Micaiahfied

my 92 is used to seeing 20-24mpg on the highway depending on my speed and other factors. on this last trip we finally pulled the 5th wheel. it probably weights about 9000#'s with the truck weighing in about 7000 or a little more loaded. so total wieght of 16-17k. i was hoping to see 13-14mpg but no luck there. the best tank showed 11.89 and worst was down at 10.48 . i can say i was in a hurry and not traveling the slowest but still expected better than that. the boost gauge pretty well sat at 10psi on the flats and all the way up to 24psi or so on the hills. tranny temps forced me out of OD on many hills but not all. the BHAF was my only thought to help improve, i am still on a stock filter and it's not brand new. if the stock truck only ever saw 12psi and i've doubled that but haven't given the turbo a better source of air i may be making it work too hard to get the air? what are your thoughts and or suggestions

jrussell

Yes, you really need a BHAF to help move all that air.

Ace

Sounds like it is making plenty of boost. Isn't that where your intake restriction will show up first? BHAF certainly couldn't hurt, though..

jrussell

Yes, but perhaps his truck will make 26-27psi of boost with a BHAF. You wouldn't notice the restriction until you changed to a BHAF.

It probably won't increase your mileage by 5mpg (unless your current filter is really dirty), but it's such a simple and cheap mod why not give it a try and see?


EDIT TO ADD: Oh, Micaiahfied, I forgot to mention that I seem to get around 15mg while towing my crawler (about 5k) on a combo of level ground and twisty hills at 45mph-70mph. And that is making sure I keep up with my buddy's Duracrap the whole time so he can't talk ****!

Ace

I'd be curious to know how much of it was going out as heat through the TC. Thought about putting a temp gauge on that tranny yet?

jrussell

For tranny and water temp gauges, I highly recommend the Equus electrical series. The probes are half the size of normal mechanical ones and won't need spacers for either application on our trucks. Here's the one I got at Checker Auto Parts for $16...

http://www.iequus.com/product_info.p...ory_id=100_120

I normally only use full sweep gauges, but these just make the install so much easier and cleaner. They also react to temp changes much quicker from what I can tell. Some 90* sweep gauges have the numbers all screwed up and hard to read. This one has a simple hash mark every 20* in between the numbers, so it's very easy to read.

rlyons

I get around 20 unloaded and 12 loaded if I run 70 to 75 MPH. This summer we took a 5500 mile trip with the 5ver in tow and I set my cruise at 65 and kept there and I got 14 to 16 MPG. Speed does kill mileage.

Micaiahfied

i figure it's speed in combination with the older stock filter. BHAF will be going on when funds allow, definately before the next trip.

jrussel, i stuck with full sweep mech gauges for both water temp and tranny. i was actually able to put the water temp above the t-stat with the fittings that came with it without any restriction, i used a little extra of the yellow tape so that it would seal up earlier on the threads, no leaks yet and i will keep an eye on it! as for tranny temp i also used mech to get the full sweep in the autometer z-series. after spending probably a few hours at hardware store trying to figure out how to get the thing into the stock port without restricting flow i ended up back that the local store that i got the z-series gauge from. less than 5 minutes and we found autometer part # 2271 for like $10 it's a long adapter with 3/8th npt on the front end. so the tranny temp sender could be put into the stock sender location with one fitting and no mess! they also make the same type piece for the water temp size... part # 2240 the description on the part says "3/8 NPT extension temperature adaptor for mechanical full sweep gagues"

i put in a new 180 degree t-stat before the trip. on the longest of hills water temp got up to maybe 210 or maybe 220 at a maximum for most of the trip it didn't even hit 200 though. depening on the hills and outside air temp the tranny usually rested at 190 in cooler temps up north and 210 farther south with a few extra hills. out of OD i could pretty easily keep it at 220. those numbers seem about right?

goodtyms

I just got about 14.5 mpg while pulling a pretty light (about 2500 lbs combined) boat and single axle trailer at 65-70 mph. I normally get 16-17mpg at the same speeds unloaded.

wannadiesel

Sounds like you were pushing pretty hard, Mark. Aerodynamics is a big fuel sucker, and if you have a headwind everything is magnified.

wayne74447

well i get 20-23 mpg unloaded with mine and 16 towing my 25 foot MacGregor sailboat at 65 mph. I cant ask for more!

wayne

DBF

After you get moving, the cross-section of what you're driving and towing is the dominant factor. That 5er (doesn't matter what it weighs, just how much frontal area) is like pulling a wall down the road. After six years of dragging a 7500# 5er all over the place (Alaska, Newfoundland, etc.), I'll tell you the best I *ever* got was 13.0, downhill with a tailwind. The worst was bucking a tremendous headwind into Miles City MT at 8.5.

I suppose I could get 14 if I stayed at 45mph with no wind.

Use Google and find a place that explains Horsepower required to overcome Frontal Area Drag.

Sorry for your frustration, but that's ......

Regards, DBF

mopar2ya

Mines 4wd 5 spd w/ 3.54 and I get 16-17 hwy empty at 72-75 and 10-11 loaded. Doesnt matter if just 1 car or a 50 ft with 3 cars 10-11 mpg. Its just nuts.

DBF

It's not nuts. It's just that pulling a square front into the wind (going down the highway with a 5er) costs you. Start here:

http://en.wikipedia.org/wiki/Drag_coefficient

Regards, DBF

Micaiahfied

DBF, that is the answer i was afaid of, but at least that means nothing is broken. i know the truck has the aerodynamics (sp?) of a brick wall, and then i add another brick wall on top... not so great.... any idea how much the little spoiler things on the roof help?