Does Twin Charging Actually Work?
05-13-2007, 02:12 PM
#62
1.0 BAR
Join Date: Dec 2005
Posts: 397
Re: Does Twin Charging Actually Work?
Update.
I ended up using a GT30r equivilent turbo feeding the m62 blower. At 2500 rpm in 4th, if I press the go pedal, I get 8 psi. By 3500 rpm, I get 25-30 psi, depending upon the current tune. It works great. However I do need to get a bypass setup so that I can bypass the SC once I hit whatever boost I want the SC to turn off at.... But even with the parasitic loss of the SC, there is no noticable loss of power all the way to 6500. I am making about 330 whp/400 torque.
I ended up using a GT30r equivilent turbo feeding the m62 blower. At 2500 rpm in 4th, if I press the go pedal, I get 8 psi. By 3500 rpm, I get 25-30 psi, depending upon the current tune. It works great. However I do need to get a bypass setup so that I can bypass the SC once I hit whatever boost I want the SC to turn off at.... But even with the parasitic loss of the SC, there is no noticable loss of power all the way to 6500. I am making about 330 whp/400 torque.
05-13-2007, 07:26 PM
#63
3.0 BAR
Join Date: Jun 2005
Posts: 2,753
Re: Does Twin Charging Actually Work?
thank you for posting the magazine article. as soon as i saw this and started reading i knew i had that issue somewhere. Its not 8+11=19 like everybody was saying. its multiplied, so smaller amount of boost = bigger horsepower, but much more fuel and ignition the with regular amounts of boost.
05-16-2007, 01:49 PM
#64
0.0 BAR
Join Date: Nov 2006
Posts: 0
Re: Does Twin Charging Actually Work?
hmmm we are still talking about twin-charging right?
Well the setup neccessitated for an effiecient twin charging system is pretty complex for no reason. Being that you have to calculate the flow of the engine+supercharger for your compressor size (which is actually a smaller volume of air) working it out to a smaller compressor to keep it efficient. I have an idea, I actually did my senior exhibition on it, that would use a CVT pulley system to drive a supercharger at the correct speeds at any rpm. A centrifugal unit would have to be used because the roots types run out of a specific efficiency range at a set rpm, just because of the inherent design of the screws. I would love to see someone hmt my idea, it's pretty easy if you want to just figure it out, otherwise I have the patent on it so just ask if you want to see my design.
Well the setup neccessitated for an effiecient twin charging system is pretty complex for no reason. Being that you have to calculate the flow of the engine+supercharger for your compressor size (which is actually a smaller volume of air) working it out to a smaller compressor to keep it efficient. I have an idea, I actually did my senior exhibition on it, that would use a CVT pulley system to drive a supercharger at the correct speeds at any rpm. A centrifugal unit would have to be used because the roots types run out of a specific efficiency range at a set rpm, just because of the inherent design of the screws. I would love to see someone hmt my idea, it's pretty easy if you want to just figure it out, otherwise I have the patent on it so just ask if you want to see my design.
05-17-2007, 03:00 AM
#66
1.5 BAR
Join Date: Mar 2005
Posts: 723
Re: Does Twin Charging Actually Work?
The reason CVT's havent' been used in cars is mainly because they aren't stout like actual gears, meaning you can't put one in a V8 land yacht. The problem you'd face with a CVT and a ceptrifugal SC would be the speeds - using a direct drive would have to spin it at the speeds the comp wheel has to spin at, which is around 100k rpm even on a large wheel. I'm too tired to do any hard thinking on why you'd want to do that, and if it could even work. You'd have to run the comp wheel beyond the surge limit. If it can't flow enough into the motor (due to low engine speed), it can't produce a certain psi w/o surging. Surging is air moving backwards through the comp wheel, meaning you'd have to spin it incredibly fast to hold that psi in there at such low flow. Kinda the chicken & the egg.
I don't knwo why this was so hard for people to grasp last year. You can either have sequential or parallel dual-charging. Sequential is where you run the SC, then bypass it with the turbo after its making more boost than the SC. Parallel is like reddevil's car, where the turbo pushes air into the SC, which compresses it again. The problem with the latter is that at higher rpm's, you get the heat (inefficiency) of the SC to deal with on top of the turbo, and that post-sc air isn't easy to cool if its a honda (very little space by now). Sequential is done with a roots-style SC and a big turbo. THe SC produces boost, then you have a valve that bypasses it at a certain psi. Until that psi, the turbo has to work up to possitive pressure, feeding it to the SC. Once bypassed, the SC is basicly like a fan made of tumblers - very little parasitic drag (very low load), as its just moving already pressurized air from its inlet to the manifold. I should note that the TB can be put between the SC and turbo, or SC and head. With the TB after the SC, you can have a better intake manifold in most cases.
Now thats an easier way to do it, like it can be done in compact spaces with a JRSC setup. Other seups are tricky. SC to turbo would need gradual weening off the SC-fed air to the turbo. Turbo and SC feeding the TB seperately would be a pain, as you'd be dealing with a one-way/diverter valve on both that would have to both interchange states instantaniously in tandom. I prefer the turbo to sc sequential setup, as it will opperate as a slightly restricted SC setup during low boost, then a normal turbo setup on high boost.
I don't knwo why this was so hard for people to grasp last year. You can either have sequential or parallel dual-charging. Sequential is where you run the SC, then bypass it with the turbo after its making more boost than the SC. Parallel is like reddevil's car, where the turbo pushes air into the SC, which compresses it again. The problem with the latter is that at higher rpm's, you get the heat (inefficiency) of the SC to deal with on top of the turbo, and that post-sc air isn't easy to cool if its a honda (very little space by now). Sequential is done with a roots-style SC and a big turbo. THe SC produces boost, then you have a valve that bypasses it at a certain psi. Until that psi, the turbo has to work up to possitive pressure, feeding it to the SC. Once bypassed, the SC is basicly like a fan made of tumblers - very little parasitic drag (very low load), as its just moving already pressurized air from its inlet to the manifold. I should note that the TB can be put between the SC and turbo, or SC and head. With the TB after the SC, you can have a better intake manifold in most cases.
Now thats an easier way to do it, like it can be done in compact spaces with a JRSC setup. Other seups are tricky. SC to turbo would need gradual weening off the SC-fed air to the turbo. Turbo and SC feeding the TB seperately would be a pain, as you'd be dealing with a one-way/diverter valve on both that would have to both interchange states instantaniously in tandom. I prefer the turbo to sc sequential setup, as it will opperate as a slightly restricted SC setup during low boost, then a normal turbo setup on high boost.
05-17-2007, 11:24 PM
#68
0.0 BAR
Join Date: Nov 2006
Posts: 0
Re: Does Twin Charging Actually Work?
Well you'd have to make the pulleys, our design used a computer controlled mill to machine aluminum billets that we set permanant magnets in, using electromagnets operating on opposite polarities to maintain synchronicity between the pulleys, and we stole the idea from the anderson CVT unit to handle to torque (the floating sprocket bars). We only got it up to like 30000 rpm with our little motor tho.
But it's all good.
But it's all good.
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