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#72
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Yanmar Offers a Turbo Diesel Outboard
John H wrote:
On Thu, 12 Oct 2017 19:54:25 -0400, Alex wrote: Keyser Soze wrote: On 10/12/17 12:15 PM, wrote: On 12 Oct 2017 13:51:41 GMT, Keyser Soze wrote: Here's a real world example of the diesel vs gas engine trade off. Our old Bertram 33 had a 320 gallon fuel tank which seems like a lot but it had 454 gas engines which burned 35 gallons per hour. Cruising speed barely reached 18 knots on a good day. Doing the math, you come up with a safe fuel range of less than 140 miles, not enough for offshore canyon fishing in the NY area. Converting to diesel engines, the burn rate drops to about 20 gallons per hour, and cruising speed climbs to 23 knots or so, for a fuel range of around 300 miles. That's a big difference in the capability of the boat and has nothing to do with the price of fuel or reliability. --- This email has been checked for viruses by AVG. http://www.avg.com About $75,000 to $100,000 for removal of gas engines, engineering, plumbing, new pair of 250 to 300 HP diesels. If gasoline is three bucks a gallon, the conversion would cover 25,000 gallons of gasoline. Ouch. ? === The whole point of my comparison excercise was to show that increased fuel range with diesel is often the deciding factor as opposed to fuel cost savings. Oh, I agree with you, and on a 30+ footer, one or two diesels usually are a better choice, especially on a heavier boat Brilliant! Would you expect less from one who has twin Volvo diesels on his trawler (undoubtedly a 30+ footer)! Not for a minute. |
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#73
posted to rec.boats
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Yanmar Offers a Turbo Diesel Outboard
Keyser Soze wrote:
On 10/13/17 7:05 AM, Mr. Luddite wrote: On 10/13/2017 5:32 AM, John H wrote: On Thu, 12 Oct 2017 17:48:36 -0400, "Mr. Luddite" wrote: On 10/12/2017 5:05 PM, Keyser Soze wrote: On 10/12/17 4:53 PM, wrote: On Thu, 12 Oct 2017 16:42:10 -0400, wrote: I was curious so I looked it up. A fully dressed 454 with cast iron heads weighs 685 lbs from the factory. A Cummins 5.9L diesel by comparison is 1200 lbs or 515 lbs heavier. Twins would mean a weight difference of over 1,000 lbs. That's quite a bit, even for a 39' boat. Major difference is: The 454 develops 450-500 lb-ft of torque at 3200 RPM (depending on year) while the diesel Cummins develops peak torque of 610 lb-ft at 1600 RPM The extra torque probably comes from the longer stroke in the diesel. (4.0" vs 4.75") They make gasoline engines "square" or even over bore to reduce the reciprocating forces of a longer stroke for a given displacement It lets them run at higher RPMs. === I believe the extra torque is mostly a result of the higher compression ratio in a diesel. The higher ratio effectively increases the duration of the power stroke compared to a gas engine. I thought it was the result of a combination of factors, including higher compression ratio, more heat content of the fuel, higher turbo boost pressure, and greater heat content of the fuel, and continuous pushing of that fuel into the cylinders. Probably all you mentioned ... oh and also the greater heat content of the fuel in case you forgot. :-) He probably missed that with his cut'n'paste. yup. Shouldn't you boys be telling us to give Trump a chance? Shouldn't you be posting original thoughts? Anyone can search the internet for whatever fits their agenda. |
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