LT1 Fuel Mileage Modifications and Help ??

[markd79ta]

If the '97 doesn't sell, I am going to prep it as a daily driver. Fuel economy is my biggest concern followed by snow...I am about 40 miles from work. The Denali is killing me so I need to come up with something.

First, the person who did the gears will put the 3.42s back for $225. I lost about 3-5mpg with the gear install. I am getting 15/23 now where I got 18/27 before the change.

Second, does the electric water pump provide any real savings? It seams as though it should taking it off the cam although most people do it for HP.

I didn't get the cam, rockers or any other engine mod installed so I am good there. If I install the 1.6 Crane Gold Rockers on the stock cam, will that benefit or hurt fuel economy? How about the pulley sets available? Programming, etc.

When I drove this car before as a daily driver, I used the stock tire size 245/50/16 with BFG KDWS. However, I am not sure this will work on the ice where I live. I am finding it somewhat hard to find studded snow tires in this size; I will need studs to get the car out of my driveway. It doesn't need to go through a blizzard; my Denali is good for that. Any thoughts on this?

Any suggestions will help. The car is driven between 5,200 and 10,000 feet.

[Joe 1320]

First, the person who did the gears will put the 3.42s back for $225. I lost about 3-5mpg with the gear install. I am getting 15/23 now where I got 18/27 before the change..

You might even consider 2.73 if mileage is a top concern.

Second, does the electric water pump provide any real savings? It seams as though it should taking it off the cam although most people do it for HP.

.

The reason they do it for HP is at higher engine rotations, the mechanical drag of the water pump is decreased. What you will see however, is a increase in electrical draw which will be a load on the alternator. Will it affect fuel mileage? I doubt that it would be a cost effective mod for that.

If I install the 1.6 Crane Gold Rockers on the stock cam, will that benefit or hurt fuel economy? How about the pulley sets available? Programming, etc..

The 1.6 rockers will hurt economy. By opening the valves higher and longer, more air and fuel enters the combustion chamber. Pulleys will decrease drag and boost mileage a little due to reduced rotational drag of the accessories.

Any suggestions will help. The car is driven between 5,200 and 10,000 feet.

I would get a MSD 6A multispark unit. The increase in ignition energy will cause a more complete burn so that a little less throttle is used. The increase in mileage will be noticeable if you keep your foot out of the throttle. Before I went nuts on my 97WS6, I was able to get just over 30 mpg highway. That was with an automatic, 3.23 gears, stock converter, longblock and all the bolt on exhaust. Fuel consumption was reasonable. once I went with gears, rockers, etc. the fuel mileage went into the toilet. It sure went pretty fast for what it was, but economy was terrible. Gears were a real killer.

[markd79ta]

Thanks Joe! I have a multi-spark digital ignition installed; it was going to be used for a different purpose The stock 3.42s should be great with the 6sp as it was when I bought her new. The loudmouth should help reduce some restriction although I have the factory, manifolds, cats, and y-pipe still installed.

[Trash man]

drop the tire size down, go with a narrower tire(but same hight) overall and see if u can get a set of junk stock rims. i think on a 245/50R16 a 225/55R16 is the same, its been a while tho

[MN6WS6]

I don't get where the gears are making this much mileage difference argument. I can understand it in an auto car, but with a 6 speed it seems they would help. My 6 speed, 3.42 car kills me on gas mileage, but that's because 6th is basically useless until you get up to about 70 or so. Considering that most of my drive time is on roads that are 65 and lower, I have to use 5th, which means more RPM's and less gas mileage. With 3.42's in 5th at 65, the RPM's are 2152 (using an online calculator). With 4.10's in 6th at 65, I'd be at 1743. If I attempted 6th at 65 with 3.42, you are talking about 1454 and the car just feels like it is straining awfully hard and when you hit the gas it will not pull up to any faster speed with any kind of umph behind it.

Another thing is that I tow my bike on vacation with me, which is up to Deal's Gap, aka the Tail of the Dragon, in excess of 500 miles. Last year I had to pull in 5th and stayed at about 72 mph most of the way, and was getting passed like I was sitting still, meanwhile turning 2400 RPM's and destroying anything remotely considered to be gas mileage (averaged about 15 mpg or so). You can't tow in 6th because the extra weight means you have to go 80 MPH to get enough RPM's up to keep the momentum up. That's just asking for a ticket. With 4.10's at 75 in 6th I would be turning 2011, which keeps me with some power and saving 400 RPM's over last years trip, which should gain me at least 7 mpg difference.

[markd79ta]

MN6WS6

I made two trips from Colorado to Vegas. The first trip with 3.42s, I averaged 28mpg. The second trip with 4.10s, I averaged 23. The only difference between the two trips was the gear change. My average in the city prior to the gear change was 18. After the gear change, it was 15. I thought the same as you with the 6sp. However it didn't work out.

[Crazy Canuk]

Your snow tire question:

When I bought snow tires I bought michelin X-ice tires. I had to buy steel rims though because I couldn't find wide enough winter tires that could fit on a standard rim.

Those tires and 100-150lbs of sand in the back got me thru 2 winters before my engine went. The only time I had any sort of problem was when I did a sharp turn and all 4 wheels went over an ice patch (going slowly). No biggy just ended up turnning a little more then I expected

Studded tires are not allowed on our public roads here in Ontario, alot of tire manufactures make snow tires with wallnut shells imbedded into them. Worth a look at if normal snow tires arn't good enough, that or chains but I think if you have to put chains on your tires to drive a car which is 6" off of the ground, it may not be the car of choice for that day.

[Happy_Dan]

So, how much money you going to spend on mods to save gas?
How much gas do you have to save to get those mods to pay off.
That's how I would look at each one. What is the ROI?

[Joe K. 99 Zeee!!]

I agree with Dan. How much gas could you buy with the money you're paying for mods? How long would you have to drive the car before you actually start to save money?

If it's been a long time since you've used fuel injector cleaner, try that. I used some on my '98 V6 for the first time after puting 30,000 miles on it and it did make a difference. Definite SOTP feel, and slight improvement to milage.

[markd79ta]

So, how much money you going to spend on mods to save gas?
How much gas do you have to save to get those mods to pay off.
That's how I would look at each one. What is the ROI?

My wife and I currently spend about $850 a month on gas. If it goes over $4.00 per gallon, we will be in the 900s. So, to answer your question...a lot. The only thing I am for sure doing is going back to 3.42s...I liked the car much better for touring when it was stock. That will cost me $225...my gas budget for a week and half.

[3800_Firebird]

Cooper snow tires (225/55R16) and Quickcrete Sandbags 120 lbs (2 bags, each is 60lb). That got me through the deep stuff here in Michigan. That and alert driving. Make sure to get some bright bulbs for your lights, Silverstars. Winter nights can be dark!

[Happy_Dan]

Wow, how many miles do you drive every week?
I drive 100+ miles every day for work, so I feel your pain.

With that much gas, I think you are right on to try and improve your mileage. Even a small increase will be a lot of help.

3:42 is a great start.

[Joe 1320]

I tell ya, my 93Z with 2.73s and a M6 is awesome on the highway.

[markd79ta]

Wow, how many miles do you drive every week?
I drive 100+ miles every day for work, so I feel your pain.

With that much gas, I think you are right on to try and improve your mileage. Even a small increase will be a lot of help.

3:42 is a great start.

My wife drives 110 miles per day during the work week in a Liberty CRD.

I drive 70 miles per day during the work week in a Yukon XL or Buick Roadmaster.
We drive a minimum of 200 miles on the weekend.

It is about 60 miles round trip to do much of anything.


As far as the snow…

I am extremely skilled in the snow; done it my whole life. I took the ’97 over Vail Pass and up the hill toward the Eisenhower Tunnel in a Blizzard, 4” of snow, and the 315/35/17 floaters on the back…although, not something I hope to do again. The difference here is the mountain terrain. In a mostly flat area like the city, the car is fine with a good set of all season performance tires, which I used successfully in the past. However, the steep hills where I live (8,835 feet) have a lot of ice; my Roadmaster with 235/75/15 Wrangler LT MS tires can’t grip it. Without studs or 4-wheel drive, the car isn’t making it to my street. We sold my wife’s Sentra because it was way too dangerous on the ice…with or without studs. Hopefully, I will find a good wheel/tire/stud combination or it will sit all winter as it has this year. Right now, it is stuck on an ice patch on part of the driveway (my driveway is the equivalent of about 2 football fields); won’t move an inch. It has sat in the same spot since November. I pulled the Roadmaster out twice with the 'burban. It looks as though i will bag the stock 16" wheels and go with something different to handle a smaller width tire.

[97LT1Z28]

I know wolfdog (the tire expert in these parts) will bark at me for this but.......

I had tires on mine that said MAX PSI was 44 PSI. Instead of running the GM factory recommended 36 PSI, I'd go with the tire max of 44. This made a very noticeable difference in the mileage as well as a stiffer ride.