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Engine, Fuel System, Transmission, Hybrid Cars, Coupe, Convertible, Hatchback, Truck, Sedan, SUV
#197 of 206 Re: Series hybrid models [toyolla2]
Sep 24, 2007 (1:26 pm)
"I'd be surprised if a 450cc engine could generate 60 HP at less than 8,000 RPM "
I wrote 'consider the 2006 Honda CRF450R engine which weighs in at 28.9Kg, its oversquare 96mm x 62mm single could probably put out around 60Hp 9000rpm for those short bursts of vehicular acceleration.' -citation needed.
I don't have dyno figures for this engine - morons ripped the pages out my library copy of Cycleworld. So for now let's extrapolate from the Honda CBR600RR which yields 118Hp from an inline 4cyl. Each of its 75mm pistons should develop 29.5Hp. At similar piston speed and piston dia. (squared) CF450R should be capable of 48.3Hp on paper. The cooling efficiency of a single is way better than a four so it may very well be capable of 60Hp. I'll do further research on this and get back later.
Notice another benefit of the series hybrid idea that could make this engine even lighter. Honda describes this particular engine having a dual sump design in order to separate clutch/gearbox contamination circulating into the engine lubrication. A crankshaft mounted alternator would of course not need this consideration. It has a 12:1 compression moving it towards diesel effcy also.
The piston speed limitation I would place at 18m/sec or 9000rpm with the 62mm stroke. Yes, I gun for speeds higher than 8000rpm because this reduces the size of the alternator needed for an equivalent power.
Re longevity, I agree no engine will survive 9 - 10 thousand RPMs for extended periods, but if we are looking at 8 seconds to 60mph a theoretical distance of only 117 yards will be covered before the engine will be returned to speeds of 3000 rpm or less for cruising.
#198 of 206 The 1/X CONCEPT PRIUS
Feb 06, 2008 (11:22 pm)
On February 6th 2008 The 1/X Concept Prius was displayed at the Chicago Auto show.
This vehicle said to have around the same internal dimensions as the Prius and intended to seat 4 rather than 5 passengers has a curb weight of 926lbs against 2,890lbs of the Prius. It achieves this by the extensive use of carbon fiber reinforced plastic. The 500cc flex fuel engine is part of a plug-in hybrid powertrain that weighs only one quarter of the equivalent system in a Prius using a lithium ion battery. The result is a vehicle with the possibility of traveling over 600 miles on a small four-gallon tank of fuel and achieving the acceleration performance that is equivalent to the Prius.
They don't explicitly announce this is a series hybrid and no photographs of the powertrain have been put up. Furthermore I don't know whether this is a single cylinder engine either and that is rather important for cost reduction.
If we can sidebar on this for a moment - intuition would tell us that a 850cc inline four engine, for example, probably involves as many components and machining operations as a 2.7L inline four. It is therefore reasonable to expect that the price delta between these engines in mass production may be quite small. It is a fact that Tuner shops notice a similar situation in the costing of crated V8 engines between 302 cu. inch and 454 cu. inch that are produced specifically for the aftermarket.
On the production line it's the reduction in number of cylinders that would seem to bring about significant cost savings. This might be the reason Toyota is about to replace the 2.4L inline four on the Camry with a new 2.7L engine. It occurred to me that this engine may come so close to 200Hp to discourage the 20% of buyers that have usually accepted the large price delta for the upgrade to the 3.5L V6. That they would have to move up to the Avalon to get the V6 would then make more sense. It further begs the question that in the horsepower race, just when is enough enough ?
For those growing numbers more interested in fuel economy, however, when a 150mpg vehicle arrives with 0 to 60 in ten seconds I think there are going to be plenty of takers. In case there are still those who will equate this car with the 3-cyl 67Hp Insight it is well to consider that mated to a stepped transmission, albeit even with IMA assist, is a poor way to extract power from an engine. When available maximum power is limited to 67Hp, then when you need it, you must have that 67Hp right away and it must maintain continuously. It is not an acceptable system that allows vehicle acceleration only while the engine is struggling from the middle to the top of its power curve and then at which point you are forced to changeup and cause the the engine revs to sink back down to a lower power point to repeat the process all over again in the new gear. It is just poor efficacy to do this. That is what I have always been against.
Earlier posts #186, 188 and 195 have outlined different aspects of my design and it is encouraging to see that as far as engine capacity goes finally someone at Toyota 'gets it'.
#199 of 206 Is it time to end the horsepower race ?
Apr 14, 2008 (6:42 pm)
This article by Mike Allen over at Popular Mechanics seems to echo what I have been proposing in the preceding posts regarding smaller engines. He questions the choice of today's engine sizes, and in this particular case the size of the motor generator set being fitted to GM's PHEV, the VOLT. Do we in fact need an engine that all by itself could generate enough electrical power to probably chirp the tires off the line? He proposes a more modest 10Hp, and goes on to say, in effect, that a vehicle that would cover the 95 percentile of commutes might be more efficacious to economical design. The 53kw gen on the VOLT will provide 45kw continuous power which is more than enough to cruise at 100mph - but why ?
#200 of 206 Re: Is it time to end the horsepower race ? [toyolla2]
Apr 15, 2008 (10:33 am)
Maintaining highway speeds (~70mph) requires more than 10 hp even for the most aerodynamic vehicles. If you're going up hills, into a headwind, have several passengers I'm guessing a minimum of 25-30 hp would be required. Sure the heat put off by the ICE powered generator would solve some of the mentioned problems in cold weather but only after you had depleted the batteries to the point where this generator kicked in. Isn't this the situation you're trying to avoid? For my 9 mile commute this wouldn't do me any good at all. For that matter a traditional heating system is pretty worthless for the first two-thirds of my trip. And what about running the air conditioner in hot weather? Again, 10 hp isn't going to cut it. Besides, it was my understanding that battery packs put off heat. Why can't this be used to help heat the cabin? I suspect that it will be.
One of the nice things about electric motors is that increased power does not equate to a reduction in efficiency. In fact small electric motors are typically less efficient than larger ones. The electric motor on the Tesla Roadster weighs about 70 lbs. So I don't think weight is much of an issue. Certainly driving 100 mph is going to use more energy than driving 70 mph. But for the person who chooses to drive 70 the fact that he has a more powerful motor than he needs will not result in an efficiency penalty. So you can have a confuration that appeals to the performance enthusiast as well as the person trying to use as little energy as possible.
#201 of 206 press request
by kirstie_h HOST
Apr 15, 2008 (12:50 pm)
A reporter hopes to speak with anyone who purchased or considered a hybrid vehicle in 2007. If this describes you and you care to share your story with a reporter, please respond to ctalatiedmunds.com with your daytime contact information and a few words about your experience no later than Friday, April 18, 2008.
#202 of 206 RX 400H HSD simulation
May 15, 2008 (3:02 pm)
Is there a site that provides simulation for RX 400H? I kmow there are a number of simulation for Prius hybrid in which you can see the relationship between road speed, engine speed, MG1 speed and MG2 speed.
I am particularly interested on the engine speed at 60 MPH if the MG1 is frozen to zero speed. In the prius simulation, the engine speed is 2500 RPM. I want to know the engine speed of RX 400H in the same situation.
#203 of 206 2ZR-FE for 2010 Prius ?
Jul 17, 2008 (12:29 pm)
Wasn't the 2010 Prius rumoured to be subject to cost reductions ? Although so far I've not heard any details following those CEO prognostications, some say the engine will be moving to a version of the 1.8L 2ZR-FE double VVt-i. The adoption of the "R" family engine is to be across the whole range according to Kdhspyder, our resident 'mole' if he doesn't mind me saying.
I see also that Chrysler, not to be outdone, has gone this route of providing the wider camming authority of double VVt in the 4 cylinder engines of their current offerings of Caliber,Jeep Patriot, Compass, Sebring, Avenger and Journey.
At Toyota we know that the Corolla has already gotten the 1.8L 2ZR-FE. Wiki shows a third member, the 2.0L 3ZR-FE at 140 Hp, which could be a base engine for the Camry line as gas enters $5 territory. The Hybrid Camry could then become the power version for Camry replacing the V6. That would clarify the Avalon role to be the sole choice for a V6 sedan at the dealership.
It appears that all three engines share the same bore of 80.5mm which is up from the previous 75mm for the Prius. Normally piston bore is a good indicator of power for a given piston speed. In this case power varies between the three engines because of increasingly longer strokes while leaving red line max rpm almost the same for all three engines at 6000, 6000 and 5600rpm resp. , with power ranging from 124Hp to 140Hp. Since they have the same bore it is clear that Toyota gets the power via higher and higher piston speeds across the range afforded purely by increasingly longer strokes.
There must be cost savings in having the same bore size over a range of engines. Makes you wonder though how critical bore/stroke ratio can be in the final analysis ! That does prompt the question regarding a business plan that builds three engines which differ overall by only 16 Hp. Perhaps someone out there could enlighten us ?
The 1.8L 2ZR-FE double VVt-i is as mentioned the current Corolla engine and I can't see them using this in the Prius when the smaller 1.6L 1ZR-FE engine at the bottom of the "R" range is available. This smaller engine still outperforms the 1.5L 1NZ-FE by 20Hp. A 40Hp increase by the Corolla engine seems excessive even when reduced by Atkinson camming.
I have to assume they are going with the 1.6L 1ZR-FE. They may also slow it down to 5000rpm. The following estimations show the effect. This junior member of the "R" family has a much reduced stroke of 78.5mm compared to 87.4mm previously The Prius piston speed will now be 90% that of the previous engine because of the new shorter stroke. When you factor that in along with the larger bore you would expect a 3.5% increase in power with the 1.6L but you would be wrong. In this case double VVt- i appears to deliver almost 20Hp or 20% more power which is hard to understand.
On the torque side we would expect Atkinsonizing to cause a drop off of 25lbs-ft of torque so we might expect 90lbs-ft to come through this time instead of 82lbs-ft. It will be interesting to see how MG1 handles this. Either the PSD ratio will be increased speeding MG1 beyond 10000rpm or MG1 will be beefed up to handle the new torque.
#204 of 206 A question to Toyolla2..
Aug 21, 2008 (6:58 am)
...that I have not been able to find an answer anywhere on the net.
In the HSD system - at startup - at a standstill - there is a 10 sec delay designed into the running of the drive system. This I believe is called phase 0 in some discussions. The vehicle is READY if the driver chooses to drive immediately but if the vehicle remains stationary then nothing happens until the ICE kicks in - giving a boost to the traction battery.
My admittedly non-technical hypothesis is that MG1 draws some juice from the traction battery to get the ICE pumping and spinning without actually injecting any fuel into the cylinders. This to make the ICE ready to jump into action in an efficient state. If the vehicle doesn't actual go into drive mode then the ICE starts to pump fuel and generate power which goes to 'pay back' the juice borrowed initially.
After the ICE has paid back its debt it shuts down until needed.
How much of this is accurate? Thanks
#205 of 206 Re: A question to Toyolla2.. [kdhspyder]
Aug 21, 2008 (7:14 am)
I believe the HSD system waits about 7 seconds after ready before starting the ICE, if necessary. MG1 will spin the ICE only if it intends to start it and spins it up to about 1000 RPM without fuel or sparks until oil pressure is established. Once oil pressure is established fuel and sparks are added and you have a running ICE.
#206 of 206 Re: A question to Toyolla2.. [kdhspyder]
Aug 25, 2008 (1:05 am)
I am not saying this is the answer.... but my understanding is that whenever the engine starts up it must continue until it has brought the Oxygen sensor up to temperature.I seriously doubt that one start cycle alone is a significant battery draw to require a recharge.
The 10 second delay on the Prius system engine startup may be the coolant temperature bypass valve allowing hot fluid stored in the thermos reservoir to be circulated through the engine. When that has been accomplished it enables starting of the engine to proceed.
Why is it programmed to do this ? I can only guess that the assumption is that if the car is not going to be moved in electric mode after a reasonable time delay, all bets can be covered if the engine is pre-emptively 'prepped'.