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gas vs diesel

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white90burb

1/2 ton status
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I know this has been asked before but looking for some new insight. Right now in my 75 k5 I'm running a tbi 350. Its got about 250k miles on it. It still runs strong but I know its only a matter of time before its done. Im only getting 10-12 mpgs out of it. I know I'm driving the wrong vehicle if I'm worried about mileage but when I'm going long distances and camping in the sticks everything helps.
So here's my thoughts. I can rebuild it to a 383 seems most people are able to get them tuned with the tbi. My other thought is a 6.5 turbo diesel. From what I've read a 6.5 puts out about the same as a 350tbi power wise but blows it away mileage wise. I know there are thing to be done to make it better as well.
The main goal of my rig is camping exploring mountain runs going snow boarding etc. So reliability and mileage are key for me. As for the rest of the drive train I have an nv4500 and an np241. Currentry half ton axles with 3.73s and 35 km2s. I will be upgradding to 3/4 tons once I figure out what gears I need. So any input would be appreciated.
 
Simplicity and the manual trans, I'd go 6.2...start out NA and decide from there. I had a NA 6.2 with a SM 465, 4.56's and 40's, and I wasn't unhappy with it at all power wise.
 
I'd say you're a little undergeared for a 35, which can lower your mileage, although the low first on the 4500 mitigates that somewhat. 10-12 really isn't bad for a gasser though. You'd probably be lucky to see 18-20 from a 6.5 on the highway in a square body with 35s.

Diesel is definitely the mileage champ, but it can also be the more expensive route. More expensive to purchase, more costly fuel, maintenance items (glow plugs, filters, injection pumps, etc). If you don't do a lot of driving, it may take a while to reap the benefits. Drivability is typically better with a gas motor (opinions vary), but if you're gonna tow, go with the diesel. There are tradeoffs either way. What kind of budget are you working with? The diesel means buying a motor or donor truck, while a 383 you can build from your existing motor.
 
Yeah I know I'm a bit under geared but with all the highway driving which is all flat here it works well. As far as driving I plan on putting a bunch of miles on it. And in the future I do plan on an off-road camp trailer with a dirt bike so not a lot of weight but I will be going up mountains. Not sure budget wise but it gonna be a sit on the stand build up till my motor goes south.
 
Personally, I think I should have gone diesel. Significant increase in mileage means a lot more time off-road without having to worry about more fuel, and even on-road it's a big deal. IMO it's not really about saving money, these things use so much gas the return on investment isn't really there, but the longer range between fillups is the real benefit.
 
I've had both gas and diesel blazers and now have my restored diesel one. You can drop in a NA 6.2 w/700r with you 3.73's and be good with 33's easily if you're going mildly exploring. I am currently test driving this with the high 3.08's and 700r w/32's and it seem fine as a DD with smooth, even acceleration. It is not a drag racer off the line but really nice and everyone who's driven it says the same.

As far as cost I'm not sure if they are that much more in cost. You do change fuel filters more often but more out of oil changes. You do not change glow plugs everyday or even every year but when one goes out if it does. Yes, diesel cost more but you might be able to find a farmer or "flower child" who makes bio-diesel. B100 is a great fuel and 6.2 likes it. It also likes HHO but that is up to you.

When off road, the 6.2's low speed grunt and lack of stalling puts it head and shoulder's above my gas trucks I've had. Now I'm talking low speed crawling and easy type OR. Going balls to the wall and crazy mud slinging the gas is better.

I could own gas or diesel and I choose to own the diesel in this style trucks. No emissions, no computers, way better mileage, no DEF, ability for multi-fuel capabilities and if I thought about it longer, I'm sure I could think of more reasons. I know I drive miles and I love the fact that I get 600miles out of a 25g tank. My old M1009 that I had a 31g tank went forever without stopping!
 
I would say the diesel's ability to handle steep grades and off camber situations off road with no fear of the engine flooding or stalling at a critical moment that could be hazardous with a carbed engine--and its better low end torque makes it a better performer in those conditions..

But a fuel injected gas engine could handle the same conditions just as easily..
In the end its a toss up in ways...in a place with strict smog tests a diesel has advantages ,some places they are exempt from that,and no computer and a dozen sensors to worry about either..
 
This thread sounds like a meeting of the diesel club. :waytogo:

dyeager535 said:
Personally, I think I should have gone diesel. Significant increase in mileage means a lot more time off-road without having to worry about more fuel, and even on-road it's a big deal. IMO it's not really about saving money, these things use so much gas the return on investment isn't really there, but the longer range between fillups is the real benefit.
Click to expand...

I find the cost savings significant. My truck spends most of its miles on the road, and its mileage was its biggest selling point when I first got it. For my particular situation, I would find having fuel mileage in the teens to be a deal breaker wallet-wise.

If you are planning on "putting a bunch of miles on it" you may enjoy the higher fuel mileage.

That being said, there is a significant power difference between a 6.2 C-code and a 6.5TD, especially at higher engine speeds (I'd even say there's a noticeable difference between a 6.2 C-code and a 6.2 J-code). If you want the same high-end power as a TBI truck you may want to stick with a 6.5. I love my N/A 6.2, and I wouldn't trade it for any gas engine I've met, but it's not great for quickly passing folks on the interstate.

Good luck with the camping/expedition project. We just bought our suburban (diesel, of course) with that same goal in mind. Reliability and mileage. :waytogo:
 
I've got the 6.2 in my CUCV and I don't mind the power situation (35's and 4.56). It's not a powerhouse, but good enough. Thing is, without overdrive, it kind of tops out at 60-65 mph in terms of where I'm comfortable revving the motor.

Aside from that issue, I love the simplicity of it. I know most people don't give it a though, but I'm a bit paranoid about the computer and all that with my TBI conversion. The diesel just has one wire going to it and has all the TBI benefits in terms of off camber, etc. Plus it's basically waterproof as long as you don't suck water into the intake.

If my 350 blew up tomorrow, I'd seriously think about dropping a 6.2 in there.
 
Has anyone ever measured their "off road" MPG with the 6.2 or 6.5? I know as long as I'm off-pavement, whatever I'm doing, 10MPG is a good estimate. I always assumed the diesel economy transferred offroad too, but I've wondered how efficient they were when bouncing around logging roads and the like.
 
Mine was just as thrifty or better off road. At Blazer Bash when I went we did "crack and back", we were out all day...I may have run through a little over a quarter tank. Diesels burn almost nothing at idle, consumption is very rpm dependent. At idle a 6.2 might use half a gallon per hour. Most wheeling I do is at or near enough to idle...except getting to and from the trail.
 
My last suburban (v2500 6.5td th400) was right at 13mpg city or in the hills.
The one before that (v2500 6.2td 700r4) it didnt seem to matter how I used it, I only saw less than 20 one time (19.5mpg)
 
I can't hardly measure my off road mileage. I can tell you when I burn all night to heat my camper I'm burning between 2-3 gallons depending on how long I sleep and maybe outside temp. On average I sleep an 8 hour night.
 
dyeager535 said:
Has anyone ever measured their "off road" MPG with the 6.2 or 6.5?
Click to expand...

No, but I'll say this, while the Jeeper guys show up with an extra 5gal can of fuel, I'll show up bright and early with 1/2 tank and not think twice about it and wheel all day, then drive home.

I've noticed when I'm out crawling, I barely touch the throttle except for specific obstacles I'm slowly bumping over and accelerating/braking it, meanwhile gassers are putting their foot down. I'd say I'm just off idle most of the day. And I'm not even low geared.
 
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