burb mpg question

[black dawg]

My father in law is looking at a 90 v2500 burb, has 350 and 465, and 3.73 gears. Also has thorley tri y headers and decent duals.
He was curious about mpg, and I guessed probably 13 average, he thinks closer to 10. Basically no towing, and pretty slow driving, like under 65.

Anybody that had/has the same truck have any input?

 

[82355]

I have an '89 V1500 with a TH400 and 31x10.5x15's with 3.42 gears. It got right at 11 the other day all highway miles.

Martin

 

[82355]

In my 1988 V10 Suburban, the fuel economy didn't change when I went from a TH700R4 to an SM465.

Martin

 

[black dawg]

The reason I guessed 13, is my burb is identical other than a 454, and easily does 12 on the highway.

 

[y5mgisi]

I would say probably right at 12. Assuming everything is all in good shape and all that.

 

[y5mgisi]

My 90 burb with 350/th400/3.73s when it was stock would do between 10-11.

 

[dhcomp]

I'd guess 11-12.

My burb with 33's, 4.10's, and the 4L80e will do 12 at 75mph all day long as long as its flat.

 

[black dawg]

thanks for the input guys.

 

[black dawg]

My 90 burb with 350/th400/3.73s when it was stock would do between 10-11.

I know I have asked, but forgotten already, but what does it do for mpg now.

 

[1BEATK5]

It does great. Sitting in the yard, while he drives that sierra

 

[jeff in co]

I'd guess 11-12.

My burb with 33's, 4.10's, and the 4L80e will do 12 at 75mph all day long as long as its flat.

Pay attention to this figure. 91 (like dhcomp's) is the only year that they put in an overdrive transmission in the 3/4 suburban. The 89' and 90' have the 3 speed auto so I would suspect it would be under 12 MPG. I'd say 10-11 MPG.

Strange, my 8.1L 2004 3/4 ton gets 10-11 MPG too. Much bigger engine too!

 

[black dawg]

well crap, I guess I will have to tell him he was right with his 10mpg figure, and he likes being right.

I honestly figured a 350 would do better than my 454.

 

[y5mgisi]

With the 5.3 it had been doing about 12 around town.

 

[dhcomp]

Pay attention to this figure. 91 (like dhcomp's) is the only year that they put in an overdrive transmission in the 3/4 suburban. The 89' and 90' have the 3 speed auto so I would suspect it would be under 12 MPG. I'd say 10-11 MPG.

Strange, my 8.1L 2004 3/4 ton gets 10-11 MPG too. Much bigger engine too!

Fair, but my comparison was at 75mph. So, at reasonable speeds, id still expect 11-12 without OD.

 

[Metrodps]

OK so on my 1988 1500 with 350 and a manual with stock tires gets 13mpg. That is with a K&N air filter, TBI spacer. I am going full synth oils and a fresh cat. The one on mine is the original.

Hoping to get it up to around 15 mpg. I might have to go with duals.

 

[USSkoval]

Mine get an average of 11 or so. In my experience with square Burbs, big blocks get better hwy mpg, less throttle to shove the trucks through the breeze. City mileage in the winter is much lower though.

 

[eagle mark]

Love my 1990 5.7L 700R4 2WD 3:73 geared Suburban. Worse I get around town is 14 and highway at 70 with AC on 18.5

 

[black dawg]

I do miss my my 2.73 geared 2wd suburban, thing got stupid mpg for what it was.

 

[1sub]

Everybody says I am lying but I get 13 around town on a stock 350 qjet 400 auto and 35s with 4:11 gears.

 

[snowdriver]

Love my 1990 5.7L 700R4 2WD 3:73 geared Suburban. Worse I get around town is 14 and highway at 70 with AC on 18.5

i would have never believed that,pretty impressive for these dinosaurs,
my 1990 blazer ,bone stock,350,700r,and 31-10.5 gets about 12.5-13.5 on the hiway,but i drive upwards of 75-85,never have checked city driving mpg