lylefikse Report post Posted December 5, 2011 I have a 40 ft 2007 Damon Tuscany with the C7 350 Cat. I think I have enough power on hills, but wondered if one of the new chips may help fuel economy? I drive between 60 and 65MPH and average about 7 MPG. I don't want to risk damage to my rig. This summer we pulled Highway 20 in Washington State pulling a Toyota Avalon on a dolly. The temperature gauge hardly moved. Saw several cars stopped boiled over on that grade. Has anyone tried this with a 350 Cat? Share this post Link to post Share on other sites
wildebill308 Report post Posted April 30, 2015 Well I haven't experimented with Cat but hear are a couple places to start looking. http://www.tsdieselperformance.com/site/1617113/page/916611 https://www.pittsburghpower.com/index.php?manufacturers_id=6&sort=4a&filter_id=22 http://www.ultrarvproducts.com/store/index.php?route=product/category&path=17_67&filter=235 Most places are selling POWER not economy. I would never run with out a boost gage and a good EGT gage. Bill Share this post Link to post Share on other sites
wolfe10 Report post Posted April 30, 2015 Slowing down a couple of MPH will help MPG. Share this post Link to post Share on other sites
hermanmullins Report post Posted April 30, 2015 FYI, I normally travel 2 to 3 mph below the speed limit, 75 = 72/73, 70 = 67/68 and so on. My normal average mpg is 6.7 to 6.8. Followed a friend last week. His highway speed was 60 to 61 all the way. 7.8 MPG, I did the same on the return trip and it was 7.9 over all. Guess where I will be setting the cruise control from now on. I guess the ole statement "Slow down and save" is true. Share this post Link to post Share on other sites
wildebill308 Report post Posted April 30, 2015 I tend to travel where my coach shifts into 6th gear at 65. in econ mode depending on speed limits and conditions. Bill Share this post Link to post Share on other sites
ckcarpenter42 Report post Posted April 30, 2015 You may want to check the following discussion thread on the potential benefits of "performance chips." http://forum.dieselrvclub.org/index.php/topic,5490.msg9447.html#msg9447 Share this post Link to post Share on other sites
jleamont Report post Posted May 1, 2015 I tend to travel where my coach shifts into 6th gear at 65. in econ mode depending on speed limits and conditions. Bill WILDEBILL308, I have almost the same shifting pattern as you. I shift into 6th at 63MPH which has made me want to run at 64. I would rather prefer to run 60 in 6th since the RPM's are more desirable for fuel economy and the HP on the ISL is plenty strong to hold me there. I have tried to manually up shift but it will not let me. joe Share this post Link to post Share on other sites
wolfe10 Report post Posted May 1, 2015 Joe, With peak torque at 1,300 RPM, your Allison should be programmed to allow you to run just above that in a gear. You might make a note of the lowest RPM in each gear immediately after each upshift with normal/light throttle driving. If all are more than 100 RPM ABOVE that 1,300 RPM, you can have your Allison ECU reprogrammed by an Allison dealer. But it will affect all gears, not just 6th, so you would have to verify that lowering each shift point 100 RPM would not put you below peak torque RPM in each gear. Yes, some coaches are geared such there there is no "good economic speed", as 6th gear comes high enough on the speed curve that Aerodynamic Drag is significant. Share this post Link to post Share on other sites
wildebill308 Report post Posted May 1, 2015 Jo, what is your mileage at 64? We have different engines my little ISB 5.9 likes 65-66. It will hold 6th gear if you back off down to 62 but any increase in load will drop it into 5th gear and it won't shift up till it is back up to 65. Doing this waste more fuel than just maintaining my speed at 65. One other thing is check your speedometer for accuracy. I checked mine and found I need to use a correction factor of + 5.8% to get my actual speed/mileage. Brett, what engine are you running and what is your average mileage? Bill Share this post Link to post Share on other sites
jleamont Report post Posted May 1, 2015 I would really like to switch my shift pad to the newer type that displays the actual gear you are in, when I am trying to relax and take in the scenery I find myself counting shifts in my head. Not sure if this can be accomplished by just changing the shifter? Brett, I will have to try your recommendation and rethink if I should have that changed or not. I do always run in economy mode, another thing is when I need to power it doesn't seem to down shift enough to give it, once I recall manually pulling it down, I have tried this with the Economy button on and off, doesn't seem to matter on down shifts but does make a difference on upshifts. Bill, the last time I checked mileage was running up I-81 from TN to PA I was holding it at 65 mph and I got 10.05 mpg, it just felt great to have a coach that could handle 65 so I did it. We just went to Ocean City MD last weekend and I ran at 60 down and back with my eyes on the tach and my mind counting gears, I havent topped off the tank yet to see what MPG I got but it looked great from the little the gauge moved (less than 1/4 used in 280 miles round trip), more to follow on this. Your shift points do the same as mine it upshifts at 63 into 6th and down to 5th at 59, at 62 I am at 1600 rpms in 5th (which is way too high for me) so I find myself paying too much attention to this when I should be relaxing. I purposely run up to 64 and back down to 60 and set the cruise which I think I recall the tach being at 1400. Mother nature is always fighting us....we only seem to travel when its windy so it never fails a gust hits the front of the coach and I'm back into 5th grinding my teeth doing it all over again. Overall I am really pleased with the ISL's performance and fuel MPG given the size and weight of the unit, if I could master the shift points I might be able to keep more money in my pocket. Share this post Link to post Share on other sites
wildebill308 Report post Posted May 1, 2015 If you are getting over 10mpg at 65 I would lean back and enjoy the ride. As you noted there are so many variables that one tank or one trip will not give an accurate picture of mileage. In February I made a trip to south Texas. I was lucky and had a front blowing through both going and coming back. My mileage for that trip was not so good in the low 7s but I know conditions played a big part. I track my fuel usage and I like to use at least 10 fill ups to get a average. Bill Share this post Link to post Share on other sites
wolfe10 Report post Posted May 1, 2015 Brett, what engine are you running and what is your average mileage? Bill Bill, I really hate to get involved in these, as my driving style is ABSOLUTELY MPG DRIVEN. Current coach has ISL400. Gearing is such at 1500 RPM is 58 MPG (per GPS). And that is what I normally drive-- we enjoy secondary roads and only travel interstates if in a real hurry to get somewhere. Always in economy mode. Manually down/up arrow as needed. Recent trip east Texas to California and back: 10.1 MPG. That is subtracting .5 gallons/ generator run hour. All gallons in divided into total distance driven. Share this post Link to post Share on other sites
wolfe10 Report post Posted May 1, 2015 Bill, I agree, over 10 MPG at 65 would be WOW! Given the aerodynamics (or lack thereof) of coaches, fuel consumption goes up rapidly over 55 MPH. Share this post Link to post Share on other sites
obedb Report post Posted May 1, 2015 Knowing about where Joe lives, the engine doesn't have to work that hard to get south of 95 and onto the flat Delmarva Peninsula. Then on to Ocean City. Headwinds are probably not significant on that heading, but that is still a very impressive number. Wish that I could get close to that fuel mileage, but I am the kind of guy that runs in headwinds westbound. Months later on the return eastbound I am facing strong headwinds. How can that be? My luck! DPs usually have the drag coefficient of a BARN! Share this post Link to post Share on other sites
wolfe10 Report post Posted May 1, 2015 Yup, kind of like sailing. If the wind is not on your nose, you are going the wrong way. Don't have to take off my shoes to count the number of times in 25,000 sailing miles we were on a broad reach is good conditions (but it DOES happen and boy is that fun). In the motorhome, we have been in conditions were we were fighting a 30-40 MPH headwind. Just slowed down to 50 in 5th gear and "toddled on". Share this post Link to post Share on other sites
wildebill308 Report post Posted May 2, 2015 ObedB, Come on down to Texas there is a reason they are building big wind farms hear. That little run I made from Fort Worth to Pharr Texas, it's only 497 miles, had us running in wind gust over 50 mph. That wasn't to bad as sometimes the wind blows hard. On the way home I ran into the last big sleet and ice storm temps went from 70 to 23. Had to spend a couple of days letting the storm wind down and the roads to clear. Brett, I would like to see 10mpg and will let you know after my next trip. We are going East/North this summer. The roads back east are not as easy to make good mileage on, in my opinion. I did make 9.3 towing my CR-V out west last summer. That was by dividing fuel into miles about 12,500. The only time my driving style was ABSOLUTELY MPG DRIVEN was in California where I tested the "drive slower in a lower gear to get better mileage" theory that keeps cropping up. For a little over 30 days while in CA I drove 55 or less. some roads in the flat valley at 50 I had to run in 5th gear at about 1600 rpm. I was hoping for some amazing mileage figures. Well they were down to mid 7s. Bill Share this post Link to post Share on other sites
jleamont Report post Posted May 4, 2015 ObedB, Come on down to Texas there is a reason they are building big wind farms hear. That little run I made from Fort Worth to Pharr Texas, it's only 497 miles, had us running in wind gust over 50 mph. That wasn't to bad as sometimes the wind blows hard. On the way home I ran into the last big sleet and ice storm temps went from 70 to 23. Had to spend a couple of days letting the storm wind down and the roads to clear. Brett, I would like to see 10mpg and will let you know after my next trip. We are going East/North this summer. The roads back east are not as easy to make good mileage on, in my opinion. I did make 9.3 towing my CR-V out west last summer. That was by dividing fuel into miles about 12,500. The only time my driving style was ABSOLUTELY MPG DRIVEN was in California where I tested the "drive slower in a lower gear to get better mileage" theory that keeps cropping up. For a little over 30 days while in CA I drove 55 or less. some roads in the flat valley at 50 I had to run in 5th gear at about 1600 rpm. I was hoping for some amazing mileage figures. Well they were down to mid 7s. Bill Wildebill, I know all about your winds down there. We took our last coach (Coachmen 311SB) accross the country in the summer of 08. While driving accross the Panhandle the wind and rain were so strong I had the steering wheel at 5:00 to go straight, by the time we got to Arizona all of the caulk on the bunk was gone and we started to de-laminate. Good times, best vacation we ever had other than the beating the coach took. Share this post Link to post Share on other sites
