improved MPG

[DaDa102250]

Once again thanks for the info, insight and personal experiences. Like any good discussion it all helps one to decide on a plan of action. I am a recent member, just a month or two and there are a thousand threads to all things Chevy here. It takes awhile to go thru it all. That being said there is no guarantee that someone hasn't come up with some new info or solution to a common problem that could benefit the members. Not all of us have been dealing w/autos as long as others and have the same expertise. So for the trolls that have stuck their nose out from under the bridge a question. How much spray area is needed for aerobic system for a 3 bedroom house? What soil conditions will have a bearing on this? Or if one has to lay 2500 ft. of 16" SDR 26 in a curve with a radius 100ft. on a ten percent slope how much deflection is allowed at each joint? you can get on the internet and do a dozen searches or to one site with people that have the knowledge. where are you going to go first? Not everyone is a walking encyclopedia of automotive knowledge. Not everyone can design an OSSF etc. When someone in a group shows their A _ _ in a thread it sheds a bad light on the whole group. Luckily there are others here that can get the same point across without the attitude.

 

[73c20jim]

m20 - 2,54 low
m21 - 2.20 low
m22 - 2.20 HD "rock crusher"

 

[shiftpro]

Once again thanks for the info, insight and personal experiences. Like any good discussion it all helps one to decide on a plan of action. I am a recent member, just a month or two and there are a thousand threads to all things Chevy here. It takes awhile to go thru it all. That being said there is no guarantee that someone hasn't come up with some new info or solution to a common problem that could benefit the members. Not all of us have been dealing w/autos as long as others and have the same expertise. So for the trolls that have stuck their nose out from under the bridge a question. How much spray area is needed for aerobic system for a 3 bedroom house? What soil conditions will have a bearing on this? Or if one has to lay 2500 ft. of 16" SDR 26 in a curve with a radius 100ft. on a ten percent slope how much deflection is allowed at each joint? you can get on the internet and do a dozen searches or to one site with people that have the knowledge. where are you going to go first? Not everyone is a walking encyclopedia of automotive knowledge. Not everyone can design an OSSF etc. When someone in a group shows their A _ _ in a thread it sheds a bad light on the whole group. Luckily there are others here that can get the same point across without the attitude.

Yeah but just let us be who we are, it's all good. Count your blessings you didn't go to Pirate4x4 with your extraordinary question.
Oh and... welcome all the same!

 

[rpcraft]

I'm a walking encyclopedia of useless BS on most days. ;o) When it comes to Square bodies there is a lot of knowledge here though and hopefully I can elaborate on what it will cost to achieve probably a 3 - 4 mpg increase, if you can even get that going

All things considered, the best course to get better mpg is going to be an overdrive transmission and a reasonable set of gears. It's not the most cost effective but it will offer the best results straight up.

Considering you are talking about the potential to spend 1000 in used parts, which has it's own pit falls, and then even more (by a factor of 2 to 4) in order to have new or rebuilt, and then tuning up the motor to ensure it is running as efficiently as possible. The set of gears will depend on your desired tire size.

When you consider power vs mpg a reasonable cross over gear with a standard(ish) tire size is actually in the 3.40 range like you have. If you combine that with a 700R4/4l60E or a 4l80E (if towing is a priority) you really would be well setup for being able to tow and still getting the rpm's down for your best mpg. Ideally on the 5.7/350 blocks you kind of want to hover around 1700 to 1900 for your standard cruise speed on an auto trans. If towing is not something you will be doing much of then you can get a taller gear, like a 3.08 and there are a bunch of them available because it was the primary "efficiency gear" that GM liked to put in most of the half ton C and K models and you can probably find one in a wrecking yard that just needs to be cleaned up and swapped in with new brakes and an oil change.

The other course of action is you can find a standard 5 speed transmission from the later model trucks. Don't quote me here because grinders are not my specialty but I think the nv4500 is a bolt in OD grinder and if I recall you already have a standard so the third pedal is there and it would be nice to keep it that way (would be my approach and many love the idea of finding their own gears). I think you can find all the parts for what you need for a pretty reasonable price, again you will want to resource from a salvage yard because they usually have great prices and can really keep the budget down but it might take some time to find a complete setup or amass all the parts.


What that means is first you have to decide what tires you are going to run, after that you can count on a OD ratio of about .75 or .76 on any OD trans. Once you get there it is just a matter of doing the math on what gears you need.


Also, the reason some of us talk about adding parts to the engine to make more power is that the engine is basically an air pump, and the goal isn't necessarily to make more power (well for most it is) but rather to make the engine run as efficiently as possible and the more air you can push through the motor the more efficiently it runs (and the byproduct is usually more HO and torque) and at that point you are using less of the fuel pedal to achieve more work and that translates to better fuel economy.

Now there is a point of diminishing returns and you have to ask yourself is it worth it to spend 1 to 2 K changing your transmission and rear end (which honestly I would probably keep the 3.40 on anything under a 31 inch tire), and then say another 1200 to 1500 on engine upgrades (those being vortec heads, and probably a good carb, cam, and intake combo, and I apologize if my SBC dollar math is off... I've been buried in the LS world for a while so its been a while since I price shopped for small blocks and when it comes to labor... I am the labor, at least until it involves machining assemblies..

So you see 17 mpg is probably doable, but it requires a lot of sweat equity and probably around as little as 1000 to as much as 3k realistically, plus driving like you are driving miss daisy.

And for anyone mentioning 1000 dollar LS swaps, please reconcile your parts list and double it or triple it when you factor in all the mistakes that can be made along the way, and consider that you can probably plan on spending at least 500 dollars on a good harness conversion and base tune, and the idea of that is a tune that will allow you to enjoy your truck a little bit after you get it running and then run it over to a dyno tuner so you can get it running to its best potential.

 

[rpcraft]

Sorry for the wall of text but it hopefully gives you some food for thought.

 

[Big Chip]

I'm a walking encyclopedia of useless BS on most days. ;o) When it comes to Square bodies there is a lot of knowledge here though and hopefully I can elaborate on what it will cost to achieve probably a 3 - 4 mpg increase, if you can even get that going

All things considered, the best course to get better mpg is going to be an overdrive transmission and a reasonable set of gears. It's not the most cost effective but it will offer the best results straight up.

Considering you are talking about the potential to spend 1000 in used parts, which has it's own pit falls, and then even more (by a factor of 2 to 4) in order to have new or rebuilt, and then tuning up the motor to ensure it is running as efficiently as possible. The set of gears will depend on your desired tire size.

When you consider power vs mpg a reasonable cross over gear with a standard(ish) tire size is actually in the 3.40 range like you have. If you combine that with a 700R4/4l60E or a 4l80E (if towing is a priority) you really would be well setup for being able to tow and still getting the rpm's down for your best mpg. Ideally on the 5.7/350 blocks you kind of want to hover around 1700 to 1900 for your standard cruise speed on an auto trans. If towing is not something you will be doing much of then you can get a taller gear, like a 3.08 and there are a bunch of them available because it was the primary "efficiency gear" that GM liked to put in most of the half ton C and K models and you can probably find one in a wrecking yard that just needs to be cleaned up and swapped in with new brakes and an oil change.

The other course of action is you can find a standard 5 speed transmission from the later model trucks. Don't quote me here because grinders are not my specialty but I think the nv4500 is a bolt in OD grinder and if I recall you already have a standard so the third pedal is there and it would be nice to keep it that way (would be my approach and many love the idea of finding their own gears). I think you can find all the parts for what you need for a pretty reasonable price, again you will want to resource from a salvage yard because they usually have great prices and can really keep the budget down but it might take some time to find a complete setup or amass all the parts.


What that means is first you have to decide what tires you are going to run, after that you can count on a OD ratio of about .75 or .76 on any OD trans. Once you get there it is just a matter of doing the math on what gears you need.


Also, the reason some of us talk about adding parts to the engine to make more power is that the engine is basically an air pump, and the goal isn't necessarily to make more power (well for most it is) but rather to make the engine run as efficiently as possible and the more air you can push through the motor the more efficiently it runs (and the byproduct is usually more HO and torque) and at that point you are using less of the fuel pedal to achieve more work and that translates to better fuel economy.

Now there is a point of diminishing returns and you have to ask yourself is it worth it to spend 1 to 2 K changing your transmission and rear end (which honestly I would probably keep the 3.40 on anything under a 31 inch tire), and then say another 1200 to 1500 on engine upgrades (those being vortec heads, and probably a good carb, cam, and intake combo, and I apologize if my SBC dollar math is off... I've been buried in the LS world for a while so its been a while since I price shopped for small blocks and when it comes to labor... I am the labor, at least until it involves machining assemblies..

So you see 17 mpg is probably doable, but it requires a lot of sweat equity and probably around as little as 1000 to as much as 3k realistically, plus driving like you are driving miss daisy.

And for anyone mentioning 1000 dollar LS swaps, please reconcile your parts list and double it or triple it when you factor in all the mistakes that can be made along the way, and consider that you can probably plan on spending at least 500 dollars on a good harness conversion and base tune, and the idea of that is a tune that will allow you to enjoy your truck a little bit after you get it running and then run it over to a dyno tuner so you can get it running to its best potential.

...and the final words had been spoken and the mystery has been solved.

 

[Honky Kong jr]

...and the final words had been spoken and the mystery has been solved.

Yeah and he would of gotten away with it if it wasn’t for them meddling kids and the dog!!!!

 

[CSFJ]

Don't we have enough fuel mileage threads right now to put them all in their own sub-forum?

 

[Honky Kong jr]

Don't we have enough fuel mileage threads right now to put them all in their own sub-forum?

My exact thoughts but they would have to add a few mods to collect them all. Or to at least apply the cream to curtail the next out break.

 

[CSFJ]

My exact thoughts but they would have to add a few mods to collect them all. Or to at least apply the cream to curtail the next out break.

Looks as though we've had some good nominees for those spots join the site lately.

 

[Honky Kong jr]

Looks as though we've had some good nominees for those spots join the site lately.

For sure.

 

[Honky Kong jr]

xc_hide_links_from_guests_guests_error_hide_media

 

[Honky Kong jr]

Once again thanks for the info, insight and personal experiences. Like any good discussion it all helps one to decide on a plan of action. I am a recent member, just a month or two and there are a thousand threads to all things Chevy here. It takes awhile to go thru it all. That being said there is no guarantee that someone hasn't come up with some new info or solution to a common problem that could benefit the members. Not all of us have been dealing w/autos as long as others and have the same expertise. So for the trolls that have stuck their nose out from under the bridge a question. How much spray area is needed for aerobic system for a 3 bedroom house? What soil conditions will have a bearing on this? Or if one has to lay 2500 ft. of 16" SDR 26 in a curve with a radius 100ft. on a ten percent slope how much deflection is allowed at each joint? you can get on the internet and do a dozen searches or to one site with people that have the knowledge. where are you going to go first? Not everyone is a walking encyclopedia of automotive knowledge. Not everyone can design an OSSF etc. When someone in a group shows their A _ _ in a thread it sheds a bad light on the whole group. Luckily there are others here that can get the same point across without the attitude.

LMMFAO I actually didn’t read your post. I didn’t much care to. I’m glad I did, it made me laugh. When you come on a forum and ask the same question that’s been asked 100 times before it is evident you never searched for it. To call me a troll that’s funny.

 

[shiftpro]

Usually guys talk about gearing. Well depends where and how you drive. Here in the mountains if your full size truck is hanging under 2000 rpm at say, 60 mph... you will be ****** when facing the next hill. Reducing rpm is only one thing to consider when attempting to stretch fuel economy.

My approach is more complicated. I like to call upon the God of Compression. In my world you can't get anything done without it. That's why I like propane so much. A stable cheap fuel with high octane. 10.1 compression or anything higher. Don't need a big cam or there goes the economy. Just an rv/torque cam and headers.
But sadly it's not always an easy fix, to make compression that is. There is more involved than just plunking in domed pistons. Decking the hell out of the block is almost always reqwuired. And any head made after say... 1978, is junk. It won't flow and has a big open chamber reducing compression. And these heads are too thin to shave anything off that would make a difference.
And then more labor as you have to pre-assemble the engine and verify that the valves are not kissing the pistons.

I've also found that porting heads does not decrease economy. A good flowing head makes power. If you want to use the extra power you made, say goodby to economy. If you still drive your new torqy beast like grandma you may be surprised at the economy.
Best bet in my experience is larger exhaust valves, and open the bowl up under the valve seats. Seems like all heads have restricted exhaust, thus imo we see the cam builder offering cams with more duration on the exhaust side. Get that exhaust flowing and use symmetrical cam profiles.

 

[rpcraft]

We could go on about compression and propane, and that certainly falls under the domain of upgrading your motor but I think we can all agree that there is a point of diminishing return.

Like I said, the engine is an air pump so anything you can do to increase it's ability to move air will increase its VE, from porting, to better intake, to fuel that is more combustible (so long as it's not detonating).... It all helps provide better efficiency but there is a line you have to draw in the sand as to how much will be spent for the improvement... Is it worth it to you to spend 2500 USD just to chase 1 or 2 MPG's?

It might just be better to use it as a down-payment on something newer, but then that's another story about being in debt to save a few mpg's.