Rear end

[DFlynn21]

I have a 91 s10 with a 3.73 gear. I want to put 3.08 to get better mileage out of my v8. Is there anything that has to be changed besides ring and pinion gear?Does anyone know the service code for the S10 with the posi rearend?

[steve]

I think the 3:08s go on a different carrier then the 3:73s when it comes to a GM 10 bolt 7.5 ring gear. Sort of remember there being a cut off point some were in there when it comes to gear ratios, but I think there was a spacer or something to fix this issue. I sort of remember something like that, could be wrong though. And I know the limited slip option only came with one gear ration with the s10s, but I don't remember which one. It has been over a year since I did all the research for my rear end so my memory is a little cloudy on the details. Sorry. I hope some one can clear it up for you.

[DFlynn21]

Thanks Steve! Someone was telling me that the cuttoff was at the 3.23 carrier and if it was to go down it would have to be changed. I dont know anything about the spacer but hopefully someone on here can help me out with the info I need. Thanks

[Danny_SS]

Is your V8 Carb or EFI?
What tranny are you running?
If you are running a carb, you should REALLY look into geting a EFI setup. You will gain drivability, power and Mileage.
If you have a 350tranny, go for a 700 so you get a better 1st gear plus overdrive.

Now about the rear end, I dont like the 3.08. I think its slows you down too much. Camaros, vettes have 3.42's and they make decent mileage.
Instead of swapping gears, You should swap rear ends, you'll be glad you did.
Try to find the posi rear end with the 3.42 gears in it.
I think the posi is G80, I'll look it up once Im home later.

[DFlynn21]

Thanks Danny SS, I am running the Carb with the THM 350 Tranny. By chance do you know a rear end that will mount up to the S10 or one that is close?

[daryl]

G80 is the 3.42 posi rear end

[Dimemaster]

You can use taller tires to do the same thing as a gear swap. You might not like the performance drop of the 3:08s. You'll need a tire about 10% taller (about 2.75 inches) than your current tire to replicate the gear swap. Run the tall tires during the week and swap on your short tires for weekends.

[s10350racer]

i may be out of my tree here, and im not tryin to be an ass, but why are people using v8s and still super concerned with gas mileage? i realize that gas is expensive these days, but i put a v8 in for performance knowing that i would be lucky to get 10 mpg. i understand that it is possible to have the best of both worlds, but efi setups and other gas saving devices can be expensive and sometime limit power. i am an advocate for overdrive however. if you dont have one, get one. not only will it save your gas, it will save your engine and other components from the higher rpms.

[daryl]

Yeah, some people are funny that way get huge v8 suvs and want gas savings...I bought my v6 blazer knowing it would get 16mpg and expected it to be more than my 2.2 ca was. People are funny that way :), I guess they love power and awesome milage but the world doesn't work that way. As for EFI its not just about milage its more POWER and MILAGE so that is a good suggestion there makes more sense than some other ones you hear :) .

[Dimemaster]

Hmmm? My 81 with a 383 put 408hp on the ground and returned 18mpg around town, 22mpg on the highway. Not to many 4.3s get 22mpg. I'm building a destroked 305 specifically for gas mileage and expect 230hp and 280lbs/ft, way more than any but the hottest 4.3s, and high 20s for mileage, on 87 octane, with a quieter, smoother running engine. Yes, you can have your cake and eat it, too. Yes, the Edelbrock Pro-Flo setups are expensive, but no carb will deliver what the EFI will.

[Danny_SS]

MY Carbbed 350 S-10 gave me 10mpg (driving hard) and 13mpg when driving normal in miami city traffic. If it had been EFI I would have gotten 16mpg easily which is the same as my 4.3 with the added performance of the V8. I could have made it stickand I would have made even more mileage. Just because it is a V8 does not mean that it has to drink gas, just look at the new Vettes making 400hp AND 28mpg.
A big factor in fuel economy is the weight of the vehicle. That is why the big suv's make crappy mileage not the V8. You caput a V6 in there and it will waste just as much gas.

[screamn91]

As far as that spaceryou can proablly get it at a speed shop ofany kind. Ask for a Series 2 to a series 3. This is what I had to do to my 91 when we put rear discs and posi in it. I beleive that I only paid about $35 for the spacer and the bolts. My lt1 and a 6 speed get 24 highway and 19 in town. That is conserative driving though. If I really hammer down on it, it will get around 10MPG. EFI is where it is at. This is the very first one i have ever had in a toy. Never again will I have a Carb on something of mine.

[InProgress]

yeah, in theory, a mild V8 setup should return decent mileage if tuned correctly and if you're not running super steep gears. you're putting a very minimal strain on the engine during normail driving since the truck is so light. You may look into your tune. that can severly alter your fuel consumption.

Also, YES, i'd look into an overdrive. There's a reason EVERY car built nowadays has one.

And the rearend, yes, 3.23 is the cutoff on the carriers. And G80 is the posi designation. :)

[s10350racer]

not EVERY car built today has them...Chrysler is still pumpin out 3 speeds in their minivans and small cars

[Mike D]

not EVERY car built today has them...Chrysler is still pumpin out 3 speeds in their minivans and small cars
Alright im not trying to be a d!ck but I was curious about your claim so I looked all over Chrysler's/Dodge's website and I could not find a single 3 speed anything. They do however put Four speeds in a decient amount of there veichles. I could be wrong though.

[s10350racer]

i work at a transmission shop. they still use the 3 speeds in the new caravans and voyagers. im not too sure but for some reason i also seem to remember seeing one in a base neon as well. you could be right though as i havent seen any 05 models but i can recall seeing 03s and 04s in with broken cases and mangled differentials from spinning the tires in snow and what not.

[eriks98s10]

You cant just say screw gas mileage, I want my car to go fast!! Unless your building a car for performance only like for drag racing or whatever. A lot of people have v8s in ther vehicles because they like the feel and power of v8s. So for a everyday street car, gas mileage should definitley be considered, maybe not be obsessed about, but definiltey considered.

[s10350racer]

i agree it is something to be considered. it just bugs me when i see people with these big supposedly performance engines spending hundreds of dollars on worthless junk that claims to boost the mpgs. im all for gas mileage i even have a 1.9 escort for that sole purpose but if i want to go fast fuel mileage is most definately on the bottom most portion of my list

[spib]

I sure like this s10350racer guy, hell yes I have a geo to drive to work it gets kick ass gas mileage, my 67 shortbox with 327 who cares, fill with gas, have fun and my 400hp 355 sure as hell doesnt get gas millege, IN fact it likes trick racing fuel at $6 a gallon, when it is running it is between 3500-7000 fun, fun thats a heathy chevy v8, and yes it has a drinking problem!!!!!!!!!!!!!!!!1