

Infiniti wows with its latest electric car concept


Source: CarScoop

Comments     Threshold


RE: I like it
By lagomorpha on 2/26/2012 3:23:48 PM , Rating: 2
As much as the long maintenance interval of turbines excites me, I don't see the high price of small turbines attracting too many car manufacturers. If the battery/electric motor is doing most of the work why increase the production cost by thousands in order to change the engine which is less often used? I'm not saying it's not a better solution, but the price does make it less practical.

Now if we were talking about turbine-hybrid heavy and medium duty trucks...

RE: I like it
By Dan Banana on 2/26/12, Rating: -1
RE: I like it

RE: I like it


RE: I like it


RE: I like it
By Mint on 2/26/2012 7:31:40 PM , Rating: 3
The problem with microturbines is that they're not as efficient as the best piston engines. The Capstone 30kW microturbine you mentioned has ~27% thermal efficiency:
Generally, the best are around 30%. The best ICEs can get near 40% peak.

The weight saved only makes a small difference in efficiency. In a 3500lb car, you'd need about 500lbs to increase the cruising resistance by 5%, and regenerative braking can recover most of the additional kinetic energy put in during acceleration.

Turbines are cool, and are great when you need power density (e.g. aircraft), but they don't have much potential in hybrid cars.

RE: I like it
By lagomorpha on 2/26/2012 8:07:49 PM , Rating: 2
Commercial aircraft don't use turbines for their power density, they use them because having few moving parts means their maintenance intervals are much longer. Constantly rebuilding the multiple big 36 cylinder radial engines it would take to keep a jumbo jet in the sky to FAA specifications would get prohibitively expensive. The problems that come from props that approach the sound barrier limiting flight speed don't hurt the case for turbines, but that first point alone makes turbines better for large passenger aircraft.

While you make a good point about the lower thermal efficiency of the microturbine, if the car is running off electricity it got from the wall 80% of the time is the extra cost of an almost 50% thermal efficiency direct-injection diesel justified? Probably not because the more of the energy is coming from charging the batteries off the grid the less important the combustion engine's efficiency is. Better to stick in whatever is cheapest to manufacture because it's not being used the whole time anyway.

RE: I like it
By Mint on 2/26/2012 9:26:39 PM , Rating: 2
I thought I mentioned reliability as well, but I clearly I didn't. You're absolutely right. Still, for a PHEV that uses that engine only 20% of the time, greater reliability over an ICE (which already last 300k+ miles) isn't much of a factor.

You're also right about efficiency not really mattering there, but when you look at the shit that the Fisker Karma takes for its 20MPG rating in range-extended mode, it's clearly something you don't want on your car's sticker in the showroom. This looks like it'll be a fairly pricey car, too, so you don't want to cut corners on something that will undermine the green image its going for.

FYI, I wasn't talking about a diesel, but rather a Prius-esque Atkinson-cycle engine.

RE: I like it


RE: I like it

RE: I like it


RE: I like it

RE: I like it
By FredEx on 2/27/2012 5:43:00 AM , Rating: 2
I was wondering about the spin up time and warm up with a turbine. Wouldn't that also add to them being a pain in the a**? Start up a piston engine and it is ready to go.

I read a while back about small piston engines in these instances could go ceramic, no need for oil and it boosts the efficiency due to very little thermal loss. Decades ago they fell out of favor in the engine design labs due to difficulties in mass manufacture and the extreme high cost, but that has changed tremendously. In a small engine used to just drive a generator perhaps they could work.

RE: I like it
By JediJeb on 2/27/2012 10:52:33 AM , Rating: 2
I guess the other thing to consider if using a turbine engine is what happens when the owner fails to maintain it properly? Blow a piston engine and you most likely break a rod or at worse throw it through the side of the block which absorbs most of its energy, have a catastrophic failure in a turbine and at worse you get a spray of turbine blades throwing shrapnel everywhere.

I haven't worked with gas turbines, but I have worked with small turbine vacuum pumps and when the bearing goes in one of those you can disintegrate the entire rotor into a spray of aluminum fragments filling the vacuum chamber.

RE: I like it
By Dan Banana on 2/27/2012 10:47:09 AM , Rating: 2
Re-looking at the Capstone range extender system the 30 kw figure is not the power output of the turbine engine itself but is the electrical power output of the charging system attached to the turbine. This gets confusing since in the USA we don't generally quote ICE power output in watts while Europe does. :-) At any rate in normal use the car would run mainly on the electric motor and batteries not the range extender be it a piston or turbine unit. The real thing to be seen here is will Nissan actually build this car and if so will it resemble these images.

RE: I like it
By ilkhan on 2/27/2012 1:36:57 AM , Rating: 2
The nice thing about an electric is that the recharging source doesn't change the 0-60 times. Stick a 5hp outboard in it to power a generator and this infinity would still blow the socks off alternatives.

Small diesel, small gas, turbine, hamsters. Long as they'll charge the battery they'll do the job.

RE: I like it
By lagomorpha on 2/27/2012 8:53:59 AM , Rating: 2
Stick a 5hp outboard in it to power a generator

Provided you're happy to limp home on 5hp or wait around in a parking lot while the battery charges if you manage to run the battery down. Would it extend the battery capacity by constantly charging it at red lights? Yes, but by how much?


Related Articles
