turbo vs. supercharger
03-23-2012, 10:10 AM
#21
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Post the same question over at www.miatasupercharger.net. See how helpful they are (not very) and then come back here and we will help you put a turbo on your car.
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03-23-2012, 10:22 AM
#22
It depends, if you daily drive the car, the stress that a turbocharger's unpredictable power delivery can impart on your drivetrain can dangerously increase the chances of side fumbling. One of the possible fixes for this is to include a turbo entabulator in your build.
Unfortunately, most of us end up losing important engine internals to said side fumbling, so we ultimately end up ditching our turbo projects in favor of much more reliable and predictable superchargers for power delivery.
(welcome aboard.
read a bunch of build threads and start planning a turbo build. you won't be sorry.)
Unfortunately, most of us end up losing important engine internals to said side fumbling, so we ultimately end up ditching our turbo projects in favor of much more reliable and predictable superchargers for power delivery.
(welcome aboard.
read a bunch of build threads and start planning a turbo build. you won't be sorry.)
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03-23-2012, 11:16 AM
#31
I have never ridden in a supercharged miata so I was operating off of an apparently incorrect assumption that they behaved like other superchargered vehicles I have ridden in that have a very good low end powerband and then kind of taper or plateau up top. I guess I should have also considered that the other vehicles had larger engines and would inherently behave much differently
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03-23-2012, 12:53 PM
#32
A supercharger, therefore, would be for a "commuter" who could tell his friends that he's added 120hp to the car without actually being panicked by the fact that his car isn't driving as he expected it to.
A "driver" actually understands how car-stuff works (either that, or he's at least gets some enjoyment out of driving). If you told a "driver" that you were going to add 40hp to his car by changing to synthetic oil, he would put his credit card back into his wallet and drive to another shop. If you're a "driver", then you want to go turbo. Unfortunately for the "commuter", a turbocharger changes EVERYTHING about the car - the way it feels, the powerband, the way it sounds - all things that mean FREAK-THE------OUT as far as the commuter is concerned. Fortunately for the "driver", he *expects* that his car is going to act differently when he triples the engine output, and when his expectations are met, it is pure bliss to the driver.
Unfortunately, when a "driver" installs a supercharger system, the car continues to act exactly like it always has - with a disappointing powerband all the way to redline. It's not that superchargers have "grunt" down at the low end, it's that superchargers lack the "oompf" for the other 9/10ths of the rev range.
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03-23-2012, 04:46 PM
#37
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The mild pulley'd SC w/ TDR intercooler with big-*** TB Does provide largely instantaneous power when you mash the loud pedal, however it also is a bitch to idle, and real pita to drive when you're used to a car w/ throttle response. I suppose you could get used to it, I'd rather not.... It sucks a lot of the fun out of the car.
With that said, there is a range of about 1500-2200 rpm where my gt2560 just will not make positive pressure but the SC does. And umm... yeah, thats about it. And honestly, its not much more power than stock, the car is still a dog there... Not too mention, even at an autocross.... you never use those 700 rpm.
Tapping an oil pan, messing w/ exhaust.... All totally worth it... And the Turbo car is always going to get better gas mileage than the SC car, except at the track because the turbo car will almost certainly be making more power, thus burning more gas anyway
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03-23-2012, 06:40 PM
#39
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A commuter would hate that a supercharger would give him bad fuel economy all the time due to its drag and inefficiency even when you are not "using" it. It is on all the time.
And it is wearing out all the time. You only get so many revolutions before it needs to be rebuilt. Do you know what it costs to rebuild it?
Most turbo rebuild kits cost $60 to $100. They are so simple, with a little instruction you could even rebuild it yourself.
My whole turbo cost $250 brand new. I consider that to be a plus.
You can choose a turbo that will enhance your powerband at 1500 rpm or 15000 rpm if you want. It is up to you. The right turbo will make more power with greater efficiency than any positive displacement supercharger at any rpm you select. If you want 5lbs of pressure at 1500 rpm for some stupid reason, you can get it.
Many people who elect to go with positive displacement superchargers do so because they are too lazy to learn how to pick the right turbo. Every moron knows how a fan belt works.
Sidebar: Has anyone ever discussed the fact that very high cylinder pressures at incredibly low rpms is horrible for an engine. Gasses escape the combustion chamber past the rings at a given rate when they are at a given pressure. At 2500 rpm those harsh, sooty gasses have twice as much time to get past the rings into the crankcase and contaminate the lubricants as when operating at 5000 rpm.
Additionally, the side loading of the piston skirt against the cylinder wall would be accentuated, and would also allow more time for the oil film between the skirt and cylinder wall to be displaced. This will accelerate wear and additional piston rock and slap.
The oil volume and pressure will be significantly less at 2500 rpm than at 5000 rpm. And twice as much time will exist with that extreme pressure load on top of the piston trying to squeeze the small volume of oil out from between the rod bearing and the crankshaft. Less oil would also be slung up to the wrist pin at those speeds and far less cooling oil would contact the underside of the piston.
The piston would also be exposed to extreme high heat for a longer duration between exposures to a fresh cooling charge of air and fuel precipitating an increased piston temperature and therefore increasing the propensity of detonation. The hot spots in the combustion chamber would likewise be aggravated by the duration of exposure to extreme heat and the added detriment of a significantly slower flow of helpful coolant.
I was admonished at a young age never to "lug" an engine because it was detrimental to an engine's life. I guess some people were not similarly admonished in their youth.
And it is wearing out all the time. You only get so many revolutions before it needs to be rebuilt. Do you know what it costs to rebuild it?
Most turbo rebuild kits cost $60 to $100. They are so simple, with a little instruction you could even rebuild it yourself.
My whole turbo cost $250 brand new. I consider that to be a plus.
You can choose a turbo that will enhance your powerband at 1500 rpm or 15000 rpm if you want. It is up to you. The right turbo will make more power with greater efficiency than any positive displacement supercharger at any rpm you select. If you want 5lbs of pressure at 1500 rpm for some stupid reason, you can get it.
Many people who elect to go with positive displacement superchargers do so because they are too lazy to learn how to pick the right turbo. Every moron knows how a fan belt works.
Sidebar: Has anyone ever discussed the fact that very high cylinder pressures at incredibly low rpms is horrible for an engine. Gasses escape the combustion chamber past the rings at a given rate when they are at a given pressure. At 2500 rpm those harsh, sooty gasses have twice as much time to get past the rings into the crankcase and contaminate the lubricants as when operating at 5000 rpm.
Additionally, the side loading of the piston skirt against the cylinder wall would be accentuated, and would also allow more time for the oil film between the skirt and cylinder wall to be displaced. This will accelerate wear and additional piston rock and slap.
The oil volume and pressure will be significantly less at 2500 rpm than at 5000 rpm. And twice as much time will exist with that extreme pressure load on top of the piston trying to squeeze the small volume of oil out from between the rod bearing and the crankshaft. Less oil would also be slung up to the wrist pin at those speeds and far less cooling oil would contact the underside of the piston.
The piston would also be exposed to extreme high heat for a longer duration between exposures to a fresh cooling charge of air and fuel precipitating an increased piston temperature and therefore increasing the propensity of detonation. The hot spots in the combustion chamber would likewise be aggravated by the duration of exposure to extreme heat and the added detriment of a significantly slower flow of helpful coolant.
I was admonished at a young age never to "lug" an engine because it was detrimental to an engine's life. I guess some people were not similarly admonished in their youth.
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