I have a 1998 F150 XLT ex-cab 4X4 w/the 4.6. I use the truck primarily to haul a 21ft boat. The truck stuggles alittle while in tow. I wouldn't say struggle is the right word but, you can feel the truck working hard while towing the boat. I did a few things to help. I added the Superchip, new exhaust system and the K&N airraid style kit. It's doesn't really seem to make any noticable difference. I was considering changing the spark plugs. The truck has 35000 mile on it. I was thinging either the split fire triples or the bosch 4. I had a Ranger w/4.0 v6 and had the split fire plugs in it. The dealer said they were doing more harm than good. Which would be the best for my engine and hauling situation? Are the any other mod's I can do to help with the hauling duties? Don't want to spend too much more. Next time I'll get the 5.4. I was told the 4.6 would be fine for my use and would get better mileage. Is there a big differnce in the 5.4 over the 4.6? Any advice would be great. Overall is the 4.6 a good motor? One last thing. I only use Castrol oil in all my vehicles. What weight should I use for hauling the boat? The weather here ranges from 75 to 105 degrees in the summer. Thanks again...

 

I forgot to mention I have BFG AT tires on the truck. I believe they are 285's which I think is like a 33" tire. Should I change gears?

 

I would say that your problem is the tire size! I have a 2WD with the 4.6, and although it is "not a race truck" it tows my trailer loaded with 300 gallons of water with no sweat!

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1999 4.6 Extra Cab-Short Bed
Silver Clear Coat Metalic
K&N Airfilter
17 Inch 2000 Chrome 4X4 Wheels Wrapped in 275/60/17 ZR Yokahama AVS
White-Faced Luminescent Gauges
Flowmaster 3 inch Cat Back 40 Series Exhaust
3.5 Inch Polished Thermal Research Exhaust Tip
Clear Corner Lenses
Super White Headlight and Turn Signals
Trends Billet Antenna
Stull Billet Grill
e-mail SILVERFORDF150@AOL.COM






[This message has been edited by FORDTRK (edited 05-19-2000).]

 

I think I'm going to have to check into changing the gears. I'm not sure what is in it now. I do know it came with the tow package. When my speedometer says 55 I'm actually going about 62 to 64. Thats not good for tickets. Glad I didn't find out the hard way. ( speeding ticket)

 

Actually it is the other way around larger tires make your speedometer show slower speeds, smaller tires make your speedometer show faster speeds.

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Mods:K&N Intake,
3"Flowmaster,
Transgo Shift Reprogrammer
Dyno:228.6HP, 309.8TQ
4R100 TRANS
9.5" Converter 2500 Stall
Micheline 275 75 R16
Heavy Duty RearEnd W/355

 

I have seen tests where higher performance spark plugs will not perform any better with a stock ignition. The engine may be a bit smoother, but no real power advantage.

You may have to consider upgrading the ignition system with an MSD (or the like) and upgrading the wires with some Magnecors (best stuff I've ever seen).

Another idea is to upgrade your fluids. The better syns (in the engine, tranny and transaxle) will have much lower coefficients of friction and will leave more HP for the tow.

Otherwise, sounds like you are on the right track.

Randy

 

I was hauling the boat down the freeway. The speedometer said 55-58. A body of mine that was following me drove up next to me and said whats the hurry? He said I was going about 64-66. I'm almost possitive stewdog is not correct in his post.

 

rich, I think I have this figured out. While you indeed switched to larger tires obviously, your buddy must have switched to much smaller tires. He is ridin around town, shaking his head, thinking everybody is a speed demon.

 

I'm gonna put bigger ones on the back and smaller ones on the front to help my gas mileage. Always be goin down hill then you see.

 

cphilip, I was thinking along those lines too.
I'm planning on putting much larger tires on the right side of the truck.
I'm always forgetting to turn my left blinker off and that way, I'll be covered.

 

Unless I'm reading wrong, richgonfishn and stewdog said the same thing. Richgonfishn says the speedo says 55 while the actual speed is over 60. Stewdog says speedo reads lower then actual speed with larger tires... Whats the beef???
I think the 33 inch tires are larger then stock, don't you???

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Black 1997 F-150 Supercab Flairside. 4.6L with Jocobs DIS, K&N Generation II, Cat back Exhaust (my own, nice rumble). 17" Off Road wheel pkg. Lots of body mods. 4 yrs old and still turns heads...

[This message has been edited by WLF (edited 05-19-2000).]

[This message has been edited by WLF (edited 05-20-2000).]

 

Raoul,
Great sense of humor!! LOL...

 

stewdog is most definitely correct on the tire size affecting the speedometer. If tire is larger, outside diameter is larger, so if your axle makes x number of revolutions a minute at a certain speed, then with the larger tire diameter, you are traveling more distance at the same speedometer reading and same revolutions of the axle over the same time.

Something like that anyway

 

Stewdog is correct. Think about 2 trucks going down the road at 60mph. One has 36" tires and one has 20" tires. The 36" tires aren't moving as fast to cover the same distance as the 20" tires. So, with the big tires, the speedometer is showing slower than 60 and with the small tires the speedometer is flying past 60.

Get yourself some gears or a supercharger. I pull a 21ft boat all the time that weighs in about 3100 pounds with my 4.6 and don't have a problem.

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hytek1dr@yahoo.com
http://www.geocities.com/MotorCity/Freeway/7515/

 

All I know is, when I switched to bigger tires my drive to work went from 25 miles down to 22 miles, so I was happy.

Still takes the same length of time to get to work though. I guess traffic must be getting worse.