OK, I had a strange idea for my Blazer......

[ABLAZN]

After spending $50 a week in gas for my daily driver for gas, I started to of ways to get my Blazer a little more fuel efficient. The original plan was to take out the 454 and turbo 350 trans and replacing it with a 350 Vortec EFI motor and 4L60 overdrive trans that I have from a 1999 Tahoe. I figured that it that should put me into the 14 mpg city and maybe 17 freeway. Then I started to remember the early days of the pre-runners. They were 2WD's that were lifted to look like like 4WD's. Since my Blazer is going to be a street rig only, I thought it might help out a little more with the mpg's I'll admit I have a little to much time at work to think of such things, but I was wondering what your thoughts were on such an idea.

[AJs72K5]

Are you thinking just pulling your front drive shaft or an all out prerunner? All out would entail: pull the xfer case and run the rear drive shaft directly from the tranny, pull the front shaft, and gut the front axle to save weight. Issues that come to mind: you'll need a longer rear shaft, a different tailshaft on the tranny, and some means to hook up a speedo. I'm sure there's more I've missed... I can't say that I'd do it, but it's an interesting thought.

[Mint68]

I had the same problem with mine. I was spending close to $300 a month on gas driving from one end of town for school, to the other for work. My conclusion, park the blazer and get something else. Paying for a nother vehicle that is easier on gas seems to be woring out ok. I spend about the same each month, I have another vehicle, and the blazer gets to hang out in the garage and save wear and tear on it.

[vtblazer]

IMO you'd get a better return swapping in the Tahoe drive train with over drive.

Even so, your thinking has merit.
A 4wd drive train has a fair amount of parasitic drag.
You loose something like 30% from the motor to the ground.

One example:
It takes 54HP to run a th-400. (that's just the tranny)

The cost might be prohibitive though, to get any real returns you'd need to do an entire 2wd swap and that in itself would get $$ fast.

The mileage lost on your 4x4 is minimal, by unlocking your hubs, your then truly running a 2wd other than power running through the transfer case.

If you really need optimum fuel mileage, build a motor/drive train that will give it to you.
Finalize your truck, meaning know how it will be in the 'done' stage.
Tire size and gears being the need to know parts.
With that knowledge, build a motor that produces it's peak efficiency at those highway RPM's mandated by the tire/gear combo your running.

Spec the intake, heads, cam and timing curve to those parameters and mileage could be decent. (another expensive option)

If you already have the Tahoe drive train, that's the best option.
Great all around driveability, injected with overdrive are about the two best thing's you can do, with over drive being #1.
Still comes down to tire size and gear ratio even with the new set up though.

[Big J]

Maybe leave your 4x4 the way it is and find a 2wd blazer or a 2wd swb to drop your vortec into.

[Jtrux]

I'll probably be the only one who says this but hopefully not. Keep the 454 in it.

50 bucks a week in gas is nothing, ALOT of people including me pay alot more than that.

It's your DD, unless you have a backup that's reliable don't go digging into this swap unless you have it all figured out, it won't be as bolt in as you think. Your going from carb to FI and even though the motor will bolt right in there will always be little gremins that will hinder your swap.

You have a 6 inch lift and 35's, I don't think you're gonna ever get 17 mpg with either regardless of gears, tranny, motor, etc,etc. My K5 has a 260 hp GM motor with 3.07's and 32 cheapo M/T's and it gets 13 at best with a strong tailwind. Maybe others do better, who knows but that's my experience.

Sell the other motor and tranny for some extra gas money or keep it for another project.

In the meantime if you want mileage gains start trading your lift for someone with a smaller lift and some different tires. I think that would be your best option but even then don't think you're gonna jump from 10 mpg to 20 mpg.

I hope I didn't stir anything up but it's only my opinion and everyone else will probably some other input on this.

[ABLAZN]

Maybe I should have mentioned this first, but my Blazer is not my DD. My Blazer my project that is a summer time play rig. My DD is a gas sucking full size Bronco that I wish would just go away. My $50 a week is just around town and to and from work. During my 4 month hunting season I drive 2 to3 times as much in a week. It just got me thinking about my Blazers mileage, since I would like to drive it as much as I can when it is finished.

[vtblazer]

It's the price of gas, your basically running through 1 tank of gas that a few years ago wouldn't have mattered.

Besides...put in a small block and you'll miss the big block, I'd bet.

[Tom Vogel]

Why not just get a small car for milage, and leave the Blazer as is? It might pay.

[Critter]

Everyone’s got an opinion...and here's mine

1st - get rid of the Bronco, regardless of gas prices (sorry couldn't resist), get something a little more economical like a small car or 2wd s10 or something.

2nd - find a higher paying job / second job. I promise that would be easier than trying to get decent fuel mileage out of these body style trucks! especially a 4wd with a lift and tall tires.

I have had a few different trucks like this and even the 2wds with high gears still only get and avg of 15 or so no matter what you try.

If you do finally do enough engine/trans/gear swapping you will have spent thousands of $ which far outweighs the little bit more you spend at the pump as it is now. Once again, just my meaningless ramblings and opinions.

[Jtrux]

Originally Posted by Critter

Everyone’s got an opinion...and here's mine

1st - get rid of the Bronco, regardless of gas prices (sorry couldn't resist), get something a little more economical like a small car or 2wd s10 or something.

2nd - find a higher paying job / second job. I promise that would be easier than trying to get decent fuel mileage out of these body style trucks! especially a 4wd with a lift and tall tires.

I have had a few different trucks like this and even the 2wds with high gears still only get and avg of 15 or so no matter what you try.

If you do finally do enough engine/trans/gear swapping you will have spent thousands of $ which far outweighs the little bit more you spend at the pump as it is now. Once again, just my meaningless ramblings and opinions.

I don't think anyone would complain about gas prices if we all drove our blazers as much as you drive yours.

[Mint68]

I just thought about this again, and I realized I was not thinking about it clearly. Instead of trying to change your blazer, I think you should just start buying more blazers. Eventually you will find a blazer that does good on gas; if not, you will have a very nice and large collection of blazers.

[ABLAZN]

Originally Posted by Critter

Everyone’s got an opinion...and here's mine

1st - get rid of the Bronco, regardless of gas prices (sorry couldn't resist), get something a little more economical like a small car or 2wd s10 or something.

I would love to see it go, but I am sure that I can't even give away a rig that gets 11-12 mph. In the end I still need a 4wd for hunting and back seat for the kids

2nd - find a higher paying job / second job. I promise that would be easier than trying to get decent fuel mileage out of these body style trucks! especially a 4wd with a lift and tall tires.

I already work a 48 hour rotating shift and have been at the same place for 12 years, so I give up a little money for the stability

I have had a few different trucks like this and even the 2wds with high gears still only get and avg of 15 or so no matter what you try.

If you do finally do enough engine/trans/gear swapping you will have spent thousands of $ which far outweighs the little bit more you spend at the pump as it is now. Once again, just my meaningless ramblings and opinions.


One the other main factors in this built is the drive-ability that I will gain with the EFI/ overdrive combo. Right now the big bock with the 4:56 gears really is not a good set up. Also, the PO's install of the big motor sucks to say the least. It hits the back firewall, the headers hit the frame and I can't even turn the distributor to set the timing right.

Originally Posted by Mint68

I just thought about this again, and I realized I was not thinking about it clearly. Instead of trying to change your blazer, I think you should just start buying more blazers. Eventually you will find a blazer that does good on gas; if not, you will have a very nice and large collection of blazers.

Now here is an idea I like, I could set up a DD with a 4.3 Vortec and a 5 speed. Then I could have my show/ cruise in rig and another for 4 wheeling...... of course my wife would kill me, but that is a small price to pay right .

[Angelse68cal]

Do do that to your blazer. If its gas you want to save on go by a 300 dollar road bike and ride it. It will not cost you anything but time. Not to mention it will keep you young and in shape. LOL

[ABLAZN]

Originally Posted by Angelse68cal

Do do that to your blazer. If its gas you want to save on go by a 300 dollar road bike and ride it. It will not cost you anything but time. Not to mention it will keep you young and in shape. LOL

It is obvious that you don't know Oregon weather The rain here makes year round bike riding less then desirable. Still, I like to get out and peddle when I can.

I guess I'll stick to my first plan and put in the Vortec with the 4L60-E and keep it a 4x4. The Blazer is really going to be a summer time cruiser so, I won't run it enough to notice. Still, it is fun to toss these ideas around and get some input from you guys to keep me on the right path.

[myblazer72]

I get between 13-14 MPG
I have the 260 HP 350, 700, 410s, six inch and 35s.
My milage increased by 2-3 when I did the 700. It really jumped when I switched gears from 3:08s. My wife drives a 06 silverado crew with a six inch lift and 35s and she only gets 13.5. IMO a good setup with a light foot works as well as fuel-injected. Although I did buy my buddies prelude for 400 bucks and that gets driven four days a week.

[69TowRig]

Are the axle gears correct for the tire size you are running? Do you even know if they were ever changed?

[ABLAZN]

Originally Posted by 69TowRig

Are the axle gears correct for the tire size you are running? Do you even know if they were ever changed?

I my case, no, the gears are all wrong as they are now. With the 4:56 gears and 34.4 inch tires, it would turn my 454 at almost 2900 rpm at 65 mph and that does not include torque converter slip. With the overdrive 4L60-E, the small block with be running 2026 rpm at 65 mph and no converter slip since it is a lock up style. If I were to go down to 4:11's I could drop it down to a little over 1700, but I want to try the gears I have now to see how they work with that set up.

[1LoC10]

drop in a straight 5 out of a new Colorado