eRAM electric supercharger
03-08-2004, 06:51 AM
#17
Race Director
It's a basic energy conversion equation here. Assuming 100% efficiency in converting electricity to mechanical power, then that mechanical power into boost and that extra boost into chemical enegy, and that chemical energy back into mechanical power again.
Assuming all of these steps are 100% efficient, let's start by going forwards and converting that 57-amps of current draw as the initial energy we add to the system:
57amps * 13volts = 751 watts
751 watts * (1hp/745.7watts) = 1.007 HP
So this fan is adding 1.007hp to the system assuming that its 57amp draw makes it to the ground with 100% conversion efficiency in between.
Let's work backwards from the claimed 4% power increase to see what the input would need to be at the beginning.
4% * 217bhp = 8.68 hp
8.68hp * (745.7watts/hp) = 6472 watts
6472watts / 13volt = 498 amps
So to generate a 4% increase in power with 100% conversion efficiency, we'd need to draw 498 amps not the claimed 57amps... Something doesn't match here...
I'll let someone else compute the size of wire necessary to carry 498 amps from the 4 alternators you'd need to be running at 100%. And somehow, I'd think that 4 alternators working at 100% capacity would probably cause more drag than the 8.68hp that would be generated by the electric supercharger...
Assuming all of these steps are 100% efficient, let's start by going forwards and converting that 57-amps of current draw as the initial energy we add to the system:
57amps * 13volts = 751 watts
751 watts * (1hp/745.7watts) = 1.007 HP
So this fan is adding 1.007hp to the system assuming that its 57amp draw makes it to the ground with 100% conversion efficiency in between.
Let's work backwards from the claimed 4% power increase to see what the input would need to be at the beginning.
4% * 217bhp = 8.68 hp
8.68hp * (745.7watts/hp) = 6472 watts
6472watts / 13volt = 498 amps
So to generate a 4% increase in power with 100% conversion efficiency, we'd need to draw 498 amps not the claimed 57amps... Something doesn't match here...
I'll let someone else compute the size of wire necessary to carry 498 amps from the 4 alternators you'd need to be running at 100%. And somehow, I'd think that 4 alternators working at 100% capacity would probably cause more drag than the 8.68hp that would be generated by the electric supercharger...
03-08-2004, 12:37 PM
#19
Drive-by provocation guy
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"But what about using it to keep the turbo spooling at low speeds? who cares after that.I wonder if it could greatly reduce lag?"
That is why I posted it and was my line of thinking.
That is why I posted it and was my line of thinking.
03-08-2004, 02:13 PM
#20
It draws current from the battery, not the alternator.
The idea of it spooling the turbos seems interesting. I imagine this thing has its own lag issues, although at least it could be plumbed to work through a very short pipe.
It would take some genius to plumb it and wire it to fan a turbo impeller, but that would be a good way to also keep the turbo bearings moving and reduce heat soak. A little. I guess ...
The idea of it spooling the turbos seems interesting. I imagine this thing has its own lag issues, although at least it could be plumbed to work through a very short pipe.
It would take some genius to plumb it and wire it to fan a turbo impeller, but that would be a good way to also keep the turbo bearings moving and reduce heat soak. A little. I guess ...
03-08-2004, 02:46 PM
#21
I never notice, anyway
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theres also the fact that it can move air but CAN NOT COMPRESS AIR. our turbos could move a helluva lot more air if it wasnt being compressed. all the air would slip back out of this thing.
think of it this way: ram air inductions dont work because air is virtually incompressible until mach 0.5, or about 370 miles per hour. it take a LOT of force to really compress air. this thing isnt near powerful enough to do anything.
think of it this way: ram air inductions dont work because air is virtually incompressible until mach 0.5, or about 370 miles per hour. it take a LOT of force to really compress air. this thing isnt near powerful enough to do anything.
03-08-2004, 04:17 PM
#22
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Hey Danno, very good point, but I think your logic is lacking one important point.
I think you are ignoring the huge chemical energy inherent in fuel itself. You are correct in your assertion that this is a basic energy conversion, but what I think is incorrect is the assumption that the Energy needed to move "X" amount of air into the engine is equal to the energy that "X" amount of additional air would produce.
I think this equation is incorrect:
Energy to drive supercharger = Energy produced by supercharger
If this was true, then at 100% efficiency, the mechanical drag produced by a common belt driven supercharger would cancel out the energy it provided. We all know this is not the case. The key being the huge potential energy of fuel. The supercharger allows the engine to injest more air, and thereby add more fuel, and the chemical energy of the added fuel is much more than the energy required to drive the supercharger.
Very Basic stuff:
Obviously, we all know that when tuning cars, we try to combust the most amount of fuel possible, in order to release the most chemical energy stored in the fuel. Since combustion is a reaction that also requires oxygen, it only benefits us to inject fuel in the proper ratio (this case 14.7:1). In a perfect world, where there is perfect mixing of air and fuel, going past the stoichiometric ratio does not yield any more power. We are always after ways to get more oxygen into the cylinders, so we can combust more fuel. I am getting off on a tangent here, let me try to tie this back into my point:
Lets assume this little guy can make 1 psi of boost with a 57 amp draw (which, at low rpms, I think is possible). That 1 psi is responsible for "X" amount of air being moved into the cylinders (whatever "X" may be). Since we have "X" more air, we can add (X/14.7) amount more fuel. When you consider the huge chemical energy stored in even that small amount of fuel, I think its obvious that the enery released by (X/14.7) amount of fuel is much greater than the energy of the 57 Amp draw used to move the original "X" amount of air.
I hope I am making sense.
It's a basic energy conversion equation here. Assuming 100% efficiency in converting electricity to mechanical power, then that mechanical power into boost and that extra boost into chemical enegy, and that chemical energy back into mechanical power again.
I think this equation is incorrect:
Energy to drive supercharger = Energy produced by supercharger
If this was true, then at 100% efficiency, the mechanical drag produced by a common belt driven supercharger would cancel out the energy it provided. We all know this is not the case. The key being the huge potential energy of fuel. The supercharger allows the engine to injest more air, and thereby add more fuel, and the chemical energy of the added fuel is much more than the energy required to drive the supercharger.
Very Basic stuff:
Obviously, we all know that when tuning cars, we try to combust the most amount of fuel possible, in order to release the most chemical energy stored in the fuel. Since combustion is a reaction that also requires oxygen, it only benefits us to inject fuel in the proper ratio (this case 14.7:1). In a perfect world, where there is perfect mixing of air and fuel, going past the stoichiometric ratio does not yield any more power. We are always after ways to get more oxygen into the cylinders, so we can combust more fuel. I am getting off on a tangent here, let me try to tie this back into my point:
Lets assume this little guy can make 1 psi of boost with a 57 amp draw (which, at low rpms, I think is possible). That 1 psi is responsible for "X" amount of air being moved into the cylinders (whatever "X" may be). Since we have "X" more air, we can add (X/14.7) amount more fuel. When you consider the huge chemical energy stored in even that small amount of fuel, I think its obvious that the enery released by (X/14.7) amount of fuel is much greater than the energy of the 57 Amp draw used to move the original "X" amount of air.
I hope I am making sense.
03-08-2004, 05:09 PM
#25
Race Director
Awwwwwwww go on! It looks so sweet dude. You would score all the car hoes with that bolted on. I wonder if we could cut a hole in the bonet to mount this outside do draw in all that cold rushing air?
03-08-2004, 05:44 PM
#26
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they have 180 plus cfm bilge fans. I was just using a number and had no data in front of me at the time. The one I bought by the way is 240cfm. But its just a fan. It has a plastic fan blade. And yes its spools exremely fast, but your car will begin to attemp at some point to suck more air that that fan is capable of producing. I think it probably would break?
03-08-2004, 05:44 PM
#27
Race Director
I actually think this thing might have a greater impact on an NA car since they're more sensitive to the harmonic induction effects. Rather than having to use vacuum to such all the air in, if you can negate some of that vacuum in the intake, even just to atmospheric pressure (no boost needed), it would help. The real question here is not whether it works or not, we know that it does, but the issue is exactly how much of a benefit does it provide? I'll pony up $100 for dyno-time if anyone wants to try this.
03-08-2004, 06:13 PM
#28
Race Director
You the man Danno. I wonder if it would be a restriction on a turbo car once the turbo is spooled and the fan does not turn fast enough or acts like a big as air flow restrictor?
03-08-2004, 06:26 PM
#29
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Better do some research before you classify a 750+ watt axial flow compressor, with a "bildge pump" first of all, a bildge pump , pumps out water. what I think you are trying to say, is that is a boat engine bay vent fan. (we stopped these Kooks on ebay for patent infringement, and false advertising, and there were 1000s of them!!)
however , if you look close, its a 2amp 50 watt device that barely moves 200cfm and no pressure.
we are talking about a 1psi net change in intake pressure, or a 5% change in HP on the dyno.
check out the site, more details there.
by the way, if you have a 944 with an AFM, its a pretty good HP adder!
we got 10hp on a 84 3.2 liter porsche. not just one car, a few of them.
if you go to the 928 list, Ive listed the mods Ive done over the years and the costs. this falls pretty much in line with all the hp gains and costs Ive done . (175 rear wheel stock HP all the way to 290 rear wheel hp )
Mk
however , if you look close, its a 2amp 50 watt device that barely moves 200cfm and no pressure.
we are talking about a 1psi net change in intake pressure, or a 5% change in HP on the dyno.
check out the site, more details there.
by the way, if you have a 944 with an AFM, its a pretty good HP adder!
we got 10hp on a 84 3.2 liter porsche. not just one car, a few of them.
if you go to the 928 list, Ive listed the mods Ive done over the years and the costs. this falls pretty much in line with all the hp gains and costs Ive done . (175 rear wheel stock HP all the way to 290 rear wheel hp )
Mk
Originally posted by bdellis
Its a builge pump motor and not a very good one. Dont bother with it.
If you are seriously interested I in an electric supercharger I do think that some larger turbo diesel trucks use true low rpm electric superchargers. And yes I do think they work at low rpm's, but they are not cheap. That builge pump blows about 180 CFM or so. Its like a hair dryer....
Look up any marine web site and search for electric builge pump. I just put one in my boat last summer! 20$ and its exactly like that one>..
Its a builge pump motor and not a very good one. Dont bother with it.
If you are seriously interested I in an electric supercharger I do think that some larger turbo diesel trucks use true low rpm electric superchargers. And yes I do think they work at low rpm's, but they are not cheap. That builge pump blows about 180 CFM or so. Its like a hair dryer....
Look up any marine web site and search for electric builge pump. I just put one in my boat last summer! 20$ and its exactly like that one>..
03-08-2004, 06:33 PM
#30
Rennlist Member
Danno, please dont post equations if you dont fully understand what you are doing! you start out ok with the math, but then it falls apart trying to show that the eRAM is breaking one of the basic laws of physics, that of conservation of energy. However it is not, just as a mechanical supercharger driven by a belt requires say, 10hp to make 5psi, the gains could be in the 100hp range. 10:1 is quite commone. we are using the 750 watts to burn 5% more air and FUEL. that yeilds 5% gains.
what you are talking about is if we decieded to use the eRAM motors to drive pulleys and drive the engine or car itself! wow, what a concept, its called the hybrid!!!
mk
QUOTE]Originally posted by Danno
It's a basic energy conversion equation here. Assuming 100% efficiency in converting electricity to mechanical power, then that mechanical power into boost and that extra boost into chemical enegy, and that chemical energy back into mechanical power again.
Assuming all of these steps are 100% efficient, let's start by going forwards and converting that 57-amps of current draw as the initial energy we add to the system:
57amps * 13volts = 751 watts
751 watts * (1hp/745.7watts) = 1.007 HP
So this fan is adding 1.007hp to the system assuming that its 57amp draw makes it to the ground with 100% conversion efficiency in between.
Let's work backwards from the claimed 4% power increase to see what the input would need to be at the beginning.
4% * 217bhp = 8.68 hp
8.68hp * (745.7watts/hp) = 6472 watts
6472watts / 13volt = 498 amps
So to generate a 4% increase in power with 100% conversion efficiency, we'd need to draw 498 amps not the claimed 57amps... Something doesn't match here...
I'll let someone else compute the size of wire necessary to carry 498 amps from the 4 alternators you'd need to be running at 100%. And somehow, I'd think that 4 alternators working at 100% capacity would probably cause more drag than the 8.68hp that would be generated by the electric supercharger... [/QUOTE]
what you are talking about is if we decieded to use the eRAM motors to drive pulleys and drive the engine or car itself! wow, what a concept, its called the hybrid!!!
mk
QUOTE]Originally posted by Danno
It's a basic energy conversion equation here. Assuming 100% efficiency in converting electricity to mechanical power, then that mechanical power into boost and that extra boost into chemical enegy, and that chemical energy back into mechanical power again.
Assuming all of these steps are 100% efficient, let's start by going forwards and converting that 57-amps of current draw as the initial energy we add to the system:
57amps * 13volts = 751 watts
751 watts * (1hp/745.7watts) = 1.007 HP
So this fan is adding 1.007hp to the system assuming that its 57amp draw makes it to the ground with 100% conversion efficiency in between.
Let's work backwards from the claimed 4% power increase to see what the input would need to be at the beginning.
4% * 217bhp = 8.68 hp
8.68hp * (745.7watts/hp) = 6472 watts
6472watts / 13volt = 498 amps
So to generate a 4% increase in power with 100% conversion efficiency, we'd need to draw 498 amps not the claimed 57amps... Something doesn't match here...
I'll let someone else compute the size of wire necessary to carry 498 amps from the 4 alternators you'd need to be running at 100%. And somehow, I'd think that 4 alternators working at 100% capacity would probably cause more drag than the 8.68hp that would be generated by the electric supercharger... [/QUOTE]