Born Free Leap'n Lions RV Club Info & Discussion Forum

We have a few questions we’d like to ask about the 26/27 RSB unit. We live in Colorado at 4500 ft. elevation. We have to drive over 8,000 to 11,000 ft mountains to go just about any direction. We are favoring the 26 RSB unit because of the added space, but also considering a smaller one due to maneuverability, less stress on the engine in the mountains, less need for towing, etc.
What are your experiences driving in the western mountains in the 26 RSB unit? Do you feel like you have plenty of engine in the mountains? Do you tow a vehicle, and if so, do you have plenty of engine for towing and what do you tow? If not have you felt the need for a toad? If you don’t tow, is the unit relatively easy to maneuver in parking lots, towns, along roadways, etc.
Any information you might give us regarding these questions would be helpful as we make a decision.

In Colorado, using Regular 85 gasoline (I wonder whose idea was to impose this brand on Colorado) will give you 40-45 MPH average on the slopes of Vail Pass, Eisenhower Pass, Lizard Head Pass etc. Using 87 lets you maintain easily 75 MPH on I-70 and more, or 50-55 MPH on the slops.

The E-450 10 cylinder engine is very robust and would handle the RV as well as any toad.

A lot of members of this forum tow all kind of vehicles effortlessly with no significant degradation of the MPG.

Happy RV-ing.

I have a 2002 Born Free 26' RSB coach on the Ford E450 chassis with the 305 HP V10 gas engine. I tow a 3400 lb 2005 Chevrolet Malibu. I have been over the Eisenhower Pass at an elevation over 11,000 ft. While noticeably down on power at that high elevation, I still had sufficient power to run there.

Octane is really only a measure of the anti-knock characteristics of gas. 87 octane gas, 89 octane gas and 91 octane gas all have the same energy content and will provide the same power for an engine designed for 87 octane fuel at sea level. Higher octane gas will only provide more power in an engine designed with higher compression - the increased octane is necessary to prevent knocking in a higher compression engine.

The reason that the fuels in the Denver area (and other higher elevation locations) are formulated with a lower 85 octane rating is that at those higher altitudes, the less dense air means that the tendency for an engine to knock is lower so there is no need for the fuel suppliers to provide the higher cost 87 octane fuel when 85 octane fuel will provide the same anti-knock protection at 5000 ft as 87 octane fuel provides at sea level for engine designed for 87 octane fuel.

When I was a young man with my first car, a 1954 Pontiac, I would sometimes fill it with premium high test (high octane) gas thinking I was giving the car a special treat and thinking I would enjoy a temporary boast in power and performance. Someone advised me that the only one I was treating was the gas station as the more expensive high octane fuel in a car engine that did not require it did absolutely nothing to boast power and performance.

Anyone with a background in this field please chime in if I am wrong on this issue.

I think Bill is correct relating to octane and the fact that 85 has the same energy content as higher octanes. An ethanol blend would have somewhat lower BTU content. We've done a lot of mountain driving with the V-10 and you just have to accept that it's not a diesel and that you will be slower and higher rpm's than flatland performance.

Rich Flaugh wrote:...We've done a lot of mountain driving with the V-10 and you just have to accept that it's not a diesel and that you will be slower and higher rpm's than flatland performance.

And even at that, with the V-10 you will find yourself passing others on the uphill grades.

Bill

Modern engines have knock sensors which alter engine parameters, most importantly timing, to keep engine safe. This only becomes relevant at high loads, but most definitely power available is lower with 85 octane. You likely pay a quite small penalty in fuel mileage also. If you look in owners manual, always a good idea, FOMOCO rather strongly discourages going below 87 octane, but in that instance IMO it is safe to disregard same. We are talking gasoline engines here, not diesels, so the essentially equivalent energy content of 85 and 87 octane is does not change the above. The petroleum industry practice of marketing lower octane at elevations above 5000 feet or so goes back to the days of carburetors (SP?), no catalytic convertors, no "feed back" or computer controls. if anyone really cares, PM me and I'll likely go on and on concerning this subject.
Ralph

bigdipper wrote:Modern engines have knock sensors which alter engine parameters, most importantly timing, to keep engine safe. This only becomes relevant at high loads, but most definitely power available is lower with 85 octane. You likely pay a quite small penalty in fuel mileage also. If you look in owners manual, always a good idea, FOMOCO rather strongly discourages going below 87 octane, but in that instance IMO it is safe to disregard same. We are talking gasoline engines here, not diesels, so the essentially equivalent energy content of 85 and 87 octane is does not change the above. The petroleum industry practice of marketing lower octane at elevations above 5000 feet or so goes back to the days of carburetors (SP?), no catalytic convertors, no "feed back" or computer controls. if anyone really cares, PM me and I'll likely go on and on concerning this subject.
Ralph

Ralf, I could not agree more. It is the efficiency of the engine that deteriorates, using less than recommended 87 octane.

I dont know - In my younger days it seemed like I won more street races pushing Sunoco 260 on a re-turned engine. Just sayin

But, The 260/re-tune was only for special occasions, I was probably starving the poor thing with the cheap stuff most the time. During 1973 gas crisis I believe gas skyrocketed to around .55 a gallon.

Again remember that 85, 87, 89 & 91 octane gas all have the same energy content (BTUs/gallon). The only way to extract more power from higher octane fuels is to use it in an engine with increased compression ratio.

Guess we should take ethanol blended gas into consideration as it does change the BTU/gallon ratings?

Do they sell the ethanol blend in mountainous regions?

What effects would a ethanol blend have at higher altitudes and steep grades?

The only thing I do now is make sure the tank is low and I fill up with non-ethanol blend as I am returning home. I dont want ethanol in the RV if it isnt going to be used for a week or two.

I have tried to do a octane level to MPG comparison and a ethanol/non-ethanol to MPG comparison but didnt really have a controlled environment or baseline so my numbers were all over the place and I found no significant conclusions.

Anyone else?

I did the calculations several months ago and determined that the BTU energy content of E10 fuel (90% gas/10% ethanol) was 3.3% less than the BTU energy content of 100% gas. I would then expect about 3.3% less mpg running E10 fuel versus 100% gas.

Currently in Spencer, IA, E10 costs $2.999/gallon and 87 octane regular gas costs $3.299/gallon. To me this means that if you run 87 octane regular fuel, you are paying 10% extra cost per gallon to get only a 3.3% increase in mpg.

Bill,
I absolutely agree with your analysis and only wish that gasoline with no ethanol was available out here for periods when RV is in storage. If you care, my oil company experience goes back to before ethanol came on the scene and I could PM you with the reason why pure gasoline became available (actually never went away) in IA and some other farm belt states.
Ralph

Power going up mountains?

Ray wrote:Power going up mountains?

Sorry. Didn't mean to hijack the thread.
Ralph

I am confused - Bill is saying in comparison that you should buy ethanol blend - and Ralph says he absolutely agrees and wishes he could get non-ethonal blend

Help - Am I reading this wrong?