Electric Superchargers on ebay, says FSAE use

[drivetrainUW-Platt]

http://cgi.ebay.com/ebaymotors/Electric-Supercharger-Tu...dZ1QQsspagenameZWDVW (http://cgi.ebay.com/ebaymotors/Electric-Supercharger-Turbo-Kit-Vortec-Blower-Greddy_W0QQcmdZViewItemQQcategoryZ33741QQitemZ8008 780498QQrdZ1QQsspagenameZWDVW)

more info please, I'm intrigued on how those worked out, look a little more serious then those hair dryer electric superchargers ppl sell for 50 bucks on ebay

[DRTorkay]

That is actually our listing for Cal Poly Pomona. We used it on our 2000 car and had some success with it. The system is a little heavy because we had to use a full size GM alternator to power it. From what the old team members tell me it was pretty easy to hook up.

[kozak]

hey DRTorkay since you seem to have some knowledge of charging fsae motors what boost do turboed fsae cars usually run. can you just get a regular car sized supercharger and run like 30psi to overcome the restriction. and i'm pissed some one beat me to the electric supercharger. i was thinking about it this year (unrelated)

[osubeaver]

..like 30psi to overcome the restriction


Haha that is funny..overcome the restriction.

[kovacs]

You can't just slap any old supercharger on it. Most Ford SVT superchargers (or most OEM applications) are way TOO big for a little 600 cc engine...and 30 pounds of boost....thats INSANE, that would destroy that little 600 cc engine. the SRT 4 runs a max of 25 pounds (with their stage 3 kit) and most supercharged applications (im talking big V8) run at most 10....and they are strong motors.

[kovacs]

no offense but electric superchargers are not the best idea.....

[K. Werkley]

Those are not just any superchargers, Turbodyne has alot of experience when it comes to boosting motorcycle engines.

[DRTorkay]

When they ran the supercharger on the car in 2000 they put out about 75 rwhp and it had a nice flat torque curve, and that is really what helped the corner exits in the car. I don't understand what you mean but running a large turbo to overcome the restrictor. The performance would just be horrible. You can only suck so much air through a 20mm restricor. The whole idea of the electric supercharger was the make the whole forced induction aspect more efficent by using less power to make the same amount of boost.

I was told that electric superchargers were origionally intended for engines puting out 110ish HP. They also could not run them 100% continuously. We wired in a throttle switch to turn it on and off at about 80% throttle.

[Marshall Grice]

a little more info about it. the supercharger flowed enough air to maxout the restrictor at any rpm. this equated to about 75whp(measured on our engine-to-chassis dyno adapter)all the time depending on alternator load. I think max boost was around 10psi at 5000rpm which is also about where our motor idled(due to poor idle maping). the trick was that for short burst(~5secs) you could disable the alternator to free up an additional ~10hp depending on rpm. all in all it was a blast to drive and good enough to take a 600lb car to the top in the accel event.

[Ché]

"We wired in a throttle switch to turn it on and off at about 80% throttle."

Isn't that drive by wire and throttling after the restrictor?

[kozak]

well here's what i am thinking. any given engine can only flow so much air, naturally. superchargers increase the incoming air pressure (Have to add more fuel also) to make the engine seem to be bigger than it is and overcome the natural restricion of the engine. on an fsae engine i've heard that the restrictor makes the engine seem like a 250cc. so in turn you are using aprox half the fuel of a regular 600cc. so increase the incoming amount of air (the only way to do that because of the restrictor is supercharging) normal teams use (guessing) 12 psi and 60% of regular 600cc fuel flow. so increase the incoming air pressure and increase the fuel until you get back to that normal non restricted 600cc engine fuel flow. i don;t think i explained that real well but would that work? again right now i'm just talking about the flow theory, lets not get into manufacturing drive systems and computer controllers for the supercharger.

[Marshall Grice]

Isn't that drive by wire and throttling after the restrictor?

no, it has nothing to do with the throttle body. you're simply turning the supercharger/alternator or or off.

[Bryan Hagenauer]

Forced induction does not change the amount of air coming through the restrictor. Once the restrictor is maxed out, there is nothing you can do about it.

What forced induction does is keep the restrictor maxed out at times when the motor wouldn't be doing that on its own, like low rpm or between intake strokes. You get a wider power band, not a taller one- for the most part.

[osubeaver]

Originally posted by kozak:
well here's what i am thinking. any given engine can only flow so much air, naturally. superchargers increase the incoming air pressure (Have to add more fuel also) to make the engine seem to be bigger than it is and overcome the natural restricion of the engine. on an fsae engine i've heard that the restrictor makes the engine seem like a 250cc. so in turn you are using aprox half the fuel of a regular 600cc. so increase the incoming amount of air (the only way to do that because of the restrictor is supercharging) normal teams use (guessing) 12 psi and 60% of regular 600cc fuel flow. so increase the incoming air pressure and increase the fuel until you get back to that normal non restricted 600cc engine fuel flow. i don;t think i explained that real well but would that work? again right now i'm just talking about the flow theory, lets not get into manufacturing drive systems and computer controllers for the supercharger.

It sounds like you are saying that with a supercharger, you could just cram in as much air through the restricter as would flow in an unrestriced motor. While this would be nice, it is not the case.

[Chris Davin]

I would be cautious about the rules implications of running an electric supercharger. The rules outlaw hybrid powertrains that store energy, although I am not sure about the exact wording. I would consider an electric supercharger system, where energy is stored up and then delivered to the compressor when the driver demands power, to violate the intent of this rule. If the alternator were driven directly off the crankshaft and powered the compressor through a separate circuit, with nowhere for energy to be stored (like a battery), I would imagine it would be OK.

[Chris Davin]

Originally posted by kozak:
well here's what i am thinking. any given engine can only flow so much air, naturally. superchargers increase the incoming air pressure (Have to add more fuel also) to make the engine seem to be bigger than it is and overcome the natural restricion of the engine. on an fsae engine i've heard that the restrictor makes the engine seem like a 250cc. so in turn you are using aprox half the fuel of a regular 600cc. so increase the incoming amount of air (the only way to do that because of the restrictor is supercharging) normal teams use (guessing) 12 psi and 60% of regular 600cc fuel flow. so increase the incoming air pressure and increase the fuel until you get back to that normal non restricted 600cc engine fuel flow. i don;t think i explained that real well but would that work? again right now i'm just talking about the flow theory, lets not get into manufacturing drive systems and computer controllers for the supercharger.

Any modern naturally aspirated 600cc four-cylinder motorcycle engine can choke the restrictor and reach maximum power. Therefore, any sort of forced induction system will not increase the engine's peak power output, only make its power band wider (choke the restrictor at a lower RPM).

[DaveC]

I think a turbo is most likely a better solution, as turbos do not require electric power. Especially with a wastegate that opens when the restrictor is choked.


Any modern naturally aspirated 600cc four-cylinder motorcycle engine can choke the restrictor and reach maximum power. Therefore, any sort of forced induction system will not increase the engine's peak power output, only make its power band wider (choke the restrictor at a lower RPM).


Really? Can you guys make 95hp without the turbo? The higher NA numbers I've seen are 75 hp or so. Not to mention torque, I have not seen a NA go over 45 ft lbs, I think I've seen about 65 from Cornell, which is a sure sign of more air going into the motor. So, either the turbo DOES move more air past the restrictor, or your cheating http://fsae.com/groupee_common/emoticons/icon_wink.gif.

[Marshall Grice]

It sounds like you are saying that with a supercharger, you could just cram in as much air through the restricter as would flow in an unrestriced motor. While this would be nice, it is not the case.

not what we're saying at all. what we are saying is that it will pull as much air through the restrictor as will flow through the restrictor.


I think a turbo is most likely a better solution, as turbos do not require electric power. Especially with a wastegate that opens when the restrictor is choked.

turbos have to spool, electrics don't. also,we never said that the torque curve was flat. it makes a lot of torque very low in the rpm band and it continually decreases as rpm's pick up, which equates to a relatively flat HP curve. NA motors have a tough time developing torque at low rpms due to poor VE, forced induction makes a big difference here be it turbo, supercharger, or electric supercharger.


Really? Can you guys make 95hp without the turbo? The higher NA numbers I've seen are 75 hp or so. Not to mention torque, I have not seen a NA go over 45 ft lbs, I think I've seen about 65 from Cornell, which is a sure sign of more air going into the motor. So, either the turbo DOES move more air past the restrictor, or your cheating .

in my opinion the real difference is they're using an engine dyno to measure their hp so the drivetrain losses aren't taken into account. if you put an NA motor on an engine dyno i'm quite certain there are many teams that would make 95hp too. I mean look what happened when they chassis dyno'd their car at detroit in 04, they made 75ish hp. I'm not trying to start any pissing contests here. i'm sure they make a lot of power, i'm just reiterating the fact that dyno numbers aren't the end all be all.

[Chris Davin]

Originally posted by DaveC:
I think a turbo is most likely a better solution, as turbos do not require electric power. Especially with a wastegate that opens when the restrictor is choked.

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content"> Any modern naturally aspirated 600cc four-cylinder motorcycle engine can choke the restrictor and reach maximum power. Therefore, any sort of forced induction system will not increase the engine's peak power output, only make its power band wider (choke the restrictor at a lower RPM).


Really? Can you guys make 95hp without the turbo? The higher NA numbers I've seen are 75 hp or so. Not to mention torque, I have not seen a NA go over 45 ft lbs, I think I've seen about 65 from Cornell, which is a sure sign of more air going into the motor. So, either the turbo DOES move more air past the restrictor, or your cheating http://fsae.com/groupee_common/emoticons/icon_wink.gif. </div></BLOCKQUOTE>

My original post was basically a first-order approximation for the behavior of the engine/restrictor combination. You are absolutely correct that there are many more complicated effects going on. I was just making the point that putting a turbo on an FSAE car isn't like putting a turbo on your average street car - you can't expect a 50%+ jump in peak power.

But, to answer your question: yes, if you simply pulled the turbo off our engine, or held the wastegate open, the peak power would be less. There are many reasons for this, most of which I won't go into. But mainly, our overall powertrain is the result of years of evolutionary development, and the whole engine package is designed to work with the turbo. It wouldn't be a fair comparison, so to speak. As an example: our engine (the block) is actually one of the lowest-performance sport bike engines currently in production. We use it because it's a good match for the turbo. But, if we wanted to run naturally aspirated, we would most likely want a different engine.

With regard to torque, our higher torque peak is an indication that we're moving more air past the restrictor at low RPM, when a NA motor at the same speed wouldn't be choking it. Torque is proportional to cylinder pressure, so when we're on boost, our torque will be higher than a NA engine. This goes back to the wider powerband.

[DaveC]

in my opinion the real difference is they're using an engine dyno to measure their hp so the drivetrain losses aren't taken into account.

Got me, I wasnt thinking about that. But, the torque numbers are directly related to airflow, 65 vs 45 ft lb is more drivetrain loss than might be expected. BTW, the "or your cheating" was a joke, just to be clear... What were your torque numbers with the electric?

Spool is an issue, but having owned turbo cars (AWD Talon) for over 10 yrs, you learn to deal, but it does bother a lot of people who arnt used to it.

[Chris Davin]

Originally posted by Marshall Grice:
in my opinion the real difference is they're using an engine dyno to measure their hp so the drivetrain losses aren't taken into account. if you put an NA motor on an engine dyno i'm quite certain there are many teams that would make 95hp too. I mean look what happened when they chassis dyno'd their car at detroit in 04, they made 75ish hp. I'm not trying to start any pissing contests here. i'm sure they make a lot of power, i'm just reiterating the fact that dyno numbers aren't the end all be all.

The last two years we made around 77 hp peak on the dyno in Detroit. Both tests were purely inertial, so it's hard to compare them to other teams' runs, which I think were mostly steady-state. To my knowledge, though, we had the highest-power inertial run both years. Correct me if I'm wrong. But regardless, there is far more to an engine package than the peak power read off a dyno curve.

[Charlie]

Originally posted by DaveC:
Got me, I wasnt thinking about that. But, the torque numbers are directly related to airflow, 65 vs 45 ft lb is more drivetrain loss than might be expected.

At the risk of having you go on another tirade about me being 12 years old or something, that's just not true.

Torque is not directly related to airflow, power is (generally). Same airflow at a lower RPM means more torque. You are applying a linear solution to a non-linear problem. You are simplifying and coming up with bunk conclusions.

Any forced induction after the restrictor (required by rules) still has the same problem as NA engines. You only have ambient pressure on the outside. So in the end the total max airflow cannot change. You can get more airflow at low RPMs, meaning more horsepower and torque at lower RPM ranges. This is the benefit of forced induction in FSAE.

[Mustang Mac]

We have made over 80hp NA for a few years. To reiterate what has been said, the turbo is just moving more air into the cylinders at lower rpm, but no more air than a choked restrictor will allow. A turbo will increase the low end of the torque curve but the peak numbers theoretically should be close between NA and forced induction with a well executed powertrain. I would think that the losses for the alternator would far outway the gains, even though it wasn't constantly on.

As for turbo lag, these turbos are so small that the spool time should not be an issue if properly executed. A big and heavy car with lots of power may be able to go fast in a straight line, but FSAE is not a drag race.

[Marshall Grice]

What were your torque numbers with the electric?


it's been a couple years and i can't find a dyno plot off hand but 67ftlbs @ 6000 sticks in my head.

the difference between 65 ftlbs and 45 ftlbs is the rpm. like everyone is saying you make more power down low. so if you're making the same power at a lower rpm...you're making more torque.

and the issue with lag isn't dealing with it, it's having more power under the curve.

[DaveC]

the difference between 65 ftlbs and 45 ftlbs is the rpm. like everyone is saying you make more power down low. so if you're making the same power at a lower rpm...you're making more torque.

OK, I see. I do remember torque tapering off at higher rpms on turbo cars curves.

[murpia]

Originally posted by Charlie:
Torque is not directly related to airflow, power is (generally). Same airflow at a lower RPM means more torque
...
You can get more airflow at low RPMs, meaning more horsepower and torque at lower RPM ranges. This is the benefit of forced induction in FSAE.
Maybe a clarification is in order?
Torque is proportional to cylinder mass charge. (Hence you modulate Torque by modulating cylinder charge with a Throttle).
Power is proportional to Torque and Speed.
The restrictor limits mass flow, hence it limits cylinder mass charge above a certain rpm for an NA configuration.
Simplifying to a 'perfect' engine and no losses, you could theoretically get a constant power engine with an inlet compressor after the restrictor, and therefore the torque curve would be asymptotic to the x and y axes of a graph.
Ian

[Charlie]

Sure that was a bit oversimplified but the point it was trying to counter was pretty basic too.

I guess you would say power is directly and mostly linearly proportional to mass air flow rate. Torque is not.

Sure torque changes with mass airflow, but over a range of RPM if you kept mass air flow constant, HP would be constant too but torque would change. Assuming as you say an engine with no losses.

The restrictor limits ultimate mass flow but it's not a light switch, it gradually decreases efficiency as it approaches that point.

As RPM increases, with constant mass flow, torque should degrade. I doubt it would become asymptotic with either axis, though I didn't try and plot the limits, seems unlikely to me. Probably, my lazines will mean I'm wrong.

The point was that if someone says '65 ft-lbs means you have more airflow than 45 ft-lbs' that's not true; however power is a good inidcator of that.

Like most details of an engine or vehicle for that matter, you can continue to delve into more detail and find ways to repeat statements with more accuracy if you use more words. http://fsae.com/groupee_common/emoticons/icon_wink.gif

[DaveC]

The point was that if someone says '65 ft-lbs means you have more airflow than 45 ft-lbs' that's not true; however power is a good inidcator of that.

It would be true if measured at the same rpm point. As murpia said, torque is directly related to VE, or mass charge, or airflow... Power (HP), again, is also a product of speed. At higher rpms, turbo cars curves do lose their huge advantage, although I'd like to see how Cornell's ewastegate system extended the powerband.

I'm going to have to disagree, Charlie, As I understand it, torque is more closely related to how much air is in the cylinder than HP. However, you are right I came up with a bad conclusion, because I wasnt thinking about behavior across the rpm range, and considering the whole picture. Marshall made that clear. And, no, I dont have to go on a tirade and compare you to a 12 yr old because youre not behaving badly http://fsae.com/groupee_common/emoticons/icon_smile.gif.

[Marshall Grice]

I'm going to have to disagree with dave disagreeing with charlie. http://fsae.com/groupee_common/emoticons/icon_smile.gif charlie said torque doesn't depend on mass flow rate, which is true. not to be confused with VE, which torque does depend on.

although I'd like to see how Cornell's ewastegate system extended the powerband.

search, they've posted dyno plots before iirc.

we're pretty much covering old ground now so i'm done. the auction ended, for WAY more money then any of us were expecting btw, and it didn't go to an fsaer so all this disscussion isn't of much use considering nobody has any electric superchargers here...

[kwancho]

Bet somebody bought it for their street car and is gonna have a biotch of a time trying to instal it, and then summarily blow their engine. lolz.

[DaveC]

OK, sorry. I was relating torque to VE, which doesnt have much to do with total mass flow rates, my mistake not communicating legibly...

[Z]

Two points:

1. Murpia summed up the torque/power/air-flow-rate stuff quite well. A turbo/supercharged + restricted IC engine is similar to an electric motor - ie. a flat power curve and torque that drops asymptotically to the X-axis - which is a good thing for FSAE conditions.

2. Since a T/S/C'd engine can make more torque at lower rpm (achieving the same max power allowed by the restrictor) it will likely have less frictional losses than a high revving N/A engine. Frictional power loss is mostly function of rpm^1, 2 & 3. Hence the T/S/C'd engine, "all other things being equal", will likely show more power on the dyno (output power = combustion chamber power - frictional losses).

Z