Turbo vs. S/C
07-17-2006, 01:45 AM
#1
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Turbo vs. S/C
I searched for this thread and couldn't find it. I understand the dynamics of both the turbo and the S/C. Questions I have for a '82 US A/T.
1) Which would gove me the biggest bang for the buck.
2) Which one would be easier on/off installation
3)How diferant would the sensations be
4) Fill me in on anything I'm too dumb to ask
1) Which would gove me the biggest bang for the buck.
2) Which one would be easier on/off installation
3)How diferant would the sensations be
4) Fill me in on anything I'm too dumb to ask
Last edited by oceanvue; 07-17-2006 at 02:06 AM.
07-17-2006, 02:40 AM
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My opinion:
1. SC
2. SC
3. SC immediate, possible more linear, Turbo possible lag, more impact the higher you rev
I am sure the vendors will have their own perspectives
1. SC
2. SC
3. SC immediate, possible more linear, Turbo possible lag, more impact the higher you rev
I am sure the vendors will have their own perspectives
07-17-2006, 02:53 AM
#3
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You might wanna do a search. In fact, please do a search. This has been discussed thoroughly and heatedly on the board.
Just a warning. This could go on for 15 pages of posts.
Just a warning. This could go on for 15 pages of posts.
07-17-2006, 03:24 AM
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07-17-2006, 03:38 AM
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When was the last time an F1 was powered by a supercharger?
Both have their plus and minuses - but at least 90% of the time, if it is a boosted road racer it is turbocharged and if a drag racer it is supercharged.
Porsche uses turbochargers. Has there EVER been a Porsche that was factory supercharged.
Here is a quick summary of differences (not 100% accurate, but accurate in principle).
A supercharger is powered by the motor. They consume horsepower. On 4,000 horsepower dragsters, the supercharger can require as much as a whooping 800 horsepower to run! However, for a street car
it will be in the 20 to 60 horsepower range - depending upon size of supercharger, type and boost being made. The more power being made by the supercharger, also the more power it takes to run the supercharger - though there is a definite net gain.
Superchargers make a nearly steady boost level across the entire rpm range of the motor. So you will have the same boost at 2,000 rpm, 4,000 rpm or 6,000 rpm. As the motor is running the supercharger, there is nearly a constant level of boosting regardless of shifting and rpms.
Turbochargers are compressors driven by exhaust gas (or otherwise wasted energy) and therefore take very little horsepower away from the motor. However, their level of boost increases with the increase in the amount of exhaust (rpms) and does not do so equal to motor rpms. Rather, the higher the rpms, the
higher the boost. Boosting can be somewhat regulated (limited) by a turbo wastegate on the turbo (filters off exhaust before it goes into the compressor - and/or by a blow off valve (BOV) after the air is compressed.
So, depending upon your turbo setup, you might have no boost whatsoever at 3,000 rpm, 3 psi at 4,000 rpm, 9 psi at 5,000 rpm and 24 psi at 6,000 rpm! The wastegate (and if you have it BOV) is set up to limit your maximum boost - so if your goal was 5 psi, it would not allow over 5 psi from around 4,500 rpms and up.
Of you pick whatever turbo(s) you want for boost to kick in at what rpm you wanted it to.
As it takes time for the turbo to "spool up" - or build speed, there is a "lag" time between hitting the gas and boost matching the increase. There also is "over boosting" that can occur during shifting (turbo still spinning fast while rpms go down.)
The reason drag racers pick superchargers, is that the momentary lag (turbo lag) is unacceptable and they will give up horsepower to avoid it.
The reason road racers pick turbochargers is that maximum engine efficiency on a race that last minutes or hours is far more important than 1/5th of a second lost here and there while speed shifting. Turbochargers are more power and fuel efficient than superchargers.
Do you want constant boosting? Maybe yes, maybe no. If you are running down the highway on a trip, do you really want 6 psi boosting continuously at 2,700 rpm? With most turbo setups, for ordinary driving your turbos will not be making any boost at all (less heat, less wear, better fuel economy then).
But, with a supercharger, if you hammer it, the response is virtually instantaneous, where with a turbo there will be a fraction of a second delay.
A turbo may allow you to feel comfortable running a higher level of performance boost - and you are not boosting continuously. Thus, up to 3,000 rpm, there is little to no boost, but as you get into higher rpms (where performance action happens, you can have 5, 8, 10, 15, 20, 25, 30 psi - whatever you have installed for turbos - and via the wastegate you can also make that adjustable without changing turbos. Just adjust the wastegate - either by turning a nut or screw on it - or spend a bit more and be able to do so from inside the cockpit.
The alter boosting on a supercharger, you change the pulley(s) to change the ratio. However, superchargers generally are not able to run at extremely high rpms (those sold for our cars anyway) and the more you increase the boost, the more power it will consume.
Both turbos and superchargers generate intake air heat - therefore give rise to denotation. One other maybe plus is that it is easier to have a system to reduce or shut down boosting if denotation is occuring in a turbocharged motor (or just shift up so driving at lower rpms and therefore less boosting). There is no way to reduce (or increase) boosting on a supercharger without changing the pulleys. Unfortunately, I have not seen a kit for our cars that offer a pulley clutch for the supercharger (something BMW offered).
If you are confident that you are going to be happy with boosting not much more then 7 psi - and that you will not have a denotation problem under any circumstance with that level, you'd probably like a supercharger better. If you maybe want lots of boost possible and to be able to drive without boosting at all for ordinary driving, a turbo(s) is the way to go.
A supercharger system (if a kit) will be easier to install (probably). With a turbocharger kit, you would not be buying headers.
With a supercharger you will get supercharger whine (soft or loud depending upon which type). To many, that sounds really cool. Turbochargers provide a bit of muffling effect on the exhaust, until the wastegate kicks in and then is sounds like a truly screaming motor.
Acceleration with supercharger will be instantly hard, firm and a fairly steady climb. With a turbocharger, the faster you go, the faster you go with acceleration really pouring on up the rpm scale.
As for the Porsche company itself? They are 100% turbocharger people obviously, but then they don't drag race their Porsches.
Also, there are two different types of superchargers: 1.) Rootes or postive displacement (a box on top of your motor with spinning rotors inside to make compression) or 2.) a vane style supercharger, which is similar to a turbocharger compressor - but is driven by a belt and therefore is fairly constant.
Rootes style (such as the twin screw) have the best appearance, a tad more rapid response, and if seeking really high boost are better at high psi (if the right one selected for it). Vane style (such as offered by 928 Motorsports) are lighter weight, a bit more efficient (take a bit less horsepower to run), are less expensive to repair or replace and probably last longer.
Twin turbos will have less turbo lag than a single turbo, and pros tend to mismatch the turbos with one set up for mid-range boosting and the other for high rpms (using the wastegate on the mid-range one to prevent over boosting) - which further reduces lag time as the smaller a turbo is, the faster it can spoil up.
Ballbearing turbocharger units spool up faster than non-ballbearing turbos. Turbochargers commonly spin up to 100,000 rpms or more - meaning you gotta get oil to the bearings. Some supercharger units are self contained in lubricating (though I am a tad skeptical of how many miles those are good for.)
A replacement turbo would cost maybe 1/4th to 1/5th the price of a replacement supercharger, but both can be rebuilt is this is done before serious wear or failure occurs.
Porsche uses turbos because they are more efficient and Porsches are road course cars. Manufacturers tend to opt for turbos over superchargers because both give them higher hp at the top, but turbos do not boost except up the rpm range (meaning not boosting at all for ordinary driving) - meaning less wear on the motor, better fuel economy and less wear on the turbo over a supercharger too.
You choice. You'll LOVE either system!
Mark O
Both have their plus and minuses - but at least 90% of the time, if it is a boosted road racer it is turbocharged and if a drag racer it is supercharged.
Porsche uses turbochargers. Has there EVER been a Porsche that was factory supercharged.
Here is a quick summary of differences (not 100% accurate, but accurate in principle).
A supercharger is powered by the motor. They consume horsepower. On 4,000 horsepower dragsters, the supercharger can require as much as a whooping 800 horsepower to run! However, for a street car
it will be in the 20 to 60 horsepower range - depending upon size of supercharger, type and boost being made. The more power being made by the supercharger, also the more power it takes to run the supercharger - though there is a definite net gain.
Superchargers make a nearly steady boost level across the entire rpm range of the motor. So you will have the same boost at 2,000 rpm, 4,000 rpm or 6,000 rpm. As the motor is running the supercharger, there is nearly a constant level of boosting regardless of shifting and rpms.
Turbochargers are compressors driven by exhaust gas (or otherwise wasted energy) and therefore take very little horsepower away from the motor. However, their level of boost increases with the increase in the amount of exhaust (rpms) and does not do so equal to motor rpms. Rather, the higher the rpms, the
higher the boost. Boosting can be somewhat regulated (limited) by a turbo wastegate on the turbo (filters off exhaust before it goes into the compressor - and/or by a blow off valve (BOV) after the air is compressed.
So, depending upon your turbo setup, you might have no boost whatsoever at 3,000 rpm, 3 psi at 4,000 rpm, 9 psi at 5,000 rpm and 24 psi at 6,000 rpm! The wastegate (and if you have it BOV) is set up to limit your maximum boost - so if your goal was 5 psi, it would not allow over 5 psi from around 4,500 rpms and up.
Of you pick whatever turbo(s) you want for boost to kick in at what rpm you wanted it to.
As it takes time for the turbo to "spool up" - or build speed, there is a "lag" time between hitting the gas and boost matching the increase. There also is "over boosting" that can occur during shifting (turbo still spinning fast while rpms go down.)
The reason drag racers pick superchargers, is that the momentary lag (turbo lag) is unacceptable and they will give up horsepower to avoid it.
The reason road racers pick turbochargers is that maximum engine efficiency on a race that last minutes or hours is far more important than 1/5th of a second lost here and there while speed shifting. Turbochargers are more power and fuel efficient than superchargers.
Do you want constant boosting? Maybe yes, maybe no. If you are running down the highway on a trip, do you really want 6 psi boosting continuously at 2,700 rpm? With most turbo setups, for ordinary driving your turbos will not be making any boost at all (less heat, less wear, better fuel economy then).
But, with a supercharger, if you hammer it, the response is virtually instantaneous, where with a turbo there will be a fraction of a second delay.
A turbo may allow you to feel comfortable running a higher level of performance boost - and you are not boosting continuously. Thus, up to 3,000 rpm, there is little to no boost, but as you get into higher rpms (where performance action happens, you can have 5, 8, 10, 15, 20, 25, 30 psi - whatever you have installed for turbos - and via the wastegate you can also make that adjustable without changing turbos. Just adjust the wastegate - either by turning a nut or screw on it - or spend a bit more and be able to do so from inside the cockpit.
The alter boosting on a supercharger, you change the pulley(s) to change the ratio. However, superchargers generally are not able to run at extremely high rpms (those sold for our cars anyway) and the more you increase the boost, the more power it will consume.
Both turbos and superchargers generate intake air heat - therefore give rise to denotation. One other maybe plus is that it is easier to have a system to reduce or shut down boosting if denotation is occuring in a turbocharged motor (or just shift up so driving at lower rpms and therefore less boosting). There is no way to reduce (or increase) boosting on a supercharger without changing the pulleys. Unfortunately, I have not seen a kit for our cars that offer a pulley clutch for the supercharger (something BMW offered).
If you are confident that you are going to be happy with boosting not much more then 7 psi - and that you will not have a denotation problem under any circumstance with that level, you'd probably like a supercharger better. If you maybe want lots of boost possible and to be able to drive without boosting at all for ordinary driving, a turbo(s) is the way to go.
A supercharger system (if a kit) will be easier to install (probably). With a turbocharger kit, you would not be buying headers.
With a supercharger you will get supercharger whine (soft or loud depending upon which type). To many, that sounds really cool. Turbochargers provide a bit of muffling effect on the exhaust, until the wastegate kicks in and then is sounds like a truly screaming motor.
Acceleration with supercharger will be instantly hard, firm and a fairly steady climb. With a turbocharger, the faster you go, the faster you go with acceleration really pouring on up the rpm scale.
As for the Porsche company itself? They are 100% turbocharger people obviously, but then they don't drag race their Porsches.
Also, there are two different types of superchargers: 1.) Rootes or postive displacement (a box on top of your motor with spinning rotors inside to make compression) or 2.) a vane style supercharger, which is similar to a turbocharger compressor - but is driven by a belt and therefore is fairly constant.
Rootes style (such as the twin screw) have the best appearance, a tad more rapid response, and if seeking really high boost are better at high psi (if the right one selected for it). Vane style (such as offered by 928 Motorsports) are lighter weight, a bit more efficient (take a bit less horsepower to run), are less expensive to repair or replace and probably last longer.
Twin turbos will have less turbo lag than a single turbo, and pros tend to mismatch the turbos with one set up for mid-range boosting and the other for high rpms (using the wastegate on the mid-range one to prevent over boosting) - which further reduces lag time as the smaller a turbo is, the faster it can spoil up.
Ballbearing turbocharger units spool up faster than non-ballbearing turbos. Turbochargers commonly spin up to 100,000 rpms or more - meaning you gotta get oil to the bearings. Some supercharger units are self contained in lubricating (though I am a tad skeptical of how many miles those are good for.)
A replacement turbo would cost maybe 1/4th to 1/5th the price of a replacement supercharger, but both can be rebuilt is this is done before serious wear or failure occurs.
Porsche uses turbos because they are more efficient and Porsches are road course cars. Manufacturers tend to opt for turbos over superchargers because both give them higher hp at the top, but turbos do not boost except up the rpm range (meaning not boosting at all for ordinary driving) - meaning less wear on the motor, better fuel economy and less wear on the turbo over a supercharger too.
You choice. You'll LOVE either system!
Mark O
07-17-2006, 08:49 AM
#6
Race Director
A SC is generally easier and cheaper to bolt on than a turbo solution and both systems can be very good. I would say that a turbo solution would be a better solution but it is a lot more involved to install one due to the extra plumbing.
07-17-2006, 09:54 AM
#7
Man of many SIGs
Rennlist Member
Rennlist Member
W/ an automatic trans. you probably want to go with the SC. Search for Goldmember and read about Kuhn's 1st turbo car. He spent tons of time and effort ( also some $$$) building a really nice turbo engine and ended up being disapointed due to the auto. transmission.
This sc vs turbo debate can get quite heated here on Rennlist. Be careful what you ask.
This sc vs turbo debate can get quite heated here on Rennlist. Be careful what you ask.
Trending Topics
07-17-2006, 10:29 AM
#8
Race Director
Originally Posted by Fabio421
W/ an automatic trans. you probably want to go with the SC. Search for Goldmember and read about Kuhn's 1st turbo car. He spent tons of time and effort ( also some $$$) building a really nice turbo engine and ended up being disapointed due to the auto. transmission.
This sc vs turbo debate can get quite heated here on Rennlist. Be careful what you ask.
This sc vs turbo debate can get quite heated here on Rennlist. Be careful what you ask.
What most blown 928's seems to lack is good tuning, taking fuel and ignition map from a N/A and just add fuel with a rising rate fuel pressure regulator is a bandaid solution. Here on Rennlist it is a few clicks to read the 944 turbo boards where people who are serious about their cars use logging for lambda, exhaust gas temperature and boost along with a knock sensor device. Getting these items will cost $1000-1300 USD and that must be considered cheap considering what repair cost a seemingly well running time bomb engine can cost once it grenades.
07-17-2006, 10:57 AM
#9
Addict
Rennlist Member
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Large injectors and SharkTuner will take care of just about any tuning problems without changing anything else on stock injection or ignition system. It's only matter of time ST is applied on turbo 928 with good results. In SC side it's old news already.
07-17-2006, 10:59 AM
#10
Race Director
Originally Posted by Vilhuer
Large injectors and SharkTuner will take care of just about any tuning problems without changing anything else on stock injection or ignition system. It's only matter of time ST is applied on turbo 928 with good results. In SC side it's old news already.
07-17-2006, 11:09 AM
#12
Race Director
Originally Posted by Normy
Shark Tuner is only built for '87 and up cars. Earlier cars...you need a dynamometer for proper tuning.
N
N
07-17-2006, 11:16 AM
#13
Addict
Rennlist Member
Rennlist Member
Originally Posted by sweanders
Correct, but how many have used it?
Normy, older models are other thing completely. They lack stuff from factory to be easy to tune.
07-17-2006, 11:17 AM
#14
Rennlist Member
RUF uses a centrifugal supercharger on a 997. Looks like Murph isn't charging enough - money not boost.
The twin screw uses a bypass valve so parasitic loss when not under boost is 1/3 hp or so, gas mileage is unaffected during normal driving.
Do I dislike turbo? No, but now there are proven SC kits available. It looks like turbo kits both single and twin will be available. It's nice to have options.
RUF Kompressor Conversion for all 996 and 997 Carrera
A RUF performance upgrade for all naturally-aspirated Porsche 996 and 997 Carrera
Many of these naturally-aspirated owners would like to have additional horsepower for their Porsches. RUF provides the integrated solution! RUF‘s Kompressor Conversion, with maximum boost of 0.6 bar, provides noticeable improvement in torque that translates into improved acceleration and top speed. The power curve is increased throughout the RPM range.
The Kompressor Conversion is based on a centrifugal compressor, mechanically driven by a Poly-Rip belt, and is a fully integrated system:
The engine compression ratio is lowered
Special Ruf-designed Fuel Injectors are installed
Special Ruf-programmed electronic engine management system is harnessed
Ruf water-cooled intercoolers are incorporated into new intake manifolds which are fed by a dedicated cooling system via separate front radiator that utilizes an electric coolant circulation pump
The system is further complimented with new catalytic converters specifically tuned to enhance the Kompressor's torque curve
Basic Engine Performance Torque Installed Price
3.4 liter (996) adds 80-100 hp adds 40ft/lbs $22,900
3.6 liter (996) adds 80-100 hp adds 40ft/lbs $22,900
3.6 liter (997) adds 80-100 hp adds 40ft/lbs $22,900
3.8 liter (997) adds 80-100 hp adds 30ft/lbs $23,900
A RUF performance upgrade for all naturally-aspirated Porsche 996 and 997 Carrera
Many of these naturally-aspirated owners would like to have additional horsepower for their Porsches. RUF provides the integrated solution! RUF‘s Kompressor Conversion, with maximum boost of 0.6 bar, provides noticeable improvement in torque that translates into improved acceleration and top speed. The power curve is increased throughout the RPM range.
The Kompressor Conversion is based on a centrifugal compressor, mechanically driven by a Poly-Rip belt, and is a fully integrated system:
The engine compression ratio is lowered
Special Ruf-designed Fuel Injectors are installed
Special Ruf-programmed electronic engine management system is harnessed
Ruf water-cooled intercoolers are incorporated into new intake manifolds which are fed by a dedicated cooling system via separate front radiator that utilizes an electric coolant circulation pump
The system is further complimented with new catalytic converters specifically tuned to enhance the Kompressor's torque curve
Basic Engine Performance Torque Installed Price
3.4 liter (996) adds 80-100 hp adds 40ft/lbs $22,900
3.6 liter (996) adds 80-100 hp adds 40ft/lbs $22,900
3.6 liter (997) adds 80-100 hp adds 40ft/lbs $22,900
3.8 liter (997) adds 80-100 hp adds 30ft/lbs $23,900
Do I dislike turbo? No, but now there are proven SC kits available. It looks like turbo kits both single and twin will be available. It's nice to have options.
07-17-2006, 11:27 AM
#15
Three Wheelin'
There are enough Rennlister who are running under boost that you could probably take a couple of rides for comparison. It may help you decide what you prefer.
I love what forced induction has done to my GT. The AFR tuning was not what it needed to be with the kit out of the box, but with the SharkTuner and custom chip it is simply spectacular. I am running a roots blower. The pulley change is easy - literally 15 mins. But if you need to change the belt to accomodate a big change in pulley diameter, it is more time consuming. The look factor is good, too. Alot of interest at the DE's, especially at tech inspection time. The last weak link is in the power steering pully set up. I have not had problems in the last 6-8 months, but I still plan to clean it up a bit long term. DR has taken care of this in his version of the setup with a masterpiece of a pulley assembly. That is where I want to get to.
I like the low end grunt that the positive displacement blower provides. Downshift simply not required, unless you really want to put the hurt on someone. Tire shredding power all the way through the rpm range.
I am pleased that the 928 community has real choices in the area of forced induction. Kudos to all those folks who have put in the time to come up with real alternatives for us in this area. You will have to decide for yourself which direction you want to go. I wouldn't trade the 'twin screw' approach for anything else out there, but that is just me.
I love what forced induction has done to my GT. The AFR tuning was not what it needed to be with the kit out of the box, but with the SharkTuner and custom chip it is simply spectacular. I am running a roots blower. The pulley change is easy - literally 15 mins. But if you need to change the belt to accomodate a big change in pulley diameter, it is more time consuming. The look factor is good, too. Alot of interest at the DE's, especially at tech inspection time. The last weak link is in the power steering pully set up. I have not had problems in the last 6-8 months, but I still plan to clean it up a bit long term. DR has taken care of this in his version of the setup with a masterpiece of a pulley assembly. That is where I want to get to.
I like the low end grunt that the positive displacement blower provides. Downshift simply not required, unless you really want to put the hurt on someone. Tire shredding power all the way through the rpm range.
I am pleased that the 928 community has real choices in the area of forced induction. Kudos to all those folks who have put in the time to come up with real alternatives for us in this area. You will have to decide for yourself which direction you want to go. I wouldn't trade the 'twin screw' approach for anything else out there, but that is just me.