# supercharge or turbocharge?



## franka (Jan 23, 2006)

Turbo boost is not instantaneous and its not free.

1) What has changed with turbos so that they no longer have lag? What specifically has eliminated lag? What is the technical development that has eliminated all turbo lag? There is none.

2) The vast amount of miles driven are driven between 1400 rpms and 2400 rpms. If you have a twin screw or a roots and you jump on the gas pedal you have immediate, full boost. Instantaneous boost. As fast as you can move your foot.

Not so with a turbo. A downshift and a few seconds or more are required to get the turbo up to speed. Its called lag and it will always be there and it will always have a response time that is greater than a screw.

3) The exhaust that drives a turbo is not exactly free. A turbo requires pressure in the exhaust system to drive it, back pressure. That back pressure prevents the cylinder from completely emptying of all exhaust. After the turbo has been spun up high the boost pressure in the intake tract will help to scavenge the exhaust but not for free. Contrary to beliefs there is a cost to run a turbo. Turbo boost is not free, it comes with a certain amount of loss or cost depending on how you look at it. A turbo always requires back pressure to function.

Turbos are great for top end power because they do not have as much drag on the engine as a screw at full rpms. But for instant boost you can't beat a screw compressor. Instant torque down low and higher up, exactly when and where you need it on the street.


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## franka (Jan 23, 2006)

As an example only, lets say the twin screw puts out the same volume as the engine's displacement. Lets say that is 300 cu inches per revolution of the engine and the blower. For simplicity I assume both are pumping the same volume and both are turning the same rpms. Other examples with different volume of engine and blower and different rpms each but locked together in any combination will still yield the same results which is that as rpms go up so does the blower's as per their fixed ratios.

At low rpms or high rpms the screw will always be putting out proportionally the same exact volume as the engine which is full volume at any and all speeds. 

Engine pumped volume at 1000 rpms = 300 cuin/rev x 1000 = 300,000

Blower pumped volume at 1000 rpms = 300 cuin/rev x 1000 = 300,000

The numbers can be changed but the result will always show that the engine and the blower's pumped volumes are proportionally in lock step with each other at ALL rpms. If one goes up the other goes up and does so proportionally. 

The blower being tied to the engine's crank is not a disadvantage, as you state, it is an advantage. Being locked together is good, not bad.

The blower's pumped volume is always in a fixed relation to the engine's pumped volume.

This is a critical point to the understanding of screw compressors and why they are good for the street.


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## chucksrt (Nov 4, 2008)

Hey, 

I'm new to BMW, I just bought a 540i6sp love it!!!! I have to +1 the turbo!!! I have driven many different cars with both set ups and The turbocharged cars did have all of the benefits mentioned by black out. The turbo is the point of backpressure but there is no back pressure required beyond that point, What very little flow you do loose via the turbine is nothing compared to the loss of power due to the addition of another accessory that's belt driven. Turbo lag is not much of a factor, VNT turbos are nice but are prone to blade failure due to the constant flexing they are able to do. a well setup turbo system has limited lag and on a engine that is N/A from the factory it is even less of a concern being that they are generally running higher compression and have slightly higher torque which assist it's low end performance and make the lag less noticed. There are a ton of reasons I love turbocharged cars over supercharged cars but to each their own. It seems that either way you decide to go for a bmw it will be expensive!!! If you can do any of the fab work yourself then turbo may even be cheaper then a S/C. I am going to be picking up an extra E39 4.4 engine and designing a turbo system for it, Time and wife permitting? nice to be on this forum and see so much love being put into these cars!!!
Chuck


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## franka (Jan 23, 2006)

chucksrt said:


> The turbo is the point of backpressure but there is no back pressure required beyond that point, VNT turbos are nice but are prone to blade failure due to the constant flexing they are able to do.


Hi Chuck, you have it a bit wrong on 2 points.

Back pressure exists from the exhaust valve, even from inside the cylinder, all the way to the turbo. The higher the back pressure the faster the turbo spins.

Turbo blade failure is not due to blade flexing, but if it was it would be due to the back pressure since there is nothing else it could be from.

Blade failure is due to the high centrifugal forces it sees, over and over again, at very high temperatures and very high rpms like 180,000 rpms and more. And to make the enviroment even more hostile centrifugal force is proportional to the square of the rpm.


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## Black-Out (Nov 1, 2008)

franka said:


> Turbo boost is not instantaneous and its not free.
> 
> 1) What has changed with turbos so that they no longer have lag? What specifically has eliminated lag? What is the technical development that has eliminated all turbo lag? There is none.
> 
> ...


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## Black-Out (Nov 1, 2008)

franka said:


> As an example only, lets say the twin screw puts out the same volume as the engine's displacement. Lets say that is 300 cu inches per revolution of the engine and the blower. For simplicity I assume both are pumping the same volume and both are turning the same rpms. Other examples with different volume of engine and blower and different rpms each but locked together in any combination will still yield the same results which is that as rpms go up so does the blower's as per their fixed ratios.
> 
> --------------------------------------------------------------------------------------------------------------------------------------------------------------------------
> **Obviously.....I have already stated this so this point is moot, but go on....**
> ...



I would check your math on this one because it's not possible for an automotive supercharger to do this in one reveloution, nor is it a good idea to partake in theoretical semantics using a 1:1 drive ratio for a device that is typicaly undersized and overdriven to produce it's positive displacement effect.......It's not uncommon for a blower to have to be driven 2-3 times it's engine speed just to produce good enough flow to make pressure at all, let alone at part throttle and thats with a properly sized unit for your theoretical engine...... If this was the case most blowers would have a pulley the same size as the crank shaft they were attached to, and the engine would have difficulty idling due to the compressive forces produced in one supercharger revoloution.
This is just not adequate in terms for searching for scientific justification to support your views. I would definately get some hard info and then repost the proper formulas needed to calculate what you really want to prove, which is the low speed airflow advantage a supercharger has over turbocharging,But with what you have provided me with I do not remain convinced that a supercharger is the better performing choice. A less expensive choice, maybe, but not a better one.
The fact is turbos aren't slow and lethargic unless your running to the top end like you make them out to be, which is why the turbo system is growing to become the most saught after in the main stream performance aftermarket. Far more companies are making turbo kits because they no longer have the hang-ups they used to be known for from relaibility to responce and effieciency to NVH (Noise Vibration and Harshness) they are just plain better...but hey,thats my oppinion, again to each his own.......:soapbox:


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## franka (Jan 23, 2006)

Turbos have lag despite ball bearings, ceramic vanes, trap doors, etc, etc. 

Lag is not as bad as days gone by but it is still there. There are methods to get around lag like injecting fuel into the exh manifold when shifting to keep the revs up but they are all band aids that are external to the turbo.

A twin screw is a true compressor. Ambient air pressure in and boosted pressure out. It doesn't matter if the engine is at 1,000 rpms or 4,000 rpms. In all cases the TS's output is boosted.

Turbos, TS, Roots, Centrifugal they all have their own unique features and capablities.


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## Black-Out (Nov 1, 2008)

I understand what your saying how ever I never said that turbos didn't have lag..... I just said it wasn't crippling to the turbo systems performance on the street like you suggest. 
And I am sorry but there isn't a supercharger on earth that's going to give you enough flow to reach boost thresh hold at 1000rpm's so saying there is, just isn't accurate, neither device can flow that much air that quickly.

No one tuner injects fuel into the exhaust manifold for spool up, they simply increase injector pulse width and retard timing to heat up the exhaust gasses to maintain turbine speed between shifts.......(Anti-lag, a common feature in most well designed stand alone management systems and hardly what I would call a band aid) But this is used mainly for motor sport application, the percentage of people whom use this on the street are extreamly low and have cars usually fitted with turbochargers that have monsterous compressors (60mm and up) 

Speaking of band-aids.....why would you suggest that technological advances made in turbocharging are mere band-aids? That would be like me suggesting that the built in by pass valve on some twin screw superchargers are band aids for the parasitic drag they reduce when boost isn't needed. Or that the 4 bladed helical cut impellars on the newer roots blower are band aids for poor flow and compressor inefficiency.....That just doesn't make sence, they are all improving the basis of the origional concept and doing so improves the efficiency of both devices. Just as turbos still have lag superchargers still have parasitic drag both devices will never eliminate their negatives they can only make them less obvious, the turbo just has more space to show improvement because it has many more sizes to choose from and combinations to exploit.

Do you realize compound turbocharging (a large turbo feeding a smaller turbo which feeds the engine and is commonly used on diesels) can produce boost pressures beyond boost thresh hold as low as 1800rpm? They have to because a diesel engine can't rev much beyond 4000rpm. Compound turbocharging and twincharging (using both a supercharger and a conciderably large turbocharger) are just a couple of examples of how forced induction used on diesels has had a profound effect on the way turbocharging is used on gasoline vehicles now. Both systems can be applied to gasoline engines and neither concept is considered a band-aid by the automotive community.

All have their own capabilities true, each shines in a different area of the performance realm it just depends on how much efficiency plays into your power requirements, and the intention on the use of said car. The larger the turbo the larger the lag obviously but, with that said, the larger the supercharger the higher the drag..... if 400hp is your goal it can be achieved without the lag commonly associated with that kind of power output. That's just how far the game has come in the last 20 years.:thumbup:


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## franka (Jan 23, 2006)

A twin screw compress the air before it leaves the SC. Every turn of the TS compresses the air. That is why it is called a positive displacement SC.

RPMs are not a factor. They are in a turbo but not in a TS.

http://www.whipplesuperchargers.com/content.asp?PageID=67


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## Black-Out (Nov 1, 2008)

franka said:


> A twin screw compress the air before it leaves the SC. Every turn of the TS compresses the air. That is why it is called a positive displacement SC.
> 
> RPMs are not a factor. They are in a turbo but not in a TS.
> 
> http://www.whipplesuperchargers.com/content.asp?PageID=67


Thats not true:thumbdwn:.......again, its common knowledge that a supercharger compresses the air before it leaves the charger but this has nothing to do with the flow requirements to reach and go beyond boost thresh hold on any given engine........pressure and volume are not linear with one another.

As pressure goes up, volume goes down. This is fact. The volume of air displaced at 1000 rpm on any supercharger will not be anywhere near enough to create boost as you suggested it, due to the blowers physical displacement, which is usually only 1/3 the engines total capacity (I believe I already stated this.) Even on a turbo charger when the compressor reaches the edge of it's efficiency you will not gain any power from simply "turning up the boost" as the compressor will not flow anymore air with out heating it up causing a decrease in air density from the increases in charge air temp, thats why people fit larger turbos and even superchargers to gain horsepower. The gains in power can usually be seen even at a stock boost levels because the flow rate increases at the same pressure ratio, and charge air temp goes down.

Because of the superchargers volume difference in respect to the engine, there is no way to produce the amount of volume required to exceed the engine displacement at such a low rpm (1000) no matter how much compression occurs with in your twin screw.....By the way that is also why parasitic drag is such an issue with twin screw compressors and roots type blowers.

As I have stated before this drag can be equivicated to turbo lag, which is why superchargers of this type provide their responce the way they do. 2400rpm is where you usually "feel" the blower begain to work.......As stated in previous posts, a stock Porsche 911 (996/997) twin turbos you can actually get that same feeling between 2200 and 2500 rpm depending on weather or not the car is an X-50 package with larger turbos........the point is a turbocharger chosen properly with a reasonable maximum power output will respond just as quickly as a twin screw or roots blower and out do a centrifugal supercharger, hands down.

Not to sound like an ass, but are you reading the details within my posts? cause we're actually starting to go in circles here.:dunno:

I almost feel like I'm playing a game of chess......It's your move chief.........lol.....

By the way I see this as nothing more than a friendly debate so please tell me if I'm irritating you or pissing you off, I'm not here to troll or aggrivate people......:thumbup:


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## franka (Jan 23, 2006)

Dah..you spin the blower faster than the engine. Not 1:1 as you said giving only 1/3 the volume you claim. And if that is not enuff you go to a larger blower. That is so elementry. (splg?)

After reading the Whipple link you should be able to understand that it is a "positive displacement" blower and what that means. It is not variable displacement like a turbo or a Roots. Not all blowers compress the air before they leave the blower.

I'm not going to keep arguing with someone that doesn't understand this simple fact. 

Knock yourself out now.


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## Black-Out (Nov 1, 2008)

:nono::nono: Well this would be great if I was the one who didn't understand, but I do, it's you who doesn't grasp it......If you care to read any of your own post you would find that YOU were the one whom suggested the 1:1 ratio and not me......I corrected you on it as I've done the remaining parts of this thread. 

Originally Posted by franka View Post
As an example only, lets say the twin screw puts out the same volume as the engine's displacement. Lets say that is 300 cu inches per revolution of the engine and the blower. For simplicity I assume both are pumping the same volume and both are turning the same rpms. Other examples with different volume of engine and blower and different rpms each but locked together in any combination will still yield the same results which is that as rpms go up so does the blower's as per their fixed ratios.




Ring a bell? how about this........





At low rpms or high rpms the screw will always be putting out proportionally the same exact volume as the engine which is full volume at any and all speeds.
Engine pumped volume at 1000 rpms = 300 cuin/rev x 1000 = 300,000

Blower pumped volume at 1000 rpms = 300 cuin/rev x 1000 = 300,000

The numbers can be changed but the result will always show that the engine and the blower's pumped volumes are proportionally in lock step with each other at ALL rpms. If one goes up the other goes up and does so proportionally.





Or how about this one.......






Originally Posted by franka View Post
A turbo will be much harder to tune than a SCr because the turbos rpms are up and down and all over. Turbo rpms have no fixed relation to engine rpms and that is a major source of problems. Trying to match the injector's shot volumes and ignition timing and relief valves with the engine rpms and varying throttle demands and varying turbo speeds is a nightmare. Tuning a turbo set up to run clean and smooth is difficult. It takes much more time than to tune a SCr

A Roots or a Twin Screw's rpm always matches the engine's rpms at a fixed ratio. More rpms and the SCr pumps more volume to force feed the engine's displacement. A SCr is always in synch with the motor. This simple fact makes tuning much easier.

Turbos have lag, even the best set ups have lag. Lag, lag and then the turbo starts to catch up with the engine and starts to make some boost for power. Its a slow process when compared to a driven SCr

A screw type SCr like a Roots or a Twin Screw, has NO lag, you get full boost immediately, as fast as you can open the throttle, mili-seconds not 2 or 3 full seconds.

But this is not true for a Centrifugal SCr, it too needs rpms to build boost much like a turbo. A Dinan SCr and the VF SCr are centrifugal types. They build boost like a turbo, with rpms. Boost at low rpm is quite small and can not be increased.

For street use a Roots or a Twin Screw SCr, only they can deliver full boost instantly and at low rpms and all the way up to the engine's rpm limit. That is why the new Corvette and the Ford GT40 LeMans has a Roots SCr and not a turbo.

A turbo, on the same motor, will make more net hp at the top end because there is no screw to spin, but it is a poor choice for street use. 

I could go on in more detail but I will not spend my time on this subject when you can Google it and get all the info you ever would want.




That wasn't me, all that mess up there is yours......you seem to be the one who needs a link to explain the simple facts......I have plenty of literature on forced induction involving turbocharger and superchargers.

 Care to tell me I wrote and edited anymore of YOUR posts?




I already know that not all blowers compress the air before they leave the charger, I said Roots blowers and twin screws DO, and centrifugal blowers DON'T....Please don't try to take parts of my post and make it sound like I don't know what I'm talking about, I view that as....... well........rather pathetic. :gay:

There friend, I have knocked myself out......Next time high light your link so I can notice it and maybe I'll check it out, but I have enough info already, you don't seem to.
Feel free to review your post as well as mine thoroughly, so that you may post intelligently before claiming someone said what you implied to be fact first.

I know what I said I can go back and pull it all up,then confirm the information.......but you are not reading your own past statements, and then passing them off on me. Is it because you made a mistake and are trying to save face? If I make a mistake and someone proves it to me, I'll at least acknowledge it and give credit to the one who is correct.....Can't say as much for you unfortunately.

If you want to call your self right on this topic, then by all means be my guest, but being correct takes a lot more then suggesting theoretical operation or scenarios which have absoloutely no scientific calculations to support your desired out come.

There......... now you can knock yourself out.......I'm more than done trying to explain simple technological advances in forced induction to a brick wall, stuck in the dark ages.
Enjoy!
:madrazz:


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## franka (Jan 23, 2006)

Black-Out (and other turbo fans)

1) You must have a lot of emotion tied up in being right, to spend the amount of time you have to go back to my prior post and bring them up to post. You have more invested than me.

2) I stand by my posts, all of them.

3) I can see that I failed to present my thoughts in a manner that all can easily see and understand. So I will try it one more time. 

4) When I say one engine rev I mean two full revs beacuse it is a 4 cycle engine. Or 720 degrees.

When I said 1:1 what I meant was that whatever the pressurized engine could take in in volume and pressure in one revolution (one cycle) that the TS would be sized to produce that much. That was my error, I failed to explain it in more detail and more clearly. My fault but it doesn't change some facts.

I will make up some hypothetical numbers to illustrate the point. This is all hypothetical so please don't jump on the numbers here and claim the engine or the TS can not produce this or that.

If you have an engine that can injest 300 cubic inches at a pressure of 10 psi in one revolution then one could size the TS itself (the size of the blower) and the speed of the TS to deliver 300 cubes at 10 psi. in a fixed manner. So we have the TS delivering what the engine can injest in one revolution. That is what I should have said. That is what I meant. Now recalling that a TS is a positive dispacement supercharger we know that whatever the engine rpms are, that the TS will be pumping the volume and pressure to match what the engine is injesting. A positive displacent blower compresses the air internally, none of it wasted or escapes around the sides.

Now the important point is that at whatever the engine rpms are, 1000 rpms or 4000 rpms the blower will be pumping the volume and pressure that the engine can injest. So at 1000 rpm or 4000 rpm the engine will respond immediately.

A turbo can't do that at 1000 rpms because it is not a positive displacement SC. The turbo needs rpms to make power. The turbo is great at top end but it can't match the TS on the low end. That is why a TS is the best for a daily driver. Instant torque. Look up Whipple again and you will see that that is what they are saying. There are more TSs than Whipple. Try twin screw in Google

Like I said in one of my prior posts, because the TS is tied directly to rpm it will be easier to tune than the turbo. The turbo will require more maps of engine load, rpms, high and low speed, etc than the TS.

I'm not bashing turbos, they great for max power, top end power but they will never be able to beat a TS at low and medium rpms. They will not have the grunt. That is all I need to say.

I will respond to resonable, factual posts but not emotional or insulting ones.


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## franka (Jan 23, 2006)

Black-Out said:


> :
> 
> I already know that not all blowers compress the air before they leave the charger, I said Roots blowers and twin screws DO, and centrifugal blowers DON'T....Please don't try to take parts of my post and make it sound like I don't know what I'm talking about,[ QUOTE]
> 
> ...


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## Black-Out (Nov 1, 2008)

franka said:


> Black-Out (and other turbo fans)
> 
> 1) You must have a lot of emotion tied up in being right, to spend the amount of time you have to go back to my prior post and bring them up to post. You have more invested than me.
> 
> ...


Now that reply makes MUCH MUCH more sence, and had you gone through the explanation that way this would have been much different. Now in going back and looking again your correct in the assesment of the roots blower it isn't a positive displacement device....but do you know what is?

The turbocharger......It seems that the turbocharger and the centrifugal supercharger both compress air in the cold housings before forcing it down the throat of the engine. (Positive displacement by definition) Oddly enough I didn't remember this fact so I looked it up in a third source after looking through my books...(Wikipedia) and found supporting information on this fact.

More imediate responce is the effect of a supercharger but not without the drag associated with its operation and that still does not change the fact that a properly set up turbo system will rival a supercharger on the street and then some.

You still won't really address any of the facts I've stated on such cars named that have low speed high responce turbo systems that rival the supercharger on the street so I will name a few....
Cars by comparison that are equipped with a turbo system that responds comparitavely are

1: Porsche 911 turbo-485hp engine responds as low as 2400rpm 
2: Porsche 911 GT-2 540hp near same responce as above
3: Ford Falcon XR6
4: BMW 335i (or any twin turbo BMW for that matter)
5: Mazda RX-7 Twin Turbo
6: Toyota Supra Twin Turbo
7: Porsche 959 
8: Bugatti Veyron EB 16.4
9: Bugatti EB 110
10: Mercedes Benz ......pick any one of their turbcharged cars I'm sure you will find they deliver power so smoothly you'll think it's a big N/A engine not a turbocharged one.
11: Nissan Skyline GT-R

That's just eleven examples....I'm not saying I can't be wrong obviously, I've been that before as have you. But I will say that the idea that turbos don't produce power at low rpms has been long since a dead issue with forced induction...anymore manufacturers use supercharging over turbocharging as a cheap means of boosting output, and doing it in the close confines in certain engine compartments, than they do for producing power outputs at low engine speeds.

I appoligise for being snappy in my last post, but I don't care for it when someone puts words in to my mouth. That's what I felt like you did, that's why my responce was what it was.

Go for a ride and see what I mean cause I've beeen in both supercharged and turbo cars and I'm telling you the difference is almost non existent........don't take my word for it try one out.


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## Shunn (Mar 15, 2009)

you tune cars on a daily basis but didn't know/forgot that turbocharger's compress the air via the turbine in the cold side?


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## franka (Jan 23, 2006)

Shunn said:


> you tune cars on a daily basis but didn't know/forgot that turbocharger's compress the air via the turbine in the cold side?


Makes one wonder about that.....:dunno:


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## Shunn (Mar 15, 2009)

I'm not back either of you two up. i was just questioning it. maybe he -works- at a tuning shop but isn't the one doing the tuning :dunno:

both setups are good. both have their pros and cons but if someone decides to get a supercharger then consider forking out the dough for a twin screw or roots type.. as a centrifugal blower at a low setting(8psi for example) wont even start making boost until after 4K rpm XD


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## CR67 (Apr 26, 2009)

:banghead: Reading that post wore me out! Think I'll go take a nap now.
I've read the whole turbo/SC debate on a number of different forums over the years and the one thing I've found consistant is that turbo guys love their turbos and SC guys love their superchargers. Their are pros and cons to both and it really boils down to how much money you want to spend as they'll both give you some nice HP gains.


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## franka (Jan 23, 2006)

Its the area below the hp and/or torque curve that matters. A roots or twin screw will have more area under the curve than a turbo.

For comparison I'm stating same rated max boost pressure and same max boost volume.


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## San Diego E36 (Apr 19, 2009)

I would do a turbo system that has a small turbo so it would be funner, supercharge if I was hitting the track a lot, and big turbo if I drag raced a lot.


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## franka (Jan 23, 2006)

Thanks for the insight.


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## RX7 FC Guy (Sep 9, 2009)

turbos are the better choice for power. they have next to no lag. as long as there set up properly there is no real down side except for creating alot of heat in your engine bay. you can always set it up like STS and put the turbo where your muffler is and eliminate that problem all together.

superchargers cause parasitic loss on the engine at idle and do choke out if you romp on them from idle. 

I am also a Tech and deal with both often.


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## franka (Jan 23, 2006)

CR67;4181372 the one thing I've found consistant is that turbo guys love their turbos and SC guys love their superchargers. Their are pros and cons to both and it really boils down to how much money you want to spend as they'll both give you some nice HP gains.[/QUOTE said:


> The younger and less experienced guys go "turbo" because they hear of them much more frequently, some auto mfgrs offer them, turbos can make a big hp number at max revs and that is what catches their attention, there is all the turbo tech on Hondas and the other imports that they grew up with and the word turbo sounds cooler to them than Roots or Twin Screw or Centrifugal.
> 
> It takes some effort to learn about the 3 other ways to SCrg and the pros and cons of each. Many reading this can not tell you what the differece is between a TS and a Roots.
> 
> Ya know what I mean?


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## franka (Jan 23, 2006)

RX7 FC Guy said:


> turbos are the better choice for power. they have next to no lag. as long as there set up properly there is no real down side except for creating alot of heat in your engine bay. you can always set it up like STS and put the turbo where your muffler is and eliminate that problem all together. superchargers cause parasitic loss on the engine at idle and do choke out if you romp on them from idle. QUOTE]
> 
> Turbos have lag lag and lag. Wishing or saying no more lag is just factually incorrect. BMW haas gone to two smaller turbos on the 335 to decrease lag but still not eliminating it.


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## JasonSC540ia (Aug 11, 2009)

franka said:


> A twin screw compress the air before it leaves the SC. Every turn of the TS compresses the air. That is why it is called a positive displacement SC.
> 
> RPMs are not a factor. They are in a turbo but not in a TS.
> 
> http://www.whipplesuperchargers.com/content.asp?PageID=67


Franka

Dead wrong. A superchager is an external compression device, and a turbo in an internal compression device. The air exiting a "roots" style or screw style SC is not compressed. It is simply moving larges amounts of air that cause it to back up in the intake system...by that it gets compressed (thats why there "aftercoolers" are in the intake manifold). The air leaving a turbo compressor or a centrifugal superchager (vortech, Paxton, ect.) the air is compressed already.

You sound like a very intelligent guy with maybe an engineering degree of some sort, but it sounds like you lack the "hands on" experience.

Black-out is 100% correct in everything he has posted...suggest you listen to him.


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## jhstealth (Mar 31, 2009)

i say supercharge because its allot easier to get and cheaper generally.


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## franka (Jan 23, 2006)

JasonSC540ia said:


> A superchager is an external compression device, and a turbo in an internal compression device. The air exiting a "roots" style or screw style SC is not compressed. It is simply moving larges amounts of air that cause it to back up in the intake system...by that it gets compressed (thats why there "aftercoolers" are in the intake manifold). The air leaving a turbo compressor or a centrifugal superchager (vortech, Paxton, ect.) the air is compressed already.QUOTE]
> 
> External compression, what the hell is an external compression device? Please show me one. Your comments are so far off the wall that I have to think you are just posting to get a rise out of me
> 
> ...


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## JasonSC540ia (Aug 11, 2009)

> External compression, what the hell is an external compression device? Please show me one. Your comments are so far off the wall that I have to think you are just posting to get a rise out of me
> 
> Your above several posts are about 15% correct and 85% wrong and I'm not going to argue it. If you want to know the facts just google for them. Try 'twin screw compressor'. For those looking for real, correct and the truth please check the below links and have a good time reading all about SCs.


Calm down...dont get your panties in a twist. I already explained to you what an external compression device is. A "roots" style or screw type supercharger do not compress air. There just large air pumps that move massive amounts of air, but do not compress it. A turbo compressor or centifigel compressors are internal compression. Meaning, by slinging the air outward and forceing it through the gap in the compressor housing forces the air to compress.

One of the reasons why screw type and roots SC give instant boost is because the boost starts in the cylinder and moves back towards the manifold. And the reason you have "lag" from a turbo is because you have to wait for the already compressed air to come from the turbo's compressor housing, into the manifold, and then into the cylinder.

Iv been a jet engine machanic rebuiling/testing axial flow and centifigal compressors for the past 19 years. Iv been building custom turbos for my applications since I had my first car at 16. I dont need to google anything.....maybe you should stop googling.

Everytime I see people quoteing "facts" they saw on the internet about forced induction, I try to help them out and point them in the right direction, because I know most people dont have the experiences that I have.

I suggest you stop giving people false info, and spend more time in your garage..."doing". Better yet, just stick with upgrading head lights, tail lights, and such. Leave the serious stuff for people who know before you melt a piston (do you need me to explain to you what a piston does?) Like I said before...you lack the hands on, and it shows.

Black-out knows what hes talking about with forced induction. Its plainly obvious why he stop replying to you....because you dont.


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## PDP///M (Oct 9, 2008)

Hey franka, you said superchargers make more low rpm power than a turbo. Sorry but have you ever seen two dyno sheets of two same cars, same peak boost, one with a supercharger, and one with a properly sized turbo? Which car do you believe has more hp and torque under the curve? Its not the supercharger. And i have one on my current car. When the turbo is spooled, e.g. At 2500rpm, you can have full boost from that point till redline. Which car has more power under the curve?


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## franka (Jan 23, 2006)

http://www.whipplesuperchargers.com/content.asp?PageID=79

Read it all


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## franka (Jan 23, 2006)

If more power is what you crave…Whipple Superchargers has the solution…heart-stopping acceleration, complete bolt-on packages, emissions legal supercharger kits that boost power up to 60%. By utilizing the Whipple Twin Screw Supercharger, we provide the largest effective power gains, while maintaining safe, trouble-free operation. The Whipple Charger gives you the unique combination of maximum power at low rpm’s for incredible drive-ability while still providing ultra high efficiency for top-end horsepower. Just squeeze the throttle and the engine responds immediately, from idle to redline. the thrill ride never stops! 

The results are breathtaking…0-60 times drop dramatically, up to 60% power increases throughout the operating range, incredible throttle response, emission compliance and virtually maintenance-free. How is this possible? It’s the integration of the Whipple Twin Screw Supercharger and Whipple's superior engineering that makes it all possible.

Over the past fifteen years, Whipple Superchargers has risen above the competition to become the true supercharging leaders with proven performance, reliability, customer service and quality. Other companies claim to be leaders with incredible power levels, but the results speak for themselves. 

WHAT SEPERATES WHIPPLE FROM THE COMPETITION


Positive displacement twin screw design has the highest efficiency of all superchargers including roots and centrifugal 
Higher efficiency means more power at all rpm levels 
Unique Whipple twin screw design provides the largest power gains across entire rpm range 
Similar screw compressor design as the Ford GT supercar 
Same screw compressor technology that Mercedes has utilized on all their latest vehicles including the 600hp McLaren SLR, E55AMG, S55, CL55, SLK32 and SL55 
Dyno proven to produce more horsepower and torque than any other supercharger throughout the entire rpm range. 
21st century fuel injection that has more processing power than the factory computer resulting in incredible drive-ability 
Whipple designed air-bypass system for unsurpassed fuel economy 
Commitment to quality and excellence 
Astounding customer support from our well trained, performance enthusiast personnel 
Nobody can compare to the OEM packaging and quality of parts Whipple provides 
50 state emission compatibility 
Unmistakable industry leading fit and finish 
100% complete systems ready for an easy installation and trouble free operation 
Systems consistently produce very low levels of noise, commonly undetectable 
True technological leader in supercharger industry 
SUPERIOR ENGINEERING

:thumbup:


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## franka (Jan 23, 2006)

OEM manufactures utilize positive displacement superchargers due to their incredible throttle response and drive-ability of a big cubic inch motor. When building a system for the consumers, you must provide a very broad power ban with a high peak horsepower level, only the screw compressor can give you this. This is due to the high adiabatic (up to 80%) and volumetric efficiency levels (up to 99.9%). The Whipple screw compressor is the latest generation, durable and dependable performance-enhancing item ever designed for either low boost or high boost levels. Available in a complete unit or a “rotor assembly” for builders own housings. 


The screw compressor is by far the best supercharger available today; it’s the only supercharger to provide a positive displacement design for maximum low-end torque as well as high efficiency for maximum top-end horsepower. No other supercharger in the world can offer the same unique benefits. Centrifugals and turbos have tremendous lag time during shift points, on-off throttle and off the line boost. Roots-type superchargers have been proven to not be very efficient, especially at higher boost levels. Whipple Superchargers has a variety of screw compressors for all types of applications, anywhere from a 100 cubic inch compressor to the 510 cubic inch compressor. Whipple also has a wide assortment of drive lengths, pulley combinations and bypass valves for all types of applications.


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## PDP///M (Oct 9, 2008)

i thought we were talking about bmw applications. can't get a whipple for a bmw unless custom.


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## franka (Jan 23, 2006)

So much for turbos.

And so much for ...Black Out and JasonSC540


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## PDP///M (Oct 9, 2008)

there are plenty companies that sell bolt on turbo kits for bmw.


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## QuoteWarz Insurance (Dec 17, 2009)

Yes, there are a lot of different companies that sell bolt-on turbo kits. It is just a matter of finding the right kit that will fit within your budget and power goals. Yes, the supercharger kit will offer a little more grunt off the line, but there is nothing like when you turbo hits boost and you are pinned in your seat.


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## franka (Jan 23, 2006)

QuoteWarz Insurance said:


> but there is nothing like when you turbo hits boost and you are pinned in your seat.


exactly...'when your turbo hits boost' .... and how long is that?


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## JasonSC540ia (Aug 11, 2009)

franka said:


> So much for turbos.
> 
> And so much for ...Black Out and JasonSC540


Dude...are you running any kind of forced induction...right now?

Here is a video clip of a turbo car I built some years ago. This was 25psi on a very large turbo (Frankenstein level 4 minus 10 degree turbine wheel clip). Notice how fast second gear is finished. Notice the gear changes, and how there is zero lag in between.

Point out the lag Fanka.

http://s849.photobucket.com/albums/ab53/JasonSC540ia/?action=view&current=launch.flv


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## franka (Jan 23, 2006)

Nice clip, good job, but its just a few seconds in time. It doesn't begin to show the difference btw a screw and a turbo.

Congrats to your work.


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## PDP///M (Oct 9, 2008)

So franka you didnt answer the question at hand. Do you own or have you ever owned a f/i vehicle? If the answer is yes, i'd like to see pictures. Thanks


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## franka (Jan 23, 2006)

No


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## JasonSC540ia (Aug 11, 2009)

Thanks for the compliment Fanka. I was'nt expecting that.

Your right. the video clip is kinda short. We were borrowing a camera from a friend and could'nt figure out how to make longer videos (old cam that only shot about 10 seconds worth). Still you can get an idea of how little lag there is. And that was with a bushing turbo...not ball bearing. The ball bearing turbos are insane with the response they have.

If I had the funds, I would make a custom twin turbo kit for my 540 and ditch the Vortech. Its just you would have to do a ****load of pluming do to lack of space. You'd have to mount the turbos way back underneath the car.....$$$$.

My SC 540 has ****loads of torque right off idle. However, it really lacks the midrange punch/top end that my turbo cars had. Dont get me wrong...it still hauls ass (it will pass 120 like nothing and keep going).


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## franka (Jan 23, 2006)

I have ideas of how to mount and duct a twin screw SC onto a 540, thru an intercooler and into the stock intake manifold.

But I and many others do not know how to tune it, using the standard 540 ECU. :dunno:


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## JasonSC540ia (Aug 11, 2009)

If your gonna go that far (or twin turbo), I would suggest going with a Mega squirt or similiar stand alone computer. Im sure there is a way to hach the factory ECU but I would think it would be more trouble then its worth. If you have the $$ you can always go with a Motech computer. Iv assisted in tuning one before and you can adjust fuel and ignition curves right down to each rpm (1440, 1441, 1442 ect). Very nice.:thumbup:


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## franka (Jan 23, 2006)

Doesn't a separate Mega Squirt, or any separate system, kill most of the electrical and electronic BMW functions and capabilities? 

:dunno:


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## JasonSC540ia (Aug 11, 2009)

Yep!:thumbup: Thats the great thing about it. Although, we...(99 and above) might have a problem with that and getting our drive by wire throttles to work. I would think you could switch to a 97-98 TB and be good.

In my mind, all that BMW BS with the oil level sensor and coolent level, is for rich people that buy the cars in the first place, and dont know 1 thing about how a car/engine works.

CE light cuz my gas cap is'nt on tight. Come on...im really.:rofl:


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## franka (Jan 23, 2006)

You have a point there. What good is that info on a car that was chopped up (heavily modified in a good way)?


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## JasonSC540ia (Aug 11, 2009)

I know it is possiable...Iv seen it done(Sema show Vegas). However, Im not far enough into my project to be that deep in wiring diagrams yet. I would like to maintain the stock interior 100%. I want to tastefully hide all gauges/computers in the glove box. The trick would be haveing no caution/warning lights and all factory gauges funtioning.


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## QuoteWarz Insurance (Dec 17, 2009)

It is kind of hard to explain, but the turbo will kick it a certain RPM depending on your set up. There are so many factors like turbo size, engine size, exhaust size, etc. You need to find the proper set up and that will come from doing research and setting goals for what you want out of the car. It might be a pure daily driven street car or a road racer maybe.


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## franka (Jan 23, 2006)

QuoteWarz Insurance said:


> It is kind of hard to explain, but the turbo will kick it a certain RPM depending on your set up. There are so many factors like turbo size, engine size, exhaust size, etc. You need to find the proper set up and that will come from doing research and setting goals for what you want out of the car. It might be a pure daily driven street car or a road racer maybe.


Excuse me please, but what are you talking about?


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## JasonSC540ia (Aug 11, 2009)

Franka

All he is saying is you have to set a horse power goal. 

Example : "I want 500hp @ the wheels and still be a daily driver."

Turbo/SC selection is very critical. Bigger is not always better. It has to be precise. You have to learn to read compressor maps. He's just saying you cant bolt any ol' parts on and hope to reach your goals.

You said you had a plan for mounting 2 SC, and still maintaining the stock manifold. I would really like to hear about your ideas. Dont get me wrong...Im not mocking you. I'am truly interested in hearing about that idea. I love $hit like that.:thumbup:


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## franka (Jan 23, 2006)

JasonSC540ia said:


> You said you had a plan for mounting 2 SC, and still maintaining the stock manifold. I would really like to hear about your ideas. Dont get me wrong...Im not mocking you. I'am truly interested in hearing about that idea. I love $hit like that.:thumbup:


Me too, I enjoy that. No time to write this morning B4 work. I'll catch you after work today.

Above you wrote "2 SC", is that short for twin screw?


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## JasonSC540ia (Aug 11, 2009)

franka said:


> Me too, I enjoy that. No time to write this morning B4 work. I'll catch you after work today.
> 
> Above you wrote "2 SC", is that short for twin screw?


No...I meant 2 superchargers. I thought you said you had a plan for 2 twin screw superchargers on a stock manifold. Thats why I wanted to hear your plan, because it sounded so outragous.

Maybe Im mistaken.

Id still like to hear your plan...even if its 1 roots/screw SC hooked up to a stock mani.


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## franka (Jan 23, 2006)

Its one twin screw pumping into an intercooler and then into the stock intake manifold.

Details to follow. Its pretty straight forward.


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## franka (Jan 23, 2006)

Here are some rough plans to run a Twin Screw Supercharger in a 540. 

So looking at the engine hood up, the right side is the driver side. Move the power steering unit and the oil filter and anything else that is there and relocate them. That is where the TS SCr goes. 

Fabricate a mounting plate for the TS out of aluminum plate about 3/4" thick or more if required. Simple if you have access to the right tools. Then fab some steel brkts to mount the plate and TS off of the engine such that the pulley on the front of the SCr is inline with all the other pulley's.

The mounting plate would allow the TS to huff and puff and blow down (vertical) into ducting that would connect to a 90 degree duct at the bottom that then runs horizontal and forward to connect up with the intercooler's intake that is also low and on the same side.

The intercooler runs across the front of the car as usual and then discharges as high as possible into a horizontal duct that connects to the OEM intake ducting, leading to the intake manifold. 

The OEM intake manifold is not designed for pressure, however I have been studying a loose one that I bought off of here. Its a rigid and strong pc that will hold at least 1.0 atm and maybe 2.0 atm, althought 1.0 is more than enough.

Paxton, Dinan and other superchargers are usually mounted in this same space. :thumbup:


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## JasonSC540ia (Aug 11, 2009)

Intersting

I just dont see the space being there to mount it. Also, fabing that bracket would be no easy task. Ofcourse anything is possiable with enough time and money.

I think it would be easier, and more cost effective to just mount a large turbo (T3 25g) back in the same place as the factory resagnator. 25g compressors have been known to support over 600whp. This turbo is only $450 new (see link below). Oil lines and a pump to move the oil back to the engine $200. Intercooler, exhaust, and inlet piping with fittings...maybe another $400-$500. Figure another $500 for an HKS additional injector controller and injectors and lines (run two 550cc-720cc). You could do the whole set-up for less then $2k

How much is just the supercharger you want to mount?

http://cgi.ebay.com/ebaymotors/OBX-Street-Power-Turbo-Charger-T3-25G-DSM-HONDA-500HP_W0QQcmdZViewItemQQhashZitem56392bbadfQQitemZ370326354655QQptZMotorsQ5fCarQ5fTruckQ5fPartsQ5fAccessories


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## franka (Jan 23, 2006)

JasonSC540ia said:


> How much is just the supercharger you want to mount?
> QUOTE]
> 
> I haven't a clue of the price since I have no plans to pursue installing a TS, or any SCr.
> ...


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## JasonSC540ia (Aug 11, 2009)

I guess what Im trying to ask is; What would the brake-down cost wise be?


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## franka (Jan 23, 2006)

If you are asking me about costs you are out of luck because, like I said, I don't know. :dunno:

Regarding the space, there is a lot of vertical room to the hood. The sound insulating material in the hood makes the vertical space appear to be less than it actually is. Check it out and see for yourself.


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## QuoteWarz Insurance (Dec 17, 2009)

Fabing a kit like this is never as easy as it looks. It will end up costing you a lot more time and money in the long run then just getting a production kit.


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## franka (Jan 23, 2006)

QuoteWarz Insurance said:


> Fabing a kit like this is never as easy as it looks. It will end up costing you a lot more time and money in the long run then just getting a production kit.


In general I have to agree, of course.

But for me specifically.....I'm not building a thing. Never was intending to and I'm not now.


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