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6.2 or 6.5 diesel versus 350 V8Tbi. Out of which diesel engine is better than the 350?

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blackandgold51

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Was thinking about this question and thought it would be insteresting. And to learn more about the history of these diesel engines.

Sorry if i asked i just thought.

Plus i may want to put a 6.2 or 6.5 diesel in a 1990 suburban v1500 4x4 thats has a 700R4 transmission.

Plus unleaded gas here in New Orleans is 1.89 Cents a gallon while Diesel is around 2 something a gallon
 
Well to put it simply the 6.2s were designed to give comparable power of a 350 but with greater, usually double, fuel economy. The 6.5td gives power that's kind of an in between the 350 and 454, again with greater fuel economy. This is when compared two similar model year 350 and 454 engines.

The greatest benefit to both the 6.2 and 6.5td is there pretty much direct bolt in replacement for any GM V8. They have some quirks and will never be as powerful as a modern diesel but when cared for they are very reliable and stupid simple to work on.
 
KirsL said:
Well to put it simply the 6.2s were designed to give comparable power of a 350 but with greater, usually double, fuel economy. The 6.5td gives power that's kind of an in between the 350 and 454, again with greater fuel economy. This is when compared two similar model year 350 and 454 engines.

The greatest benefit to both the 6.2 and 6.5td is there pretty much direct bolt in replacement for any GM V8. They have some quirks and will never be as powerful as a modern diesel but when cared for they are very reliable and stupid simple to work on.
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Im wondering about the fuel economy part because i use my suburban almost everyday to commute and i dont do heavy towing much either. Mostly light towing

Ive been hearing that the 6.2 and 6.5 diesels are not reliable. Is that true?
 
Turboed 6.5 burb on 35" tires gets 21-23 depending on season

Identical burb with a non turbo 6.2 got 19-21 again depending on season

My turboed 6.5 90 crew cab on 35" with a TH400 would do a consitent 18-20 but you would have to stick to about 65 or the mileage tanked
 
KirsL said:
When cared for they're very good engines and will give good reliability.
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Absolutley , keep them cool and change the harmonic dampner often . Do that and do your basic maintenace and they last a long damn time.

The 6.5 in my crew cab has well over 400,000 on it now and its been flawless
 
Yah the 6.2 in my Jimmy has over 400k on it.

My 84 burb ( stock ) gets 19 ish. I haven't seen 20 yet.

My lifted 89 Jimmy gets 16 to 17. It's a 6" lift and 37s.
 
yellowK20 said:
Turboed 6.5 burb on 35" tires gets 21-23 depending on season

Identical burb with a non turbo 6.2 got 19-21 again depending on season

My turboed 6.5 90 crew cab on 35" with a TH400 would do a consitent 18-20 but you would have to stick to about 65 or the mileage tanked
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So the 6.5 and 6.2 were basically economical engines like a mercedes benz engine. Built for good fuel mileage but not for heavy towing.

I think this might be good because i have a tbi and want to modify the 350 v8 for fuel economy: High Performance Coil Distributor, MSD Coil Spark Plug Wires, High Performance Distributor, Long Tube Headers, MSD Ignition and High performance Intake and maybe some high performance heads. But i thinl that might not be enough for a gas engine.

Which iv been wondering take that out that motor and put in a diesel
 
yellowK20 said:
Turboed 6.5 burb on 35" tires gets 21-23 depending on season

Identical burb with a non turbo 6.2 got 19-21 again depending on season

My turboed 6.5 90 crew cab on 35" with a TH400 would do a consitent 18-20 but you would have to stick to about 65 or the mileage tanked
Click to expand...
I 4got to mention i got a 700R4 rebuilt transmission
 
I tow moderate to heavy loads with mine , they will tow just dont expect modded cummins or dmax power.

A good turboed 6.5 is as good or better then a tbi 454 , and double the mileage
 
The 6.2 has power & torque more like a 250 or 292 straight six than a 350 V8 in my opinion--they only make 140 HP and the torque is nearly identical ,and peaks at low RPMs much like a straight six does (about 1600 rpms)...

Both of my 6.2's never broke 20 mpg more than once or twice..to me they are not really much more economical in the long run,with diesel costing more than gasoline..and today's EFI V8's will get better mpg than that..the diesel does have the advantage of not needing a tune up,no plugs,wires,cap & rotor,but glow plugs do fail and are around 10 bucks each..

Google "6.2 reliability" and you'll find 1000+ posts varying from "mine is running sweet with 500K on it ",to "they SUCK,the cranks snap like glass,they are noisy,eat injector pumps,blow head gaskets,etc"..all depends on who you ask,and how good or bad their luck is..

A gas 350 will leave a 6.2 diesel powered truck in the dust in a standing start 0-60 race...while a 6.2 might tow a light load OK,I would not want to use my truck for towing--trying to get it up to 65 mph empty when merging onto a highway is scary enough !--especially if its an uphill grade..
 
yellowK20 said:
Turboed 6.5 burb on 35" tires gets 21-23 depending on season

Identical burb with a non turbo 6.2 got 19-21 again depending on season

My turboed 6.5 90 crew cab on 35" with a TH400 would do a consitent 18-20 but you would have to stick to about 65 or the mileage tanked
Click to expand...

What gearing/tranny were each of these running, Gus? :popcorn:
 
blackandgold51 said:
So the 6.5 and 6.2 were basically economical engines like a mercedes benz engine. Built for good fuel mileage but not for heavy towing.

I think this might be good because i have a tbi and want to modify the 350 v8 for fuel economy: High Performance Coil Distributor, MSD Coil Spark Plug Wires, High Performance Distributor, Long Tube Headers, MSD Ignition and High performance Intake and maybe some high performance heads. But i thinl that might not be enough for a gas engine.

Which iv been wondering take that out that motor and put in a diesel
Click to expand...

By the time you mod the daylights out of that 350, you will have spent more time, likely more money, and you still won't have the same mileage of a 6.2/6.5TD.

If you want a simple, bolt-on mod to greatly increase mileage, it's hard to beat these engines. Reliability? They can be fragile to hotrodding or abusive towing. But commuting & the light towing duties of the average handyman with a boat trailer is *exactly* what the 6.2 was designed to do. The 6.5 tries to keep up with the heavier-duty towing engines, but it is still an overbored commuter engine. So if commuting is what you do, these are excellent choices (and your current 350 is ok, too).

Keep in mind that the diesel engines prefer to spin more slowly, so mileage gains are somewhat dependent on tranny/gearing/tire size parameters. It's not just an engine that makes an efficient ride, the whole truck must be set up accordingly. This is true no matter what engine you run.
 
campfire said:
By the time you mod the daylights out of that 350, you will have spent more time, likely more money, and you still won't have the same mileage of a 6.2/6.5TD.

If you want a simple, bolt-on mod to greatly increase mileage, it's hard to beat these engines. Reliability? They can be fragile to hotrodding or abusive towing. But commuting & the light towing duties of the average handyman with a boat trailer is *exactly* what the 6.2 was designed to do. The 6.5 tries to keep up with the heavier-duty towing engines, but it is still an overbored commuter engine. So if commuting is what you do, these are excellent choices (and your current 350 is ok, too).

Keep in mind that the diesel engines prefer to spin more slowly, so mileage gains are somewhat dependent on tranny/gearing/tire size parameters. It's not just an engine that makes an efficient ride, the whole truck must be set up accordingly. This is true no matter what engine you run.
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Keep in mind that i dont drag race and not in the driving fast thing. Although i would like some decent accelration, ive heard you can add a turbo to the diesel motors
 
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