So Has Anyone (Dumb Forced Induction Idea Inside)

Has anyone taken a starter motor and used a belt or a gear and powered a supper charger or a turbo with it?  I was thinking more of a boost on demand type setup with a button in the cabin.  Basically use either the solenoid on the starter or use a ford starter solenoid.  Then install either a gear or pulley on to it and have that spin a turbo or a supper charger.  Like I said boost on demand type of setup. 

Lets say for a drag race or maybe as part of an autocross run that may have some sort of concourse part and maybe the event organizers are looking for some weird/inventive engineering content for said concourse part of the event.

Probably a very bad idea that I am sure there is a technical reason why this will not work by I have always wanted a boost on demand switch in my car.  You know for getting to the next stoplight as fast as you can.    

So kind of like how Max could turn his supercharger on and off whenever he wanted?

I want to think that I read somewhere there was a Toyota that came supercharged from the factory that could be turned on and off by a switch.

I do like your thinking, though.

In reply to dean1484 :

Damn dude, you are bored.

The starter spins at x rpm and to make boost the turbine needs to spin at y rpm. So you will have to gear it up with belts or gears or something.

I did see a turbine home built that was a large diameter which reduced the rpm for lbs of boost. It was used on something else but could have boosted an engine.

For even better "wtf" factor that turning was made of plywood and sheet metal vanes.

Because you are thinking electric motor you can mount it in any orientation so a large diameter like 2 feet could lay flat on or in plane with the hood.

Turbochargers spin at very high RPM, so you'd be hard pressed to push a starter motor that hard for very long as they don't spin very fast.

There have been designs that leverage a turbocharger inducer, paired with a high speed electric motor.  Not cheap though and tends to work like a centrifugal supercharger.

A supercharger, paired with a starter motor is closer to working, but again starter motors don't last long in sustained use.

I think stealing the motor from an electric scooter or balance board would work better.

The tradeoff is that turbochargers use waste energy to create power, an electric blower would add load to the alternator which requires HP to turn it.

One would have to look at the engine power needed to generate the necessary electrical power to spin the electric motor and compare it to what it would take to spin a supercharger via the engine.

If you want the fun of switching power on/off, then have the wastegate solenoid controlled via switch or a bypass solution made for the intake tubes from a throttle body and a stepper motor.

I have never cast anything this big but if you want to be seriously crazy

It shows how to cast your own housing. We are stuck at home.....

I am thinking gear or belt reduction to increase the speed of what ever I am spinning (large pulley on the starter and small pulley on the turbo/suppercharger).  I envision the starter being used for 10-20 seconds.  It would pull power mostly from the battery that would be then replenished with the alternator over time. 

Use it like a push to pass setup that would then have to regenerate. The time for regeneration of energy would obviously be much greater time than the usage time.

The reason I am thinking starter is they have good torque and are good for relatively short bursts of usage.  Get one from a diesel engine that has more torques than a small gas motor.

Any yes I am board I am setting up a cloud based server for my employees to use and I am currently watching files transfer.

I have both turbos and superchargers and starters on the shelf to play with.

Thinking supper chargers for a moment since it is not direct drive off the motor you could get a much bigger supper charger than you would normally use and then not have to spin it as fast to get boost. Say an M122 for a 2.5L motor.  This would greatly reduce the speed you would need to spin the supper charger to get boost.  The down side is that as RPM's clime boost will fall off so you would want to pick your boost amount at or close to redline and spin the supper charger at that RPM constantly and them let a wast gate regulate the boost at lower RPM.  When the supper charger is not powered you would activate a bypass valve.  

Starter motor is probably a bad choice.  Designed for torque and short use, even 20 seconds use is enough to develop some heat in them.

Brushless and high speed would be a better choice.

What about skipping the boost part and just direct driving the wheels or driveline?

If you could find a way to spin it faster you could leave it in the stock position and power the flywheel directly.

Or you can power your alternator backward.

But if you are set on spinning a pressurizer, the alternator might be better since it can do thousands rpms and not hundreds.

Robbie said:

What about skipping the boost part and just direct driving the wheels or driveline?

If you could find a way to spin it faster you could leave it in the stock position and power the flywheel directly.

Or you can power your alternator backward.

But if you are set on spinning a pressurizer, the alternator might be better since it can do thousands rpms and not hundreds.

Which is a MUCH more efficient use of limited electrical energy.  Light hybrids are much more efficient and cheaper than e-boosting of any kind.

alfadriver said:

Robbie said:

What about skipping the boost part and just direct driving the wheels or driveline?

If you could find a way to spin it faster you could leave it in the stock position and power the flywheel directly.

Or you can power your alternator backward.

But if you are set on spinning a pressurizer, the alternator might be better since it can do thousands rpms and not hundreds.

Which is a MUCH more efficient use of limited electrical energy.  Light hybrids are much more efficient and cheaper than e-boosting of any kind.

Efficient, maybe.  But boosting allows you to utilize limited energy to 'buy capacity' to add additional fuel + oxygen to the process to extract more power.

In reply to ProDarwin :

You are limited by how much power you can get from the increased air flow, and the increased air flow is limited by the amount of power you can put into the pump.  For a shaft driven blower, getting power is pretty easy.  For an exhaust driven blower, getting power is pretty easy.  For an electrical driven blower- it's way more efficient to put that same power to directly power the drive shaft both on a cost and thermal efficiency basis.  But mostly on the cost part.

BTW, the efficiency part I talk about is more about getting the power out of the system.  For an e-boost system to really work well, you need some storage, and you need to run it a very high voltage to reduce losses- otherwise direct drive of the blower is going to result in more power.  Especially if you are taking essentially waste energy from the exhaust.  I'd wager a bet that the e-boost systems used in F1 are in the multiple hundred volts to keep them worth while, and they only are used very briefly until there's enough energy in the exhaust to use.

Or just run it off a belt and make it work properly? You already have to plumb it to the intake tract

I remember watching the Mad Max supercharger thing and wondered how that would work. I came up with the idea of using a air conditioning electric clutch on the drive pulley for a supercharger. Not sure how/if it would work on a GMC style blower that feeds direct into the head but may work with the type that mounts off the intake manifold. Don't really know much about superchargers. Would air/fuel flow through the blower that isn't turning? Which is my thoughts on the top mounted GMC style blower.

alfadriver said:

In reply to ProDarwin :

You are limited by how much power you can get from the increased air flow, and the increased air flow is limited by the amount of power you can put into the pump.  For a shaft driven blower, getting power is pretty easy.  For an exhaust driven blower, getting power is pretty easy.  For an electrical driven blower- it's way more efficient to put that same power to directly power the drive shaft both on a cost and thermal efficiency basis.  But mostly on the cost part.

BTW, the efficiency part I talk about is more about getting the power out of the system.  For an e-boost system to really work well, you need some storage, and you need to run it a very high voltage to reduce losses- otherwise direct drive of the blower is going to result in more power.  Especially if you are taking essentially waste energy from the exhaust.  I'd wager a bet that the e-boost systems used in F1 are in the multiple hundred volts to keep them worth while, and they only are used very briefly until there's enough energy in the exhaust to use.

 

At a high level: Lets assume you have n units of mechanical power (post conversion from electrical back to mechanical) you want to turn into mechanical power at the flywheel.  You can apply those directly to the crankshaft, or you can apply them to a compressor and then add additional fuel.

This is exactly the same tradeoff as a shaft driven blower.  You can take n units of mechanical power and either A) keep them (apply to crankshaft) or B) apply them to a compressor and add additional fuel.  B results in more power.

I agree from a thermal efficiency standpoint this is terrible.  I am also not taking into account the voltage, because in this case it does not matter.  The same amount of mechanical power is fed back into the system no matter what (assuming we aren't changing the motor).

Couple years ago there was a starter powered roots blower on the market.

Here are some numbers:

Let's say you have a 1.6 liter motor, why? That's about 100 cubic inches (97.8) = easy numbers.

1 HP = 550 ft∙lbs/s = 6600 in∙lbs/s = 396000 in∙lb/min

4 cycle runs half displacement per revolution = approx 50 ci per revolution or 50,000 cu in per 1000 revolutions.

(50,000 ci/min)*1psi = 50,000 in∙lb/min = approx 1/8 HP. Cool, then 1 HP would give 8 psi at 1000 RPM, 4 psi at 2000 RPM, 2 psi at 4000 RPM, or 1 psi at 8000 RPM.

Rough numbers 80% efficiency for turbine, 90% efficiency for some sort of belt drive, and 90% for efficiency through the intake track? Approximately 2/3 efficiency total.  A 2HP starter would have 1.3 HP worth of boost, so multiply all those psi numbers above by 1.3. At the same time, running a 350 small block? Divide all those numbers by 3.5.  Either way, you are above your ability to make useful boost long before your 20 seconds of starter time are up.

Want to run 20 psi in a 2.0 at 6000 RPM? 22 HP at 100% efficiency or about 34 HP of electric motor in this example.

Pressure*Volume/Time = Power, you just have to watch your units.

Want to know how many crankshaft HP your turbo uses?  Look at the turbine tables for your turbo, remember that there is a pressure drop through your exhaust ports, and there you go.  Yep, turns out there are no free lunches.

If you sharpen your pencil, you can poke holes in the above, but it is still a good ballpark exercise.

How about using a turbo compressor with a set of gears driven by the serpentine belt.

The professional version works quite well. A home grown version would be seriously cool.

alfadriver said:

In reply to ProDarwin :

You are limited by how much power you can get from the increased air flow, and the increased air flow is limited by the amount of power you can put into the pump.  For a shaft driven blower, getting power is pretty easy.  For an exhaust driven blower, getting power is pretty easy.  For an electrical driven blower- it's way more efficient to put that same power to directly power the drive shaft both on a cost and thermal efficiency basis.  But mostly on the cost part.

BTW, the efficiency part I talk about is more about getting the power out of the system.  For an e-boost system to really work well, you need some storage, and you need to run it a very high voltage to reduce losses- otherwise direct drive of the blower is going to result in more power.  Especially if you are taking essentially waste energy from the exhaust.  I'd wager a bet that the e-boost systems used in F1 are in the multiple hundred volts to keep them worth while, and they only are used very briefly until there's enough energy in the exhaust to use.

 

Those pesky laws of physics :)

I agree.  Energy isn't free.  If you have a 60A motor to drive your supercharger and a 60A alternator, it will take about three seconds for your plan to generate zero additional power.  Once you start drawing 60A and the alternator starts yanking 60A worth of power from the belt, you will have pretty much a zero net gain.

If you could, maybe, use a DPDT relay to shut off the charge circuit while under boost, you can just tap into your savings (the battery) while your switch is on.  Bypass the alternator for a minute or two while you're playing.

Turbos work by utilizing heat energy that would otherwise just go out the tailpipe, so you get a net increase in power when you tap that wasted energy.  Using electricity means you have to first make the electricity.  Kinda like those scams from the 90s that claim you could run your car on water by simply electrolyzing it into H2 and O2.  Since you only get back the same amount of energy that you put INTO the water to split it, it was perpetual motion, which we know doesn't exist.

Curtis73 (Forum Supporter) said:

Turbos work by utilizing heat energy that would otherwise just go out the tailpipe, so you get a net increase in power when you tap that wasted energy.  Using electricity means you have to first make the electricity.  Kinda like those scams from the 90s that claim you could run your car on water by simply electrolyzing it into H2 and O2.  Since you only get back the same amount of energy that you put INTO the water to split it, it was perpetual motion, which we know doesn't exist.

Steam turbines work that way; turbos not so much. Does some of the power come from heat?  You bet, but only as a portion of the heat lost between the upstream side of the turbine and the downstream side.  Turbos run on pressure differential and some of that differential can come from heat, but all of the pressure on the upstream side (and more) is still pushing against your pistons during the wrong part of the cycle and therefore taking HP from the crank.  It is mostly crank HP, but it is gathered reasonably efficiently, reasonably inexpensively, and easy to turn up.

Spending HP on boost gets more HP than it costs (assuming an appropriate design), you just pay for it in wear and tear and gas.  The reality in this situation is that the extra weight of the starter, belt/gear drive, bracketry, more alternator, and more battery will likely slow you down more than just pulling and extra 2 hp off of the front pulley.  You could just as easily make your alternator cut out every time you were on boost, to about the same effect.

I think you are forgetting about time. The electric motor can extract power from the battery much faster than what the alternator can make it. As such you will only have the power loss of what ever the maximum amps the alternator can provide. As such the battery becomes the power source for the short bursts needed that are replenished over a much longer period of time by the alternator. So the premise that you will cancel out any power gain against power taken by the alternator is flawed because of the time period the power is taken is much shorter than the time period that it is replenished. 

the real question is how fast does a starter motor spin?  I want to do some math to see what the sizes of the gears would have to be. 

In reply to dean1484 :

That part is easy.  You need to know what it spins under load (when it is turning a motor over).  What RPM does it crank the motor at? How many teeth on the starter? How many teeth on the flywheel?  There are ways to measure by diameter, but that gets tricky on really small, coarse gears, like a starter has.

(Crank RPM)*(Number of teeth on flywheel)/(number of teeth on starter) = Starter RPM at load

I know how to do the math I was hoping that there was actual stats out there. I have not looked I am hoping someone here knows this. 
 

Some  quick guesstimating based on loose tooth counts a Porsche starter spins at about 8,000-8,500 rpm.