Turbo vs. Supercharger...
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Turbo vs. Supercharger... I was reading through the "Fastest turbo M6" thread and found something that Chris said really interesting. Albeit, I believe it's from my lack of knowledge, but hey, that's the reason I'm on this board. I always had it in my mind that a turbo car would be better for the drag strip because theoretically you would build full boost sooner than a supercharged car. Chris ARE 360 (I think you said this) mentioned that during shifts, you lose load, and you have to respool the turbos basically from scratch, while with a supercharger being RPM dependant, it would be faster in the long run. Does that mean if you had identical cars except one being a supercharged car and one being a turbo charged car... on the same boost, would the supercharged car be faster because of this?
Re: Turbo vs. Supercharger... It's difficult to keep boost in a manual car sometimes depending on the setup, most stalled/turbo cars have no problems because you can keep the motor spinning in a certain range and you wouldn't lose as much boost through shifts. Also depending on setup you can get boost EASY off the line with a turbo, so there goes the instant boost arguement from SC guys. Another setup dependent factor is with a turbo, if you can keep your foot outn of it you stay out of boost and you get decent gas mileage. All depends on setup though, both have pros and cons 
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Re: Turbo vs. Supercharger... That's what I had thought, but as it turns out, there are more pros and cons to both sides than I had previously considered or even thought about. I find this interesting, no one I know has an FI car. Everyone is doin H/C/Spray around here that I've seen.
Re: Turbo vs. Supercharger... FI cars are a bit harder to tune and from what I've seen are a bit more time consuming to get running right than a straight up heads/cam/spray car. I personally love the sound of a turbo shrieking 
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Re: Turbo vs. Supercharger... this is gonna be an interesting thread... I do have an FI car, but I've just recently gotten into the FI scene, since I bought my car with the blower already on it. I know the basics, but it's cool to hear about all the turbo vs supercharger stuff...
could someone list out the boost basics of the whole blower vs turbo thing? is there one that is clearly better?
could someone list out the boost basics of the whole blower vs turbo thing? is there one that is clearly better?
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Re: Turbo vs. Supercharger... That's why I started it, I was hoping to make an interesting one 
I'm by far a neophyte with FI, but my basic understanding is that a supercharger's boost is in direct relation to the rpm of the engine and that it pretty much starts building some kind of pressure (not necessarily positive boost) from idle and up. With a turbo, it stays out of boost until a certain rpm/load condition and then it jumps almost instantaneously to full boost and holds that boost up until redline. From the way I understand it, a turbo reaches full boost sooner and holds it longer than a supercharger.
Now... what I'd like to know from the experts is if I'm in the right track in my thinking or if I'm way out in left field.
I'm by far a neophyte with FI, but my basic understanding is that a supercharger's boost is in direct relation to the rpm of the engine and that it pretty much starts building some kind of pressure (not necessarily positive boost) from idle and up. With a turbo, it stays out of boost until a certain rpm/load condition and then it jumps almost instantaneously to full boost and holds that boost up until redline. From the way I understand it, a turbo reaches full boost sooner and holds it longer than a supercharger.Now... what I'd like to know from the experts is if I'm in the right track in my thinking or if I'm way out in left field.
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Re: Turbo vs. Supercharger... Garret you're pretty close to right on the money. SC's introduce a parasitic draw on the engine and actually draws horsepower to actually spin the unit itself. Not bad in most cases, but the fastest top fuel cars, the blower actually requires more horsepower than most cars are making to actually sping the blower. 400-450hp just to spin those huge *** roots style blowers. Turbo's are spun from from gasses from the exhaust manifold. Someone that has more experience, correct me if I'm wrong, are intercoolers more ideal for a turbo application based on where the air is drawn from to spin the impeller, wouldn't a turbo benefit more because the insanely hot gasses are used to spin it instead of a SC driven off a belt?
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Re: Turbo vs. Supercharger...
Garret you're pretty close to right on the money. SC's introduce a parasitic draw on the engine and actually draws horsepower to actually spin the unit itself. Not bad in most cases, but the fastest top fuel cars, the blower actually requires more horsepower than most cars are making to actually sping the blower. 400-450hp just to spin those huge *** roots style blowers. Turbo's are spun from from gasses from the exhaust manifold. Someone that has more experience, correct me if I'm wrong, are intercoolers more ideal for a turbo application based on where the air is drawn from to spin the impeller, wouldn't a turbo benefit more because the insanely hot gasses are used to spin it instead of a SC driven off a belt?
The exhaust heat in a turbo is on the turbine side of the unit, not on the compressor side. The air still gets heated because of compression, but the heat bleeding from the exhaust side is pretty minimal (I think).
The discussion is interesting. I think it boils down to the fact that in theory a turbo can be much better. But in reality, the turbo is a much more complicated system to design and tune correctly. People often say that a turbo is free HP, but I really think that is BS. Nothing is free, especially if it is not balanced just right. Back pressure in the exhaust and spooling requirements is the downside of a turbo, but if the design is correct and the system is well balanced, it works great and produces gobs of power.
So to answer the question, I think the turbo would be faster, but only if the system was really well designed and tuned. The centrifugal superchargers are butt simple compared to a turbo and often produce more power on the ls1s because of the simplicity.
Re: Turbo vs. Supercharger... Yeah I know its important in both, I was just curious if a turbo benefited more than an SC setup because of how the impeller is actually spun, seeing as hot air is getting in there SOMEWHERE, I figured it would bleed into the compressor side of the unit regardless, but who knows. Still learning this stuff myself
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Re: Turbo vs. Supercharger... The hot gases from the turbine (exhaust side) of a turbo do not get in the compressor (air intake side) of the turbo. The heat is strictly (well you do get some heat transfer) Both superchargers and turbocharger create heat to compress the air, no way around that. The design of the compressor, amount of air, efficiency all play into this. This is why you need to a heat exchanger (whatever you call it intercooler,aftercooler it is still getting rid of heat).
Gary
Gary
Re: Turbo vs. Supercharger... I think that the centrifrugal superchargers also neeed speeed shifting to hold boost too so I don't see shifting style as the deciding factor on what's faster.
Turbo systems on paper look faster but extreme turbo setups have issues just like extreme blower setups.
Turbo systems on paper look faster but extreme turbo setups have issues just like extreme blower setups.
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Re: Turbo vs. Supercharger... Why do the centrifugal supercharges also need speed shifting? Is it because of the parasitic drag on the crank? What I mean is, would that wind up slowing the engine down so fast that you would be out of your power range by the time you get into the next gear? 
By the same token, does anyone know WHY a turbo needs load to produce boost? I would think that an engine turning at a specific rpm, would produce boost regardless of whether or not a load is placed on the vehicle through the drivetrain. I mean, would you not still have the same amount and speed of exhaust gasses passing through the turbine for any given rpm?
By the same token, does anyone know WHY a turbo needs load to produce boost? I would think that an engine turning at a specific rpm, would produce boost regardless of whether or not a load is placed on the vehicle through the drivetrain. I mean, would you not still have the same amount and speed of exhaust gasses passing through the turbine for any given rpm?
Re: Turbo vs. Supercharger...
I think that the centrifrugal superchargers also neeed speeed shifting to hold boost too so I don't see shifting style as the deciding factor on what's faster.
Turbos cars do benefit from fast shifting... that's why autos and turbos mesh so well (besides the fact that you can stall them up at the line and make boost) but since the engine is always under load during a pass... the boost should rise upon launching and never drop from it's predetermined point with an auto at WOT
By the same token, does anyone know WHY a turbo needs load to produce boost? I would think that an engine turning at a specific rpm, would produce boost regardless of whether or not a load is placed on the vehicle through the drivetrain. I mean, would you not still have the same amount and speed of exhaust gasses passing through the turbine for any given rpm?
turbos work off of exhaust heat/pressure... which is created by cylinder pressure.
Think about it this way.. with your car in neutral... you can easily rev it to redline by only cracking the throttle blade right? Well you are only taking in a little air to get to that point.. well little air only requires little fuel and when exploded, only makes little cylinder pressure... so nothing to accelerate the turbo. It's always spinning.. just not enough to really do anything.
A two-step creates cylinder pressure in half the cylinders at a time by alternating the firing code. So now your throttle is all the way to the floor... and the cylinders that are firing are taking in more air and making more cylinder pressure than they would free reving with all the cylinders helping.
So the result is you build boost... how much depends on the set-up/limit rpm's etc... but you will never make full boost.
Since a blower moves the same amount of air at 5,000rpm's under load as free revving... well you get instant full boost.
A two-step does wonders on a manual turbo car.. there was a mustang guy(twofast) with a '95 GT and Incon's... he went from 11.4's to 10.8's on the same day by just launching off the two-step.
oh... this cylinder pressure theory is the same reason it is bad to free rev an engine to redline... because there is little cylinder pressure there which helps slow the piston down before it goes back down.... if that makes sense.
Ok.. Harlan and others... correct me if i muffed something up.
Thanks,
-Jarrod
Think about it this way.. with your car in neutral... you can easily rev it to redline by only cracking the throttle blade right? Well you are only taking in a little air to get to that point.. well little air only requires little fuel and when exploded, only makes little cylinder pressure... so nothing to accelerate the turbo. It's always spinning.. just not enough to really do anything.
A two-step creates cylinder pressure in half the cylinders at a time by alternating the firing code. So now your throttle is all the way to the floor... and the cylinders that are firing are taking in more air and making more cylinder pressure than they would free reving with all the cylinders helping.
So the result is you build boost... how much depends on the set-up/limit rpm's etc... but you will never make full boost.
Since a blower moves the same amount of air at 5,000rpm's under load as free revving... well you get instant full boost.
A two-step does wonders on a manual turbo car.. there was a mustang guy(twofast) with a '95 GT and Incon's... he went from 11.4's to 10.8's on the same day by just launching off the two-step.
oh... this cylinder pressure theory is the same reason it is bad to free rev an engine to redline... because there is little cylinder pressure there which helps slow the piston down before it goes back down.... if that makes sense.
Ok.. Harlan and others... correct me if i muffed something up.
Thanks,
-Jarrod
Re: Turbo vs. Supercharger...
In both cases you don't want to fall out of boost.
I was cutting 1.57's-1.60's on my mustang with stock suspension and the blower but only running low 12's at 114-115 mph... but with the turbo and same boost/engine... because i was bogging off the line, my 60's suffered... best was mid to low 1.8's but i was making alot more power/torque...and running 11's at 121-123mph.
Re: Turbo vs. Supercharger... I'm not sure I agree.
From what I saw with a buddy's 96 LT1 M6 with a Vortech, speed shifting took the car from 113 to 118mph (a few years ago). I think blown setups needs speedshifting too.
From what I saw with a buddy's 96 LT1 M6 with a Vortech, speed shifting took the car from 113 to 118mph (a few years ago). I think blown setups needs speedshifting too.
Re: Turbo vs. Supercharger... the gain was from actually speedshifting... just like any N/A car would do. Watch Jason99T/A drive... that's how you do it.
I didn't mean to imply that speedshifting didn't help.... it helps with every form of set-up... just meant that there is no benefit with respect to holding boost on a belt driven blower. They are rpm dependant all the time.
I didn't mean to imply that speedshifting didn't help.... it helps with every form of set-up... just meant that there is no benefit with respect to holding boost on a belt driven blower. They are rpm dependant all the time.