[V8] Diesels and Hybrids

[Professor GT gmail]

Lots of conversation, so I thought I'd add to the mix.

Hybrids: the theory is to power the vehicle with electric motors, ASSISTED by an IC (internal combustion) engine, and a diesel being the best of both worlds. The absolute best hybrid in the world is the Allison Hybrid used in transit busses. This system uses two 100hp electric motors integrated into the auto trans, and has a diesel engine in front of it as well. Instead of a 14liter diesel as found on a non- hybrid bus, the hybrid system employs the use of a 5.7 liter diesel, so a much smaller displacement engine is used, AND with the electric motors performs better AND yields at least a 50% improvement in fuel economy, AND a 90% reduction in emissions.
The key with ANY hybrid system is that the maximum benefit is only realized if the vehicle duty cycle matches the intended design parameters. What this means in simple terms is that driving a hybrid in anything other that dense stop and go traffic is a complete waste of money. The advantage of a hybrid comes from regenerative deceleration  and regen braking. This is when the electric motors are switched to power generators, and the energy they generate is stored in the battery packs, and immediately used on the next acceleration when the driver tips into the throttle and the generators are instantly switched back to motoring mode to propel the vehicle. Conservative estimates show that about 50% of the energy is reclaimed in this process. Standard non-hybrid drivetrains do not recover any of this energy, so it is wasted.

Bottom line on hybrids: If the commute involves highway driving and minimal stop-and-go traffic, save your money and buy an econobox that gets max fuel economy. The extra costs associated with a hybrid will not be recovered unless the drive cycle matches design intent. The Prius, which is pretty much a downscaled copy of the Allison system is the best automotive hybrid, but again is not a wise choice unless the drive matches design intent. Factor in the staggering costs of the inevitable battery replacement and although it's really cool technology, not for my money! 

Diesels: These power plants offer the best efficiency of any IC engine known to man. With SCR technology (selective catalyst reduction) which is basically urea injection, the tailpipe emissions are ultra-clean. So, in spite of GM ruining the diesel market here in the states with the Olds Diesel debacle of the 1970's, this technology still reigns supreme. Problems: consumers perception of diesels as noisy, dirty, and unreliable - thanks GM! Also, greedy fuel companies raising the price of diesel fuel, something that costs less than gasoline to produce, just because they can! Lastly, a relatively recent concern is that the newer modern automotive diesels were designed to run on no more than 10% biodiesel content. Some states like Illinois are foisting higher concentrations on the market in a willy-nilly hap-hazard manner. Many consumers have no idea they are even pumping this stuff into their tanks! The problem is that in under 10k miles this stuff can destroy one of these engines and it's after-treatment system, and this is NOT a warrantable matter. I know of at least one manufacturer that is considering a stop-sale on all diesels in Illinois for this reason. Biodiesel is great for older non-electronically controlled diesel engines if the right precautions are followed, in fact I have been running one for over 50k miles with no issues, on straight waste vegetable oil. Unfortunately the new generation of diesel engines and their control systems will not tolerate anything more than 10% biofuel. None is best on these engines, which are designed to run on ultra-low sulphur diesel fuel. 
Bottom line is IF you know you can get  straight diesel, or no more than 10% bio, diesels are the hands down winner  in the efficiency wars. With proper maintenance they last longer too, so like most things, you get what you pay for!

The choice is yours, but my money goes with the diesel!


Thanks,

ProfessorGT
(Sent from my iPhone4)