Turbo vs Supercharger
12-01-2004, 05:33 PM
#46
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Originally Posted by BrendanC
Do I manufacture my own turbos or superchargers? Nope. Do you?
12-01-2004, 05:37 PM
#47
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Originally Posted by 944J
so it seems like the general verdict is that the SC is better for low RPM power and the Turbo is better for redline RPM power.
So for road racing the Turbo is better and for drag racing the SC is better.
So for road racing the Turbo is better and for drag racing the SC is better.
Also, the reason you don't see turbos in Top Fuel drag racing is they are illegal. A turbocharger top fueler would easily outperform a SC'd top fueler.
12-01-2004, 05:43 PM
#48
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Originally Posted by Jack '84 928s
If superchargers are so good and so much better how come the 18 Wheeler truck market uses turbos? Hell my dads semi has like 800,000 miles on the turbo... I guess that means turbos are better to me.
Diesel engines are ideal turbocharging candidates. The exhaust is cooler so more turbo life, theres TONS of exhaust, and diesel engines by their nature can take loads of boost. Hell the pickup truck drag guys can run 40/50PSI or more.
And then theres the VATN turbos, on diesels those can make a BAR of boost at idle...
12-01-2004, 06:00 PM
#49
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Don't forget that one of the things that makes Diesels so great with a turbo is they have a very limited rpm range compared with a gasoline engine. This makes selecting/engineering a great performing turbo matched to the engine much easier. One of the major challenges in selecting a turbo for a gasoline engine is getting a turbo that will work well over the broad rpm range.
12-01-2004, 06:46 PM
#50
Originally Posted by Jack '84 928s
Why isnt this on the 928 forum, ill tell you why. The CS Supercharger guys constantly bicker and flame about turbos like they are the devil. Except for andy i like his roots type blower kit since its cheap and works well.
Originally Posted by Jack '84 928s
I was doing some research on superchargers once and turbos, have read sevral books and they all come to the conclusion that roots and CS chargers loose effiency over 14psi of boost. Hell a roots blower 12 is like pushing it.
12-01-2004, 06:51 PM
#51
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Originally Posted by Geo
I'd be very very careful making such an assumption.
Also, the reason you don't see turbos in Top Fuel drag racing is they are illegal. A turbocharger top fueler would easily outperform a SC'd top fueler.
Also, the reason you don't see turbos in Top Fuel drag racing is they are illegal. A turbocharger top fueler would easily outperform a SC'd top fueler.
And I'm just saying that from what I've heard in this post and what I've read that SC's offer immediate boost but loose efficiency at high boost levels (like Danno said a SC is good for mid range power around town (and maybe autocross) 300rwhp and a turbo is better for road racing where the rpm's are kept high and peak power is the goal.
And it might be more fun to drive a 951 with an SC with 350rwhp than one with a a turbo with lag since I doubt I'll be going over 65mph very often.
12-01-2004, 06:59 PM
#52
From a post on the board here, there was a guy a while back that raced his friend's turbo with his SC 944 and his car was faster. The car has more torque and lass lag. The 944 N/A can beat a 944 turbo in stock form.
IS this a fair comparison? probably not. The SC has a higher compression engine, and who knows what the boost was set at?
The SC and the Turbo are both good and reliable. Who prefers what is a different story. The SC does have no lag - big plus. Can it hit the high efficiency at high RPMs? Probably not. Then again, what about going to dual smaller turbos to delete the lag like many car manufacturers have tried? There are many possibilities, it just depends on what the person defining it prefers. The variables would have to be set equally to compare the two, and as far as I've seen, no one has done a test like that yet.
IS this a fair comparison? probably not. The SC has a higher compression engine, and who knows what the boost was set at?
The SC and the Turbo are both good and reliable. Who prefers what is a different story. The SC does have no lag - big plus. Can it hit the high efficiency at high RPMs? Probably not. Then again, what about going to dual smaller turbos to delete the lag like many car manufacturers have tried? There are many possibilities, it just depends on what the person defining it prefers. The variables would have to be set equally to compare the two, and as far as I've seen, no one has done a test like that yet.
12-01-2004, 07:04 PM
#53
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Brenden how can you say say its ill fitting to put a turbo on a 928 without serious head and vavetrain upgrades? But its ok to run a supercharger? Your argument is flawed. I see another flaw, if the CS and Roots do not produce near the heat level why are tim and andy using intercoolers on the higher boosted engines... If you run any engine at wide open throttle for long enough the exhaust manifolds become redhot and glow. It actually looks kinda cool. I wouldnt mind the lag with the turbo because i can cruise around town normal, and when i want to go fast i just wait what 1-2secons to hit 3k rpms and put the fear of god in lesser cars.
The WRX, Evo, SRT-4 - all use turbos. Rally cars use turbos. The only real place you see people using CS superchargers are at the dragstrip. Andys kit doesnt come out to as much as tims kit. Tims kit is what 8,000$, thats alot of money for a 1200$ supercharger headunit.
The WRX, Evo, SRT-4 - all use turbos. Rally cars use turbos. The only real place you see people using CS superchargers are at the dragstrip. Andys kit doesnt come out to as much as tims kit. Tims kit is what 8,000$, thats alot of money for a 1200$ supercharger headunit.
12-01-2004, 07:09 PM
#54
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This is very interesting to me....
Yes, Brenden you can say what you want...my results speak for themselves, 8 lbs turbocharged and intercooled on a 4.5 liter with crappy cams yields over 300 RWHP and about 355 ft-lbs of torque. 9 lbs with a Powerdyne CS with Intercooler on a 4.5 liter was shown to make about 280 RWHP and about 295 ft-lbs. So on 1/2 to one pound less boost I made 20+ more HP and 50+ more ft-lbs. Read that 50 ft-lbs again, because that tells the story. Now, mind you this is not even fair, because the 79 that ran that supercharger has cams with more duration and lift than the 80-82 cams do....like 0.040" more lift and 5 degrees more duration on each lobe. Which car do you think is faster on the road? Think those 79 cams might help my car any? I'd lay money they are worth 20 HP up top. The fact is I have put together two turbo cars while you continue to bicker back and forth on what you are doing with your car...is it still in pieces these days? I'm looking for an S4 to turbocharge (did I mention those big hybrid Garretts are 78% efficient?)....maybe you should send me the engine to start with...or do you too own stock in MURF928? Like I couldn't make a CS kit for the 928 for less money? EASY, but I refuse to do it because it is clearly inferior to a positive or a turbo. $7,500 for a 928 CS kit is what I call a rip-off when the same hardware for a Camaro/Mustang is like 2/3 that number. We have yet to see any real world performance numbers from Murf, Lag, O/N, Gretch or the others out there who own stock in MURF928. Not one of them has measured 0-60 or 1/4 mile? Come on...I bet you Andy's positive unit beats them on a lb. per lb. basis and he has no issues posting time slips. Dyno sheets don't tell the whole story. So, do tell us all why MURF928 stock holders can't give real world measured performance numbers. Clever use of smoke and mirrors I must say. These days the CS is mostly "me too" if you ask me. Easy to do and technically inferior. The goal with the twin-turbo 928 was to offer a unique package that is a pavement pounder and that was done in 1983 by Reeves Callaway and again by me this year....others have done it too, but they choose to be silent. Just because you haven't done it doesn't make it impossible or inferior. It is not easy, which makes the rewards that much sweeter when you are finished. BTW...Reeves sends all his inquiries about Callaway 928 TTs to me these days, so I don't think I have any credibility issues to worry about. I don't have any comments on your credibility because it really doesn't matter to me. Those reading can formulate their own opinions.
Yes, I agree a Positive Displacement Supercharger will offer more off idle performance than the turbo...the turbo will take over above 3000 RPM or so. Don't forget you have to shift before the redline, which is the point you have to wait till to get full boost off of that ultra efficient CS you refer to.
Did I mention the noise?
Yes, Brenden you can say what you want...my results speak for themselves, 8 lbs turbocharged and intercooled on a 4.5 liter with crappy cams yields over 300 RWHP and about 355 ft-lbs of torque. 9 lbs with a Powerdyne CS with Intercooler on a 4.5 liter was shown to make about 280 RWHP and about 295 ft-lbs. So on 1/2 to one pound less boost I made 20+ more HP and 50+ more ft-lbs. Read that 50 ft-lbs again, because that tells the story. Now, mind you this is not even fair, because the 79 that ran that supercharger has cams with more duration and lift than the 80-82 cams do....like 0.040" more lift and 5 degrees more duration on each lobe. Which car do you think is faster on the road? Think those 79 cams might help my car any? I'd lay money they are worth 20 HP up top. The fact is I have put together two turbo cars while you continue to bicker back and forth on what you are doing with your car...is it still in pieces these days? I'm looking for an S4 to turbocharge (did I mention those big hybrid Garretts are 78% efficient?)....maybe you should send me the engine to start with...or do you too own stock in MURF928? Like I couldn't make a CS kit for the 928 for less money? EASY, but I refuse to do it because it is clearly inferior to a positive or a turbo. $7,500 for a 928 CS kit is what I call a rip-off when the same hardware for a Camaro/Mustang is like 2/3 that number. We have yet to see any real world performance numbers from Murf, Lag, O/N, Gretch or the others out there who own stock in MURF928. Not one of them has measured 0-60 or 1/4 mile? Come on...I bet you Andy's positive unit beats them on a lb. per lb. basis and he has no issues posting time slips. Dyno sheets don't tell the whole story. So, do tell us all why MURF928 stock holders can't give real world measured performance numbers. Clever use of smoke and mirrors I must say. These days the CS is mostly "me too" if you ask me. Easy to do and technically inferior. The goal with the twin-turbo 928 was to offer a unique package that is a pavement pounder and that was done in 1983 by Reeves Callaway and again by me this year....others have done it too, but they choose to be silent. Just because you haven't done it doesn't make it impossible or inferior. It is not easy, which makes the rewards that much sweeter when you are finished. BTW...Reeves sends all his inquiries about Callaway 928 TTs to me these days, so I don't think I have any credibility issues to worry about. I don't have any comments on your credibility because it really doesn't matter to me. Those reading can formulate their own opinions.
Yes, I agree a Positive Displacement Supercharger will offer more off idle performance than the turbo...the turbo will take over above 3000 RPM or so. Don't forget you have to shift before the redline, which is the point you have to wait till to get full boost off of that ultra efficient CS you refer to.
Did I mention the noise?
12-01-2004, 07:15 PM
#55
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Ive also thought about the fact that a turbo with turbo lag is easier on the engine since it allows the engine to get up to speed before the power comes on. Is this true? So you can use smaller engines with less reinforcements without blowing it up?
12-01-2004, 07:15 PM
#56
Originally Posted by Jack '84 928s
Brenden how can you say say its ill fitting to put a turbo on a 928 without serious head and vavetrain upgrades? But its ok to run a supercharger? Your argument is flawed. I see another flaw, if the CS and Roots do not produce near the heat level why are tim and andy using intercoolers on the higher boosted engines... If you run any engine at wide open throttle for long enough the exhaust manifolds become redhot and glow. It actually looks kinda cool. I wouldnt mind the lag with the turbo because i can cruise around town normal, and when i want to go fast i just wait what 1-2secons to hit 3k rpms and put the fear of god in lesser cars.
The WRX, Evo, SRT-4 - all use turbos. Rally cars use turbos. The only real place you see people using CS superchargers are at the dragstrip. Andys kit doesnt come out to as much as tims kit. Tims kit is what 8,000$, thats alot of money for a 1200$ supercharger headunit.
The WRX, Evo, SRT-4 - all use turbos. Rally cars use turbos. The only real place you see people using CS superchargers are at the dragstrip. Andys kit doesnt come out to as much as tims kit. Tims kit is what 8,000$, thats alot of money for a 1200$ supercharger headunit.
How is my argument flawed? The SC is at the front of the engine, nearly a foot from the heads. It is producing heat, but alot of that is taken out by the intercoolers. How does that require valvetrain changes, as well as Sodium fillede valves, ceramic exhaust ports, as the turbo system in the 951 has (and requires)
On the point of the intercoolers for andy and tim, - any boosted application requires an intercooler. To do so without is going to limit the boost level to about 6 or less - depending on the application. My point is the temp differences. Any boosted ap at 11psi will require an intercooler.
BTW - You (will most likely) have an *abnormal* restriction in your exhaust headers on any vehicle that is not turbocharged if they are red hot. This is a problem and requires repair. DO they get hot? Hell yes - its exhaust.
12-01-2004, 07:20 PM
#57
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Originally Posted by Z
It really depends on the specific application and intended use of the vehicle. While not as high as the efficiency map of the turbo posted above, there are superchargers that are more efficient at higher boost levels than the map of the Vortech posted above.
The maps are generated on a test stand of some type, and don't take into account some factors present in the actual operation on the engine in a vehicle. The drag of the supercharger would be measured on the test stand, as would be the drag of the turbo. The loss due to the exhaust backpressure to the engine with the turbo would not be taken into account on the test stand though. Every turbo owner knows their boost pressure, but how many know their exhaust backpressure that the engine is seeing and has to work against to pump exhaust out?
The potential effects of added heat from the plumbing routing and turbo being confined in the engine compartment wouldn't be considered in the maps either. I'm sure everybody's seen pictures of turbos glowing red hot. Anybody ever seen a supercharger like that?
The maps also doesn't take into account lag, but how important that is again depends on the specific application, what the specific goals are, and how the vehicle will be used. With real estate it's location, location, location. With cars it's application, application, application. An awful lot of people don't consider that. To get the best setup, you have to realisticly decide exactly what you want the car to do, and how and where you're going to drive it before you make your decision as to how to set it up.
The maps are generated on a test stand of some type, and don't take into account some factors present in the actual operation on the engine in a vehicle. The drag of the supercharger would be measured on the test stand, as would be the drag of the turbo. The loss due to the exhaust backpressure to the engine with the turbo would not be taken into account on the test stand though. Every turbo owner knows their boost pressure, but how many know their exhaust backpressure that the engine is seeing and has to work against to pump exhaust out?
The potential effects of added heat from the plumbing routing and turbo being confined in the engine compartment wouldn't be considered in the maps either. I'm sure everybody's seen pictures of turbos glowing red hot. Anybody ever seen a supercharger like that?
The maps also doesn't take into account lag, but how important that is again depends on the specific application, what the specific goals are, and how the vehicle will be used. With real estate it's location, location, location. With cars it's application, application, application. An awful lot of people don't consider that. To get the best setup, you have to realisticly decide exactly what you want the car to do, and how and where you're going to drive it before you make your decision as to how to set it up.
12-01-2004, 07:35 PM
#58
Race Director
Originally Posted by 944J
You'd think that somewhere there would be drag cars doing turbo's?
12-01-2004, 07:37 PM
#59
I've given you chance upon chance to NOT be a dickweed. I try to stay civil as I can, while still keeping to my points, etc. *But of course, you MUST attack my projects again - and this is a personal attack*
Yes, Brenden
- Ah, see, simple intelligence problem here. My name is clearly stated by the side of each of my posts. What do you do? Spell it wrong. Nice.
... The fact is I have put together two turbo cars while you continue to bicker back and forth on what you are doing with your car...is it still in pieces these days? ......I'm looking for an S4 to turbocharge (did I mention those big hybrid Garretts are 78% efficient?)....maybe you should send me the engine to start with...or do you too own stock in MURF928
Well, I have attempted to ask you in threads about what solution you have for the S4s. No response unless you can come up with one from a previous day. Ship you my engine? And what, pay you 12 grand? Why do you choose to attack my projects that I clearly update in my sig every few days or weeks? Does that make you feel better about yourself when you attack other's personal work? Infact I have two 928s in pieces, and quite proud of it as that means I will learn. I guess you've learned alot to - how to berate other's process and accomplisments. This crap always has to get personal with you. Thats a horrible sign of intelligence I'm afraid. Very concerned indeed. I have a job, and a Child at home.... I can't spend whole weekends doing this, so it takes a while. Why would you berate that?
[/QUOTE]
Originally Posted by John the dickweed..
Yes, Brenden
Originally Posted by John the dickweed..
... The fact is I have put together two turbo cars while you continue to bicker back and forth on what you are doing with your car...is it still in pieces these days? ......I'm looking for an S4 to turbocharge (did I mention those big hybrid Garretts are 78% efficient?)....maybe you should send me the engine to start with...or do you too own stock in MURF928
[/QUOTE]
Last edited by BC; 12-02-2004 at 12:34 PM.
12-01-2004, 07:40 PM
#60
Race Director
Originally Posted by 944J
Ive also thought about the fact that a turbo with turbo lag is easier on the engine since it allows the engine to get up to speed before the power comes on. Is this true? So you can use smaller engines with less reinforcements without blowing it up?