45 replies to this topic

[TopCatCustom]

"So" where are we going to put a 15-20 hp electric motor...

So- a very efficient motor would not require 15-20 bhp to make the same boost that a 40 year old design roots blower with thick ribbed belt, 3 pulleys, 4-6 bearings uses.

I'm just saying that I think it will be possible in the near future! If you look at the technical advances we've had over the last few years, is it so hard to picture a decent electric motor spinning a compressor?!?! Especially as most cars only make boost for a few seconds at a time!

[mini13]

the charger on the bini consumes nearly 15 hp on std boost, at a decent boost level on a turbo you will need the 15-20 hp I stated.

by the time you start looking at motors of this size you may as well ditch the engine all together and go electric.

[JustSteve]

there's one big flaw in this..


you would have to put MORE effort into generating the power, than the gain you'd get.

You can never get in increase in power, only loose it as heat/sound

[Sprocket]

The turbocharger is effectively an energy recovery system. It uses the waste energy in the exhaust gasses to drive the compressor. It consumes no generated power from the engine in its operation (it can restrict it though). A mechanical supercharger on the other hand consumes valuble generated power, as would any electric driven system, through the alternator.


An accepted destinction between a supercharger and a turbocharger is easy. A turbocharger is a gas turbine driven compressor, a supercharger is a mechanical driven compressor. The compressor can be screw, centrifugal, recip or scroll. Both the turbocharger and supercharger are in effect a 'super charger'

[TopCatCustom]

Dont be daft!

The turbo is driven by waste gas yet- but the pistons have to push the gas through the turbo, there is NOTHING for free. The more boost the turbo makes, the harder it is to spool so the engine does have to drive it by compressing the exhaust gas and forcing it through the turbine.

And Steve, what you have just said would mean that there is never any point in having forced induction. We've already said the turbo's and especially superchargers take power to turn, so if you were right then that would be wasted power.

A top fuel dragster takes nearly 1000bhp just to spin the supercharger! But the result- it makes 8000bhp, which is several thousand bhp more than a naturally aspirated comparable engine. This represents the whole point in forced induction, you get out more than you put in, even though the 'chargers take energy to spin.

That is why I don't see the arguement of people saying, yeah but it would use too much energy!- the existing technology uses even more energy due to the mechanical drive! Turbo's will be hard to beat but I think beating supercharger efficiency is far from impossible.

[ibrooks]

/whiney voice on/ "You can't get something for nothing" /"whiney voice off"/

We aren't talking about getting anything for nothing - we are dumping a huge amount of energy into the sysem. The form we get it in costs over a pound a litre and is going to get 3p per litre more expensive in August.

Big electric motors.... no just powerful ones. The one being used is a variation on this range rated at 10hp.

http://www.aliexpres...nting-seat.html

Notice the tables and that their power ratings are 6-7KW. 1KW is 1.3hp so those are 8+hp motors (and run at higher voltages you get more than the manufacturers rating). They are for model aircraft where you can't stop and start so those ratings are continuous they will happily do more in short bursts with no ill effects. Notice also their vital statistics - 80mm diameter 107mm long that's about the size of a coffee mug. Notice the weight 1400g - less than one and a half kilograms.

Is it getting through yet that it is quite possible to drive a supercharger with an electric motor? or will it take a hammer to get it through some of the thicker skulls?

Current draw on the system in the MX whilst going down the strip is approx 200A. The battery pack weighs less than the motor but I think he runs two at a time. There's also a speed controller to account for - that'll be a circuit board weighing about as much as a fag packet plus a couple of kilos of wire since you can't run that sort of power down speaker wire.

Still sound like an April Fool's joke?

[Ethel]

For the exhaust gasses to get out of the cylinders they have to move, which means they have momentum, some of that can be used to spin the compressor without impinging on the piston, especially after the exhaust valve closes.

Cheesy analogy: It's like being crammed into a lift, when the doors open the occupants spill out into a less crowded corridor with a turnstile at the end. There will be pressure from the crowd to go through the turnstile but nothing like as much as there is to empty the lift, so everyone still moves forward; once the lift doors close everyone left in the corridor will continue to make there way through the turnstile to find even more space on the other side.

To be fair, the point of any forced induction system is to shove more air in the cylinders so you can burn more fuel with it - the fuel is the energy source, so as long as your compressor consumes less energy (be it mechanical or electrical) than the extra fuel releases you will get an increase in hp at the flywheel. A leccy system offer the potential to store the energy in a battery so if you want lots of HP over a short time not as much needs to be diverted into spinning the blower as soon as it's made instead of spinning your tyres.

[mk3 Cooper S]

So? Electric PAS takes 50-60 amps, thats more than a standard mini alternator can make on a good day. And superchargers are not as efficient as turbochargers, so we can assume that a turbo compressor directly driven by an electric motor is going to take a hell of a lot less than a supercharger to make the same boost. Just stating facts, at the end of the day, even if it were no more efficient, why does it matter how you drive the same thing? Like vehicles, can be mechanical with a clutch and gears, auto's have a liquid connection in the torque converter to do the same job, hydrostatic is done with a big belt which is another way, hydraulics can be used to do the same job or new cars can be electric. It's just transferring power from the engine to the ancillary by one means or another.

Electric PAS can take 50 - 60 amps and more on full lock but requires very little with little steering angle or straight ahead.
That would be a electrical load balance calculation and may work out to be a net 10 - 15 amps. With all deep discharge batteries they are designed to take a hit on full lock or starting current for example but in reality act as a buffer or filter for periodic high current requirements.
It is unrealistic to determine that the alternator would need to supply worst case constantly.

Same with an electric supercharger for example, The amount of time that it would required to work at 100% duty cycle (Max electrical requirement) would be quite short - maybe different on a race car?

Edited by mk3 Cooper S, 05 April 2012 - 11:48 AM.

[diogoteix]

Many seem to have trouble thinking out of the box!
I totally support the idea of a "temporary electric super charger". It is conceptualy sound and, more importantly quite easily feaseable with off the shelf components!
Who will try build a kit for a Mini?

Cheers

[mini13]

I'm Impressed by those motors, but I'm a bit concened by the size vs the power, in a RC plane they are going to be cooled by a lot of air which they arnt going to see under a car bonnet. obiously size = heat dissipation= longevity

What sort of boost level is the MX running? Whats the battery life? Cost? can you tell I'm inruiged now lol

anyway to further my comment about ditching the engine altogether...

/whiney voice on/ "You can't get something for nothing" /"whiney voice off"/

We aren't talking about getting a
nything for nothing - we are dumping a huge amount of energy into the sysem. The form we get it in costs over a pound a litre and is going to get 3p per litre more expensive in August.

Big electric motors.... no just powerful ones. The one being used is a variation on this range rated at 10hp.

http://www.aliexpres...nting-seat.html

Notice the tables and that their power ratings are 6-7KW. 1KW is 1.3hp so those are 8+hp motors (and run at higher voltages you get more than the manufacturers rating). They are for model aircraft where you can't stop and start so those ratings are continuous they will happily do more in short bursts with no ill effects. Notice also their vital statistics - 80mm diameter 107mm long that's about the size of a coffee mug. Notice the weight 1400g - less than one and a half kilograms.

Is it getting through yet that it is quite possible to drive a supercharger with an electric motor? or will it take a hammer to get it through some of the thicker skulls?

Current draw on the system in the MX whilst going down the strip is approx 200A. The battery pack weighs less than the motor but I think he runs two at a time. There's also a speed controller to account for - that'll be a circuit board weighing about as much as a fag packet plus a couple of kilos of wire since you can't run that sort of power down speaker wire.

Still sound like an April Fool's joke?

[HUBBA.HUBBA]

Who will try build a kit for a Mini?

Cheers

Me

[ibrooks]

I'm Impressed by those motors, but I'm a bit concened by the size vs the power, in a RC plane they are going to be cooled by a lot of air which they arnt going to see under a car bonnet. obiously size = heat dissipation= longevity

What sort of boost level is the MX running? Whats the battery life? Cost? can you tell I'm inruiged now lol

Boost level I dunno - he was looking at sticking a boost gauge near to the rev counter and trying to video them together so that he could see what sort of boost he was actually getting versus revs but heard nothing more since. I didn't keep up with the project as I prefer cubic capacity to make my power (I'm shoehorning a 2.9 Cosworth V6 into a Focus for my kicks).

Cost - he had the stuff "lying around" as he's an inveterate tinkerer so there's always something kicking around from the previous project. Not cheap I would imagine if you are going out to buy the stuff new in one lump.

Cooling - the motors. We have found a use for the "electric superchargers" sold on ebay!!!!!!!! Seriously though I suspect he hasn't had an issue given his short burst use as it'll get a chance to cool between runs. Bigger might well improve longevity but it could be twice the size of those without impinging on space in a normal engine bay or adding silly amounts of weight. Certainly not approaching the size of the existing engine as was previously suggested.

Battery life will depend on the packs used but again all I've seen used in anger is small packs used for maybe 30 seconds at a time (burnout, wait, gooooooooo!). How much is left at the end I dunno.

Whether it would be useable in a road situation with an acceptable load of batteries is one for someone else to dig into.

Iain

[samsfern]

Make sure you get one of those electronic speaker things that make the chavvy dump valve noise too

[holmesy]

ive got this in the garage dunno where i can tap 200v out of the mini but the turbine is about 9 inches  CIMG0482.jpg   1.62MB   10 downloads

[HUBBA.HUBBA]

ive got this in the garage dunno where i can tap 200v out of the mini but the turbine is about 9 inches  CIMG0482.jpg   1.62MB   10 downloads

An inverter would do that.