From my searching I can not find anything about any recent Prii models using direct injection engines. If this true is this due to the requirements of our Atkinson cycle engines? If not it seems Toyota is, yet again, missing out on using technology that would give us better mileage and more power. Their other Toyota (excluding Lexus) engines, to my knowledge, do not use it. And ya gotta wonder why.
Or Ford may just be ahead of Toyota with its Lithium C-Max hybrid. Compare Side-by-Side Also, remember the Elantra was once rated at 40mpg!
I do not see anything that precludes use of Direct Injection in an Atkinson Cycle engine, but I do suspect nothing about the Otto Cycle version will be unmodified. One advantage of DI in an Otto cycle engine is reduced pumping losses, which are already greatly reduced in a Atkinson Cycle engine. Gasoline direct injection - Wikipedia, the free encyclopedia
The 2014+ Accord Hybrid has an Atkinson cycle engine with Direct Injection. Honda claims (see link) that it is "the most energy efficient mass produced gasoline internal combustion engine available in the world, based on internal testing." 2014 Honda Accord Hybrid: Powertrain - Honda News That being said, DI engines do have their downsides, including the increased potential for carbon buildup. I certainly wouldn't be surprised to see the next generation Prius engine with DI.
I have owned several Honda Accords before. I find that the new Accord with DI is on the noisy side. But why not Valvematic(Corolla Eco), about 10% more power and 10% more fuel efficient.
Toyota is moving to DI. I think the non-hybrid NX is one of the first models to get it in the US market.
Direct Injection also creates more emissions (air pollution) along with carbon buildup on the valves since the gasoline detergents (additives) no longer contact the back of the valves. The Prius was largely a result of California's very low emissions requirements that only Toyota could initially meet.
DI increases particulate emissions. Europe may require them to equip exhaust filters. Some port inject gasoline engines exceed the particulate limits that required diesels to have DPFs. Gasoline cars aren't required under US regulations to have their exhaust tested for particulates. The older generation of DI had issues with carbon build up. The current generation has a more precise level of injection timing that should reduce such carbon build up. Not that it couldn't happen, but the engines have been on the road for over 3 years, at least. Major issues should have arisen if they were going to in the models that now have DI. The car manufacturers may return to port or a hybrid port and direct injection(Toyota used this on a past Lexus engine), but if they do so, it will be to avoid having to install an exhaust filter, and not because of carbon build up.
Direct injection has these main benefits that I'm aware of: - Lean burn under low load - hybrid engine is never run under low load - More power under high load - efficiency drops Gasoline and diesel engine will in some point in the future meet with certain same characteristics. Petrol engine will get a option to run in compression ignition (direct injection is the only way), diesel engine will get lower compression and less lean burn under low load with variable valves (miller cycle).
They have just been waiting on the normal life cycle of engine families and car models. That is why GM just started releasing DI in the US last year.
exliderider, getting a bit snarky aren't we? ;o) Cool yer DI jets, man. My question was, as you see, not just directed at the Prius but at the entire Toyota line. If Toyota had even begun to use DI somewhere in their lineup I would ask only about the Prii. Trollbait says it's comimng in the NX. GOOD! Yes, DI means a much higher pressure fuel pump and fuel lines. And it means no cleaning of intake valve seats. The intake valves will have to "suffer" along with the exhaust valves. Thanks to those of you who posted the more informative posts (everyone below bisco's 1st) explaining the ins and outs of "to DI or not to DI" (or to do a hybrid DI & port injection). I had no knowledge of the carbon buildup and particulate problems with DI. Particulate emissions is a great concern since it is airborne particulates that land on snowfields and accelerate glacial decline and shrinking fresh water reserves. And GasperG's post is intriguing regarding the future of internal combustion engines.
The turbo NX already has it. Though it does appear to have port injection in addition. An early Lexus DI engine did the same to reduce the carbon build up. It may not be needed for that purpose any longer, but it likely also reduces particulate emissions.
Ok, to get you Americans up to speed Green Car Congress: Toyota’s second turbocharged gasoline engine now available in Auris in Japan; 36% thermal efficiency Note that Toyota was claiming 38% efficiency from a normal NA 1.3 engine, a turbo version is there only to get the power and lower consumption under "light foot".
