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?

 

Hey Rich,
The Bosh platinum +4 plugs seems to be the top choice around here. I've heard a lot of bad things about the split fires, tips breaking off ect.. Sounds like a gear change would be your biggest gain. I have a 5.4L and only pull an 18ft boat (2500lbs).
Just curious, what type exhaust system did you install? If you went for the "true duals"
and big 3" pipes you've lost a lot of low end torque = no power for towing.
As far as the oil goes, I use Mobile 1 5w30. The summers get really hot here in Georgia too.
Good Luck !!

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2000 F-150 XLT Supercab 4x2. Bright red clearcoat w/gold two tone.5.4L, 3.55LS, class III towing, keyless entry, overhead console and captains chairs.
Ford bug shield and vent shades, Ford(duraliner)bedliner, Extang Black Max soft tonneau, Westin platinum SS nerf bars. Hellwig rear sway bar, Flowmaster 2 chamber dual out the sides catback, Airaid FIPK, Superchip

 

Dear richgonfishn,

By far the biggest problem you have right now is those tall tires. Those 33" tires are forcing that engine to work significantly below it's power band, which is why you're not feeling a whole lot from your modifications. Those mods are in fact working, but with the engine struggling below it's power band, it's going to be a tough situation. Yes, you do need to do a gear change, and I would suggest at least 4.10's, but with 33's, you may need to go a bit further. I don't have one handy, but I'm sure someone can chime in here and list some of the conversion "engines" on the Internet that will allow you to plug in your new & old tires sizes, and get the appropriate gear ratio to compensate so that you will at least get back to square one. Meaning, so that the engine will be turning the same rpms' it originally was before the large tires were installed.

In your situation, you are towing a large load in an underpowered vehicle, with tires that are sunstantially taller than stock (most stock tire & wheel combos on the F-150 range in height from 29-30 inches), which causes the engine to labor far below it's power band.

Nothing is going to substantially help that until you increase torque multiplication via gear change, *or* go back to stock or close to stock tire sizes. The gear change will need to be done to both front and rear differentials, so you're looking at some expense doing this. You will need to decide whether it's worth it to you to spend the $1000 & more than this can cost. But you will either have to do this gear change front and rear, or else go back to your stock tire size to get your performance back, there isn't going to be any substitute I'm afraid.

You are not alone in this situation, we deal with a lot of peoople who have done just that, put much bigger tires on the vehicle (which it looks much better with in most cases!), and then wonder where their power has gone. It's very common, unfortunately, and in a lot of cases, had the customer *known* ahead of time what these taller tires were goiong to do to the performance of that vehicle, and that they need to do a gear change to compensate, they wouldn't have gone for it. Or, they would have waited until they could budget in the additional $1000 - $1500 that doing both differentials can cost, especially if they are limited-slip.

If you like, you can give us a call and we can work with you to help you determine exaclty what gear ratio you need to restore the performance of this vehicle. You may decide that you just want to go back to the stock tire size for the time being, to lower the cost of getting the perforemance back up, that is of course up to you. But do feel free to call us if you'd like some help with that, ok?

On spark plugs, the Bosch Platimnum +4's are pretty much the hot ticket. You are most likely not going to feel a seat of the pants power gain from them, but they will help give you a bit sharper throttle response and perhaps a tiny bit better mileage. But with your taller tires, that too is going to be effectively negated until the gear change or tire size change is done.

Best of luck, and call us if you like,

------------------
Mike Troyer
Performance Products, Inc.
National Distributor of Superchips
(540) 862-9515
Email: mtroyer@compuserve.com
Performance Products F150Online Superchip ordering system: F150Online Superchip Ordering System

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

 

I just ordered the S-chip on Wednesday (Thanks Mike T.) and will be getting it on Monday for kinda the same reason....I upped my tire size from 265/70 17's to 285/75 16's and noticed that there just wasn't the same get up and go.....Put on the K&N Gen II FIPK, noticed a difference but not the gains I expected....searched the site some more and came accross a thread stating the S-chip should be the first mod and gives you the best gains for the buck....I ran my tire change through the Miata Tire Size Calc and on paper only picked up 1.2" in Diameter and the *Spedometer reading with non stock tire is 3.87% too slow* Which is 2.1 mph at 55, 2.5 mph at 65, 2.9 mph at 75.....not a whole lot in my book.

Now my question, did I do the right thing by ordering the S-chip, or should I have been saving up to change the gears (I don't think it changed enough to warrant the expense$$$)? I hope that I too will see the gains that everyone else writes about on this board...but posts like these where people state these mod's really don't *seem to make ny noticable difference* worry me!

Somebody help me out here...

P.S. I'm only doing light towing, my Jet Skiis, and the occasional friends boat...and the truck handles it fine, but with the tire change I notice ther're back there a little more than I did before.

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'97 F150 Lariat 4x4, 4.6L V8, 3.55 LS, 285/75R16 BFG AT TA KO's, 16x8 Weld Racing Typhoon's, K&N Gen II FIPK, 4 Explorer Pro Comp ES 3000 Shocks, Superwhite Bulbs, Tinted Windows, Colonels Fiberglass Tonneau Cover painted to match, Tow Pkg, 6CD Changer

Mods to come: Superchip http://dopealicious.tripod.com/page_3.htm


[This message has been edited by MAK 3 (edited 05-19-2000).]

 

MAK 3
Every inch in wheel/tire size changes the gear ratio 1/10. So, 1 1/2" bigger changed the 3.55 to about 3.40. You have lost a good deal of low end grunt/torque.
About the Superchip, it really firms up the shifting, changes the shifts points to about 400 rps higher than before. Ideal for towing!
The higher shift points keeps the tranny from " gear hunting " so much. It is worth the money for the shift improvements alone. The extra hp is a bonus!! Keep in mind , 25 hp is not going to pin you in your seat in a 5,000# truck. You will feel the difference though!!

Hope this helps
Good Luck!!

------------------
2000 F-150 XLT Supercab 4x2. Bright red clearcoat w/gold two tone.5.4L, 3.55LS, class III towing, keyless entry, overhead console and captains chairs.
Ford bug shield and vent shades, Ford(duraliner)bedliner, Extang Black Max soft tonneau, Westin platinum SS nerf bars. Hellwig rear sway bar, Flowmaster 2 chamber dual out the sides catback, Airaid FIPK, Superchip




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

 

Did someone say 'Chime in'?

Here's some stuff to chew on Rich:

Making the following assumptions - your original setting was 255/70-16 with 3.55:1 differentials and your current set up is 285/75-16 with the same gears.

Stock - 255/70-16 30.05" Tall
Now - 285/75-16 32.83" Tall

Your actual Ratio is 3.25:1. To equalize the added height of your tires you would need a gear ratio of 3.88:1.

If I've made the wrong assumption on actual tire sizes you can play with these numbers by visiting http://www.4lo.com to figure gear ratios and http://www.miata.net/garage/tirecalc.html to play with tire sizing.

I hope this helps some.

Tom in Tacoma

 

E mac - Thanks for the response...from all the other posts I've read I'm sure you're right and I'll feel it, and it probably get me right where I want to be.

I know I'm being picky here but the tire diameter went from a 31.6 to a 32.8 wich is a 1.2" increase not 1.5" increase.....does that .3 diference make a difference? Probably not , but again it hasn't made that big a difference and wouldn't take very much to get me back where I was or beyond that (the FIPK alone helped a lot a higher RPM's)...

 

richgonfishn,

Inexpensive changes would include synthetic oil in the tranny & T-Case but this will not help much. I agree with E mac that gears will help the most.
What tires did it have when you got it? If you had 255s then they were 30.3 inches tall going to a 33 inch is about 10%. 10 % of a 3.55 gear is 3.90 and they don't exsist so the closest thing is a 3.73 or 4.10s. As I never go to the higher side I would recommend 4.10s. Now that will restore your towing back to the way it was before tire changes. If that was ok then switch gears. If you found that towing with the original tires and the chip exhaust & airaid was not good enough I would go for 4.30 gears. Be forwarned that your MPGs will suck with 4.30s when it is empty. Don't forget you have 2 sets of gears to change.

Regards

Jean Marc Chartier

------------------
00 F-150 XLT SC Flairside 4x4 4.6 w/5spd 3.55LSD
Warn XD9000i, skid plates, Draw tite class III,
Rancho RSX Reflex shocks,
Borla Cat Back
Modified Air Cleaner Outlet Tube
and air box, K&N air filter,
Superchips

 

HI MAC3,

Just to give you an idea of what you actually got from the airbox elimination kit in terms of horsepower, they yield 12 hp on the 4.6 motor, and 14 hp on the 5.4 motor. Keep in mind that because it's an airflow type of mod, it's going to make itself felt more at higher rpms. It's a good horsepower maker, it's just not quite as good at making additional torque down low like a big heavy truck needs. It is a very worth while mod, and we use them on all our vehicles that a kit if available for.

Your tire size change has also put a bit of a damper on this, as remember, anytime you go to taller tires (more circumference), you have effective lowered your numerical gear ratio.

I know there are a couple of calculators out there that say for each inch of tire height change it's only a .10 difference in gear ratio, but I do not agree with that at all. As a matter of fact, I actually saw that claimed on one of the Saturday TNN shows I watch, Trucking or something, I can't remember the exact name. Anyway I saw one of the guys take 2 tires, but them side by side, and say that a 3 inch change equals only a .30 difference in gear ratio, in other words, 3 inches taller making a 3.55 only down to 3.25, and I do not agree with that at all, it makes a bigger difference than that.

What we do is to take how many rpms' the vehicle was *originally* turning at say, 70 mph in Overdrive, and make the gear ratio change based on getting the engine back up to at least that rpm range, and usually just a big higher, to compensate for additional engine load, so we can get thr vehicle as close to possible to it's original performance level, so you can get a fair feel for what your actual power-adding modifications will do.

Don't worry, the Superchip is *always* going to make the additional power; it's a matter of how much impact can that added 10%-12% power have on that particular vehicle's weight and gearing combination. The Superchip is always going to do it's job.

------------------
Mike Troyer
Performance Products, Inc.
National Distributor of Superchips
(540) 862-9515
Email: mtroyer@compuserve.com
Performance Products F150Online Superchip ordering system: F150Online Superchip Ordering System

 

Thanks MIKE T! I'm sure it's going to be fine....I'm just trying to educate/prepare myself for what kind of realistic gains I can expect (which we discussed on the phone).

Rich's situation (I responded to in his subsequent post) is totaly different with bigger ramifications....So it isn't fair for me to use it as a comparison...

I will get the chip installed and report back how it goes....I am also towing to the lake for Memorial Day and will really be able to see how it affects the truck on hills, in the flat, in the heat, etc...I'm sure I won't be disapointed!

Thanks again for your knowledge and insight...most times I find this site more helpful when trying to get info about my truck than the Hayes Manual!

 

Sorry about the misleading information on the tire size and gear ratio. I read that somewhere a long time ago.
Just trying to help.

 

Hi E mac,

No need to apologize, you were just trying to help!

I've seen those same numbers quoted by people who are generally considered to be very sharp, I think they just made a mistake in what source they used is all. It's a very easy mistake to make.

------------------
Mike Troyer
Performance Products, Inc.
National Distributor of Superchips
(540) 862-9515
Email: mtroyer@compuserve.com
Performance Products F150Online Superchip ordering system: F150Online Superchip Ordering System

 

Hi MAC 3,

Good luck on your trip!

Sounds like you're making this a Memorial Day weekend outing?

------------------
Mike Troyer
Performance Products, Inc.
National Distributor of Superchips
(540) 862-9515
Email: mtroyer@compuserve.com
Performance Products F150Online Superchip ordering system: F150Online Superchip Ordering System