HP to GCWR of Class A motorhome

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It's not the position of the radiator that uses more horsepower but rear radiator configurations generally use a direct drive fan while the side radiators usually have a variable speed fan.  Rear radiators also tend to get dirtier as the air flow from the engine out.  When the adjustable speed fan is turning is uses about the same horsepower as the direct drive.
 
The bigger reason for side radiators vs. rear radiators is due to the engine size and the amount of heat that needs to be removed.  The side radiators are a little larger which result in more surface area to dissipate heat. The larger the engine the larger the radiator needs to be to rid the heat.  Rear radiators can only be so big due to frame width and other items tucked into the rear engine bay.

Mike.
 
Why have so many of the newer models of MH gone away from side radiators or just my imagination?  I see few if any Winnebago newer or older products with side radiators.  My imagination?

Chuck
 
howellad said:
So Jim, most manufacturers saving money buy going with rear radiators to save money over more efficient design?
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I left out this in my original post, it is easier and more efficient to use the rear radiator design as less drawings, parts, etc. are required for and during the actual manufacture of the chassis.

Efficient design does not result in their cost savings but yours thus where is their incentive for efficient operation.  In the auto world it is, one required by the requirement for fuel mileage and two it is a sales  advantage if they are a leader.  Where is that in the RV world??

In the airline world, the guy that builds the cheapest to operate plane and has a comparable cost to buy or lease gets the business.  Again where is this in the RV world.

The same type of thing applies when the government buys on a cost plus contract vs a fixed price one.  Cost plus a product I was involved with was over $500,000, fixed price it was about $150,000.  Get the idea?

The difference in fuel mileage between a rear radiator and a side radiator is almost if not impossible to see for the average RVer so the remaining issue is maintenance and the manufacturer is not concerned with reducing that as there is no incentive and in fact there is an advantage to the chassis dealers in that they will have more work to do.

Frusrtating!
 
I would have to check and I don't know where to get the data but both fans will require a lot of HP.  They are big and pump a lot of  air.  The side ones can have speed regulation depending on the amount of cooling required.  I'm not so sure about the rear ones.
 
The fan on our 330 Cat Freightliner used 40 or 48 horsepower when running full out. Our controller failed which leaves the fan on and our mileage dropped 11/2 mpg. The difference in mileage between 95 degree driving and 50 degree driving (fan off) was over 1 mpg.
 
Thanks for the information and sounds like no real consensus on side vs. rear radiator.  Cost, cost, cost, and dealers want to sell product!

Chuck
 
howellad said:
Thanks for the information and sounds like no real consensus on side vs. rear radiator.  Cost, cost, cost, and dealers want to sell product!

Chuck
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Not necessarily.  The radiators job is to expell heat, the more heat is generated by larger engines the more there is to have to get rid of.  With the larger engines a radiator with more surface area is required.  A rear radiator can only be so big due to coach frame and body widths.  With a side radiator there are a lot more options for radiator sizes. 

Mike.
 
btizzle84 said:
True Jakes (which most RVers call every exhaust brake a "Jake" and its simply not true or accurate in anyway) you can't see because they're within the engine.
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True "Jakes" are made by the Jacobs company. Some compression brakes are made by other companies. The original was made by Jacobs.

Ken
 
Jacobs makes exhaust brakes as well as compression brakes.
 
The fan's power consumption is a factor, of course, only when it is running.  On our C12 the fan comes on at 207 degrees; with our new 195 degree thermostat I've yet to see the engine coolant temp go above 199 so the fan remains off and uses absolutely no power!  Our side radiator provides extremely easy access to the engine and I think that is worth it by itself.
 
Gene,

We did not take the AZ trip instead are here in Bend, OR.  We are in the final steps of purchasing a 2005 Country Coach 36' Quad slide Inspire 330.  We have really looked it over and think this is the one.  Big test drive tomorrow and then will make a final decision.

Chuck
 
bucks2 said:
True "Jakes" are made by the Jacobs company. Some compression brakes are made by other companies. The original was made by Jacobs.

Ken
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The other compression brakes are usually proprietary. Cummins has its own, PACCAR has its own, Navistar has its own (which trickles down to the new Ford diesel truck--or will be--having a compression brake). They can't call them "Jacobs Engine Brake" though...
 
btizzle84 said:
The other compression brakes are usually proprietary. Cummins has its own, PACCAR has its own, Navistar has its own (which trickles down to the new Ford diesel truck--or will be--having a compression brake). They can't call them "Jacobs Engine Brake" though...
Click to expand...


IIRC the Pac Brake compression brake is sold aftermarket.
 
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