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Topic: Horsepower - How Much Is Enough...Too Much? (Read 704 times) previous topic - next topic
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Horsepower - How Much Is Enough...Too Much?

Yahoo Message Number: 72326
I would love to draw on the collective intelligence of this board. We're leaning towards a 2007 Intrigue Jubilee with a 525 HP Cat engine. But also at a couple of older coaches (some CC, others not).

Here's the questions

We're in S. CA and would be traveling up into the mountains (summer and winter) as well as throughout the US (continential divide crossing will NOT be uncommon). Would be looking at a quad slide 45' with tag axial. May have a toad...but may not (if so around 6,000lb - heavy sucker!).
So is 400 hp okay? 500 ~ 525 too much or perfect for hill climbs without loss of speed? Do NOT want to be the far-right-lane-flashers-going at 15mph up a long grade. Yet the 600 HP Raphsody...burn rubber in a motor home...really? I have no need or intention of doing 100 mph in my coach...just pass me the Grey Popon and I'll be happy!
Related question - does the horse power change mileage significantly. Someone was telling me by having a high HP engine, it's never maxed out and gets better mileage than a smaller HP engine on same coach ~ true?

Would love any and all thoughts!

Thanks in advance!
Mark

Re: Horsepower - How Much Is Enough...Too Much?

Reply #2 –
Yahoo Message Number: 72330
For that big of a coach, and 4 slide weight, with that size possible toad. I would stay with the C-13 or ISM as the minimum engine. The ISL is a fine engine, and would get it done, but 'more' would be better at size and weight.

The link from Jack, is a good one...

Good luck,
Smitty

04 Allure 31017
04 Allure Sold to a nice new owner! Now enjoying a 07 Magna Rembrandt 45' ISX600 #6775
"We're ONDROAD for THEJRNY!" (Toad and Coach license plates, say Hi if you see us!)

Re: Horsepower - How Much Is Enough...Too Much?

Reply #3 –
Yahoo Message Number: 72332
Jack, that is an outstanding resource. I had not read it before. Thanks for sharing it with the group.

R. D. Vanderslice
Sob

Re: Horsepower - How Much Is Enough...Too Much?

Reply #4 –
Yahoo Message Number: 72333
have had an Inspire with a 400 cat, and now an affinity with a cummins 600 isx. We have been pulling a 22' stacker trailer cross country with both coaches......the Inspire did not have the power we needed to cross the rockies a few times a year, so traded for the Affinity. On hills that would have us down to 20mph in the Inspire, we can now do 40+ mph AND get better fuel mileage........when not pulling the trailer, the Affinity still gets better mileage.....at 65 we average around 8 1/2-9mpg( depending on wind/road/etc)....never got that in the smaller coach. go for the HP!, can't have enough IMHO....
Luther Wikle affinity 6600

Re: Horsepower - How Much Is Enough...Too Much?

Reply #5 –
Yahoo Message Number: 72336
We have an '06 Intrigue 40' with the 525 Cat. It goes where we want it to go with power to spare. We travel in the Sierras and have been over the Continental Divide twice with this coach. It has power when you need it.

S. Brandt, '06 Intrigue #11964

Re: Horsepower - How Much Is Enough...Too Much?

Reply #6 –
Yahoo Message Number: 72350
Go with the biggest engine that any particular coach came with.

First issue:

The fuel consumption is not any more than a smaller diesel engine for the same coach. This is not true for gas engines though. Bigger diesel engines usually have different gearing in the transmission or drive gear so they run at a slower RPM, for the same speed, going down the road and therefore burn the same amount of volume of fuel and air at a slower RPM speed. It is the displacement of the cylinders and the speed at which the engine is running that determines fuel consumption. Some may argue that fuel milage has to be better with the smaller engine but that really only applies to gas engines or if the tranny and drive axel gear ratios are not matched to the engine torque curve.

Second issue:

As anyone knows that has been going up mountains, That extra torque (not necessarily HP) gives you more power to the drive axel. Focus on maximizing the torque of the engine and not the HP. Once you get to the maximum torque, any more pedal and you are just wasting fuel by watching the HP rise. The peak torque curve usually hits before the peak HP curve. Diesel engines develope torque by the fact that diesel burns slower through the power stroke than gas engines. Gas explodes by the spark plug firing at or near TDC. Where as diesel burns more evenly through the entire power stroke giving more constant power to the crank shaft. This is why Diesel engines are considered far more efficient for moving heavy objects.

Third issue:

Bigger engines, especially the 'real' Jake Brake engines (most Cat's engines) give you up to three engine braking speeds(one for each two cylinders on a 6 cylinder engine) and that is important if you are going down grade and do not want to heat up your service brakes. Some engines have the Exhaust brakes and require more maintenance I have yet to use my service brakes going down the hills I have travelled with my C12 unless to slow down quickly. Never had a problem with RPM's going over 2100rpm in 4th gear. Bigger engines develope more compression to use for engine braking. Think of the engine brake (compression brake) as a big compressor when the valves are rotated in compression mode. More volume to compress, the more engine brake with the bigger engine. You are not using hardly any fuel when in compression mode.

Fourth issue:

Dealers love to carry the bigger engine coaches because they sell better. I was told this by a few dealers when I was looking for a coach. I have not heard of anyone wanting to get a smaller engine after having a bigger engine (more torque).

This is my opinion based upon my experience.

Dallas 2004 intrigue 11688 w/C12

Re: Horsepower - How Much Is Enough...Too Much?

Reply #7 –
Yahoo Message Number: 72352
Thanks to all that have replied.

While the brochure link was really informative, Sharon Brandt's response really hit the nail on the head. From her comments and the brochure's data, I'm guessing that any time a higher output engine was offered on the same coach as an option, you may not only gain "climbing/towing power" but perhaps even better mileage?

Does that sound accurate?
 

Re: Horsepower - How Much Is Enough...Too Much?

Reply #8 –
Yahoo Message Number: 72358
Having lived in and driven many coaches in the mountains of Colorado and the west for the past 45 years, I would not even consider a smaller engine. I ordered my Intrigue with the C-13 Cat (3 speed Jake brake) and it is amazing. I tow a full-size Toyota Tundra truck (usually loaded down) and stay in the left lane up most mountain passes, while rarely needing to use the service brakes going down the pass with the 3-speed brake. We typically get around 7 mpg average fuel consumption. If you are a "driver" don't go with the small engine.

Dick Bradley

04 Intrigue #11830 C-13 Cat