Pelican Parts Forums - crazy thought of tday: stored boost for instant HP

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Quote:

Originally Posted by sammyg2 (Post 8621851)

With the emphasis today on hybrids .... small efficient turbo engines etc a thought just popped into my head:
stored boost.

Suppose we had a small compressor that built up presure in an air tank and that pressure was released into the intake manifold on demand, = instant (and temporary) boost.

Why? it could be charged while iding, while decellerating, with significantly less detrimental parasitic losses than a conventional supercharged or turbo engine.

Heck why not take it another step, have one or two cylinders switch from internal combustion to air compression on decell, like a jake brake or such. It'd help with braking and take that energy and save it instead of turning into heat.

Wouldn't do much for constant cruise but would be nice for stop and go driving.

'spose it could build up 15 or 20 psig in a 10 gallon tank, maybe that's too big for packaging but we'll go with it for 'sposes.

On a small 1.6 liter engine that could produce a 5 psi boost under accelleration for what, 10 seconds maybe longer? Haven't done the math here, so just guessing so far. Who doesn't want an extra 50 hp once in a while, and if it's basically free with ZERO lag ....

We don't need much power on steady cruise or gradual accelleration, just on initial start up to 30 or 40 mph, that would allow a much smaller engine to push around a bigger vehicle.

Yes it'd be fairly complex, prolly more than I could pull off in my garage with all the computerized stuff, but the big car makers could do something like that in their sleep.

Oh well, just a thought.

Hhhmmmmm...... is someone watching us?

Quote:

Compressed air gives Volvo's turbo engines a boost
Volvo has put a new spin on the turbocharged engine.

The 2.0-liter 4-cylinder diesel motor in its upcoming S90 sedan doesn’t just use a turbocharger to compress air into the cylinders for increased power, but also uses compressed air to give the turbo itself a boost.

Turbochargers are typically driven by only the exhaust gas exiting an engine, which takes some time to accelerate the turbine. This leads to what’s known as turbo lag, which is that moment right after you step on the accelerator pedal when not much happens, before the full effect of the boost kicks in.

Automakers have developed various measures to minimize the effect, including the combination of an engine-driven supercharger, which delivers boost at low engine speeds until the turbocharger takes over at high revs. Volvo currently offers an engine with this type of arrangement in several of its vehicles.

But its new PowerPulse technology approaches this issue in an even more novel way. It features an electric air compressor that fills a two-liter canister with filtered pressurized air, releasing it into the exhaust manifold in bursts or “pulses” whenever you step on the accelerator. This quickly brings the turbo up to speed, filling the gap and virtually eliminating lag, Volvo says.

You’ll have to take its word for it for the time being, because there are no plans to offer a diesel version of the S90 in the United States when it goes on sale here next year.

Compressed air gives Volvo's turbo engines a boost | Fox News

Just yesterday I was interviewing George Montgomery. He was one of the first to be successful with turbocharging a drag racing car. Turbo lag was a huge problem. He developed a system where the turbo was taken off line at low RPM - the air intake was closed so it could spin up with very little energy input. A separate intake system let the engine run at low RPM. When he dropped the hammer, it opened the air intake for the turbo. Since the turbo was already running at full RPM it started pumping at full pressure immediately. It was a pretty ingenious system. Probably too complicated for a street car.

http://forums.pelicanparts.com/uploa...1449608573.jpg

That's pretty much how sequential twin turbos work.
One small one spins up easily to get things started and the bigger one kicks in for real boost.

Always loved the boss 429.

BTW, that's pretty much how the turbo on my 914 worked even though I only had one.
At lower rpm/idle, the air inlet (suction) was closed, unloading the compressor. But the exhaust still flowed through it keeping it spinning pretty fast.

When I opened the throttle and allowed air to hit the compressor, inertia kept it spinning long enough for the exhaust to build and spool it up.
Well almost.

Quote:

Originally Posted by sammyg2 (Post 8909725)

I guess that is easier on the turbo than surging if the blowoff valve is too small but it would overspeed when you close the throttle and there will still be an impulse when you open it. Aside from that, would the time required for the compressor blades to go from stalled to working properly be greater or less than the normal spool up time?

Quote:

Originally Posted by sammyg2 (Post 8909725)

Always loved the boss 429.

George hated them.

I don't know anything about them, so I have no opinion myself.