Hey guys, I'm new to this forum so please bear with me. I realize that the question I am asking has probably been asked 100+ times before, but my searches through past threads don't seem to be producing the definitive answers I am looking for. So, here goes...

I own an 04 expy 2wd with the 5.4 liter. We recently purchased a travel trailer and will be towing it with this vehicle. If I were to install modifications such as K&N fipk, Gibson exhaust, and Hypertech programmer, would I see any appreciable gains in performance for the money I would be spending? Improved MPG would be nice, but I'm not looking to make up the money by saving gas. I would like to pick up some extra HP and torque without having to go beyond these types of modifications.

Like I said, I know it's an age old question, but I usually find that I will get a straight answer when I ask a straight question. Thanks in advance for your experiences and expertise.

 

I think gears are likely your best bet.

Unless you have 3.73 rear gears (not common), installing 3.73 or even better, 4.10 rear gears will make the most appreciable difference when towing.

I run 4.10s with stret tires on my 2WD Expy.
Second-best mod I ever did, and I've done them all (almost).

 

I know that it has limited slip differential but I will have to check to see what the gears are. Thanks for the tip!


Anybody else?

 

A friend of mine did a bunch of bolt-ons on his 02 F-150 5.4, and the SCT programmer, headers and exhaust made the biggest difference. A drop in K&N is a good upgrade as well.

 

Thanks Blurry. I clicked on the "SCT" link and it just sent me to MotorHaven. Is SCT a brand of programmer or is it a certain type of programmer? Also, you mentioned the use of a drop-in K&N filter; would you recommend that over the FIPK? I suppose there might not be that much of a difference between the two except for cost, considering how the OEM filter and housing are shaped. What are your thoughts?

 

Motorhaven is an SCT dealer so you can get a an X-Cal programmer from them.

The stock air duct is good and it pulls the air in from the fender wall instead of the engine compartment. If gas milage isn't an issue, then taller gears (as mentioned above) will definately help.

 

Thanks again Blurry. I like the idea of saving a few bucks by getting a drop-in filter. Maybe I could re-invest the savings into a set of headers. Do you suppose headers, exhaust, K&N filter and a programmer would do the trick? I'm not so sure about switching out the gears; sounds like a job for a mechanic and I'm not sure if it's the right mod for driving around town, which is what my wife uses the Expy for. I'll need to do some research into the gears job to see if it's worth the trouble.

 

Filter, headers, exhaust and tuning will definately make a considerable difference, as per 'seat of the pants dyno'.

 

I've been doing some searching and reading, and maybe I should just bite the bullet and go for a supercharger. It looks like that's the way to go for major gains on HP and torque. Anybody have any opinions about which brand has the most bang for the buck? Is it advisable to tow with a supercharger?

 

you wont want alot of boost to tow heavy loads with a s/c...an intercooler may help this problem, but still. Gears are the best thing for towing, the more leverage your engine has on the tires the better...its like when you were a kid with a 10 speed....youre always the same power output, but you could cook up a hill when the chain was on the big sprocket out back, your legs just moved faster but as long as you didnt wind yourself out you could mosey on up the hill....but when you put it on the small sprocket on the tire you had to work as hard as you could to get that bike to move. Gears are your best bet.

to gain any real serious hp by modding stuff like exhuast or getting a chip you need to have the rest of the engines functions up to par...sure they will help a big on a stock engine, but why spend money on exhuast and a programmer....when you could put the exhuast money into new injectors to compliment the chip? then youll need some induction mods to keep the a/f mixture right.....(see how its going now?) then youll need some better flowing exhuast to get rid of all that extra air and fuel you pumped in there. So again, if you want to keep it simple and just need to tow easier...get lower gears (numerically higher)
-Al

 

Stop and go driving, as well as towing, is where you'll get the max benefit from gears.

 

So, street driving won't see a significant change in MPG, but highway driving (higher RPMs) will reduce MPG? Aren't 3.73s decent towing gears? I thought if I had those gears and went with a supercharger, I'd get the best of both worlds.

 

well whats the highest posted speed limit you travel on? and what are the engine rpms at while doing said posted speed? if its 60mph, and your engine is running 2000 rpm (lets just say it is) and your vehicles gear ratio now is around 3.55:1 and you go to 4.11s your new rpm would be about 2250 rpm.

 

with a s/c you would need a chip or a programmer to handle the added fuel delivery a s/c requires....see how this loop is working yet? lol. Modding vehicles is fun hey!

 

Yes, but most s/c kits come with a programmer/chip flash, and some come with larger injectors. I'm not looking for a s/c with boost more than 8psi, so I'm hoping to get a s/c kit and maybe a better exhaust if necessary.

Also, my Expy has the 3.73s in it. The highest posted speed limit here in SoCal is 65, but everybody drives 80 when there's no traffic; if you're not going at least 75, you're going too slow!