Diesel vs biopower vs gasoline

This is a post for the hardcore fuel engineering types. For the record, I’m not one of those. I’m just a driver and an enthusiast. But it’s a good article if you’ve got the patience to read it through……maybe twice.

The headline gives you a pretty good idea: Will diesels have a future in Europe?

The author, Chris Ellis, questions the long term viability of diesel model cars in Europe and the rest of the world. As I alluded to, it’s a long and detailed article, venturing into engine development, fuel efficiency testing and even geopolitical factors. It’s not just assessing Europe either, despite the headline.

Diesel powered cars, now made with much cleaner engines, have enjoyed significant growth in Europe due to favourable tax conditions in many countries and fuel efficiency benefits. This article questions how much more growth there is in this marketplace, and the rest of the world, given the emergence of fuels such as E85 and the search for an acceptable “world fuel”.

Naturally, the discussion of an E85 vehicle brings the Saab 9-5 Biopower into play, and it’s reviewed quite favourably:

The success of E85 in Sweden has not gone unnoticed in Brussels, Berlin, Paris and Madrid, even if London has only just woken up to its attractions……

…..Equally interesting is Saab’s BioPower engine. While the application of flexible fuels has been pretty casual in most US designs, Saab have done a professional job on their latest engine, now that Sweden is committed to biofuels. As any petrol-head knows, high compression is good in a gasoline engine, and a key limitation is the octane rating of the fuel, typically 95 or so globally. But E85 is 104 octane, which potentially means more power and better efficiency, and a reduction in the compression ratio advantage enjoyed by diesel. As a general statement, US E85 engines are naturally aspirated and must run with gasoline compression ratios. That means they take no advantage of the superior efficiency that E85 affords. Bearing in mind that GM owns Saab, let’s imagine what a US Saab might be able to do by next year, using technology that is already shipping all over Sweden…..

…..Let’s assume ‘our’ Saab’s owner is based near a gas station with an E85 pump. So most of the time the Saab is refueled with E85, and can deliver up to 180 bhp from its 2.0 liter engine. And its fuel cost per mile is much better than on gasoline, because E85 burns more efficiently and is priced to compete on a cents per mile basis with two dollar a gallon gasoline (of blessed memory). But now our heroine has to go into darkest Gotham, where the wicked Oil Barons live who won’t let E85 be sold anywhere within 100 miles…..

…..the Saab is smart. However much gasoline our heroine mixes in with however much E85 is still swilling around in the gas tank, the car senses the new mix and signals the variable boost turbo charger to back off appropriately. Now the E42.3 (say) is fed in, with air boost at a pressure low enough to avoid pre-ignition, and the Saab shoots off into the night. If ‘shoot’s the right word, because the 180 peak power has now dropped back to a mere 162 bhp. Not exactly dangerously slow, but still a little sluggish. Mind you, it’s still more than the 150 bhp of the standard issue gasoline Saabs favored by Gotham’s yuppies.

What if the BioPower engine replaced the 4-cylinder diesel in the new Swedish-built, Europe-only Cadillac BLS? You don’t imagine GM haven’t already thought of that? For an encore, add an AWD surge power unit with at least 200 bhp, and you could give the Batmobile a bit of competition, at least until that big turbine spooled up properly. Could GM sell some in the States? Is Bob Lutz a pilot?

It’s an interesting article, not for the time-challenged, but worth your attention. To read the full text, click here.

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2 Comments

  1. Very Interesting read.

    Chris Ellis has actually put a real case forward for Hybrid technology. Unlike Other Journalists that say Hybrids are just a gimmick.
    I think that people are buying diesel cars today because of the average 40-50mgp (UK) but get the same performance and maximum speed of an equivalent horse power petrol car.

    I think people would buy a full electric engine if it had the same 0-60mph, top speed as a petrol car. I also think they would pay 1,2 or £3,000 more that car that, if it would cost a fraction to re-fill or recharge.

    I pay 86Euros to fill a 9-3 1.8t SportSaloon (and get about 25mpg)

    I Pay 81Euros to fill a 9-3 1.9TiD SportSaloon (and get about 45mpg)

    So the question is: would you pay say an extra £2 or 3,000 for a car that would cost a 1/4 of the price of pertol to fill or re-charge??

  2. Swade-
    US$42 to fill dzlsabe with B100,then ~40mpg but realize this was on cruz at ~85mph, I’m sure it would be better at 65-70 but thats damn hard. My problem with ethanol is we’re not seeing the oh whats the word?…bransleforbrukning(mpg)on the E85 engine….and if it’s as I suspect with E10 experience, then less mileage(in the low ’20s) and range is going to be a hard sell.
    Now don’t get me going about koldioxidutslapp!

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