IH POWER
ALL MOTOR!
Can someone give me an UNBIASED opinion of the Pros/Cons of the 6.2s, 6.5s, and 6.9s and a comparison between them? Very curious about the 6.2s and 6.5s.
6.9 vs. 6.2 vs. 6.5
- Thread starter IH POWER
- Start date
DesertBen44
Full Access Member
Im no expert but I have multiple friends who swear by the 6.2. 6.2 is the most fuel efficient, it came in a half duty pickup (for those that are into that) and there are so many military 6.2 surplus engines and parts out there they will be around for a long time. I have driven a few 6.2s and was not impressed by the performance at all. They say a banks kit will really liven it up.
I have never driven a 6.5; but in county's that don't require emissions I know of people who take early 90s 6.5 chevys, junk the 6.5 motor, putting in a 6.2 with a banks kit.
Comparing them is difficult, I have always been a chevy guy but when I wanted a 4x4 5 speed manual diesel, i bought a Ford.
I have never driven a 6.5; but in county's that don't require emissions I know of people who take early 90s 6.5 chevys, junk the 6.5 motor, putting in a 6.2 with a banks kit.
Comparing them is difficult, I have always been a chevy guy but when I wanted a 4x4 5 speed manual diesel, i bought a Ford.
Ididriver
Full Access Member
The 6.2 will give decent mileage but it'll make the 6.9 look like a dragster.
Maverick1701
Full Access Member
I have driven several 6.2s and 6.5s in our HMMWVs at the SO. They are pretty easy to work on (similar to an IDI). They get pretty good mpgs assuming we aren't bajaing through a field or something.
I have never driven a 6.9 so I cant speak to it.
I do know there are A LOT of CUCVs and other vehicles w/the 6.2 and or 6.5 for super cheap. I would venture to say that over 1/2 of the members over on my steelsoldiers forum run them and have no trouble finding parts, spare motors or spare trucks.
I have never driven a 6.9 so I cant speak to it.
I do know there are A LOT of CUCVs and other vehicles w/the 6.2 and or 6.5 for super cheap. I would venture to say that over 1/2 of the members over on my steelsoldiers forum run them and have no trouble finding parts, spare motors or spare trucks.
Ataylor
Full Access Member
Just an opinion, but I think that parts for the 6.2 and 6.5 engines will be available for alot longer than the International IDI engines because they were used in Humvees.
Archie
Archie
GOOSE
Happy IDI'er
It's been quite some time since I've driven a 6.2/6.5. The 6.2's in the boxy Chebbys get very impessive mileage and guys have gotten plenty of power out of them with turbos and other goodies. The 6.5 turbo in the IFS era trucks will probably give you the best ride out of the trucks you are comparing. They are low slung and probably easier to get in and out of.
A non turbo'ed 6.9 should run a N/A 6.2 on any given day. Somebody correct me if I'm wrong but the Navistar IDI's have quite a bit more metal in them, heavier block, crank, rods, ect.
Comparing the potential of a built 6.2, 6.5, 6.9; I will stand on the side lines and find amusement in the arguement.
A non turbo'ed 6.9 should run a N/A 6.2 on any given day. Somebody correct me if I'm wrong but the Navistar IDI's have quite a bit more metal in them, heavier block, crank, rods, ect.
Comparing the potential of a built 6.2, 6.5, 6.9; I will stand on the side lines and find amusement in the arguement.
PwrSmoke
Full Access Member
I have owned a 6.2 and a 6.9L concurrently (had the 6.2L Blazer for 8 of the 26 years I've owed the 6.9L). I have little hands-on experience with 6.5L engines, so I won't comment much on them, but from all I know second hand, in most ways, the the 6.5L is a much better and more evolved powerplant than the 6.2L and the last of them are pretty darn good engines. Not powerhouses compared to the other more modern engines, but taken about as far as they can be. I've not owned a 7.3L either... not that they are all that much different than a 6.9L
The 6.2L and 6.9L each have their good and bad years in their eras, good and bad points. NA to NA the 6.9L is the clear winner in power and performance (135/240 vs 170/315 pwr & torque). Conversely, the 6.2L is the fuel economy winner but the gap is very narrow if you focus on equivalent GVW trucks (i.e. an 6.2L in a 3/4-ton vs a 6.9L in a 3/4-ton). The power difference is also stark in that category. A 3/4-ton at a full load with a 6.2L is a pig compared to a 6.9L truck at the same load. Overall, the 6.9L is the durability winner as well. You can't really flog an NA 6.2L that hard (vs a 6.9L) before something gives and flogging is pretty much what you have to do to an NA 6.2L in a 3/4 or 1-ton platform that works. IMO, the 6.2L is a GREAT light duty powerplant, perfect for the half-ton realm. It's more compact and lighter than the 6.9L... basically it will fit anywhere a BB Chev will fit. The 6.2 responds well to a turbo and is very reliable at a 200hp/400 lbs-ft flywheel level. It's at the same place a 6.9L is at 250hp/500 lbs-ft flywheel. I came to the odd conclusion that a 6.2L with a turbo is MORE reliable than a 6.2L NA because you don't have to flog it all the time to obtain decent performance (200 hp vs 135 would kinda do that). I really think the same is true with a 6.9L.
Anyway, if you are trying to decide on a 6.2L vs a 6.9/7.3L, if you are talking older truck in the IDI era and you want a 3/4-1-ton, get teh Ford unit. A really sharp 6.2L GM with a turbo... I wouldn't automatically walk away from. I wouldn't advise getting a 6.2L NA in a 3/4-ton or up unless you also had the coin to buy a turbo kit immediately. A later 6.5L turbo GM would be OK. They had pump glitches with the DS4 electronic pump, but there are good cures for them now. A 6.5L has less power than a 7.3L PSD, however.
The 6.2L and 6.9L each have their good and bad years in their eras, good and bad points. NA to NA the 6.9L is the clear winner in power and performance (135/240 vs 170/315 pwr & torque). Conversely, the 6.2L is the fuel economy winner but the gap is very narrow if you focus on equivalent GVW trucks (i.e. an 6.2L in a 3/4-ton vs a 6.9L in a 3/4-ton). The power difference is also stark in that category. A 3/4-ton at a full load with a 6.2L is a pig compared to a 6.9L truck at the same load. Overall, the 6.9L is the durability winner as well. You can't really flog an NA 6.2L that hard (vs a 6.9L) before something gives and flogging is pretty much what you have to do to an NA 6.2L in a 3/4 or 1-ton platform that works. IMO, the 6.2L is a GREAT light duty powerplant, perfect for the half-ton realm. It's more compact and lighter than the 6.9L... basically it will fit anywhere a BB Chev will fit. The 6.2 responds well to a turbo and is very reliable at a 200hp/400 lbs-ft flywheel level. It's at the same place a 6.9L is at 250hp/500 lbs-ft flywheel. I came to the odd conclusion that a 6.2L with a turbo is MORE reliable than a 6.2L NA because you don't have to flog it all the time to obtain decent performance (200 hp vs 135 would kinda do that). I really think the same is true with a 6.9L.
Anyway, if you are trying to decide on a 6.2L vs a 6.9/7.3L, if you are talking older truck in the IDI era and you want a 3/4-1-ton, get teh Ford unit. A really sharp 6.2L GM with a turbo... I wouldn't automatically walk away from. I wouldn't advise getting a 6.2L NA in a 3/4-ton or up unless you also had the coin to buy a turbo kit immediately. A later 6.5L turbo GM would be OK. They had pump glitches with the DS4 electronic pump, but there are good cures for them now. A 6.5L has less power than a 7.3L PSD, however.
lindstromjd
Black Sheep
I've got a 6.2 in one of my trucks that I swapped in after the 350 blew on me. I wanted it for the fuel mileage, and as far as comparing it to the "emissions based" 350 (which was a dog) I saw no real power difference. I ended up putting a 6.5 turbo on it, and it really helped a lot. That's where the 6.2 has the advantage to me; the turbos are extremely easy to find and put on. Just get a 6.5 set up and bolt it all on.
The main DISadvantage of a 6.2 in an older truck (73-87) is that you can't put a 6.5 turbo set up on it and still use your A/C unless you modify the exchanger box. It's a real pain to have to do it and be able to get it right.
Some extras... the 6.2 has a known weak spot in the bottom end; the mains are notorious for cracking if you beat the crap out of the engine. The "red block" early 1983 blocks and the military blocks have much higher nickel content and thus are stronger than the later blocks. Depending on the year and the type of head you have, the pre-combustion chambers are sized differently for either more power, or more fuel efficiency. The 6.2 and 6.5 also have thick enough cylinder walls that cavitation really isn't an issue, like with the 6.9 vs the 7.3.
It did take GM a REALLY long time to finally get in to the Direct Injection diesel game though. The late 6.5's aren't exactly a good competitor for a 7.3 PSD. But, like was stated earlier, when the military uses something, parts are going to be in abundance and very easy to find for the next 50+ years. And when HMMVW's get retired, then the market will get flooded with 6.5's just like it did with 6.2's a few years back.
The main DISadvantage of a 6.2 in an older truck (73-87) is that you can't put a 6.5 turbo set up on it and still use your A/C unless you modify the exchanger box. It's a real pain to have to do it and be able to get it right.
Some extras... the 6.2 has a known weak spot in the bottom end; the mains are notorious for cracking if you beat the crap out of the engine. The "red block" early 1983 blocks and the military blocks have much higher nickel content and thus are stronger than the later blocks. Depending on the year and the type of head you have, the pre-combustion chambers are sized differently for either more power, or more fuel efficiency. The 6.2 and 6.5 also have thick enough cylinder walls that cavitation really isn't an issue, like with the 6.9 vs the 7.3.
It did take GM a REALLY long time to finally get in to the Direct Injection diesel game though. The late 6.5's aren't exactly a good competitor for a 7.3 PSD. But, like was stated earlier, when the military uses something, parts are going to be in abundance and very easy to find for the next 50+ years. And when HMMVW's get retired, then the market will get flooded with 6.5's just like it did with 6.2's a few years back.
Keeway
ALL MOTOR!
The farm near where I live has a turbo 6.5 in a gmc 3500 flatbed and It would pull a good size load when I drove it a few times but much harder to work on than my 6.9. The 6.2s have alot of bad things bout them but they are all much better than the 5.7 350 converted diesel. Stay away from those
itsacrazyasian
residentcrazyasian
The 6.5 in non electronic form was still a basket case. I had a 6.5 surburban with that stupid DS4 injection pump.
The 6.5 motor had cracked a block. I bought a surplus military 6.5 engine which was destined to be a replacement for a humvee. Cast in the center of the engine valley is the internatonal DIAMOND logo. This was the motor to have. You can buy this motor still, brand new as the optimizer block. It was the only reason why i would have considered keeping the burb. I'll take a 6.9 or 7.3 idi any day over the 6.5. the 6.2 in na form was pretty efficient though. once you got over all the common issues. The bottom ends were issues and cracking heads vs the 6.9 which had a bulletproof bottom end.
The 6.5 motor had cracked a block. I bought a surplus military 6.5 engine which was destined to be a replacement for a humvee. Cast in the center of the engine valley is the internatonal DIAMOND logo. This was the motor to have. You can buy this motor still, brand new as the optimizer block. It was the only reason why i would have considered keeping the burb. I'll take a 6.9 or 7.3 idi any day over the 6.5. the 6.2 in na form was pretty efficient though. once you got over all the common issues. The bottom ends were issues and cracking heads vs the 6.9 which had a bulletproof bottom end.
The 6.5 is still being used in bummers, and was still being put in vans up into the mid 2000's. We have 2002 gmc busses with them so parts will be made for long time.
As a owner of a 6.9, a 7.3 and a 1998 6.5, I will say they all have their pluses and downfalls. My ford idi's have way more power than my van. But they are also manual as the van is auto. I choose the fords.
As a owner of a 6.9, a 7.3 and a 1998 6.5, I will say they all have their pluses and downfalls. My ford idi's have way more power than my van. But they are also manual as the van is auto. I choose the fords.
I don't want to relive the experience on here, but I will say that the 6.2 in my GMC cube van was an utter pile of garbage. The only thing the truck has ever been good for is keeping the weeds down in my backyard for the last 13 years. The motor had to be rebuilt twice while I was using it, and it would still overheat even on flat ground at gentle speeds. My old man refuses to acknowledge that they are diesel engines(not because of misinformed rumours lol), because the reasons for buying a diesel are just not there. They do NOT have longevity or low-end torque like a diesel should have. They can get okay mileage in a half-ton pickup. My opinion is they should never have been installed in anything heavier than a 1500.
Somebody at GM must have been sleeping with somebody in the military in the late 70's. The military would have been much better served by the 6.9/7.3, and we'd be better off because instead of an abundant supply of s****y engines, there would be a lifetime supply of parts floating around to keep these trucks going for many many years to come.
EDIT: Just keep note, my 351 GASSER has lasted much longer than the 6.2 ever did as a work truck.
Somebody at GM must have been sleeping with somebody in the military in the late 70's. The military would have been much better served by the 6.9/7.3, and we'd be better off because instead of an abundant supply of s****y engines, there would be a lifetime supply of parts floating around to keep these trucks going for many many years to come.
EDIT: Just keep note, my 351 GASSER has lasted much longer than the 6.2 ever did as a work truck.
the biggest problem with the 6.2/6.5 platform is cooling system issues. the updated water pump and dual thermostat crossover solved that problem.
irregardless, the 6.2/6.5 imho is a excellent people hauler motor as long as you 1)dealt with the cooling problems 2)avoided or deleted the DS4 system. I have a 6.5 with a Banks turbo kit in my 'burb 4x4 and it is the best fuel economy truck in my fleet. if I want to haul heavy, I have other choices. If I want to haul 8 people comfortably, I use the 'burb.
irregardless, the 6.2/6.5 imho is a excellent people hauler motor as long as you 1)dealt with the cooling problems 2)avoided or deleted the DS4 system. I have a 6.5 with a Banks turbo kit in my 'burb 4x4 and it is the best fuel economy truck in my fleet. if I want to haul heavy, I have other choices. If I want to haul 8 people comfortably, I use the 'burb.
itsacrazyasian
residentcrazyasian
Ya know Cal, the problem is. Doing a ds4 delete/conversion isn't exactly what most people can handle on their own. I did that once for a customer. It was quite the undertaking. Luckily i left the ECM in place and hooked a tps up to the injector up and she shifted like nothing was wrong.
That engine broke the crank about 8000 miles later. Told customer to keep eye on harmonic balancers. He did not want to replace at the time i was doing the conversion.
That engine broke the crank about 8000 miles later. Told customer to keep eye on harmonic balancers. He did not want to replace at the time i was doing the conversion.
Black dawg
Registered User
MY opinion is pretty dang biased, seeing as how I have had both ford diesel and old chevy diesels over the last ten years.
I still have 2 old ford diesels, with very little trouble in the last 10 years. I swapped out my last 6.2 for a gasser, I am done with them.
I still have 2 old ford diesels, with very little trouble in the last 10 years. I swapped out my last 6.2 for a gasser, I am done with them.
Similar threads
