Ah..I see, or rather there wasn't much to be gleaned from this response. Perhaps a new thread (or DIY) with some specifics on your motors internals would be in order. I've considered that the heads and intake manifold are not designed for optimal velocities needed for low and mid range torque, and I'm sure I'm not the only person interested in what you've done. I confess at this point I'm a bit skeptical. The fact you run it on premium because of the Mopar PCM isn't cost effective to me.

However, if I had to spend 10 hours a week pouring over my ride for 3 extra mpg, I would buy an old Harley. Same maint, better mileage, much higher wow factor.

My apologies to the OP.

 

At least you answered directly. Now you are on the way to depart being a









dsertdog -- Seems like further insinuation of misleading by merc. I'm curious as to why when you've not presented anything in remote comparison given that merc gave a tidbit of his mods/practices. More importantly 2 things -- completely rebuilt motor as opposed to one under Preventive Maintenance type work. I only say that based on what you've posted. I'm guessing you've done more though as evidenced by the note in your Profile Field for

Vehicle: Mopar fan since 1968, owner since 1977,

Its prudent to put forth YOUR apple to apple version for discussion rather than lay a seed of doubt/misrepresentation/misleading/etc. WE ALL would benefit from things that people actually KNOW about from hands on experience.

 

A Harley don't work in the winter sorry to say and I have no desire to ride a bike were I live. An old Harley don't forget the oil catch can for the leaking primery, nothing better than a cake pan under your pride and joy to catch leaking oil. I don't have to spend 10hrs a week on the truck but I do and thats my choice not your's. You can be as sceptical as you want no skin off my a** If you were to look in my garage you can find just about all my trucks info there.

 

Whiteknuckle...I don't why you're involved, you should heed your own good advice, fill your plate with a big helping of mind your own damm business and move on. Would suggest you read some of my posts, you'll find a good deal of "hands on" experience with Mopars in general, peppered with a good sense of humor. I know how crappy old Harleys are for leaking. At least you got the idea, sorry if the joke didn't work. And it's no skin off my *** either how often you tune your truck. Thankfully it won't be other parts of my body either.

I'm asking for information, and what I recieved from both of you is nothing but sarcasm and scorn. That's not real helpful, but at least I'll be aware of what your version of "hands on experience" is.
I will check out your garage Mr Merc225, to see what apples you're offering. And Mr Nukle, your next helpful response will go unread, since you have joined a stellar cast of characters on my iggy list. Have a good'n!

 

This thread was not about my truck and what I have done to it, it was about running 315 tires and stock gears this was answered. If you need a diy on what I have done ask and I will be more thay happy to oblige to your request, I have nothing to hide.

 

Lets keep in mind stock gears for most are 3.55.....
White knuckle...I don't know What to say....I'm not benchmarking anything.... I'm speaking both from both my experience on the matter and also from years of reading the same experiences from other on here and those setups. You,ve been here what 5 months? and your already stepping into a lot of threads as self proclaimed arbitrator (A bit of pot calling kettle black there)... 35" tires and 3.55 gears make a very sluggish truck and is Harder on the transmission..... search it and research it...its no secret gearing is and its relation to power is an absolute not an opinion thing. You'll find most posters here who were honest with themselves and had experience with both factory setup and then the 35's would agree with me.... sorry if you are still trying to convince yourself otherwise... I did it myself for years when I had my Jeep and wish someone had made me smell the coffee earlier.

 

God this android phone is terrible.. sorry for the poor spelling.... Merc its clear you truck is not your average 5.9 magnum... that may explain both your power and MPG differences that vary from the normal averages reported here... this wasn't clear in the beginning of this thread and that why I asked questions.. not to discredit your statements but to understand them better. Actually you should post your mods so others can improve on out own mpg... There's a mpg thread started almost everyday and most cant seem to better 12mpg with 5.9 regardless of gears or tires... I know many here are younger and have lead feet but not all of us. I'd love to be able to improve mine that much..

 

Actually, I'm very impressed with your mods list...how's that. No sarcasm whatsoever. You've obviously built yourself an effective engine with the right parts, although I didn't see if you modded your intake manifold or TB. Better yet, I'd build my motor the same way when it's time.
Since nothing screamed uber mpg( other than bringing everything into spec or slightly better) at me, and the fact you have such an intensive maint schedule (which I have no information on what you really do) so I can't make an accurate cost anaylisis. Btw folks, this does apply to those considering motor mods or gearing mods so bear with me.
So while I can't do a true apple to apple test, maybe a red apple to green apple might suffice


Using my truck, I ran a quick comparison of my best mpg on my last roadtrip to Minnesota.
Average was about 12.1 mpg I filled up about every 3/4 tank or around 20 gallons.

Quick math 12.1 x 20 = 242 I was fillling up at around 228/230 miles but my odometer is off.

20 gals gas x 3.01 (current reg price)= $60.20

Using the same formula but at 15.1 mpg (3 mpg gain) would be

242 devided by 15.1 = 16 gallons gas used, saving 4 gallons

16 gallons X 3.24/gal (current premium price) = 51.84 cost of tank. A nice savings of $8.36 per tank. A nice savings...or is it?

Folks, we need to factor in one more variable....the cost of mods that got us the savings. I know most of you don't give a rats butt about this, but it is something anyone who intends on owning thier truck longer than a year or so should consider. Unless you're independently wealthy.

I tried to pricing together on your mods Mr. merc, but I can only guestimate, I'll do what I think is a low end guess, and (again) won't factor labor @ 10 hrs weekly either. One should put a price on ones time, shouldn't they? And granted folks, we can't take the wow factor into effect either.

I'm gonna say you have about 4 grand US in your trucks engine. With your pardon I'll apply it to my truck. MMMMM SWEEEEET!

So we'll take 4,000oo and devide by 8 (rounded down) which is the amount of money saved per fillup, and get 500. That should be the number of fillups (at 20 gallons) to recoup my investment. At one fill up a week and 52 weeks in a year, it will take 9.6 years to do so. BTW you folks should take manitenance into account but since mine is a bit limited other than 3000 mi oil changes...again your figures may vary.

BTW, the comments about tranny death and poor gearing tire combo is spot on. Not a matter of if but when. I should factor that into my above cost equation...but I already know I'm still making payments. And besides the rats are all pointing at thier asses and telling me my time is up. <<NOW THAT is sarcasm!

Last point, this thread was about running 3:55s with stock gears....it sucks....it sucks with 33's too. Thats my Mopar fan since 1968 ownner since 1977 experience. I shoulda put "this my 2nd Dodge Ram" in there too. Not that it would matter. I degress... you should either choose your mods carefully based on cost, or not do them at all. Because some rat is just waiting to make you pay out your *** for it. I would offer lower cost gears rather than expensive motor mods. Granted gears can't be shown off like a motor but the bang for buck is instant, and if your truck struggles to keep a steady mph on hills at legal speeds gearing is a better assist.

Have fun storming the castle kiddies!

 

I ram 35" tires with stock gearing for over a year, my truck was actually crusing at a lower rpm with the 35" tires.

Right now I have 33" tires and can barely tell a difference power wise stepping down a size.

I didnt downsize for gas mileage either, just because 33" tires are alot cheaper than 35's!

 

Ya know looking at the height I'm running just under 32's I think technically it would be marketed as a 32". Huh.