For the people that moan about electric turbos on ebay...
Discussion
The leaf blower idea is very similar to a ram air setup as used on many motorcycles. The air intake is via front mounted ports, the faster you go, the more air you 'ram' into the intake which improves power.
The air isn't compressed though. Even with a whole stack of leaf blowers, the air still isn't compressed.
The air isn't compressed though. Even with a whole stack of leaf blowers, the air still isn't compressed.
What about a high output electric motor (like 2000w) featuring some kind of gearbox to get a ridiculously high rpm on its fan? Maybe high enough to get the sort of compression needed without relying on exhaust pressure threshold. If it was a four cylinder engine, perhaps each throttle body could have it's own fan but only on demand.
205alive said:
What about a high output electric motor (like 2000w) featuring some kind of gearbox to get a ridiculously high rpm on its fan? Maybe high enough to get the sort of compression needed without relying on exhaust pressure threshold. If it was a four cylinder engine, perhaps each throttle body could have it's own fan but only on demand.
It would work in principle, but you'll need much more than 2kw- maybe 5 times that size per throttle body?I just re-did the calculation.
Assuming no losses
Power required (kW) = capacity (litres) / 2 * rpm/60 * pressure(kPa) / 1000
= capacity (l) * rpm * pressure (kPa) / 120,000
1 psi = 6.895 kPa, so
Power required (kW) = capacity (l) * rpm *boost (psi) * 6.895 / 120,000
So 10 psi boost on a 3l engine at 6000 rpm requires 10.3 kW, assuming a 100% efficient compressor.
A roots blower on a big-block v8 will be drawing easily three times that.
Assuming no losses
Power required (kW) = capacity (litres) / 2 * rpm/60 * pressure(kPa) / 1000
= capacity (l) * rpm * pressure (kPa) / 120,000
1 psi = 6.895 kPa, so
Power required (kW) = capacity (l) * rpm *boost (psi) * 6.895 / 120,000
So 10 psi boost on a 3l engine at 6000 rpm requires 10.3 kW, assuming a 100% efficient compressor.
A roots blower on a big-block v8 will be drawing easily three times that.
AW111 said:
I just re-did the calculation.
Assuming no losses
Power required (kW) = capacity (litres) / 2 * rpm/60 * pressure(kPa) / 1000
= capacity (l) * rpm * pressure (kPa) / 120,000
1 psi = 6.895 kPa, so
Power required (kW) = capacity (l) * rpm *boost (psi) * 6.895 / 120,000
So 10 psi boost on a 3l engine at 6000 rpm requires 10.3 kW, assuming a 100% efficient compressor.
A roots blower on a big-block v8 will be drawing easily three times that.
A typical centrifugal compressor will only be 75% efficient, and then you have to drive that compressor wheel, so either a high speed 1:1 gear emachine (huge iron losses due to the high frequency drive necessary, so probably in the mid 60% (inc inverter PE) or a low speed emachine (say 15kprm) and some form of ultra high ratio geartrain (epicyclic etc) again, that's going to struggle to get better than 60% efficiency)Assuming no losses
Power required (kW) = capacity (litres) / 2 * rpm/60 * pressure(kPa) / 1000
= capacity (l) * rpm * pressure (kPa) / 120,000
1 psi = 6.895 kPa, so
Power required (kW) = capacity (l) * rpm *boost (psi) * 6.895 / 120,000
So 10 psi boost on a 3l engine at 6000 rpm requires 10.3 kW, assuming a 100% efficient compressor.
A roots blower on a big-block v8 will be drawing easily three times that.
So, you're going to need to pull something like 20kW from the battery. At 12V nominal that's 1.66kA! Good luck with that........... In fact, a typical automotive lead acid battery can source in the region of 8kW for short periods, but the voltage drop becomes the limiting factor, as you need ultralow loss power electronics and a a very high kv wound emachine.
Assuming my maths is correct (and it's been a long day).
I originally did the maths for my car at a low boost - 1.6 l, 8000 rpm, 5 psi = 3.7 kW - say 5 kW with losses.
So that's about 100 amps at 48 volts - just on the edge of possible, but more expensive than a twin-screw blower.
Using it as a lag eliminator on a turboed engine, at 2000 rpm for 1 second or so, that's 100-ish amps at 12 volts, which is quite feasible.
I originally did the maths for my car at a low boost - 1.6 l, 8000 rpm, 5 psi = 3.7 kW - say 5 kW with losses.
So that's about 100 amps at 48 volts - just on the edge of possible, but more expensive than a twin-screw blower.
Using it as a lag eliminator on a turboed engine, at 2000 rpm for 1 second or so, that's 100-ish amps at 12 volts, which is quite feasible.
AW111 said:
Using it as a lag eliminator on a turboed engine, at 2000 rpm for 1 second or so, that's 100-ish amps at 12 volts, which is quite feasible.
Feasible yes (although, once you include all the losses and the transient dynamics, it requires about 300A @ 12Vnom) but cost effective? Not really. Interesting that this seems to be predicated on the availability of 48V electrics.
I remember reading about this and how it was on the cusp of being standardised/introduced (along with a more suitable accessory power socket, long overdue) in my Car reading days of the late 80s/early 90s. The articles I recall seem to suggest that HID lamps would require them due to the juice required to get the arc going.
Not much seems to have happened about making 48V the norm since then...what happened?
I remember reading about this and how it was on the cusp of being standardised/introduced (along with a more suitable accessory power socket, long overdue) in my Car reading days of the late 80s/early 90s. The articles I recall seem to suggest that HID lamps would require them due to the juice required to get the arc going.
Not much seems to have happened about making 48V the norm since then...what happened?
Once you get to 42v, you don't need a gear reduction starter, so you can replace the (geared) starter and (belt driven) alternator with a single motor/generator running at crank speed.
Smaller, lighter, more efficient and less parts.
Plus thinner wiring everywhere due to lower current - modern looms are a surprising weight, with all the power electronics : windows, seats, mirrors, door locks, demisters, etc.
Smaller, lighter, more efficient and less parts.
Plus thinner wiring everywhere due to lower current - modern looms are a surprising weight, with all the power electronics : windows, seats, mirrors, door locks, demisters, etc.
205alive said:
What about a high output electric motor (like 2000w) featuring some kind of gearbox to get a ridiculously high rpm on its fan? Maybe high enough to get the sort of compression needed without relying on exhaust pressure threshold. If it was a four cylinder engine, perhaps each throttle body could have it's own fan but only on demand.
A turbofan typically spins at 130'000 RPM on full boost.A typical three phase electric motor, what 10'000 RPM max?
Summary: No.
Edited by Dr Doofenshmirtz on Wednesday 31st July 14:41
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