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#728182 - September 25th 2017 10:49 am g20 mpg?  
Joined: Sep 2017
Posts: 28
nomadgames Offline
newbie
nomadgames  Offline
newbie

Joined: Sep 2017
Posts: 28
Denver, CO
What kind of mpg are you guys getting on a g20? My 78 runs great. In the three weeks that I've had it, I've already driven from Denver to SE CO and back, Denver to Santa Fe, big loop and back, and Denver to Moab and back, without any issues. But holy shit the gas is killing me. eek

#728184 - September 25th 2017 11:32 am Re: g20 mpg? [Re: nomadgames]  
Joined: Sep 2005
Posts: 8,108
CatFish Offline
carpal tunnel
CatFish  Offline
carpal tunnel

Joined: Sep 2005
Posts: 8,108
Georgia, USA
Never actually checked MPG on the GMC but I think it's pretty good...about 15 to 18 MPG in the summer maybe. Our blue '95 G20 I have checked it while towing the TT (about 2300#) and it's about 8 to 8.5 MPG in the foothills.
Our old Ford will get between 9.5 and 10 MPG summer, winter, uphill, downhill, towing or not because it don't seem to notice if there's anything back there.... laugh

#728187 - September 25th 2017 12:26 pm Re: g20 mpg? [Re: nomadgames]  
Joined: Sep 2017
Posts: 28
nomadgames Offline
newbie
nomadgames  Offline
newbie

Joined: Sep 2017
Posts: 28
Denver, CO
I guess I don't feel so bad, then. stock with 3spd auto living at 5000 ft and up, i'm getting about 14 or 15 hwy.

#728188 - September 25th 2017 12:59 pm Re: g20 mpg? [Re: nomadgames]  
Joined: Jun 2010
Posts: 12,578
frscke1 Offline
frscke1  Offline


Joined: Jun 2010
Posts: 12,578
Van Diego California
I took a trip in my '93 G30 from San Diego to the FL Keys a few yrs ago 6700 miles & I got 14.25 MPG with my 454.

I went to pick up my '92 G30 in Cedar Rapids, drove it home 2200 miles to San Diego & got 14. MPG with my other 454.

I would think a 350 can get better mileage ...


SUNSHINE VANS-VAN DIEGO
ADRENALIN BY THE GALLON & CHASIN RACIN
ONE FOR THE DIRT & ONE FOR THE STREETS
'93 CHEVY G30 454 4X4 SPORTVAN EXT 146" WB
'92 CHEVY G30 454 BEAUVILLE EXT 146" WB
#728189 - September 25th 2017 1:23 pm Re: g20 mpg? [Re: nomadgames]  
Joined: Sep 2017
Posts: 28
nomadgames Offline
newbie
nomadgames  Offline
newbie

Joined: Sep 2017
Posts: 28
Denver, CO
well shit. if you can get that MPG with a 454 i'll throw one of those in there. this thing is slow as hell. up mountain interstates i'm doing 50mph.

#728190 - September 25th 2017 1:51 pm Re: g20 mpg? [Re: nomadgames]  
Joined: Sep 2005
Posts: 8,108
CatFish Offline
carpal tunnel
CatFish  Offline
carpal tunnel

Joined: Sep 2005
Posts: 8,108
Georgia, USA
There's not gonna be much MPG difference between the BB and the mouse motor. As an old friend of mine used to say, "you're pushing a brick!" and the 454 just don't have to work as hard.
Add some extra weight or hills and the 350 has to work it's azz off.

Last edited by CatFish; September 25th 2017 1:52 pm.
#728191 - September 25th 2017 2:11 pm Re: g20 mpg? [Re: nomadgames]  
Joined: Jun 2010
Posts: 12,578
frscke1 Offline
frscke1  Offline


Joined: Jun 2010
Posts: 12,578
Van Diego California
Yeah most of the time Im barely on the gas. Weighing #9350 & #8860 it rolls a long way down hill, Im not even on the gas.

With the 4L80E over drive tranny on flat ground I barely touch the gas pedal & im doin 70.

Hell I could probably drag your van up hill & still get 14 ....lol


SUNSHINE VANS-VAN DIEGO
ADRENALIN BY THE GALLON & CHASIN RACIN
ONE FOR THE DIRT & ONE FOR THE STREETS
'93 CHEVY G30 454 4X4 SPORTVAN EXT 146" WB
'92 CHEVY G30 454 BEAUVILLE EXT 146" WB
#728192 - September 25th 2017 2:24 pm Re: g20 mpg? [Re: nomadgames]  
Joined: Sep 2017
Posts: 28
nomadgames Offline
newbie
nomadgames  Offline
newbie

Joined: Sep 2017
Posts: 28
Denver, CO
yeah, that's actually what was I assuming. I feel like mine has to work so hard, especially in the mountains, that there's no way it can be running efficiently.

#728196 - September 25th 2017 3:58 pm Re: g20 mpg? [Re: nomadgames]  
Joined: Sep 2017
Posts: 12
JAGI410 Offline
stranger
JAGI410  Offline
stranger

Joined: Sep 2017
Posts: 12
MN
First road trip was 14.9 mpg, second was 12.8 mpg. Doing a repeat of the first trip this weekend, but this time I'll have cruise control. Curious to see what that does. Fairly flat route with one "shift down" hill. 1984 305/700r4 with shift kit. The last trip I stopped for gas at my non-usual place, and I could tell the van didn't like it. Weird gas and headwind didn't help the mpg.

I have hand written calcs from the first owner's road trips, and he was getting 17.7 mpg back in 1986. Today's higher speed limits and ethanol additives will likely keep me from getting anything better than that.


Jason
1984 Chevy G20

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