Max fuel economy?

**npauli** · 03-31-2010, 20:32

Wow!

I thought I was doing good in my Duramax, but some of you guys have sure got me beat.

I've gotten a whole bunch of tanks around 25 mpg, and have flirted with 30 mpg on a couple trips, but I really gotta watch how I drive to get that.

Sounds like the right 6.2 in the right truck with the right gearing can beat that without even trying.

**millwrightjesse** · 03-19-2011, 10:43

Im getting 25.3 MPG in my suburban

**T-1000** · 03-26-2011, 11:57

Hey guys I have a question. I found a short bed 1985 two wheel drive. The body is rust free with the standard oxidization on the paint causing fading. The truck is a second owner with 155k on it. The tranny is a factory rebuild with 30K on it. The truck runs but I have not driven it yet. Someone told me the 2 wheel drive short beds with the 6.2 were rare. Always been a gas man so I need some info. from the pros. I can get it for $1000.00 dollars. This seems good to me, what do you think? How much is it worth and are these good motors. What should I look out for? Any insight would be helpful.

**Edahall** · 03-26-2011, 20:57

Originally Posted by T-1000

Hey guys I have a question. I found a short bed 1985 two wheel drive. The body is rust free with the standard oxidization on the paint causing fading. The truck is a second owner with 155k on it. The tranny is a factory rebuild with 30K on it. The truck runs but I have not driven it yet. Someone told me the 2 wheel drive short beds with the 6.2 were rare. Always been a gas man so I need some info. from the pros. I can get it for $1000.00 dollars. This seems good to me, what do you think? How much is it worth and are these good motors. What should I look out for? Any insight would be helpful.

If it doesn't have rust and the body is in good condition, this is a excellent buy even if it doesn't run. The 6.2 diesel motor is excellent for what it was designed for. It was designed as a light weight diesel engine to provide excellent fuel economy. In 1982, the engine put out 130 hp and with the right setup, would return fuel economy readings of mid to upper 20's. And with the stock power output, it was reliable as well. However, trying to get more power out of the unit often is asking for trouble. At that point, the Cummins 6BT is probably better suited for making lots or power and still being reliable.

**T-1000** · 04-02-2011, 09:07

Thanks for the info. Going to drive it this week. I think $1000 is pretty good from what I have heard.

**jMedia** · 04-21-2011, 11:58

Great info Edahall, I tried to PM you but I did not see the option to in this forum. If you could email me or something that'd be great! surfphotosd at gmail dot com.

Thanks again!

Originally Posted by Edahall

Here’s what I did to get 30 mpg (US) on my 82 Suburban.

1. I used 1982 heads with small pre-combustion chambers and large valves. These heads get the best gas mileage but suffered from cracking. Of course mine had cracks in between every valve seat so I installed liners between each valve seat.
2. Ported / polished the heads
3. Stan’s Headers – Made a big difference in power since stock power was 130 hp
4. Free flowing exhaust – Dual 2-1/2” with H-pipe and Thrush tube mufflers.
5. DSG Timing Gear
6. Ported / polished J code intake manifold
7. 700R4 automatic with overdrive
8. 3.08 rear end
9. Tall & skinny tires – 30x9.50 with 50 psi of pressure

And of course, the most important, an easy foot. To achieve 30 mpg, I have to keep it under 60 mph. Over that, it drops off rapidly with the square front end on the Suburban. For example at 75, it’ll drop down to about 23 mpg. The 75 mph gas mileage can be increased considerably with aero mods but I rarely drive that speed so I have not done any aero mods on my Suburban.

>> Unfortunately because of CA dmv I cannot do a Cummins swap.
I don’t believe the 88 Jeep Grand Wagoneer was ever offered with a diesel in the U.S. So technically, CA DMV won’t allow installing any diesel. However, if you push the right buttons, I believe you can get it through even with a Cummins. PM me if you’re serious about doing this swap and I’ll tell you how.

**tomtaylor** · 05-25-2011, 20:43

My diesel page books are packed away right now and I trying to remember when GM changed the head/precup design I have an 86, are they different from the 82 heads by much???

**Vin82k3500** · 08-12-2011, 10:02

Originally Posted by jMedia

Great info Edahall, I tried to PM you but I did not see the option to in this forum. If you could email me or something that'd be great! surfphotosd at gmail dot com.

Thanks again!

I just read this post on the 6.2 fuel economy I will keep it in mind very helpfull thanks
Vince

**Quartermiler6** · 10-01-2011, 04:17

What about machining an adapter to use an electrically controlled fan clutch such as this. http://www.summitracing.com/parts/HDA-3264/

You would just wire it through an electric fan switch and thermocouple. It wouldn't pull nearly the amps as an electric fan, and you could possibly pull as much CFM through the radiator as the stock fan. The plus would be almost zero parasitic drag from the fan clutch. The guys on the Cummins pages also install switches to activate them while in traffic to keep air flowing through the A/C condenser. What do you guys think? Maybe worth a few MPG's?

**TaxiVan** · 06-04-2012, 00:12

Lots of interesting replies in this thread -- I am considering a 6.2L diesel swap for my GMC Safari van... I use it in my taxi business... 84Blazer mentioned a cabbie talking about gasoline costs and wondered why GM never built 6.5 diesel Caprices for taxi specials... #1 Reason - EPA's EcoNazis and the rest of the tree-hugging, earth-worshipping yuppie world.

Truth be told, quite a few (number unknown) FBI fleet-package Impalas were factory fitted with either the 5.7 Olds or the 6.2 Detroit somewhere around 80-84. My guess would be that leftover warranty 5.7s went first... One of these cars is on YouTube.

I had been considering a swap using a 3.9L Isuzu NPR truck engine, but plans tend to change when your bread and butter unexpectedly dies, and you have to get creative.

It actually seems the 6.2 will actually be a better/easier swap than a 3.9L Isuzu. No trans adapters required, uses standard Chevrolet engine mounts, and no electronic or emissions BS like the 4.3 V6 I currently have.

Truthfully, from my research, I wouldn't be scared to use a 4.3 V6 Oldsmobile diesel (they were the best of the three, having 14 head bolts) with a 200-4R or 700-R4 automatic overdrive.... but these diesels are hard to find, and I already have a 6.2.

**76diesel** · 03-19-2013, 14:58

I get 40 mpg out of a 6.2 diesel non turbo engine. I put the engine in a camaro, installed a 700r4 with lockup torque converter and put a 2.73 rear gear.

I love this car, it is fast, great fuel mileage on the highway and the most fun car I ever drove.

http://www.youtube.com/watch?v=m6W5D...IiTg9w&index=6

**More Power** · 03-19-2013, 15:32

Cool! Looks like it fits beneath the hood quite well. Amazing what a lightweight and aerodynamic vehicle can do with a 6.2 for fuel economy.

I like the radio commentary playing in the background of your video....

Welcome to the board.

Jim

**DmaxMaverick** · 03-19-2013, 20:35

VERY nice! Thanks for sharing.

**joeq** · 06-24-2013, 16:22

I like a guy with an imagination. Very clean looking install. I can hear the purists on the Camaro forums now.

. You must be a very patient and inquisitive individual. I nominate you for the Nobel Peace prize. Or maybe an Oscar...(or something like that). What's next? Walking a tight-rope over the Grand Canyon?

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