5mpg increase around town possible.....??

2kwik4u · Post by **2kwik4u** » Thu Dec 21, 2006 6:20 am

Just sitting here bored today at work with most of the bosses gone, and doing some research on how to get some better MPG's from the crew. Current average is near 14.7mpg or so. I get excited when I see 16 lately

. Less than 220miles in a tank is pathetic at best considering a 13 gallon plus fillup.

SO, on to the task at hand. More MPG's.

I have an electric fan sitting in the living room I need to install. I figure that might be good for .5-1mpg or so. Been reading a ton on the MSD 6A, and hoping that will get me 1/2 or so. Thats already up to the 16mpg threshold that I seem to enjoy seeing.

I have some shop time setup to move to all Synthetic fluids. That will be shortly after the first of the year, but I'm hoping that helps a little. New transfer case, front and rear diffs, and oil is getting moved to Synthetic. I won't use Synthetic for a few reasons in the trans, btu thats a debate for another day.

I'm thinking at the same time I might move to a new cap/rotor/plugs wires to try and get a few more as well. I was reading someones rant on the light-show they found under the hood from spark leakage. While I'm only at 38k miles I'm thinking it can't hurt thats for sure. I already keep a close eye on tire pressure, and maintain about 36psi in all 4.

I'm curious as to everyones thoughts here on new pulleys. They made a huge SOTP increase in my 4cyl truck, not sure if they are worth it on the larger motor though. Also curious as to the benefit of a good free-flowing exhaust. Not for sound, but for flow. Something like a nice quiet magnaflow.

I should also be procurring tuning software around the first of the year, and will be doing some general VE table tuning on the truck. This is where I expect to see the biggest gains, but it's also where I'll be spending the most money. If I wasn't needing the software for another project with the Xtreme I most likely wouldn't plunk down the $600 or so for it.

Anyone have any other thoughts? Anything simple I've missed? I'd like to see 18-19mpg around town if possible, and mid 20's on the highway. Oonly current mod to the truck is the K&N FIPK which actually HURT my highway milage

Post by **HenryJ** » Thu Dec 21, 2006 11:31 am

I don't see 5 mpg being possible. That is a 33% increase in mileage. Just not something that would seem reasonable.

A 10-15% increase might be possible if yours is running that bad right now. The 4.3L is just not a big mileage engine.

I have done all you suggested above with the exception of the pulleys. I do maintain above the original factory mileage estimates. I am sure that If I had 29" tall tires ,3.42 gears , lowered back to stock height and didn't pack any extra gear , I could see a slight increase in mileage.

Mine is at the sweet spot right now. All the power I want and fairly good mileage for a 4x4 truck.

2kwik4u · Post by **2kwik4u** » Thu Dec 21, 2006 12:01 pm

The only reason I'm even close to hopefull about making the goal is that my Ex-Roomates Xtreme got 19.5 on average around town. He has a 4.3/4L60E combo with 245/50/16's, and 3.42's.......Where I'm looking at 235/75/15's and 3.73's

I know I've got taller tires, and steeper gears, as well as a considerable more amount of weight, but I'd like to hit that same mark.

My other big hope was that a Typhoon I was tuning for a friend was getting 16-17mpg around town with the below build.

Forged crank/rods/pistons (8.35:1 compression)
4bolt splayed billet mains
Comp Cams 412 cam (similar to 260AHR for the newer block)
Vortec heads with mild street port 1.6 full roller valvetrain
Ported and converted stock intake
50# injectors
PT52 Turbo running 15lbs of boost (initial tuning level, will be raised to 25-27psi when new trans is installed)

IMO thats a helluva build, and was getting considerable better milage (2-3mpg) than the ZR5 does STOCK. Granted I had about 40-50hrs in tuning the truck at that point, I almost HAVE to think that I can get better from the crew.

barch97 · Post by **barch97** » Thu Dec 21, 2006 12:24 pm

I suspect the most dramatic increase you'll ever see will result from spending nothing at all. accelerate more slowly. keep the tach under 2k and mileage improves. it just takes longer to get where you're going. so, the question is... how much is your time worth?

Post by **HenryJ** » Thu Dec 21, 2006 12:32 pm

2kwik4u wrote:... my Ex-Roomates Xtreme got 19.5 on average around town. He has a 4.3/4L60E combo with 245/50/16's, and 3.42's...

The accuracy of the speedometer would be in question from my perspective.
His tire size is 24.6" If the stock size was 27.95" then the speedometer could be off as much as 10%. That would put him down around 17.5 mpg. That is about what I would expect from a 2wd around town.
I see that figure from time to time on a good tank.

17 mpg might be a reasonable goal, but I doubt the expense to get there would pay off in all but the very long run.
I wish you luck, but really don't think you will find the "magic combination"

LonestarZ · Post by **LonestarZ** » Thu Dec 21, 2006 7:32 pm

You want more mileage?? Three cheap things I would suggest.

SEAfoam
Change your fuel filter, and air filter
Air up your tires.

My 2 cents..

I get 16 city and 18+ hwy and thats with my 4200lbs, 5spd, 32" tire beast.

bwenny247 · Post by **bwenny247** » Fri Dec 22, 2006 2:26 pm

IMHO the best thing to do for better millage is nothing. take all the money you would spend in add-ons and put it in your gas tank. let's do a little math

you currently get 15 MPG in town and we'll say gas is $2.25 a gallon and you fill up once a week and a half with 16 gallons,
you get 240 miles on the tank and spend $36.
you fill up arond 35 times in a year for a total of $1260 on the year.

you somehow manage 18 MPG in town after spending $400 on performance parts.
filling up the same $2.25 a gallon every week and a half with your better gas millage it only takes you 13.3333 gallons to get to 240 miles.
you end up spending $30 a fill-up, times 35 fill ups a year, equals $1050 in gas bills.

you save around $200 in gas costs, but spent $400 to get there. it will take you nearly 2 years just to break even. however after that point, you will start to get ahead, and it seems like most people get rid of their crew after 2-3 years anyways.

just my mathematical 2 cents.

2kwik4u · Post by **2kwik4u** » Sat Dec 23, 2006 7:55 am

bwenny247 wrote:IMHO the best thing to do for better millage is nothing. take all the money you would spend in add-ons and put it in your gas tank. let's do a little math

you currently get 15 MPG in town and we'll say gas is $2.25 a gallon and you fill up once a week and a half with 16 gallons,
you get 240 miles on the tank and spend $36.
you fill up arond 35 times in a year for a total of $1260 on the year.

you somehow manage 18 MPG in town after spending $400 on performance parts.
filling up the same $2.25 a gallon every week and a half with your better gas millage it only takes you 13.3333 gallons to get to 240 miles.
you end up spending $30 a fill-up, times 35 fill ups a year, equals $1050 in gas bills.

you save around $200 in gas costs, but spent $400 to get there. it will take you nearly 2 years just to break even. however after that point, you will start to get ahead, and it seems like most people get rid of their crew after 2-3 years anyways.

just my mathematical 2 cents.

Completely ignoring the other benfits to the modifications I 100% agree. However, knowing that I have a heavy foot, and enjoy the extra performance from several of the mods (like the tune, fan and pulleys) I'm really just justifying my madness a little.

In other thoughts, I'm not sure how many miles you used to do the calculations (I'm too lazy this morning to reverse figure it out, however I'd think that for someone that drives more than the average citizen it will payoff sooner....I'm in the 20k miles/year range or so. Depending on how many mods I due to the Xtreme

Post by **HenryJ** » Sat Dec 23, 2006 2:09 pm

2kwik4u wrote:...and enjoy the extra performance from several of the mods (like the tune, fan and pulleys) I'm really just justifying my madness a little.

That is pretty much my philosophy.
If the mod will help performance and have no effect to a slight improvement in performance, it is worthwhile.

LonestarZ · Post by **LonestarZ** » Sat Dec 23, 2006 4:30 pm

Who cares about the expensive mods.. Do what I suggest and it will only cost you around $20 - $25 and you will get better mileage.

If you get 2mpg better then that saves you roughly 2gallons per fillup. The mods I suggest pay for themselves after only 4 fillups.

2kwik4u · Post by **2kwik4u** » Tue Dec 26, 2006 3:00 pm

LonestarZ wrote:Who cares about the expensive mods.. Do what I suggest and it will only cost you around $20 - $25 and you will get better mileage.

If you get 2mpg better then that saves you roughly 2gallons per fillup. The mods I suggest pay for themselves after only 4 fillups.

I've already done what you suggest, and am still not happy with the performance

.....They are good suggestions though.

In other thoughts. Took a road trip for the holidays. Louisville KY to Cape Girardeau MO. Didn't quite make it on one single tank, but drove 266 miles, and got 18.6mpg on the way there. Filled up, and drove a bit of backroads from I-57 in Anna IL to Cape, then a bit of around town, and back as far as Evansville IN, and managed 19.7mpg. I attribute the difference to the GF driving on the way there, and NOT using the cruise control at all. After the fillup, I drove the rest of the trip, and use the cruise a ton. Definately shows in the MPG I think. This was a majority of the driving done at 75mph (roughly 2300RPM) on I-57, and I-64. The 19.7 is pretty close to where I want to be on the expressway. Especially with two people, a shitzhu, and the bed full of luggage and christmas stuffs. Not a ton of weight, but definately not just myself.

Personal best for the truck is 21.7 mpg three days after I bought the truck on a slow trip to Atlanta. Cruising in the 65-70mph range in a BONE STOCK truck, by myself with only a backpack of clothes for weight. If I can hit this number again on a semi-consistant basis, I'll be happy with the highway milage.

I'm also curious how bad the milage will be on the trip to S-series Nationals next year. The ZR5 will be towing the Xtreme on an open car trailer in 3rd. I have a feeling the milage will be closer to 10mpg for that trip

.....Have to wait and see though. I intend to have the MSD, Efan, and a tune on it by then.

kermit · Post by **kermit** » Tue Dec 26, 2006 3:13 pm

How big of a factor is the gear ratio?

2kwik4u · Post by **2kwik4u** » Tue Dec 26, 2006 3:33 pm

kermit wrote:How big of a factor is the gear ratio?

I'm not real sure.....I did some math on the whole ordeal of gear ratios....

with a 235/75/15 and 3.73's, I'm VERY VERY close to the same overall ratio as my in-laws blazer with 205/70/15's and 3.42's.......well not much math, but thats comparing RPM at 70mph.

I'm not 100% sure those are the correct tire sizes, but I think thats right. Either way, the taller gears with the shorter tires work out about the same as my setup.....However I have to think that more TPS is required for the truck with 3.42's than with the 3.73's......again I'm not sure what role that will play in the grand scheme of things.

I'm sure when I swap to the 275/40/17's I have planned my MPG will drop though the floor, as that is a short gear/short tire combination that is sure to keep the motor revving higher than where I want.....Good for towing, and performance though

Wrangler · Post by **Wrangler** » Sat Dec 30, 2006 3:19 am

I just got my 2003 S-10 4x4 crew a month ago. It has 3.42 gears, 235/75R15 and so far I get 16.5 to 17.5 mixed driving on winter blend gas. Sounds bad but compared to my '04 Sierra with the 5.3 that got 14-15 this time of year.

My 1995 Sonoma 4.3tbi 5sp 4x4 ext cab got 19mpg constantly around town running premium and 23mpg on the highway.

20Blazer00 · Post by **20Blazer00** » Sat Dec 30, 2006 11:54 am

Wrangler wrote:I just got my 2003 S-10 4x4 crew a month ago. It has 3.42 gears, 235/75R15 and so far I get 16.5 to 17.5 mixed driving on winter blend gas. Sounds bad but compared to my '04 Sierra with the 5.3 that got 14-15 this time of year.

My 1995 Sonoma 4.3tbi 5sp 4x4 ext cab got 19mpg constantly around town running premium and 23mpg on the highway.

Manual has less parisitic loss from slipping, automatic slips clutches in lower speeds to get torque curve/powerband into play....

michaels86svo · Post by **michaels86svo** » Thu Jan 11, 2007 6:08 am

What kind of software were you refering too geting so that you can tune your truck?I'm interested in this info.
michaels86svo@hotmail.com

Post by **HenryJ** » Thu Jan 11, 2007 4:04 pm

michaels86svo wrote:What kind of software were you refering too geting so that you can tune your truck?

EFI Live is compatible with our PCM

quickbiker · Post by **quickbiker** » Thu Jan 11, 2007 5:25 pm

I've seen some wild clams on "gained mileage", it's crazy. I recently saw some wild claims on a spark plug article, if the actual gains were only 1/2 as much as their claim, it be the hottest thing on the market, I really don't know how they get away with wild claims. I've tried it before, it's all hogwash. The thing now that's been cutting into our mileage is the freak'n ethenal junk. I've noticed a noticable drop in mileage since the ethenal's being used again. There is one gas station around here that I know of that they say on the pumps "no ethenal added", and I swear I get at least 1 or 2 more mpg's.

2kwik4u · Post by **2kwik4u** » Fri Jan 12, 2007 3:39 am

HenryJ wrote:
michaels86svo wrote:What kind of software were you refering too geting so that you can tune your truck?
EFI Live is compatible with our PCM

So is HPTuners