Lexus to introduce hopped-up ct 300h, three other new models

CT300h will be interesting. I hope it has the next gen 2.4L engine. The one used in HS250h is outdated.

 

Can you maintain FE with the 300h over the 200h?

 

I'll be anxiously awaiting a F/awd RX250h, a Lexus version of the Venza. New Venza I4 upgraded to DFI, 15:1 base/native compression ratio (Atkinson cycle). Venza rear drive system, not separate electric motor.

 

The real challenge for future hybrids is to improve hwy FE. On the hwy there is little chance for regenerative recharging of the battery so the ICE power must be often used.

The answer: Multi-mode engine, Otto/Atkinson/Miller.

Lower the engine displacement to improve "cruise" FE by adding a SuperCharger that is only to be used above ~50MPH. Double down, lower displacement reduces friction and pumping losses and SC effectively raises engine displacement only when/if needed.

SC provides BOOST only whenever hybrid battery is not able to.

Positive displacement variable speed SC also allows elimination of the throttle plate metering system. SC driven via a PSD with ICE and A/C synchronous motor inputs

 

^ Great ideas.

If you use a multi-mode engine, it won't make sense to use a 2.4 L engine. Rather a turbo or super charged 1.8 L engine may work as well.

Does it make more sense to use exhaust to turbocharge the engine, or use the battery (or electrical pathway/MG1) to electrically supercharge the engine?

 

Where's my IS400h?

 

If we are talking about the ct200, I would stick with the 1.8L mill. Toyota's concept 1 future engine adds di and longer piston stroke. Mazda's Skyactiv is built as a DI multi-mode as west suggests. Toyota has agreed to licence the psd to mazda, so we should see these parts together in the next couple of years. I'm sure any patents toyota doesn't already have they can get as part of the deal from mazda. Skyactiv in otto mode with regular gas in a prius sized 1.8L engine will pump out around 140hp. The MGs and perhaps the gearing will need to change, but this would bring us to around 175 hp. If they also change the battery to a more powerful one (same capacity but maybe lithium) the ct could get to a peak of 190 hp. This is a pretty big boost for small changes and today's technology.

As West has mentioned before turbo charging hurts efficiency at the low power range. It can help at high power and boost peak efficiency. Toyota's concept 2 uses turbo charging so this is what we can expect from them in the future.

Supercharging is more natural with an Atkinson engine to make it a miller cycle, and can boost hp at all ranges. It seems though with the psd setup a more powerful battery and the ability to use it through MG2 gives the biggest boost at low end torque. Nissan is building an ultra efficient miller cycle engine. We should see when concept II, toyota's turbo comes out whether they or Nissan with super charging did better. My bet is on twin scrolling turbo charging on the most efficient engines.

 

That Venza is a big boat! Much bigger than Prius. Seems a ways off.

I was very dissapointed renting a Venza V6 ... the stooooopid driver's seat did not lower down enough to provide proper sight lines. In a Venza? That's ridiculous. I noticed Camry has same issue for me. Accord with sunroof has plenty of headroom. I hate cars that don't accomodate for 6'2" ers that should do so. Nothing wrong with me, I fit in an Accord coupe. Partly why I'm sort of anti-Toyota.

 

next gen 2.4l is actually 2.5l AR engine

 

I would like to see both on the same car ... with the extra HP coming from the plug; not the pump. There should be a challenge for Lexus engineers, with teams competing to add as much power as possible to the existing 1.8L engine, with the requirement that the extra power must come 100% from electric and 0% from gasoline.

 

"...MG2 gives the biggest boost at low end torque.."

"low end torque".....City stop and go, slow moving traffic.

Also where you're most likely to get FREE "fuel" via regenerative battery charging.

Freeway/highway cruising, NO FREE FUEL.

SC for boost.

 

The torque also allows for greater acceleration on the highway. This allows for a downsizing of the engine which can allow it to be more efficient at cruise speed. SC can do the same thing, but will be more expensive. If you need to go beyond these getting more air through turbo or supercharging is the way to go. I was not disagreeing with you there.

SC does seem better matched for a hybrid than turbo. My guess is toyota is working on their future tech for hybrids and non, so the the turbo is winning because it can be shared across platforms. I also believe that in this implementation turbo chargers may be cheaper especially if Toyota can get costs down to the premium hyundai appears to be doing in its sonata turbo.

 

At reasonable highway/freeway cruising speeds the ICE will be turning a substantially elevated RPM level as of course also would/will the MGs. Put your foot into it for a decent level of acceleration and the MGs' RPM will be well above their low end torque level.

Couple that with the inability to regain "fuel" via regenerative braking while cruising and it becomes easy to see why an SC would be more appropriate FE wise at elevated road speeds.

Assuming, of course, the SC RPM, boost level, is totally variable and independent, fully independent, of ICE RPM. Use of a PSD, Power Split Device, as the drive input to the SC would allow the SC to simply idle along, supply only enough, just enough, intake airflow for current ICE output demand.

It pays to remember, keep in mind, that for a given level of boosted airflow volume both an SC and a Turbo require virtually the same level of input drive power. In the past Turbos were accepted as being more efficient due to the use of WASTE, "free" energy. With the advent of the adoption of the Atkinson cycle we have now learned that energy need no longer be "wasted".

 

Low end is the wrong term, you are right. The engine is loafing around at a low speed and you hit the throttle to accelerate to pass or climb a hill. The instantaneous acceleration from electrics gives a disproportionate gain to its horsepower. You can instead use some of the electricity to pump more air into the engine with a SC and with good fuel management this can also feel instantaneous. In the first case you need to recharge later by drawing more power from mg1 than mg2 needs. In either case mg2 needs to be made more powerful as it must grow with the ice horsepower in the psd.

Neither will be able to regenerate. sc can provide better sustained hp. turbos at least for the same bucks can provide the biggest hp boost with the expense of some instantaneous power at low ice rpms.

It still provides a parasitic loss either to the battery or extra power from mg1. It makes up for this by allowing for a smaller efficient engine. Implementation is important. Since MG2 needs to become more powerful under either scenario that seems the least expensive step. So in order of implementation DI and multimode provide more hp and likely more efficiency. Then upgraded motors and possibly forced air to increase acceleration.

 

What I found very early on in the ownership/driving of our '03 Prius was that even in freeway/highway cruising the use of the electrics for "re-acceleration", even slight acceleration, simply cannot be avoided. What I noticed was the hybrid battery would be allowed to discharge to some "trigger" level, <70%(?) and then the ICE would begin to be used to recharge the battery, bring it back up to a sensible level.

On a drive from Seattle to Portland this cycle seemed to repeat 6 to 8 times.

That has to be a seriously lossy path in comparison to simply powering an SC to a high enough level for those accelerations.

Plus, as you point out, the use of an SC would likely result in the downsizing of the ICE displacement volume...win..WIN..! Couple that with displacement downsizing due to adoption of DFI/GDI/DI, >15:1 base/native compression ratio, and we might just begin to see 50 MPG city/hwy.

Someone just announced a DI engine, OTTO mode engine, with....14:1 CR...!

Might that mean a Miller cycle engine with base/native CR of 17:1..?

 

"..Since MG2 needs to become more powerful.."

No, that's the way Porsche (and Lexus) thinks..make use of new technology to produce an even greater level of HP/Torque...

I would LOVE to see an LS450h using the GS450h hybrid DI 3.0L V6 engine. My very fine '92 LS400 has "only" 248HP. Or a 35 MPG 300 HP 2012 Porsche 911 even.

I am NOT proposing, supposing, an increase in the current level of HP/torque overall. SC and DI would allow downsizing of the ICE volume to improve FE while maintaining the current level of HP/Torque

 

Well you are on a thread about lexus increasing the hp of one of its cars, I do think more people will buy a $35K luxury economy car if it can hit 60 around 7 seconds instead of 10.

The GS450h drive train is a pig already. I like the path of the Infinity M hybrid better if you are going that way. The increased hp on a ct300 will still be much more fuel efficient than any of these cars.

For its class the ct300 is underpowered. Adding SC at teh current hp will add to the price and likely mean a down sizing to 3 cylinders, which is going to cause few sales than the current vehicle. If you increase the hp you can drop the drive train into bigger vehicles like the TCH, HS250, etc and increase the efficiency and drop the weight.