Quote:
Originally Posted by Ken Fry
Thems is mighty strong words, pardner. 
I agree that it would be nice to avoid the use of a catalytic converter, but the three-way catalyst was the start of a group of technologies that have permitted specific output levels from family sedan engines that are much higher than we used to get from pretty exotic sports car engines. Prior to emissions controls, we thought of 60 hp per liter as being quite good for a sports car, and put up with 10% of the fuel going out the tailpipe unburned. Now essentially nothing other than water and CO2 comes out the tailpipe, and we get 75 HP per liter from family sedans. None of the old engines were more than 25% efficient at peak, but now the Prius is 37%.
While it seems counterproductive to inject HC into the converter, that is essentially what we have been doing for a long time with spark ignition engines. Injection typically dithers between 1% too lean and 1% too rich in SI engines: whether it actually passes through the cylinder makes little difference. I'd say it's an unfortunate fact of life, or perhaps ironic, rather than disgusting.
But I agree, the Transonic system sounds pretty good. |
Ken, I couldn't agree more about the advent of the 3 way Cat. In the Nissan Z car it was the 1981 model. They raised the compression and began the pathway back to performance. Engines could be tuned for power and the cat would clean up the emissions. FI was working at 40 PSI regulated.
Now 30 years later it's time for the next "significant' jump in emissions technology. FI in some cars today is approaching 200 atmospheres pressure. Computer controls, only a dream in 1981 allow multiple injections at multiple points in the combustion stroke. In 1981 the injected fuel first had to get past the intake valve. Today the injected fuel cools the combustion chamber temps and can actually provide the means for significantly higher compression ratios, which is the source of more power (not the only source but the principle one). Precise control of the cam timing can eliminate throttle plate restrictions in many cases.
Precision control of transmission shift points, as well as the dual clutch 6 and higher speed transmissions allow more low speed higher load operation.
The wife's Sorento has a 2.4 liter 4 cylinder engine, producing 191 HP on regular pump gas. Combined with a 6 speed dual clutch transmission in a 3800 SUV, you have an EPA rating of 32 MPG highway.
The Mazda SKYactive seems to go a step further. The previously linked Chiron free piston engine, which has thermal efficiencies as high as any currently produced IC engine regardless of size, could produce fuel economy of 50 MPG in the same vehicle. Add to that an operational tactic of run at best bsfc or not run, and a capacitive regeneration system and you can only guess at the mileage. The EPA calculated an 80% improvement due to power train advancements in 2006.
Manufacturers today, in my opinion do not want to see leaps in progress that would make last years models obsolete overnight. The resulting economic disaster in the used car market would be unprecedented if a quantum leap in technology was incorporated today. The question is can we truly afford to wait until THEY decide the technology should be made available, or should we just build the damn thing our self.
regards
Mech