towing than are gasoline powered vehicles…which I completely agree with.

Now…if you want to talk about restriction…look no farther than the supercharger. There is far more power loss through all types of superchargers than there is in turbo apps. I have no idea where you came up with turbo's loosing power because of restriction. Sure…if you undersize a turbo it can choke at higher rpms.

Now…to simulate towing, I would imaging you could just throw more load on the mustang dyno for a better comparison. Because they are load based dyno's, you will typically see a turbo'd vehicle dyno better and have a broader/flatter torque/hp curve.

As far as low power/part throttle goes….keep in mind with large amounts of load (i.e. towing) you can see full boost with a very small amount of throttle. The more load…the less throttle is needed to reach full boost. The same cannot be said about superchargers.

 

[bluevenom867]

Exhaust pressure is not what spools a turbo…but rather the heat exchanged over the turbine. Large amounts of exhaust back pressure is only beneficial for quicker spool time. With today's tubo's, variable vane technology allows the turbo to do just that. Yes, I realize that the static compression is greater in diesel applications….but the turbo's work the same regardless. All your proving is that diesels are better for towing than are gasoline powered vehicles…which I completely agree with.

Now…if you want to talk about restriction…look no farther than the supercharger. There is far more power loss through all types of superchargers than there is in turbo apps. I have no idea where you came up with turbo's loosing power because of restriction. Sure…if you undersize a turbo it can choke at higher rpms.

Now…to simulate towing, I would imaging you could just throw more load on the mustang dyno for a better comparison. Because they are load based dyno's, you will typically see a turbo'd vehicle dyno better and have a broader/flatter torque/hp curve.

As far as low power/part throttle goes….keep in mind with large amounts of load (i.e. towing) you can see full boost with a very small amount of throttle. The more load…the less throttle is needed to reach full boost. The same cannot be said about superchargers.

Im not talking about exhaust pressure after the turbo,Im talknig about befor the turbine on the exhaust side.Back pressure on any application is bad,especialy on a turbo app. cause it would be working againts the rotation of the turbine.

Yes,yes...parisitic drag I know. But take the out of the picture (figuer you'll need 50-100hp more or whatever you want),and a turbo will cause a restriction on the top end if the exhaust side is to small.And if its too larger it wont spool up as quick. I guess a supercharger could be considered more "peaky" then,witch isnt a bad thing if you need power/torque to peak somewere (low end particularly).

Yea,it is hard to argue that,would be much easier than having to change a pulley to get the boost you want at part throttle,lol.Something I dont quite get though....if your under full boost at part throttle,with the throttle body not fully open,wouldnt that cause a restiction in the intake track? And a restriction will make more boost (pressure),but I wonder if it see the same volume of air between part throttle loaded full boost,and loaded full throttle full boost.....hmm.

 

[ms93gt]

Millhouse > Bluevenom

 

[millhouse]

Im not talking about exhaust pressure after the turbo,Im talknig about befor the turbine on the exhaust side.Back pressure on any application is bad,especialy on a turbo app. cause it would be working againts the rotation of the turbine.

Yes,yes...parisitic drag I know. But take the out of the picture (figuer you'll need 50-100hp more or whatever you want),and a turbo will cause a restriction on the top end if the exhaust side is to small.And if its too larger it wont spool up as quick. I guess a supercharger could be considered more "peaky" then,witch isnt a bad thing if you need power/torque to peak somewere (low end particularly).

Yea,it is hard to argue that,would be much easier than having to change a pulley to get the boost you want at part throttle,lol.Something I dont quite get though....if your under full boost at part throttle,with the throttle body not fully open,wouldnt that cause a restiction in the intake track? And a restriction will make more boost (pressure),but I wonder if it see the same volume of air between part throttle loaded full boost,and loaded full throttle full boost.....hmm.

Higher exhaust pressure before the turbo means more heat…which means quicker spool. This is where variable vane technology in turbo apps becomes beneficial….especially for towing. The turbine impellers alter their pitch….effectively altering the back pressure the turbo sees (as well as other things).

If you take parasitic drag out of the equation….then you cant compare apples to apples. Also, the top end restriction of a properly sized turbo should be virtually nil.

As far as full boost an part throttle goes…sure there is a restriction. The restriction in the intake isn't what spools the turbo however….and the turbo wastegate limits the amount of exhaust gasses the turbine sees to control this.

 

[bluevenom867]

Higher exhaust pressure before the turbo means more heat…which means quicker spool. This is where variable vane technology in turbo apps becomes beneficial….especially for towing. The turbine impellers alter their pitch….effectively altering the back pressure the turbo sees (as well as other things).

If you take parasitic drag out of the equation….then you cant compare apples to apples. Also, the top end restriction of a properly sized turbo should be virtually nil.

As far as full boost an part throttle goes…sure there is a restriction. The restriction in the intake isn't what spools the turbo however….and the turbo wastegate limits the amount of exhaust gasses the turbine sees to control this.

Interesting...I supposed you could build some kind transmission driven supercharger with more than one interal drive ratio (just like an automatic trans in a car,low gear the supercharger would be overdriven alot more),but I can see that would end up quite large.

I never was comparing apples to apples If you added more boost or whatever to get the blower to make same power,but have a large dual exhaust,there has to be less restriction.....

I wasnt talking anything about the turbo being spooled,read my post more carefully.

Towing at full boost,part throttle,the motor cant possably be able to take in the same amount of air it can at WOT,full boost,there has to be a differance,RPM alone is enough to make a huge differance in air volume demands.

 

[millhouse]

Interesting...I supposed you could build some kind transmission driven supercharger with more than one interal drive ratio (just like an automatic trans in a car,low gear the supercharger would be overdriven alot more),but I can see that would end up quite large.

Interesting about a gear drive....although I imagine between the packaging issues of adding another transmission...along with the extra power losss that would be associated with it...it would be fairly inneficient.

I never was comparing apples to apples If you added more boost or whatever to get the blower to make same power,but have a large dual exhaust,there has to be less restriction.....

I suppose I'm a bit confused. If your not comparing apples to apples....how can you possibly argue that a super setup is better for towing? Really...you cant. Upping the boost on the supercharger to compete with the turbo just proves my point even more.

Now...you keep on talking about restriction, and I can only assume your talking about exhaust. Of course there will always be more exhaust restriction in a turbo setup...as it's how they work. You cant possibly be trying to compare the exhaust restriction between a super setup and turbo setup...as doing so makes no sense.

I wasnt talking anything about the turbo being spooled,read my post more carefully.

Hmmm....ya lost me.

Towing at full boost,part throttle,the motor cant possably be able to take in the same amount of air it can at WOT,full boost,there has to be a differance,RPM alone is enough to make a huge differance in air volume demands.

After reading this last sentance....I'm now quite sure you have no idea how a turbo functions in a vehicle supplied with a throttle body. You also dont seem to grasp the function of the standard wastegate or really any other functions of a turbo setup. I'd suggest checking out www.howstuffworks.com as well as http://www.turbomustangs.com/turbotech/main.htm.