Please forgive me (I'm new here) if this is a topic that's been beaten into the ground already but I gotta ask. First the background info... 2003 Supercrew, 5.4 w/ 3.55 limited slip, and the trailer towing package, all else stock. That gives me 8,000 pounds of towing capacity per the book. Travel trailer goes about 5,000 pounds loaded with all the "can't last the weekend without it" type stuff. OK finally the question... what's everyone's experience/opinion/fact as it relates to towing power with 93 octane gas vs. 87? Is the 93 worth it or not?

Last weekend I took the kids out for the weekend which was the first time towing with this vehicle. Mr. Murphy was working his finest.... I'm headed south into a 20 mph wind out of the south on Friday and headed home Sunday into about the same speed wind out of the north. The ride down was on 87 octane and the ride home was a half tank of 87 and half tank of 93 (so I realize it wasn't a true 87 vs. 93 test). Can't say for sure that I noticed improved performance with the 93 octane.

What's everyone tow on octane-wise and do you bump up to a higher octane for an extra kick in towing/power?

Thanks for the input.

 

When I tow, I use higher octane since I use a flip chip. But if your rig runs ok on regular, no pinging, I'd use regular.

 

I wouldn't run the 93 octane if your not tuned for it. Search around the Computer Chips threads but I think I remember Mike saying that you could actually do damage to the catalytic converter by doing that.

The question I have is, do you need the extra power for towing? Did you have problems on the highway with hills or keeping up with the flow of traffic? I agree with trying to get the very best gas mileage possible but why spend a lot of extra money for 93 and a tuner/chip to utilize that fuel if you really don't need it? You may save a few MPG but does that offset the cost of fuel and tuner?

Please don't feel like I'm picking on you. I am just as guilty. I'm very quickly coming to the conclusion that if I am willing to slow down an MPH or two when I'm pulling that I get the same MPG increase than if I spend a lot of money for 93 and tuner.

 

Thanks for the input.

She runs just fine on 87 - no pinging - and I'm definately not tuned for anything as we're totally stock.

As far as keeping up with the flow of traffic and hills I do OK. Without the trailer I run 70 mph on the highway but have no interest in going that fast with it. I'm happy in the right lane doing 55 - 60. The time I would cut off the trip isn't worth the added motor/tranny strain of going faster.

To rksylves: No offense taken. Better gas mileage, while nice, really wasn't what I was thinking of or searching for. Just a curiosity about the octane being able to provide a noticable boost in power. Sounds like save my money and stick with 87.

 

BigWill;

The higher octane fuel does not give you more power on its own. Like others said, if you are not getting any pinging with 87 octane, a switch to 93 won't give you any more power. However, having said that, if your engine is tuned to take maximum advantage of the 93 octane by optimizing the ignition timing curve, you will be able to increase your power output.

You didn't say if you had auto or manual trans but I am guessing auto. If you stay out of OD you will most likely get better fuel mileage than if you try to use it and the truck will feel more responsive. I tow a similar load with my V6 5-speed and by leaving it in 4th I get far better mileage and the truck will cruise through the rolling hills of North Eastern Ontario without too much effort.

Follow a transport for a while and watch them pull a load, they use momentum as much as possible to help them improve fuel economy. Accelerate smoothly and slowly and use down hills to your advantage, especially if there is an uphill at the other side of it. The heavier the load you are pulling, the further ahead you have to think to make it go easily. Have fun! GlennMc.

 

Glenn Mc:

You raise an interesting point that runs counter to what I had assumed and is probably worth its own thread - that being towing in OD vs. NOT. Yes my transmission is an auto and I typically tow in OD. I'm in the Dallas/Ft Worth area of Texas and while there are no mountains to deal with the terrain can be rather hilly.

I tow in OD based on the assumption that 1) running at lower RPMs will place less strain on the motor and 2) it will yield better gas mileage. When running overy flat roads and up short inclines the trans stays in OD and runs between 1,500 and 1,700 RPMs at or around 55 MPH. If I get to a steep hill or a lengthy incline it will downshift and stay there until we level off and then the OD kicks back in.

I have towed with the OD turned off across the same level road and the motor runs 2,000 or so RPMs for the same 55 MPH.

I agree the motor will be more responsive running without the OD, but how will that result in better MPGs?

Also, am I doing more harm by towing in OD and lower RPMs vs. out of OD and higer RPMs.

Constructive commnets as well as smart-alick quips welcome.

 

If your truck is stock, use the 87 octane gas. There is no advantage to using the higher octane and you will get better fuel mileage with the lower octane.

It is much easier on your trucks drive train to tow with the OD turned off. Even though the motor is turning at higher RPM, it is not working nearly as hard as it would in OD (think of how hard it is to pedal your mountain bike in the higher gears vs lower gears). The less your truck has to WORK, the better fuel mileage you will experience.

 

BigWill;

GlennMc again. I make my statements about towing based on my own experiences, and they may not be identical to your own, but here is what I have had happen to me;

The first summer I owned my camper, I tried to use OD (5th) as much as possible to try and maximize fuel economy. On one of our first long trips with the camper, I left the Barrie Ont. area and drove towards North Bay, leaving with a full tank of fuel. It is normally a 3 hour drive. I actually ran out of gas about 5 km. (3 miles) short of the first gas station in North Bay. I have since made the same trip twice since using 4th gear and putting cruise control on and have made it from Barrie to New Liskeard before requiring gas. New Liskeard is 4-1/2 hours from Barrie. There were probably other contributing factors such as head winds, air temperatures and driver inexperience, but there definitely was far better fuel economy using 4th. The added benefit is that the engine never strains to get up hills and you can relax a bit more. My engine spins at 2750 rpm in 4th at 100 kmh (60 mph) and is at the start of the real torque and hp curve in the powerband.

Try a trip without OD and check your mileage but I think you will be pleasantly surprised. GlennMC.

 

These replys surprise me! I have towed both with and without od and have found to get much better mpg with od on. However i am not pulling 5k pounds either, about 3k for me. Maybe it is because I am running at 70 mph? Anyway some very good and interesting info here.

 

I can’t say that I know the topography of Wisconsin, but you may have hit it on the head. The lower weight you pull lets your truck spin at an RPM that allows it to pull well in OD, hence the good MPG. When I’m pulling my horse trailer here in New England with all the hills, if I were to leave it in OD the tranny would be in and out of OD all the time, eventually ending up overheating. All this leads to horrible gas mileage. I tow with OD off all the time because it puts the RPMs in a much more comfortable place for my neck of the woods and the amount of weight that I tow. It’s all relative.

As for octane, I’m not going near that can of worms.

 

Great input from all. Stumbled across this forum site by accident but glad I did. With any luck I'll be taking the travel trailer out weekend after next. Will take the advice posted here and run with OD off. We'll let you all know how it goes MPG-wise etc.

Thanks to all.

p.s. Nothing to do with towing but has anyone found a source for OPD compliant propane values? My trailer is a 1990 model with the older and now out of date values - the kind that they won't allow you to refill. Are the new valves available for purchase and if so is it economincal to do so or just better to go with new tanks.

 

Just adding one more vote for towing with OD off. I've noticed that with it on that the motor tends to bog very easily until the tranny shifts down. I find that with it off the motor turns between 2500 and 3000 rpms which is a little higher than normal driving but I get better mpg and the motor doesn't bog at all. It's always made me wonder just how much strain the tranny is putting up with by shifting up and down under those conditions. It's got to be a bunch.

BigWill, my opinion but I would go ahead and just get the new tanks as I don't trust propane at all. I've never seen the valves sold as a seperate unit anyway. Besides, if the tanks are the originals then they might be due for a replacement anyway if they have any significant rust on them.

Russ