Gas Mileage - R-pod Owners Forum

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brownd

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Topic: Gas Mileage
Posted: 23 Aug 2010 at 10:59am

Tidalwave,

I guess your last posting says it all. It is wind resistance and not weight that is preventing decent performance and reasonable mileage on 6 cylinder engines and for v8s you get the performance but mileage is still bad even at slower speeds. My experience with the Jayco popup as I stated when I opened this discussion was 17 mpg with no problem. As Outbound said earlier we are towing a barndoor (a pretty comfortable one when you get to camp) down the road.

It sure would be nice to hear from someone who has tried a spoiler of some sort or the 173t that already has an experimental spoiler from the factory.

Dave

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Posted: 24 Aug 2010 at 12:01am

OK I had a strange one that I found out by mistake. I went to Codurus State Park which is about 80 miles from my home with the kayaks on the roof. I had just thrown them up their in a hast and did not notice that the front was closer together than the back (basically making a large V). I averaged 13.1 miles to the gallon from the computer in the car. I then like a stooge fixed the kayaks to make them straight for the ride home and the computer showed 11.2 miles to the gallon (but no wind noise from them).

Butterfly_Lee View Drop Down

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Posted: 24 Aug 2010 at 12:43am

Were you getting wind noise when boats were in the shape of a V? You need to run that image on the airflow model. Looks like that v-shape was high enough to deflect the front shape of the POD, is it physically wider and higher? If nothing else it appears it would deflect about 80 percent of the front airflow.

Interesting.

Lee

Still a work in progress, lots of pictures.
http://podterfly.blogspot.com/

brownd

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Posted: 24 Aug 2010 at 7:36am

Yes it would be interesting to see what a the computer model says, but the best test is if the loading of the kayaks can be reproduced with the same results of around 13 mpg. If so then it appears that a spoiler/air diflector on the car would do some good. Thanks for the observation.

Dave

techntrek

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Posted: 24 Aug 2010 at 8:58am

Did you have an overall increase or decrease in altitude between home and Codorus? That slight difference could be explained if you lost/gained several hundred feet in either direction.

Doug ~ '10 171 (2009-2015) ~ 2008 Salem ~ Pod instruction manual

techntrek

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Posted: 24 Aug 2010 at 8:59am

Reply from Forest River:

Good afternoon Doug

I just got back into town from a week long road trip. The spoiler design came from the people that make our fiberglass rear cap. It was not intended to be a spoiler, they came up with the design strictly for cosmetic purposes. It was never intended to be a spoiler. We're not sure if there is any improvement with the spoiler.

Do you think if we were to develop a rear spoiler it would be beneficial??? and what do you think about us developing an after market rear spoiler?? We haven't looked into it, but what are your thoughts.

Please let me know and hope this helps,

My Reply:

Based on the posts from the link, I think you would have a market for one *if* you can demonstrate that it would lower drag in real-world tests. The computer simulations (also on that thread) show a high disturbance area on the tail area which would explain why so many of us feel a sharp drop off in available power above 50 mph.

I think the appearance of a spoiler on the back would complement the existing curves, maybe make it look “sporty”, so it shouldn’t be a problem for those of us that bought it because it is so different. I’ll pass on your questions to the forum to get more input.

Doug ~ '10 171 (2009-2015) ~ 2008 Salem ~ Pod instruction manual

Butterfly_Lee View Drop Down

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Posted: 24 Aug 2010 at 10:41am

I would be very interested in an after market spoiler. An added plus would be a channel for the water the runs down from the A/C. Plus with less turbulance in the back would there tow be easier?

So in theory..back spoiler = plus 2.5 mpg and front wedge = plus 2.5 mpg

5 mpg gain over 1000 mile trip = 50 miles = 3.33 gallons saved at $3.00 per gal = $9.99 SAVED

So lets say we plan travel 50,000 for the life of the POD, which is 499.50 dollars in fuel cost saved. With all the additions, which cost how much?.

Check my Math, I'm looking a cost effectiveness.

Lee

Still a work in progress, lots of pictures.
http://podterfly.blogspot.com/

techntrek

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Posted: 24 Aug 2010 at 12:57pm

This had been edited, someone pointed out an error in my math. Changes are bolded.

1000 miles/10 mpg = 100 gallons used

1000 miles/15 mpg = 66.6 gallons used... 33.3 saved from 10 to 15 mpg, or $100 saved @ $3 per gallon

1000 miles/20 mpg = 50 gallons used... 16.6 saved from 15 to 20 mpg, or $50 saved @ $3 per gallon

So it looks like there is an increasing return depending on where you start. In my case, using only a 'pod spoiler, I would go from 12 mpg to 14.5 mpg:

1000 miles/12 mpg = 83.3 gallons used

1000 miles/14.5 mpg = 69 gallons used

14.3 gallons saved, $43 saved over every 1000 miles.

However, I'm much more interested in getting some power back at highway speeds for uphill climbs and passing. I always had lots of extra "umph" pulling my popup even though it was many hundreds of pounds heavier than the 'pod. Passing a semi on an uphill climb was no problem, now I'm getting passed by the semis.

Doug ~ '10 171 (2009-2015) ~ 2008 Salem ~ Pod instruction manual

brownd

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Posted: 24 Aug 2010 at 2:43pm

I was going to respond to the 1st set of math being too low but I see techntrek has already done that. If one extrapolates his $43 dollars saved each 1000 miles at 2.5 mpg improvement then take the 50000 mile potential lifetime of the pod and multiply his $43 /1000 miles saved times 50 and that is $2150 over the lifetime of the pod. 5 mpg would double that. That is not too bad.

I second his opinion that the power regained from less drag on the vehicle should both lengthen the life of our transmissions, especially on six cylinder suv's, and allow us to travel with ease at 55 or maybe even 65 mph. Right now my jeep is struggeling a good deal of the time at 55 in 3rd gear and 2300 rpm or more. At 50 as I stated above the line of traffic behind is both embarrasing and kind of dangerous until you let them by.

I really want to thank Forest River for responding to Techntrek and for him exploring this with them. They have a great product that is hindered by just this issue I think. If they could talk to folks through their dealers and advertising that they have worked with owners to obtain better mileage and improved performance pulling the Pod for a 6 cylinder vehicle equiped to pull 3500 that would be a marketing plus for them. I would love to go out and experiment with different air deflectors or spoilers but can't afford to do it. If there were an aftermarket item either to add to the pod or the automobile that was reasonably priced and documented to work with the Pod, I would snap it up in a minute.

Dave

Butterfly_Lee View Drop Down

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Posted: 24 Aug 2010 at 4:45pm

Thanks for checking the Math...to much blonde hair dye when I was younger.

Leasing the drag, would certainly help the smaller vehicles. My 4 cyl Nissan would surely benefit.

I too would be very happy to be a tester, Give me even more reason to hit the road.

Lee

Still a work in progress, lots of pictures.
http://podterfly.blogspot.com/

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brownd Members Profile Send Private Message Find Members Posts Add to Buddy List Newbie Joined: 25 Jul 2010 Online Status: Offline Posts: 36	Topic: Gas Mileage Posted: 23 Aug 2010 at 10:59am
	Tidalwave, I guess your last posting says it all. It is wind resistance and not weight that is preventing decent performance and reasonable mileage on 6 cylinder engines and for v8s you get the performance but mileage is still bad even at slower speeds. My experience with the Jayco popup as I stated when I opened this discussion was 17 mpg with no problem. As Outbound said earlier we are towing a barndoor (a pretty comfortable one when you get to camp) down the road. It sure would be nice to hear from someone who has tried a spoiler of some sort or the 173t that already has an experimental spoiler from the factory.
	Dave

rpodcamper.com Members Profile Send Private Message Find Members Posts Add to Buddy List Admin Group - pHp Joined: 26 Nov 2009 Location: Reading, Pa Online Status: Offline Posts: 3990	Posted: 24 Aug 2010 at 12:01am
	OK I had a strange one that I found out by mistake. I went to Codurus State Park which is about 80 miles from my home with the kayaks on the roof. I had just thrown them up their in a hast and did not notice that the front was closer together than the back (basically making a large V). I averaged 13.1 miles to the gallon from the computer in the car. I then like a stooge fixed the kayaks to make them straight for the ride home and the computer showed 11.2 miles to the gallon (but no wind noise from them).

Butterfly_Lee Members Profile Send Private Message Find Members Posts Add to Buddy List Senior Member Joined: 19 Nov 2009 Location: Corpus Christi Online Status: Offline Posts: 131	Posted: 24 Aug 2010 at 12:43am
	Were you getting wind noise when boats were in the shape of a V? You need to run that image on the airflow model. Looks like that v-shape was high enough to deflect the front shape of the POD, is it physically wider and higher? If nothing else it appears it would deflect about 80 percent of the front airflow. Interesting. Lee
	Still a work in progress, lots of pictures. http://podterfly.blogspot.com/

brownd Members Profile Send Private Message Find Members Posts Add to Buddy List Newbie Joined: 25 Jul 2010 Online Status: Offline Posts: 36	Posted: 24 Aug 2010 at 7:36am
	Yes it would be interesting to see what a the computer model says, but the best test is if the loading of the kayaks can be reproduced with the same results of around 13 mpg. If so then it appears that a spoiler/air diflector on the car would do some good. Thanks for the observation.
	Dave

techntrek Members Profile Send Private Message Find Members Posts Add to Buddy List Admin Group - pHp Joined: 29 Jul 2009 Location: MD Online Status: Offline Posts: 9059	Posted: 24 Aug 2010 at 8:58am
	Did you have an overall increase or decrease in altitude between home and Codorus? That slight difference could be explained if you lost/gained several hundred feet in either direction.
	Doug ~ '10 171 (2009-2015) ~ 2008 Salem ~ Pod instruction manual

techntrek Members Profile Send Private Message Find Members Posts Add to Buddy List Admin Group - pHp Joined: 29 Jul 2009 Location: MD Online Status: Offline Posts: 9059	Posted: 24 Aug 2010 at 8:59am
	Reply from Forest River: Good afternoon Doug I just got back into town from a week long road trip. The spoiler design came from the people that make our fiberglass rear cap. It was not intended to be a spoiler, they came up with the design strictly for cosmetic purposes. It was never intended to be a spoiler. We're not sure if there is any improvement with the spoiler. Do you think if we were to develop a rear spoiler it would be beneficial??? and what do you think about us developing an after market rear spoiler?? We haven't looked into it, but what are your thoughts. Please let me know and hope this helps, My Reply: Based on the posts from the link, I think you would have a market for one if you can demonstrate that it would lower drag in real-world tests. The computer simulations (also on that thread) show a high disturbance area on the tail area which would explain why so many of us feel a sharp drop off in available power above 50 mph. I think the appearance of a spoiler on the back would complement the existing curves, maybe make it look “sporty”, so it shouldn’t be a problem for those of us that bought it because it is so different. I’ll pass on your questions to the forum to get more input.
	Doug ~ '10 171 (2009-2015) ~ 2008 Salem ~ Pod instruction manual

Butterfly_Lee Members Profile Send Private Message Find Members Posts Add to Buddy List Senior Member Joined: 19 Nov 2009 Location: Corpus Christi Online Status: Offline Posts: 131	Posted: 24 Aug 2010 at 10:41am
	I would be very interested in an after market spoiler. An added plus would be a channel for the water the runs down from the A/C. Plus with less turbulance in the back would there tow be easier? So in theory..back spoiler = plus 2.5 mpg and front wedge = plus 2.5 mpg 5 mpg gain over 1000 mile trip = 50 miles = 3.33 gallons saved at $3.00 per gal = $9.99 SAVED So lets say we plan travel 50,000 for the life of the POD, which is 499.50 dollars in fuel cost saved. With all the additions, which cost how much?. Check my Math, I'm looking a cost effectiveness. Lee
	Still a work in progress, lots of pictures. http://podterfly.blogspot.com/

techntrek Members Profile Send Private Message Find Members Posts Add to Buddy List Admin Group - pHp Joined: 29 Jul 2009 Location: MD Online Status: Offline Posts: 9059	Posted: 24 Aug 2010 at 12:57pm
	This had been edited, someone pointed out an error in my math. Changes are bolded. 1000 miles/10 mpg = 100 gallons used 1000 miles/15 mpg = 66.6 gallons used... 33.3 saved from 10 to 15 mpg, or $100 saved @ $3 per gallon 1000 miles/20 mpg = 50 gallons used... 16.6 saved from 15 to 20 mpg, or $50 saved @ $3 per gallon So it looks like there is an increasing return depending on where you start. In my case, using only a 'pod spoiler, I would go from 12 mpg to 14.5 mpg: 1000 miles/12 mpg = 83.3 gallons used 1000 miles/14.5 mpg = 69 gallons used 14.3 gallons saved, $43 saved over every 1000 miles. However, I'm much more interested in getting some power back at highway speeds for uphill climbs and passing. I always had lots of extra "umph" pulling my popup even though it was many hundreds of pounds heavier than the 'pod. Passing a semi on an uphill climb was no problem, now I'm getting passed by the semis.
	Doug ~ '10 171 (2009-2015) ~ 2008 Salem ~ Pod instruction manual

brownd Members Profile Send Private Message Find Members Posts Add to Buddy List Newbie Joined: 25 Jul 2010 Online Status: Offline Posts: 36	Posted: 24 Aug 2010 at 2:43pm
	I was going to respond to the 1st set of math being too low but I see techntrek has already done that. If one extrapolates his $43 dollars saved each 1000 miles at 2.5 mpg improvement then take the 50000 mile potential lifetime of the pod and multiply his $43 /1000 miles saved times 50 and that is $2150 over the lifetime of the pod. 5 mpg would double that. That is not too bad. I second his opinion that the power regained from less drag on the vehicle should both lengthen the life of our transmissions, especially on six cylinder suv's, and allow us to travel with ease at 55 or maybe even 65 mph. Right now my jeep is struggeling a good deal of the time at 55 in 3rd gear and 2300 rpm or more. At 50 as I stated above the line of traffic behind is both embarrasing and kind of dangerous until you let them by. I really want to thank Forest River for responding to Techntrek and for him exploring this with them. They have a great product that is hindered by just this issue I think. If they could talk to folks through their dealers and advertising that they have worked with owners to obtain better mileage and improved performance pulling the Pod for a 6 cylinder vehicle equiped to pull 3500 that would be a marketing plus for them. I would love to go out and experiment with different air deflectors or spoilers but can't afford to do it. If there were an aftermarket item either to add to the pod or the automobile that was reasonably priced and documented to work with the Pod, I would snap it up in a minute.
	Dave

Butterfly_Lee Members Profile Send Private Message Find Members Posts Add to Buddy List Senior Member Joined: 19 Nov 2009 Location: Corpus Christi Online Status: Offline Posts: 131	Posted: 24 Aug 2010 at 4:45pm
	Thanks for checking the Math...to much blonde hair dye when I was younger. Leasing the drag, would certainly help the smaller vehicles. My 4 cyl Nissan would surely benefit. I too would be very happy to be a tester, Give me even more reason to hit the road. Lee,
	Still a work in progress, lots of pictures. http://podterfly.blogspot.com/