some opinions of diesel

[cam.man67]

This is purely theoretical at this point, I'm not right now seriously considering swapping a diesel into my '69.

Now that that's out of the way, my question is about the 6.2 Detroit.

I had always heard that its external dimensions are identical to that of an SBC, that it bolts directly in, with no modifications structurally. Is that true?

Also, if I were to put one of these in, what kind of gas mileage can I expect with 3-speed and 3.73?

Finally, how common were the Banks turbo setups that GM offered the last year or two of 6.2 production? I see a totally new kit is something like $2200 from Summit, seems to me one that's already in a truck should be had pretty cheap.

[special-K]

The 6.2 is an easy swap. I would guess the mileage would be in the upper teens. I get 15 max from my '92 K3500 6.5TD/5spd 4.10 8,000# GMC pickup with 285/75s. I got 20 from my '91 V2500 6.2/4L80E 4.10 Suburban with 12.50/35s. I imagine my '85 K/5 6.2/700r4 with probably 3.08s and 235/75s with get 22. I think rather than do a Banks Sidewinder kit you could fins junk 6.5TD and pull what you need to convert the 6.2NA. But,I wouldn't bother with a turbo. The 6.2NAs are not at all fast but they are what they are. My Suburban moved along just fine and loved 75mph all day long. You try to pep them up and you lose it all. I had an '84 K3500 6.2/TH400 4.10 pickup that I put a Banks Sidewinder on,as well as a Gear Vendors unit,and it had more power and mileage. But,figure what I had into those two units. I think if you are looking for economy the 6.2 naturally aspired is the way to go.

[Bob B.]

There are a lot of good reasons for using a 6.2 or 6.5 in a '67-'72. As stated in the previous post, it is an easy swap. Bell housing bolt pattern is the same as any Chevy V-8, motor mount locations are the same, and they weigh about the same as a Big Block. And, as if that wasn't enough, the r.p.m. range and torque curve is similar to a gasoline V-8. You can probably get by with the same transmisson and rear axle you have now (though GM usually used a lower stall torque convertor). A Cummins 4BT 3.9 does fit, but it is very heavy, very noisy, doesn't fit without a lot of work, and has a whopping 2300 r.p.m. redline. So, after you get the thing in there, you then get to look for a overdrive transmission (assuming you want to drive on a freeway). Oh, and they make about 120 h.p..

[Uwe Blab]

I've wondered about the diesel swap as well. Ideally I'd love to have a diesel that I could convert to bio at some later date. Can the 6.2's be converted?

Along with the diesel engine, here's a list of other items I would like to install in my truck:

- dual range rear axle (like hi and lo range on a 4x4)
- rear axle limited slip
- disc brakes
- power steering

Given this list, and the interest in the diesel, are the old military blazers a good source for these items, if I could find one to part out?

Lastly I just put in a Borg Warner overdrive transmission in the truck to run behind my 250 engine, so I could keep my 3 speed on the column but still get a gear for the highway. Any chance that tranny is stout enough to run behind the diesel engine, or would the torque be too much?

Thanks,
Adam

[cam.man67]

I think that OD tranny is pretty stout if you don't abuse it. The torque the 6.2 puts out without the Sidewinder turbo would not be enough in my mind to ruin it.


Personally, I'd leave the CUCV's alone. There are plenty of other 6.2 trucks out there for a ton cheaper, especially if you're just going to use it for parts.

[Uwe Blab]

Oh, man, I do like cheaper. Thanks for the heads up Cam.man. I guess I was thinking of the CUCV's because they have been the most common ones I've seen with the diesel engine.

So would a 4x4 give me the dual range rear end I'm trying to find? I don't necessarily want four wheel drive capability (just a limited slip for adverse weather), but I would like to be able to have lower gearing on the back end if I decide to haul something with the truck, and install a small inconspicuous lever in the floor for switching out hi to lo range.

Thanks for the help.

Adam

[brad_man_72]

diesels are awesome if you don't mind hearing comments like "hey man sounds like you got a rod knocking" "should it really be smoking that much" "your truck sounds like a school bus"

tire smoke makes me horny! Lol

[cam.man67]

Another Adam, huh? Me too!

The dual range rear you're talking about could be two things:

1. On light duty trucks, this is actually a transfer case that shifts between high and low. It's attached to the transmission (not axle), and can only be used in conjunction with 4x4.

2. On the big trucks, C30 and up, I believe the axle itself does have the hi-low transfer, or at least some have that capability. I don't think those axles would be real compatible with your truck.

If it were me (diesel or not), I'd find a 4.11 posi and put that out back. With the OD ratio you have on the transmission, a 4.11 is not gonna hurt at highway speed, but will theoretically give you more towing ability.

[SWEET7T]

Originally Posted by Uwe Blab

I was thinking of the CUCV's because they have been the most common ones I've seen with the diesel engine.

So would a 4x4 give me the dual range rear end I'm trying to find?

Adam

The CUCV's trucks and blazers have/had the 6.2L NA motor, but you have to watch out for the starters and glow plugs. These rigs were 24 Volt so the glow plugs aren't going to work well on a single battery. It is still an easy thing (in my opinion) to swap out the glow plugs and the starter.

The 4x4 did not have 2spd rears. They only had the high/low range from the transfer cases. Also, the axles are stuffed with 4.56 gears (at least on the trucks), so if you acquire an axle set don't be expecting to go very fast.

As for the 6.2/6.5L swap. I'm all for doing it. It was my original plan for my '70, along with a 700R4 trans until I had a TBI454/4L80E fall in to my lap! I would imagine with an overdrive or tall rearend that you would be able to get 20+MPG. I would have to turbo it. As already mentioned, all of the turbo parts from a 6.5L will fit the 6.2L (exhaust manifolds, turbo, plumbing, ect).

[Uwe Blab]

Originally Posted by cam.man67

If it were me (diesel or not), I'd find a 4.11 posi and put that out back. With the OD ratio you have on the transmission, a 4.11 is not gonna hurt at highway speed, but will theoretically give you more towing ability.

Good name indeed Adam.

Yeah, I'm probably over-thinking the dual range angle. The 4.11 posi is probably the smartest, and easiest, swap to do in the short run. Although I've been a little disappointed with the fuel mileage I've gotten with the OD tranny so far. I went from 12 to about 14. I was hoping to be in the high teens...maybe even pushing 20. I've also had some issues with the tranny not engaging in 2nd or 3rd gear when the OD cable is pushed in, not sure what that's about...of course that's probably a discussion for a different thread.

Thanks for the help.

Adam

[special-K]

If you do find a beat CUCV or a removed engine,they are a great donor. The military blocks have a higher nickle content alloy and so did the first year '82s. Their blocks are painted red.The glow plugs are cheap. I just bought a set for my '85 Jimmy for $75. Just sell the 24v stuff to a CUCV guy and go with 12v. My son has an '86 CUCV Blazer and I can't get him away from that 24v nonsense. They only did it because all the big military stuff is and they want every vehicle to be compatible. There is no benefit to the 6.2 powered trucks,only an expensive P.I.A.
I don't think you'll find a 1t 2spd rear. I believe they were made but I've only seen one in my life. The Gear Vendors will give you that but not for cheap. Back in the day guys ran auxilary transmissions...called then Brownie Gears. You can rig up two transmissions and get multiple gears.

[cam.man67]

So '82 would be more desireable? There's a '82 C20 for $1600 on cl.

[72 cheyenne pdx]

You could possibly run a transfer case and not use the front output shafts for your hi-lo gears.

[Uwe Blab]

Originally Posted by 72 cheyenne pdx

You could possibly run a transfer case and not use the front output shafts for your hi-lo gears.

Not exactly sure how that would work. Could you explain a little more detail?

Thanks,
Adam

[special-K]

Originally Posted by cam.man67

So '82 would be more desireable? There's a '82 C20 for $1600 on cl.

Yes. After the first year GM cut back on the nickle content to save money. They are the best blocks to start with for a rebuild,too.

Originally Posted by 72 cheyenne pdx

You could possibly run a transfer case and not use the front output shafts for your hi-lo gears.

Originally Posted by Uwe Blab

Not exactly sure how that would work. Could you explain a little more detail?

Thanks,
Adam

I figured this was what you were talking about doing. Run the 4wd assembly w/o the front drive (driveshaft and axle). You would only gain the low-low.Mileage and power would decrease a bit due to turning more drivetrain. I guess that's why you don't see anyone doing it.

[Uwe Blab]

Thanks for the clarification special-K. I imagine I'm thinking in overkill terms. Probably the heaviest thing I would ever haul with the truck is an old Airstream trailer, so I guess the 4.11 rear axle and diesel engine should be sufficient for pulling that. Of course I don't have one of those Airstreams yet.

Adam

[D13]

Did you search and find the 6 other threads?

Basically you're swapping in a 305 for power, with 10-15% better fuel economy (note that diesel fule is about 7% more expensive right now...). NONE of the SBC parts fit (no the motor mount's aren't the same, but use the same frame towers). And you need about 2x radiator. And big block springs. And a non-vacuum brake booster. But it will bolt up to any early GM trans (did I mention the flywheels and flex plates are different than SBC?).

To make more power out of a 6.2 = $$$, think block studs, main girdles, etc. 6.2's have a marginal bottom end. If you want to make black smoke and impress people it's the wrong choice. If you drive it 100 miles every day it's a great choice.

Military Blazers are usually 3.08 gears.

Lots of good info here http://www.dieselplace.com/forum/

[SSC's76]

I dont think the 6.2 or 6.5 would be a good choice I use to work on them all day long not very impressive even with a banks turbo kit. Much better diesel choices out there if you plan on going this route and you need to know that most diesel owners post fuel economy thats not very realistic it very refreshing to see what Adam posted thats spot on for fuel economy. Either way you go get a complete setup from a wrecked or retired truck it will make your life so much easyer.

[D13]

My 87 R10 1/2 ton fully loaded gets 23mpg mixed driving, 3.08 gears and 700R4. But I drive like a little old lady. At 55mph it gets around 26mpg.

[C-10 simplex]

So, does Gm still produce this engine as a crate or reman?