Quote:
Originally Posted by T and C
Mr. Adventure,
I think the power to weight ratio of an RV is more complex than that. The maximum horsepower rating on any motor is at a specific rpm. If the optimum rpm for a specific engine is 5000 rpm, and that engine is only turning at 3500, it is not developing its full designed horsepower rating at that moment. Therefore the actual, (versus rated) power to weight ratio is actually constantly changing as you drive.
Tom
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"Optimum" and max horsepower are at different places on the power curve. The purpose of all those gears in the transmission is to keep the engine in a productive range. The purpose of an automatic transmission is so that we don't have to do math to find the right one
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But you're absolutely right: the Ford truck V10 engine is designed to have a broad power curve like a diesel, with lots of pulling power across a wide rpm range (it has 150+hp from 2500 to 4500rpm, and most of that range is over 200hp). It's purpose is probably not to impress us so much with it's peak horsepower as it's value in a truck engine. But it looks like the Toyota 3.5l puts out 150 hp rising to 220hp while going from about 3700rpm to over 6000rpm, which isn't shabby (torque is in the 200ft-lb range vs a max of 410ft-lb for the V10) (the data is from people trying to sell performance-ware:Toyota
http://www.knfilters.com/dynocharts/69-8611_dyno.pdf and Ford V10
http://www.gearvendors.com/images/f68.gif). So, we currently have half the torque and 1/3 of the weight as my motorhome experience, netting a 50% improvement. We're not underpowered for towing a TrailManor.
What actually counts is having enough power in a range where you can use it, and the more pounds you haul, the more power you need and the more fuel you use. It's possible that I would own a different tow vehicle if I towed over the pass and through the Eisenhower tunnel every week, but I'm not worried about visiting there again someday.