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Old 07-10-2012, 05:58 PM   #1
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hp vs length

I know of the generally used formular of 10 hp per foot, and I think it a good one. Is this true with atag axle unit as well? Would the tag axle MH require possibly more? For example there are 42 ft tag axle MHs with the 400 hp motor and while an excellent engine is this not on the weak side for this unit? Example being the HR Sceptor 42'.
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Old 07-10-2012, 06:08 PM   #2
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It depends on what you call weak. I have a 40 ft with a 330 hp, and it gets up to speed so fast it surprises me. I think the HP to weight ratio at a certain point causes a mileage penalty.
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Old 07-10-2012, 07:04 PM   #3
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Length to HP

While the rule of thumb is useful I think the weight of the unit is very important as well. Some coaches the same length can be 20 thousand pounds different in weight so the rule of thumb might not work too well on a heavier coach.
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Old 07-10-2012, 07:12 PM   #4
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Never heard that "rule". The one I've seen for years is 100#'s per 1 hp. That ignores length (which really has no bearing) and depends on what matters which is weight.

Our Dutch Star weighs around 32,000#'s and has 435 hp, which works for us.
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Old 07-10-2012, 08:33 PM   #5
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Quote:
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Never heard that "rule". The one I've seen for years is 100#'s per 1 hp. That ignores length (which really has no bearing) and depends on what matters which is weight.

Our Dutch Star weighs around 32,000#'s and has 435 hp, which works for us.

I like that, and I agree with that. We had a Tiffin 42' tag with the Cummins ISC 360 / 1050 for about three and a half years and 37K miles. Power was NEVER a problem but we weren't gonna win any drag races either. We towed the same jeep we tow now and always kept up. I prefer the extra power we have now and I do feel it when accelerating from a dead stop ..... once up to speed however, not such a big deal.
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Old 07-10-2012, 09:08 PM   #6
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does seem like better formular.

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I like that, and I agree with that. We had a Tiffin 42' tag with the Cummins ISC 360 / 1050 for about three and a half years and 37K miles. Power was NEVER a problem but we weren't gonna win any drag races either. We towed the same jeep we tow now and always kept up. I prefer the extra power we have now and I do feel it when accelerating from a dead stop ..... once up to speed however, not such a big deal.
I also like your D C's use of Banks to kick up HP. If one could save money in a buy on mh of choice that they perhaps think a little shy of hp, they can take a part of savings and bump up horses with Banks. I understand the Banks does not effect warranty either....but sure helps torque and hp.

Do you feel the tag requires more hp and.or torque?
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Old 07-11-2012, 09:00 AM   #7
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I am sure that the extra axle takes a few more up to drag, but the advantages more than offset that cost. Our 43 ft. Dutch Star has 400 hp with 35,000 lbs plus toad, and that is plenty of power. Guess that would be about 100 lbs per hp! The torque is probably the best yardstick. 1,250 ft. Lbs. I believe.
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Old 07-11-2012, 10:46 AM   #8
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I follow the rule that you can't have too much. I wanted a tag, so that meant a 40+ foot coach, and I was very leery of the 400 HP engines. Eventually focused on a 525 HP Cat 13 liter, or a Detroit Diesel 60, and wound up with a Cat.

I pull a Suburban and I drive in the mountains, and I like not just the torque and HP, I really like the braking effect of the big engine - it puts out about 400 braking HP and heading down a long 7% grade that sure is nice. I almost never use the service brakes.
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Old 07-11-2012, 10:55 AM   #9
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I am sure that the extra axle takes a few more up to drag, but the advantages more than offset that cost. Our 43 ft. Dutch Star has 400 hp with 35,000 lbs plus toad, and that is plenty of power. Guess that would be about 100 lbs per hp! The torque is probably the best yardstick. 1,250 ft. Lbs. I believe.
The 1 hp/100 pounds is what I have heard is a good ball park. I don't know if that should be translated to "at the wheel" or at the fly wheel. Probably the later since that is the statistic quoted in the specs.
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