Electric Turbo

[AbCaRed00]

BMW's patented an electric supercharger to reduce turbo lag as part of a 3-turbo system that uses a regenerative feature:
The electric supercharger functions as a generator as well where excess psi from the turbo system is bled off and back through the in-line driven electric supercharger motor/generator's impeller; additional energy is recovered.

[Cobb]

Wow, sounds like BMW is out doing themselves.

I remember the g60 belt driven supercharger vw had that ran off an accessory pulley and looks like a turbo with its circular shape and housings.

Hell, many are pulley driven so it would only need a few thousand rpms.

[RedJellyBean]

I don't see the point of an electric turbo when we already have an electric motor directly on the drivetrain. It's like converting DC to AC and then back to DC in our case, lol.

[IamIan]

Originally Posted by Bugone

I've been thinking what the effect would be of adding an electric turbo (supercharger) to an Insight, to boost low rpm performance.

Thoughts?

Sense you asked ... My thought is:

Why focus on power or torque specifically at low ICE RPMs?
Why not just run the ICE at higher RPMs to get the power you want?

[Mario]

Well, then you skimp on fuel economy. Higher RPMs means more fuel used.

Then again, when you force more air into the engine, you need to add more fuel to compensate. Overall, though, I've heard you can get about the same fuel economy or slightly better with a turbo. Somebody added one to their Insight on these forums before, did they say if their mpg changed?

[Willie Williford]

True.
Here is an interesting article.

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Willie

[IamIan]

Originally Posted by Willie Williford

True.
Here is an interesting article.

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Willie

Thanks.
That does explain some of the MPG benefit of the low RPM ICE ... at least things like lower ICE Friction from lower RPMs , and extracting some of the heat energy from the exhaust.

What I would disagree with in that article that the exhaust thrust is just wasted energy ... exhaust heat , yes ... but not the exhaust thrust ... now it is possible I suppose that the amount of kinetic energy lost by removing some of the thrust from the exhaust will be less joules of energy than the increase in joules from running the ICE more energy efficiently... which could give a net benefit , but the thrust itself is not waste.

I am left to wonder still ... although lower RPMs will have less friction ... the energy efficiency of our ICE converting the chemical energy of the fuel into mechanical energy at the shaft ... is not always better at lower RPMs .... see ISFC chart attached bellow ... yes there is an island of higher 220g/kwh at low RPMs ... but despite the additional friction losses from high RPMs there is also a better island of 210g/kwh and even a tiny 200g/kwh at much higher v-tech RPMs.... ???? hmmm ... I'll have to ponder that a bit more.

[biododge1]

for the pourpose of still running low rpms, I think a duel turbo setup would be optimum. Many diesels use this setup now. Its a very good way to reduce spool up time, run at lower rpms, and gain power when needed-but at the cost of mpg (boost=more gas used).
The idea of running a supercharger to run the turbos is old. My old truck has a 2cycle diesel with a super and twin turbos. For a gas engine it just really wouldnt be needed unless your running real large turbos

[Cobb]

I take it you never worked at a hydro electric plant? They do something like that when demand is down other than close the flood gates. They use the power from the turbines to pump water back behind the dam using their own damn power to do so.

I guess doing this allows them to have x amount on power on hand at a moments notice and when its needed they just slow down or stop the pumping and let it go out to the grid?

Originally Posted by RedJellyBean

I don't see the point of an electric turbo when we already have an electric motor directly on the drivetrain. It's like converting DC to AC and then back to DC in our case, lol.

[RedJellyBean]

Originally Posted by Cobb

I take it you never worked at a hydro electric plant? They do something like that when demand is down other than close the flood gates. They use the power from the turbines to pump water back behind the dam using their own damn power to do so.

I guess doing this allows them to have x amount on power on hand at a moments notice and when its needed they just slow down or stop the pumping and let it go out to the grid?

In my case the electric motor has more capacity to perform work than the battery charge has the capacity to deliver voltage at any given time. Might as well do the retepskinrep current mod or MIMA thing to get the electric boost; at least it won't require more fuel to be used and mechanical modifications to be done.