I tow a 27' Fifthwheel and I get 12 to 13 loaded but I pull mine at 70 to 75 mph. I get 21 empty whether in town or on the highway. I keep my pump turned back a little and my EGTs never go over 1100 degrees. My truck got 20 mpg bone stock and all the extras did was to increase power a lot and I gained 1 mpg overall.

 

I towed my 7x14 box trailer and got around 14-15mpg. For me the straight pipe made a large difference towing on the interstate because 1) the muffler is restrictive under heavy loading 2) the axle loop was crushed and repaired with 2 1/4" pipe.

 

I'll give you my $.02, even if you don't want it. I tow heavy(7500# trailer with 1 or 2 full size 4X4@6500# each), and usually my truck gets 10-12 loaded up 20,000# and heavier. Sometimes it slips down into single digits, but I get out and run, no babing. Full boost on hills, smoky takeoffs etc. I run od whenever I can pull it without down shifting. The larger injectors, and pump tweaks did not hurt my mileage, and made towing easier.

I agree your convertor is robbing you of the mileage. I would also run OD whenever the truck can pull the load without dropping to drive on every hill. Watch tranny temps.

I'll bet if your buddy with the 460 was towing with you, the gasser would be sweating when it got there. I do have a question, what did your buddy's new truck get for mileage on that trip?

Michael

 

Thanks for the advice.

My buddy was pulling 12.5 mpg with his 04.



It's sitting on 17k miles, CAI, full 4" with aero muffler, 4.10's, auto and 295's.

 

So he was getting the same mileage and a lot larger truck payment.

Another thing to remember is its going to take a certain amount of fuel to pull a load through the air at any speed, no matter what. Aerodynamics play into that, an old first gen spends more fuel pushing air then a slicker new truck. Speed just multiplys this.

Michael

 

If I may put my 2 cents in? If your wanting to accelerate faster, or clear up low end smoke, go with the 16cm housing, but I don't see It doing anything for mileage. Also advancing the timing will help mileage, but it also adds to cylinder pressures harder on the headgasket. I agree with getting a better TC and valvebody for the tranny, probably see most gain from that. But the MPG your seeing now is not that bad. I had a 92,5spd, 4x4, and a 32' 5th wheel, gross combo 20k, that I lived in and drugg all over the western US. I would consistently get 10mpg at full boggie what ever gear I could hold, most of the time 5th, only climbing large hills or mountians would I drop to 4th. The only modds It had was EGT gauge, true 3'' straight pipe "no smashed spot at transfercase or over rear axle", and a Droppin K&N "Didn't know anybetter then", and turned fuel screw 1/4 turn. I wish I still had a 1st gen great trucks good luck with the modds.

Jed

 

I feel like you would get the best gains by going with the new torque converter, and a shift kit. I have a 2nd gen, but the TC really makes a difference. Where I was at 3/4+ throttle pulling before; im at half throttle and sometimes less. You can drive with a lot less throttle. After you get a TC, and shift kit; I would suggest the 3200gs, and some pump tweaking. You will have a great pulling truck that gets really good mileage then. A little money in that old 1st gen; and you will be passing your buddies 40k dollar 3rd gen on the hills, and getting better mileage

Eric

 

Thanks guys!

You know what is funny? My friend was giving me a hard time for complaining about my mileage!!

He said, "Man, I'm making a $650 dollar payment and getting the same mileage!"


I couldn't help but hang my head low on that.



I called up DTT. Boy they aren't cheap!!! I know there stuff is considered the best..but I'm looking at $750 for a 89% T/C and $350 for the valvebody.


The tranny was just rebuilt to the tune of $1900 bucks (the PO took care of that...I wish he would have put in a decent T/C!) so I guess if I can find a good T/C that isn't dipped in gold I'm doing the transmission mods.


Got the BHAF, gonna get it in the exhaust shop...then get the gauges installed before I play with the pump. I'll be sure to report back when the next trip comes as the truck will be more than ready then for a update! I can't complain much I guess...my truck is paid for!!!

 

Go with the DTT stuff and you won't be sorry. I just pulled a camper (19 foot Jayco HYBRID) back from Honsedale, PA. Those mountains are pretty decent sized up there and my truck never came out of overdrive while on the highway. It was funny to see some other brands of truck with trailers about the same size in the right hand lane with 4 way flashers on heading up the road at 35mph while I roll up the road at 60mph plus with plenty of skinny pedal left. The only downside of my truck is that I can black out the highway when I drop the right foot

 

DTT makes great stuff, but If I were you; I would give Dave Goerend a call. I paid $650 shipped for my Torque Converter from him; and I feel like it would be even cheaper for you since it isnt a lockup converter. Also; for the valve body; just get on ebay, and do a search for transgo shift kit. Mine has been great so far. It helped my truck out a lot. While not as good as the $300-$400 valve body; it is definatley worth the $60 it will cost you for it. Here is Daves website

www.gbtransmissions.com

There are quite a few 2nd gen guys running his tranny's/converters/VB's, but doesent seem like I have seen a lot of 1st gen's using him. He makes great stuff, and my converter comes with a 100k mile warranty(even with the added power). If I were you; I would talk to him about the converter; and also ask him if he has a shift kit he could sell you for you to install since you dont want to spend the $ for the full VB. Id be willing to bet he could help you out. Give him a call and let us know how it goes TCI also makes fairly cheap converter's($300 or so), ut seems i have seen mixed opinions on them. Just give Dave a call to begin with.

Eric

 

Eric, thanks for the advice and link. I've heard his name mentioned a few times before so I will check with him before I jump.

 

Let us know what you find out. Dave builds great stuff with an awesome warranty, great customer service and is not overpriced. Thats why I decided I would go with him for my transmission. I havent been dissapointed yet

Eric