1st Gen R53 Cooper S Supercharged vs Turbo

Yup that sums it all up. Well said Sir.

 

I have seen some work with electrically driven compressors. The compressor is more like a Paxton style (like a turbo compressor but meant to run at lower rpm). So now we have the low back pressure, boost and response. The cost is probably closer to a sc vs a turbo.

Yes I want my cake and eat it too.:donut1:

 

Me to but I am holding out for the TVS 900 to replace my Heaton M45.

 

^^^ you're right about back pressure causing a loss of performance.. Heck most of us have swapped out the restrictive OEM exhaust for one that breaths better. I don't know what the pressure drop through the turbo is but I'm sure it is a only few psi. However with respect to providing intake boost, a turbocharger is generally a more efficient method, which may be why they are more prevalent in today's vehicles. A centrifugal compressor will usually have a flatter head curve compared to a positive displacement SC and the TC can do more flow. On the other hand, a SC can do more lift in a single stage of compression than a comparable single stage centrifugal (turbo). And a SC may be better at rapid changes in flow.... jump on the throttle and its nearly instantaneous. A turbo can be equipped with variable inlet vanes to nearly eliminate any lag. Usually a turbo-compressor will tend to be better at steady state operating conditions, but variable inlet vanes or a variable diffuser (exit) will take care of that too. Several auto companies are using VVT's (variable vane turbos) now too.

For automotive use, there is no single "best" method. It's really the designer's choice.

I am just starting a new compressor design project at work... It's a 5,500 HP single stage internally geared centrifugal. The best part is that after I design and build it... I get to test it to destruction. Several times..

 

^^^^^ Well....I've estimated it will weigh about 12,000 pounds so you may need to install stiffer springs....

 

Does anyone know how much power or load the R53 SC uses? It could be an interesting project to electrify one.

 

Electrify? As in, complete battery power? My mechanic said he would love to get his hands on a wreck, stick in a battery powered motor.....thing is.....even though it would produce absolutely no exhaust emissions, still would not be legal in California, you tampered with the stock emission system :crazy:

 

No not an electric motor swap. Run the SC on an electric motor instead of the crank.

 

You have to love the wonderful state of Kalifornia. :lol:

So if you made a Mini a peddle car they would not allow you to register it as a zero emission vehicle. :lol::lol::lol:

Well at least you have sun and warm weather all the time.

 

Gottcha.......not sure you would gain anything? What ever drives it would suck power away...no? And the whole point of a SC is the instantaneous power that it can produce being run directly from the crank...no?

 

Yea, it has its moments here Wish it was warm all the time where I'm at, I'll have to introduce you to our wonder Tule fog that we get here a few months out of the year :crazy: :frown2:

 

Ok just make sure you come East for some snow.

 

I got 10 feet of snow a hour away from me......that's what's nice about it...it's an hour away from me :lol:

 

I figure that if replacing the power steering pump with an electric motor saves power and gas then an electric SC should do the same

 

Maybe you could hook up a generator that turns by rubbing against the front tire, like they have for bicycles to run the headlight. That could supply electricity to the electric motor that runs your electric supercharger!

But it would probably take the same, or more, horsepower as hooking the electric motor to the car's battery, or just running it off of the crankshaft!

Those automotive engineers aren't stupid ya know! rrr: :lol:

Dave

 

I have friends that are automotive engineers. Your right they have good ideas when accounting doesn't kill them. They saved HP with electric ps so the logic would follow with an sc. Why didn't they do that? Cost. Turbos are cheaper.

 

I don't think that's true. Power steering is an intermittent load so it's ideal to electrify as that gets rid of the power loss when no steering is required. The supercharger runs all the time so it needs continual power. In a Mini that's maybe 5hp at peak or 4 kW - five times the size of the existing alternator! Just the fitting the bigger alternator and the superchargers new electric motor under the hood might be a challenge.

Even dedicated supercharger-users like Mercedes are switching to turbos and I think the main reason is fuel economy.

 

I think there's way more to it than cost.....

Emissions for example, imagine the effect an instant on demand only supercharger would have on emissions?

And if you intend to run it all the time, your fuel mileage and the hp needed to run the motor drive would cancel any savings.

There are also weight and packaging issues - a drive motor big enough to turn the supercharger fast enough would be the size of a starter motor or bigger, and need its own cooling system too.

Plus, trying to make the motor variable speed so it could respond properly to light throttle applications would be a nightmare and add cost, complexity and weight.

That's not saying it can't be done, just that there are better more cost effective solutions.