New here, into GM 2.8/3.1 engines

[wagonman76]

Hi, I just joined here today. I am looking for ways to improve on mileage with my vehicles. The main drivers are a 1989 Chevy Celebrity with 3.1 V6 (summer driver), and 1989 Pontiac 6000 wagon with 2.8 V6 (winter driver). Id appreciate any tips on modding for mileage on these engines. Both have 4 speed automatics with 3.33 final drive.

I have already done the easy stuff... take it easy, keep speed under 65 on the freeway, keep it in OD whenever possible, etc. Best I can get is 28 on 6000 and 32 on the Celebrity. BTW the 3.1 engine used to be a 2.8, when the head gasket blew I put in the 3.1 instead and gained torque and 2-3 better mpg.

Right now I have 195 tires on them. I have a set of 185s in storage that still look good, I am thinking about trying those on the Celebrity.

I also have a 1992 Pontiac Trans Sport with 3800, which I dont drive too much since it is a gas hog, any tips for that would be appreciated as well.

[Red]

Welcome to EM. 28 and 32 aren't bad numbers for a V6 autos. Try the usual tricks and tips to see if you can bump em up some.

As for the minivan, max air in the tires, and a tune up for starts?

[SVOboy]

Welcome to ecomodder!

[digitaldissent]

welcome, so many helpful people here and tons of tips.

[cfg83]

wagonman76 -

Welcome to EM! I think your Celebrity is the first one here. I went to go look at your car on the EPA website :

1989 Chevrolet Celebrity / Automatic 4-spd / 6 Cylinders / 2.8 Liters / Regular Gasoline
http://www.fueleconomy.gov/feg/calcu...lumn=1&id=5681

OLD EPA : 18/26 => 21 Combined
NEW EPA : 20/29 => 23 Combined

Based on the above, you're establishing an excellent baseline.

I did notice that a manual tranny was an option for this car, but that's a lot of work, and I'll bet they're hard to find unless they were shared across a lot of GM platforms.

CarloSW2

[Red]

The 3.1 was used in the Camero for a few years, might be able to find a stick for that one.

[wagonman76]

Thanks for the replies everyone. This seems like quite a nice place.

How about the tires I am thinking of swapping? Has anyone gotten any gains from a tire that is 10mm narrower, or is it probably not worth the $40 to change them over?

Ive thought about a manual trans swap. A few other a-body enthusiasts have done it. The parts are very hard to find. Suitable gearboxes and shifters were available from a few other GM lines, and axles can be mixed and matched from other lines to fit. The hardest part to find is the pedal assembly, since manual trans a-bodies were extremely rare. It is a lot of work and I may or may not actually do it someday. The stick would be fun for summertime though.

Another thing I would like to try if it was easier would to be swap the final drive to 3.06, 2.84 would be probably pushing it. The only thing is with the 440T4 it is easier to swap the entire transaxle which is a ton of work. On the 4T60E you can just pull the passenger side axle and cover and swap the final drive very easily. I might try swapping the van tires/rims on it for a trip and as long as they dont rub, thatll fake a 3.13 final drive and I can see how it does.

My mileage numbers are what I can get pretty much every time. My daughter's mom lives 175 miles downstate so I run down there and back average once a week for most of the year, once every 2-3 weeks in the summer. The driving is about 90% highway.

The Scangauge type unit for OBDI sounds interesting. Ill be reading up it some more.

I have built an O2 sensor modifier and MAP/TPS modifier circuit. I have messed with them a bit but mileage just goes down when I try to lean it out so I quit doing that. I be interested in tuning these engines to run leaner, even a 10% gain would be nice.

[Daox]

Welcome to the site.

Regearing will probably show a small improvement, although probably not 10%. There are a few theads on this topic if you search around.

Other than that, I'd look into some aero mods. You seem to do a lot of highway driving and that is where the aero mods really come in handy. Plus, they're cheap.

Last thing I'll mention is to look through our driving tips. You are already doing the simple stuff, but hopefully you'll learn something more you could be doing.