Building an Electric supercharger
03-23-2013, 05:21 PM
#16
Instructor
Thread Starter
Lots of stuff to respond to, here goes.
I am okay with more torque seeing how Horsepower is in relation to torque and rpm. I want a low end seeing how this is a daily driver most of the time. I would like a nice flat power band to 5500 rpm. Also flat power bands tend to be quicker than peaky ones like say Honda engines are.
I have came up with a way (still need to test it) to have a y pipe in the intake that will allow free flow when the ESC is not on due to a valve opening and closing. So that solves the drag on the intake problem.
Thanks for the info! the amount of amps sounds pretty close to what my math is telling for a 42v system. However sometimes real world testing doesn't work the same as our math calculations. That is what tinkering is for!
I have a plan for the batteries to last. Because rechargeable batteries are fine to discharge quickly and recharge if they are within around 15% to 85% so keeping their energy levels within that would mean better life for them than charging them to 100% or draining down to 0%
I am not doing this for ease or what people already know what works, otherwise I would not have did an electric water pump. I am doing this for fun. 5 psi is a lot when your compression rato is bumped over 10.6:1 Lastly for what I am spending on this project it costs less than a cam for these engines. I already have the batteries I got for free and the charger I plan to make from easy to access parts.
In order to make things work better or more efficient people have to go out and try things. To be honest I am tired of waiting for other people to make things happen. I don't mind when things fail or do not work because I learn how not to do it the second time around. To be honest my goal is to try things others won't, I am not looking for power just the fun factor of saying I made that with my own hands and it works. Or I can say I tried it without breaking the bank.
To be different. Constant things said when wanting more power from a NA 944, Sell it and buy a turbo, put a supercharger on it, use nitrous. Which how all those items work is great, I just like to be different. Also I like to make things and I see this as a fun project I can do off the car until I am ready to test it. So I can still enjoy my car and keep it very easy to smog in California with a simple intake change.
Turbo's can be pricey, and then if I turbo the car I won't have the other stuff the stock turbo cars came with. I am looking for a bump in low end without dramatically increasing weight or drag on the engine. A supercharger takes some power from the engine to spin it when in boost. A turbo creates back pressure through the turbines exhaust. I would love something that doesn't create drag or increase back pressure.
There will be a switch to toggle for the battery pack to connect to my alternator to charge. So when I want to boost I just flip the switch and then their will not be any extra draw of current to make the alternator work harder. Then while I am on the free way flip the switch and charge. Again that is just at first later I would like to create other areas to charge the battery using the airflow around the car and through the exhaust without creating the back pressure like a turbo does.
Also the battery pack I am using does not weigh more than 100 pounds. It is a little unconventional but they are not car batteries. I am using rechargeable AA batteries. So discharge and recharge should not take long. Again I am thinking out of the box. Yes I now you need a lot of them, I just so happen to have a couple buckets filled with them (5 gallon)
if the supercharger is one speed, you'll get more boost at lower rpm then higher rpm so really you'll get more torque increase then hp.
the battery weight.. will that be more in weight then power? as in power to weight. good idea but i see flaws. if your added power and added weight is 1:1 well you didn't really get far. good luck thouh
the battery weight.. will that be more in weight then power? as in power to weight. good idea but i see flaws. if your added power and added weight is 1:1 well you didn't really get far. good luck thouh
The existing proven solution on the market is essentially a starter motor connected to the cold side of a turbo. It's a simple solution that gives a significant boost to low end power/torque.
Probably a good starting point for the build.
Be aware that the downside to this style of build is it creates a drag on the intake pressures when the starter motor is not engaged.
An easy way around this problem is an A/C Clutch.
Probably a good starting point for the build.
Be aware that the downside to this style of build is it creates a drag on the intake pressures when the starter motor is not engaged.
An easy way around this problem is an A/C Clutch.
Cool project!
Just to let you know, though: Any supercharger takes about 1/4 to 1/3 of the horsepower it liberates to drive. So if you want 50 hp increase, you will need an electric motor of 12-15hp. Basic rule of thumb.
15hp motor driven from 13.6V draws about 800-1000 amps. Or from 42V, say 300A. So for your application, you could expect to see a power increase of 1hp for every 6A your supercharger motor draws.
Cheers,
Mike
Just to let you know, though: Any supercharger takes about 1/4 to 1/3 of the horsepower it liberates to drive. So if you want 50 hp increase, you will need an electric motor of 12-15hp. Basic rule of thumb.
15hp motor driven from 13.6V draws about 800-1000 amps. Or from 42V, say 300A. So for your application, you could expect to see a power increase of 1hp for every 6A your supercharger motor draws.
Cheers,
Mike
Forget about it
Batteries wont last more than one run, they will weigh more than they can produce, the compressor will create alot of drag when not in use. 5 psi is ****....at least for the trouble you're getting yourself into.
Do you want a minor power/tq increase for small amounts of money? get a hotter cam and move on.
Batteries wont last more than one run, they will weigh more than they can produce, the compressor will create alot of drag when not in use. 5 psi is ****....at least for the trouble you're getting yourself into.
Do you want a minor power/tq increase for small amounts of money? get a hotter cam and move on.
I have a plan for the batteries to last. Because rechargeable batteries are fine to discharge quickly and recharge if they are within around 15% to 85% so keeping their energy levels within that would mean better life for them than charging them to 100% or draining down to 0% I am not doing this for ease or what people already know what works, otherwise I would not have did an electric water pump. I am doing this for fun. 5 psi is a lot when your compression rato is bumped over 10.6:1 Lastly for what I am spending on this project it costs less than a cam for these engines. I already have the batteries I got for free and the charger I plan to make from easy to access parts.
I think it could work, but would be a lot of work to make it work well. My approach would be a light weight battery pack as used on electric racebikes (there's a series for that now) and some efficient electric motor (maybe one from a smaller ebike). Then the question is charging the battery bank. The alternator will not come close to keeping up with the current draw for hard track driving. It might let you take off quickly a couple of times on a longer street drive. An exhaust turbine driven generator combined with regenerative braking could work out nicely. A turbo would probably work better, be cheaper and involve much less engineering.
There will be a switch to toggle for the battery pack to connect to my alternator to charge. So when I want to boost I just flip the switch and then their will not be any extra draw of current to make the alternator work harder. Then while I am on the free way flip the switch and charge. Again that is just at first later I would like to create other areas to charge the battery using the airflow around the car and through the exhaust without creating the back pressure like a turbo does.
Also the battery pack I am using does not weigh more than 100 pounds. It is a little unconventional but they are not car batteries. I am using rechargeable AA batteries. So discharge and recharge should not take long. Again I am thinking out of the box. Yes I now you need a lot of them, I just so happen to have a couple buckets filled with them (5 gallon)
03-24-2013, 06:47 PM
#17
Three Wheelin'
Mitsubishi have been developing electric superchargers, based on their electric torpedo drives (!)
http://www.mhi.co.jp/technology/revi...74/e474007.pdf
Cheers,
Mike
http://www.mhi.co.jp/technology/revi...74/e474007.pdf
Cheers,
Mike
03-24-2013, 09:51 PM
#18
You could use some Pullies and belts and connect it to the rear axel, hook a second altinator to those belts and as long as the cars rolling your charging, You could even change your pullie sizes and get that thing really spinning.
03-25-2013, 01:59 AM
#19
Instructor
Thread Starter
I really appreciate all the positive feedback and helpful resources posted
So from some research I have been doing I discovered a formula and thought I would share this. It relates to Alternators and the horsepower draw from their loads. Because there is usually a thought that the alternator robs a bunch of power when recharging the batteries.
Amps x Volts = Watts
Watts / 745.7 (one HP) = Electrical HP Produced by the Alternator
HP x 15% Efficiency Loss = HP Loss
HP + HP Loss = Total HP Used
Example: (Max load for early 944 alternators)
90A x 14.9V = 1341 Watts
1341 Watts / 745.7 = 1.798 HP
1.798 HP x 15% = 0.269 HP
1.798 + 0.269 = 2.067 HP Total
So at max load the Alternator is only robbing the engine of 2.067 horsepower.
So from some research I have been doing I discovered a formula and thought I would share this. It relates to Alternators and the horsepower draw from their loads. Because there is usually a thought that the alternator robs a bunch of power when recharging the batteries.
Amps x Volts = Watts
Watts / 745.7 (one HP) = Electrical HP Produced by the Alternator
HP x 15% Efficiency Loss = HP Loss
HP + HP Loss = Total HP Used
Example: (Max load for early 944 alternators)
90A x 14.9V = 1341 Watts
1341 Watts / 745.7 = 1.798 HP
1.798 HP x 15% = 0.269 HP
1.798 + 0.269 = 2.067 HP Total
So at max load the Alternator is only robbing the engine of 2.067 horsepower.
03-25-2013, 03:35 AM
#20
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i'm sure it can be done. you'll be adding serious weight in the form of....
1. larger batterie/s which will supply on the order of 94~98% of the power required (short bursts).
surely, this situation could be helped by running several lithium racing batteries in parallel.
2. huge, oversized alternator.
3. considerably potent electric motor and pump (adding further weight and complexity to the bay).
2. bypass to run an alternating open/closed intake.
3. electronic management system to control the electric motor and bypass valve (best of luck).
it will be a part time system requiring over 10,000~12,000 watts (or more) just to accomplish short 2~3 psi bursts with increasing, huge parasitic losses as the motor get hot *(real world), and i'm sure all could be made to work at a cost to you of less than $30,000~40,000 dollars.
*amazing then, that the automobile companies still don't have temporary power assist systems for production cars. if only the reasons weren't so obvious; primarily costs of additional compenents, increased weight leading to poor overall fuel economy, and huge parasitic losses (the same that you will soon encounter if you take this down the road to something even close to a workable model)...... all for very minimal gains.....
what you might see in the future is a bank of stored power to run an electric traction motor to facilitate a bump of 100hp or more in short duration bursts.... but we're already close (i'm sure i'm not even up to date).... but ostensibly, as the battery technology moves forward, it's likely we'll see power on demand in an economy production car.
1. larger batterie/s which will supply on the order of 94~98% of the power required (short bursts).
surely, this situation could be helped by running several lithium racing batteries in parallel.
2. huge, oversized alternator.
3. considerably potent electric motor and pump (adding further weight and complexity to the bay).
2. bypass to run an alternating open/closed intake.
3. electronic management system to control the electric motor and bypass valve (best of luck).
it will be a part time system requiring over 10,000~12,000 watts (or more) just to accomplish short 2~3 psi bursts with increasing, huge parasitic losses as the motor get hot *(real world), and i'm sure all could be made to work at a cost to you of less than $30,000~40,000 dollars.
*amazing then, that the automobile companies still don't have temporary power assist systems for production cars. if only the reasons weren't so obvious; primarily costs of additional compenents, increased weight leading to poor overall fuel economy, and huge parasitic losses (the same that you will soon encounter if you take this down the road to something even close to a workable model)...... all for very minimal gains.....
what you might see in the future is a bank of stored power to run an electric traction motor to facilitate a bump of 100hp or more in short duration bursts.... but we're already close (i'm sure i'm not even up to date).... but ostensibly, as the battery technology moves forward, it's likely we'll see power on demand in an economy production car.
03-25-2013, 04:11 PM
#21
Instructor
Thread Starter
So I made my battery pack of the AA batteries and wanted to test it out. The result was they were great in discharge but take way too long to recharge. So I am going to have to buy batteries.
The new plan is to use Battcap Batteries (made for sound systems) 2 of them that weigh 14 pounds each. They will be taking the place of the rear seats so the weight comes out even there.
The alternator is going to stay the same size. Ideally I would upgrade it to Ideola's 150amp version, weight gain or loss is negligible.
The bypass is something I do not want to give away but the intake piping weighs just a tad more than the stock intake box. When the AFM is replaced with Rouge's MAF the weight will be even.
The Management system will consist of a trigger switch and a handful of relays, also the wiring needed to support the voltage. Yes all this has weight, however if I delete the factor sound deadening then I should come out weighing less.
As for location of the charger itself I can not say quite yet until after I have made the housing. I would like to have it under the header panel in front of the radiator so it can be air cooled properly and not take all the space in the engine bay.
I also believe car manufactures are only worried about meeting the minimum of their mpg ratings and making the best profit ever. Because we have the technology to make affordable 100 mpg cars but those darn oil companies. So the whole thing might add 100 pounds max. There are ways to take 100 pounds from our cars easy to compensate for the gain. And yes I will be spending less than $30,000 about 98% less if not even that. (not including a maf will get one after to see the gains on the stock afm)
i'm sure it can be done. you'll be adding serious weight in the form of....
1. larger batterie/s which will supply on the order of 94~98% of the power required (short bursts).
surely, this situation could be helped by running several lithium racing batteries in parallel.
2. huge, oversized alternator.
3. considerably potent electric motor and pump (adding further weight and complexity to the bay).
2. bypass to run an alternating open/closed intake.
3. electronic management system to control the electric motor and bypass valve (best of luck).
it will be a part time system requiring over 10,000~12,000 watts (or more) just to accomplish short 2~3 psi bursts with increasing, huge parasitic losses as the motor get hot *(real world), and i'm sure all could be made to work at a cost to you of less than $30,000~40,000 dollars.
*amazing then, that the automobile companies still don't have temporary power assist systems for production cars. if only the reasons weren't so obvious; primarily costs of additional components, increased weight leading to poor overall fuel economy, and huge parasitic losses (the same that you will soon encounter if you take this down the road to something even close to a workable model)...... all for very minimal gains.....
what you might see in the future is a bank of stored power to run an electric traction motor to facilitate a bump of 100hp or more in short duration bursts.... but we're already close (i'm sure i'm not even up to date).... but ostensibly, as the battery technology moves forward, it's likely we'll see power on demand in an economy production car.
1. larger batterie/s which will supply on the order of 94~98% of the power required (short bursts).
surely, this situation could be helped by running several lithium racing batteries in parallel.
2. huge, oversized alternator.
3. considerably potent electric motor and pump (adding further weight and complexity to the bay).
2. bypass to run an alternating open/closed intake.
3. electronic management system to control the electric motor and bypass valve (best of luck).
it will be a part time system requiring over 10,000~12,000 watts (or more) just to accomplish short 2~3 psi bursts with increasing, huge parasitic losses as the motor get hot *(real world), and i'm sure all could be made to work at a cost to you of less than $30,000~40,000 dollars.
*amazing then, that the automobile companies still don't have temporary power assist systems for production cars. if only the reasons weren't so obvious; primarily costs of additional components, increased weight leading to poor overall fuel economy, and huge parasitic losses (the same that you will soon encounter if you take this down the road to something even close to a workable model)...... all for very minimal gains.....
what you might see in the future is a bank of stored power to run an electric traction motor to facilitate a bump of 100hp or more in short duration bursts.... but we're already close (i'm sure i'm not even up to date).... but ostensibly, as the battery technology moves forward, it's likely we'll see power on demand in an economy production car.
The alternator is going to stay the same size. Ideally I would upgrade it to Ideola's 150amp version, weight gain or loss is negligible.
The bypass is something I do not want to give away but the intake piping weighs just a tad more than the stock intake box. When the AFM is replaced with Rouge's MAF the weight will be even.
The Management system will consist of a trigger switch and a handful of relays, also the wiring needed to support the voltage. Yes all this has weight, however if I delete the factor sound deadening then I should come out weighing less.
As for location of the charger itself I can not say quite yet until after I have made the housing. I would like to have it under the header panel in front of the radiator so it can be air cooled properly and not take all the space in the engine bay.
I also believe car manufactures are only worried about meeting the minimum of their mpg ratings and making the best profit ever. Because we have the technology to make affordable 100 mpg cars but those darn oil companies. So the whole thing might add 100 pounds max. There are ways to take 100 pounds from our cars easy to compensate for the gain. And yes I will be spending less than $30,000 about 98% less if not even that. (not including a maf will get one after to see the gains on the stock afm)
03-25-2013, 04:28 PM
#22
03-25-2013, 07:58 PM
#26
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I've occasionally taken a look at GM's Belted Alternator Starter (BAS / eAssist) setups...
Basically, instead of a normal alternator, the unit can act as either an alternator or electric motor. The first gen version (BAS) was pretty weak, adding only a few HP, and ~20lb·ft of torque.
The second gen (eAssist) is about 4 times as powerful, adding ~15hp, and ~80lb·ft torque:
The battery pack / control adds 65lbs. So, weight increase isn't horrible. I'm sure the Alternator/Motor weighs more then a standard alternator.
If I could pick-up one for cheap, I would find a way to graft it onto my 944NA... Though I do wonder how integrated the system is with the standard engine management. It might be a bit of work to reverse-engineer the control system.
03-27-2013, 11:51 PM
#29
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I honestly think you're wasting your time. with the electric supercharger. all you'll gain is a few hp with all the extra weight. you could really just bolt on a turbo from a 951. all the parts are there. you can do with out a few things like the turbo accessory water pump.. but it'll be more reliable thing the electric charger you're trying to do.
You can probably gain more power if you get the NA-Tune (rogue tuning) a camshaft degree off-set key & a 951 cat back.
You can probably gain more power if you get the NA-Tune (rogue tuning) a camshaft degree off-set key & a 951 cat back.
04-12-2013, 01:47 AM
#30
Rennlist Member
For what it's worth, there's an ongoing piece of research into these devices at the moment:
http://www.wildweasel.ca/HowTo/Auto/eturboTest.aspx
Makes for interesting reading.
http://www.wildweasel.ca/HowTo/Auto/eturboTest.aspx
Makes for interesting reading.