[AndyD]

My mission is to get my suburban to 20mpg combined city / highway. So far I'm getting about 13 with a tune-up due anyway and all stock parts.
I think it's possible with better air intake, exhaust, filters and ignition.

Does anyone have experience with a msd ignition control box like the 6a? Also, to maximize the effect, what distributor, spark plugs and wires are the best with that? What fuel filter is the best?

By the way, I put in a K&N air filter and turned the air cleaner lid upside down. That easy trick helps quite a bit with acceleration, and it also makes the truck sound much cooler. I haven't measured yet, but it seems to help gas mileage too. I also just ordered a throttle body spacer that lifts the throttle body up 1 inch. I'll post my experience with that once I put it in...

 

[ChevyFan]

RE: 20 mpg on a

That's a lofty goal, let me know if you get there!

 

[AndyD]

RE: 20 mpg on a

I don't really know if that's really possible. I think I would be happy with 18 or 19 as well. With some of the advancements in the last 20 years in motor mechanics and a well tuned engine it should be possible to improve gas mileage and emissions.

 

[gmcjohnny]

RE: 20 mpg on a

msd is nice but jacobs makes a better system thats easier to set up you can even call them with questions an thell walk you though it johnny

 

[unplugged]

It is possible

I don't really know if that's really possible. I think I would be happy with 18 or 19 as well. With some of the advancements in the last 20 years in motor mechanics and a well tuned engine it should be possible to improve gas mileage and emissions.

It is possible:
Active Fuel Management™ technology helps the 2007 Suburban equipped with the Vortec 5.3L engine deliver an estimated MPG of 15 city, 21 highway for 2WD models and 15 city, 20 highway for 4x4 models. In fact, you can drive up to 651 miles on a single tank of gas in 2WD models

Just drop in a 4/6/8 engine out of an 07 and you're there! (That's if you believe GM's advertised mileage figures)

Like all good adventures, be sure to have fun!

 

[AndyD]

RE: It is possible

I think I read a thread right here on this forum from somebody with a '07 2500 6.0. He says he gets 9mpg city and 13 mpg highway?? Anyway, I just checked after a longer roadtrip through the mountains in Montana. With about 66% highway/interstate at 75mph and 20% city driving I got 16mpg. I don't know how that compares to other 'burbs but my brother in law with his '95 2 door Tahoe only gets 13mpg.
Andy

 

[ChevyFan]

Re: RE: It is possible

I think I read a thread right here on this forum from somebody with a '07 2500 6.0. He says he gets 9mpg city and 13 mpg highway?? Anyway, I just checked after a longer roadtrip through the mountains in Montana. With about 66% highway/interstate at 75mph and 20% city driving I got 16mpg. I don't know how that compares to other 'burbs but my brother in law with his '95 2 door Tahoe only gets 13mpg.
Andy

That's pretty fair. Fuel mileage has gotten better over the years, that's for sure, it's just that vehicles are getting heavier and have better performance. If they cut some weight and manage accelleration better (slower 0-60 time) they could get mileage up to that level. People would say that it's gutless though, so it's a double edged sword.

 

[AndyD]

RE: Re: RE: It is possible

If they cut some weight and manage accelleration better (slower 0-60 time) they could get mileage up to that level.

Yes, that is true. In Germany as a student I had a '86 Golf Diesel. 54hp and a 4 speed manual. I don't think it was faster than about 90mph, but it always got over 50 mpg to almost 60 mpg. No matter if I was driving in the city or on the autobahn. Of course it didn't have AC or power anything, in fact it didn't have a trip counter or a middle console either.... but it was cheap to drive. In Germany we have paid over $6 per gallon for the last 10 years, so gas mileage counts.
I think it's sad that car makers don't make cars like that anymore. It was perfectly fine foe city driving and much cheaper and more durable than any of those new hybrid cars with better gas mileage. The technology is there, we just don't use it.
VW in Europe offered a car some time ago, smaller than a Golf, that in real driving conditions got up to 84 mpg. It wasn't too comfortable and a bit more expensive than than the standard model, but still hybrid cars can only dream of those numbers.

 

[curtolson]

RE: Re: RE: It is possible

Andy the site engineer sounds intelligent. Then I read the question and laughed very hard.
I purchased a 95 K2500 with the 454. MPG is really not an issue when one purchases a 8600 lbs truck with 4wd and a 7.4 liter engine. RAW power and braking is the concern.
If I must answer this ? it would be save the money you would spend on the aftermarket parts to obtain a better mpg and use that same money to purchase fuel. The time you spend working on the aftermarket parts has a value. Investors call it the time value of money. Really Gas is cheap.
Time is priceless. Enjoy your 454 it's a great beast.

 

[TrailLeadr]

RE: Re: RE: It is possible

While time may be priceless, you'd be hard pressed to convince a 'burban enthusiast that spending time modifying their baby is not time well spent. I'm currently rebuilding my 454, and I'm looking at this as a labor of Love. Don't tell my wife that though... :lol:
As far as doing something positive to affect your mileage you might consider changing out your rear diff. Odds are you have a 4.10 rear, drop it down to something in the low 3's if possible. You might see a power difference in towing, but if you don't tow you'll see a marked improvement in mpg.

 

[AndyD]

RE: Re: RE: It is possible

Andy the site engineer sounds intelligent. Then I read the question and laughed very hard.

Well, you know it's not just about gas mileage. A well balanced, fine tuned engine will deliver more power and will last longer with less maintenance repairs. A useful side effect of this is better gas mileage. I know a lot of people just drive their cars without thinking because they lack a fundamental understanding about mechanics, until the wheels fall off and then either throw it away or spend a fortune in new engines trannies etc. I'm just not one of these people. I like to take care of my things and keep them in the best possible condition. :wink:
And yes, that's also a hobby of mine.

 

[ChevyFan]

RE: Re: RE: It is possible

Guilty. I've enjoyed taking stuff apart for no reason for years!

I put a $50 K&N air filter on and I see about 1 MPG difference in my Trailblazer. Poor thing must have been starving for oxygen! We drive that about 12,500 miles per year, and lets just say I went from 16.5 to 17.5 MPG. So getting 1 MPG better means over the next year I will purchase 714.3 gallons vs. the 757.6 I would have bought. That's a savings of 43.3 gallons at $2.10 per gallon that's about $90. Won't make me rich, but it's an excuse to buy more toys.

 

[rwhitbeck]

AndyD, I was just curious as to whether or not you ever put on that throttle body spacer...and if you did, what effetc did it have on your mileage?? I just bought an '88 GMC Suburban 4x4 with the 350 V8 w/TBI...right now I am looking at about 9 or 10 miles to a gallon and would really like to improve on that.

Please let us all know what your experience with the spacer was...if you've done it already!

Thanks!! :great:

 

[shokwaves]

"My mission is to get my suburban to 20mpg combined city / highway. So far I'm getting about 13 with a tune-up due anyway and all stock parts. I think it's possible with better air intake, exhaust, filters and ignition." Andy.

And then reality hit me...

More than 20 mpg with a 13 year old ('94 Suburban 454) SUV is highly unlikely. Why would you spend all that time & $ to attempt such a feat? Even if you had a tremendous budget and were an engineer, this would not guarantee success or a decent return on your investment. While I am sure this vehicle is perfect for hauling boats, trailers, etc..., buy an econocar if mpg is your concern. I do agree that you should maintain a properly tuned vehicle so it peforms well and lasts a long time. However, consider a new mission such as spending more quality time with the wife and kids, or working out. It is your life after all.

 

[tbplus10]

Yea that's a big goal. Best mileage on my last suburban B/B was 17 hwy on an open flat with the wife driving on new tires, 373 gears, a new crate replacement engine with an open element air filter, new trans, and all fluids freshly changed to synthetics. We were happy to get that, after break-in it settled to 16 with her and 11 with me driving.
One nice thing about a B/B Suburban is the mileage doesnt change a lot loaded or unloaded.

 

[Flatman]

(That's if you believe GM's advertised mileage figures)

Which I don't.... :rules:

 

[rwhitbeck]

Okay...I have to ask...does nayone know AndyD...if so, did he ever figure anything out? I just want to see if anything he did worked! I did not buy my 'burb' for mileage, or to hot rod...I just like them, I needed a tow rig and this one was a steal for $1400.00. It does have a small lift to it with 33" tires, but I still want to get the best mileage I can possibly get!

Thanks!!

 

[X-Hibition]

To answer your original question I have had very good luck with the MSD 6-A, I used their wires also.

My Vortec is different than yours and I have 4.11s so we are not comparing apples and apples. I have pillar gauges, sometimes use my Airaid and sometimes my K&N (long story) and have never been and never will be close to 20 mpg. I have a Gibson cat back and have Mobil 1 in the crankcase, front/rear diff and transfer case (haven't changed the tranny yet).

Work on it, I love to. That's the cost of my money. 20 mpg...that is one of my other rides.

 

[84fiero123]

Anyone one here own one of those Big Rvs like in the Robin Williams movie?

They used to have a secondary trany, like in the 18 wheelers. Sort of like the 2 speed rear ends. So that you could sift into a higher gear and get better mileage.

I wonder if you can still buy them and if they would help on the highway? You do loose acceleration but gain mpg.

 

[TrailLeadr]

I've seen these under/over drives for sale. Not many places on the web to buy them though. Can't seem to find a link for one now though....lol