A jet of pressurerized accumulated air, is introduced to the turbine wheel of the Turbo Charger, at moments of need, for lag-free operation, and boost under accelleration.
The pressurized air is accumulated under regular driving conditions, and let to a nozzle by a computer controlled valve unit.
The introduced jet of pressurized air, is aimed at the circumference of the Turbo Charger's spinning turbine/compressor schroll.
The impulse of the velocity of the air-jet accellerates the rotating part, at a 'pause' point, where there is no real pressure differential to be overcome, and just the rotation mass-inertia of the part is acting against a spin-up.
The result is lag-less smooth power pick-up, increased sportiness (better feel for the power at the accellerator pedal), better accelleration (no pauses) times, and if the turbo is optimized to be larger, higher maximum output, still without lag (since the larger turbo's resistance to accelleration is now eliminated).-- sirau, Jun 02 2011 pre-compressed-air_20supercharger [spidermother, Jun 02 2011] An automotive turbo is a high volume device, designed to draw power from the fast flowing exhaust gas while generating the minimum possible back pressure.
A small jet of high pressure air would be a very ineffecient way of driving the turbo. A larger jet of low pressure air would require a massive tank to store enough to make any difference. (A 2 litre engine running at 3000 rpm exhausts 50 litres of gas per second at around 5 Bar pressure.)
Modern turbo engines have virtually no perceptible lag. If there is a need to boost turbo pressure, this can more effectively be done with an electric motor.-- Twizz, Jun 02 2011 it's just meant as quick busts/squirts of jet sprays, to overcome the rotational mass inertia of the turbine/compressor of the turbo-charger rotating assembly - to spool up the turbo, while pressures are low, therefore virtually no resistance/'work'=energy to transfer.-- sirau, Jun 02 2011 If there were 'virtually no... energy to transfer' then it wouldn't be needed at all.
If you want to generate a temporary boost with pressurised air, it would be more effecient to feed the air pressure directly to the manifold.-- Twizz, Jun 02 2011 What [Twizz] said.-- 8th of 7, Jun 02 2011 // it would be more effecient to feed the air pressure directly to the manifold.//
It is. It's called "air injection." It works just like oxygen-, water-, nitrous-oxide-, and custard-injection boosters.-- Alterother, Jun 02 2011 [sirau]:
//The result is lag-less smooth power pick-up, increased sportiness (better feel for the power at the accellerator pedal), better accelleration (no pauses) times//
What you want there is a supercharger: less fuel-efficient, more immediate power. No need to modify a turbo to do that when something else already does it better.-- Alterother, Jun 02 2011 Modern turbocharging setups have eliminated lag using variable vane housings and and computer managed anti-lag. This is a simpler, more efficient, more applicable way of eliminating lag. It works over and over without fail and requires no additional parts.-- WcW, Jun 02 2011 You'd be better feeding your air reserve (through an ejector) in on the intake side, as suggested in the link - that way you get to also burn the air, rather than just pumping it through the turbine.-- Skrewloose, Jun 02 2011 [WcW]:
There's the Renault-Peugoet dual-geometry schroll design of the compressor wheel, also, -makes the fixed geometry turbine function in two different flow modes, one as a small compressor, another as a higher volume one.
BMW has gone to extremes, in their bi-Turbo diesel installations : Two individual serately rotating turbo units, sequentially staged in their respective operation in the rev-ranges : A small unit for lw-revs and pick-up/accelleration, and a larger unit for high-rev/cruising. It's a high power, AND high efficiency AND responsive, engine unit, called the '535d', as opposed to the single unit '530d' - they are both 3.0 liter 6-cylinder otherwise regular Diesels.
Almost 100 HP per liter with the more advanced type charging.
So, this would be the aim : to eliminate the cost of such doubling of the not-for-free turbine- compressor charger, allowing just One Large turbo, having eliminated inertia pause effect, by a simple, almost static, air nozzle modification.
[Twizz]:
It's a response question, not a continued power supply one. The lag can be tremendously important, in for instance overtaking manouvres, and particularly in racing, where minute control of the forces acting on the contact patches of the tires, is at the highest priority.
Personally, I experienced a large turbo, on a 1.756 (1.8) liter FIAT twin-cam engine. The lag was inherent in first gear, which was all the better, as it saved to rear axle from a massive dose of torque.
In second gear, the turbo spooled up nicely, and the car absolutely flew from 30 km/h to around 90- 100 km/h, in a distance of 80-120 meters. And still, the air-to-air cooler in the nose (intercooler), wasn't operating,.. the intake air could be denser,.
On the highway, in fifth gear, the car accellerated like there was no such concept as 'aerodynamics' - the intercooler at full vigor - from 4.000 rpm to 6.000 rpm, i.e. from 140 km/h to 180 km/h, in 4-6 seconds,..
The tires were 'S' or 'H' spec, so it would have been even more 'gray zone'/speeding, to go further up the speedometer scale.
A quick dap at the accellerator proved the engine viable for up to 9.000 rpm (!!) - perfectly ballanced.
With high-speed tires, this could have led to speeds of 240 - 265 km/h, according to my later calculus.
This mentioned turbo was possibly 'huge' for that engine. In size like two fists. In Belgium, at the 'Francochamps' Ferrari dealers shop, i saw a Ferrari F40 complete engine displayed - this has two turbo's, (for an engine 1,5 - 2 times the size), and they were only half the apparent volume.
Anyway, about the lag : I eventually slid with this car, on warm, slippery, asphalt, in a curve. The tires spun, this increased the engine rpm, this in turn increased the flow through the turbo, which instantaniously increased power on the crank, leading to the wheels, increasing the slide even further.
Complicated turn of events, - I ended up with a 'montagua' complicated fracture of the left, lower arm, and a gigantic head ache from banging the forehead into the frame of the windshield (it was a 1969 A-I Fiat 124 Sport Spider, open / convertible / sports car, torque-tube type rear suspension), and the car was a wreck.
I gave the engine away, to a FIAT 131 enthusiast, and he later reported, that he had been giving a Camaro arun for it's money, in an accelleration duel.
Another type of spool up installation : An tooth- pump type wheel installed in the middle, or to the cooler side, of the turbine/compressor housing, acting on the turbine shaft, from injected pressurized oil,..,.-- sirau, Jun 02 2011 Pressure Jet RPM Boost to Turbo's _what_??-- MaxwellBuchanan, Jun 05 2011 random, halfbakery