FYI or Whats in a toad

[Bob Nodine]

When we purchased this coach 13 years ago we were consistently getting 8 to 8.5 MPG but as the years went by the fuel mileage continued to drop off to about 7 MPG. I thought maybe the engine had injector problems so two years ago at the Gathering had Bill Groves connect his laptop with the Insight software to the engine and test it. All the cylinders were at about 95% so we ruled out that theory.  It turns out the reason for our loss of fuel mileage over the years was that we kept changing to a heavier toad and were driving faster because of handling improvements. When we purchased the coach 60 MPH was a white knuckle experience but now we set the cruise on 65.  We started out with a Honda CRV, then went to a Ford SportTrac, and finally to a Silverado 1500 CrewCab. We just recently purchased a Chevy Sonic that comes in at about 2700 pounds and set it up to tow. We have made two trips so far of about 370 miles each, mostly interstate at 65, and immediately noticed a 1 MPG improvement in fuel mileage and a significant improvement in acceleration and braking. You can actually feel the improvement in acceleration and braking in the seat of your pants.  

 

[Chuck B 2004 Windsor]

A lot of interest seems to be on what we tow, not about setting up the vehicle we tow with the proper braking system.  IMO, the braking system needs to be both progressive and proportional.  In additional to the above, does the hitch on the coach have the necessary rating  to tow the weight of the vehicle being towed. 

[Bob Nodine]

13 minutes ago, Chuck B said:

A lot of interest seems to be on what we tow, not about setting up the vehicle we tow with the proper braking system.  IMO, the braking system needs to be both progressive and proportional.  In additional to the above, does the hitch on the coach have the necessary rating  to tow the weight of the vehicle being towed. 

Our coach has a receiver rated at 10,000 lbs and our tow bar is rated at 7500 lbs. The Silverado came in at about 6000 lbs. I always use a progressive and proportional supplemental braking system on the vehicles I tow. On the first three we used the Roadmater Brakemaster tied directly into the coach air brakes. You knew immediately if you forgot to connect it or install the air piston, especially with the SportTrac and the Silverado. On the Sonic we are using the RVi3 supplemental braking system because our next coach will not have air brakes.

[dl_racing427]

Yep, it's all about HP/Weight ratio.

Obviously, it takes more power to accelerate a larger weight, and more brake power to stop it. 

Physics, the only laws that CANNOT be broken. 😉

[Hotrod - R.I.P.]

Bob,

Yes a bigger heavier toad will decrease your mpg.  You can cut drag with a tonneau cover which I think you have. I can see a .25 to .5 mpg cut in my mpg when I put the golf cart in the back , which adds about 850 lb and adds a bunch of wind drag.

I also use air tabs which most don’t understand or believe that they cut drag. I only have them on top of the rig where they are not generally visible and not on the sides where you might have seen some. Anyway they create little tornados , vortices of air that bridge from the coach roof to the road and reduce cavitation between the two vehicle. The toad stays a lot cleaner too. I don’t think they cost 75$ and are easy to install. 
 

Another thing with towing more mass is when you take more mass down hill and have to use your jake or exhaust brake, that energy is thrown away. Not much you can do other than start down the hill at a slower speed or allow a higher speed before engaging the brake.  Of course it takes more energy to pull more mass up a hill. 
 

Use a good bit of air pressure on the toad tires to minimize rolling resistance . Whatever the RR is, the energy consumed is that times the velocity times the toad weight.  A good low RR helps minimize that cost.
 

I’m back up to about 8mpg after replacing a bad injector... but I used to enjoy 8.2 and I still blame that on the bio fuels.
 

Good thing my tow bar is rated for 10000lb.. next toad might be Cybertruck. 

 Bill g

06 Dynasty

[Guest Tim503]

That is physics. after the first couple years you've driven around the USA and seen what you want to see some people just pick a winter and summer destination. I remember when people would say with a diesel it doesn't make much difference in your weight but at $3 a gallon it is 40 cents a mile. I'm looking to the future when we change out these diesels for some electric motors and get rid of the roof top AC for a roof of solar panels producing 1500 watts during the day. I understand the Tesla uses 300 watts to propel it. The engine is converted to a garage for your toad and somewhere in there you have 1000 KWH of battery storage. With a little more insulation we wouldn't even need to carry propane. Imagine the possibilities. A 100 gallon tank of diesel gone and none of the constant maintenance.

Edited August 16, 2020 by Tim503