Making the most of a stock 6.2

[ODdave]

One problem, a 6.6 Duramax kit, well all the ones I have looked at use fuel injection....fuel injection is irritating to deal with when a part of it breaks so no thanks. I would rather just deal with a carburetor, sure it's outdated and rarely used anymore but it's just so much better in my book.

 

[bubba_got_you]

[FONT=&quot]…Well the 6.2 is injected, as are all diesels. But the big problem with the 6.6 is the computer. I have a 6.2 with a 6.5 turbo and 4 “ exhaust it gets up and goes just fine and with my 700r4 trans I have over drive so the mileage is good. Now I only have 3 wires going to my motor. That’s all it needs to run and drive and for me the less wires the better.
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[Preacherboy]

To rebuild a 6.2 pretty much stock will cost about $1500, if you do most of the work yourself...ask me how I know.

Start upgrading things like the guys from Diesel Power mag and it will cost big time! If you want a non-computer controlled engine with good power and fuel mileage you will have to put a Cummins in your truck...I think they are putting 6bt's and 4bt's in hmmvw's.

 

[MudmanHMMWV]

I thought about a Cummins but still not sure on that. It's a thought that I'm still mulling over, especially since Cummins has perhaps the best running diesel motors ever produced, in my book anyway.

 

[papaydsailor]

[FONT=&quot]…Well the 6.2 is injected, as are all diesels. But the big problem with the 6.6 is the computer. I have a 6.2 with a 6.5 turbo and 4 “ exhaust it gets up and goes just fine and with my 700r4 trans I have over drive so the mileage is good. Now I only have 3 wires going to my motor. That’s all it needs to run and drive and for me the less wires the better. [/FONT]

the 700r4 with overdrive is the same as the 4L80E it uses computer for the overdrive. i would use allison 1000t instead. why would anybody drive a heavy boxy body truck over the highway speed limit with a non ABS breaking. this truck are not made for speed.

 

[Tanner]

the 700r4 with overdrive is the same as the 4L80E it uses computer for the overdrive. i would use allison 1000t instead. why would anybody drive a heavy boxy body truck over the highway speed limit with a non ABS breaking. this truck are not made for speed.

Ummm... the Allison 1000T is also an electronic transmission... you're not getting away from electronic/computer controls by using the Allison 1000/2000 series transmissions. But you will get to figure out how to make a stock computer run it, as well as dealing with ABS/wheel speed sensor inputs... unless there is an aftermarket (doubtful) controller available to run it...

'Tanner'

 

[ODdave]

the 700r4 with overdrive is the same as the 4L80E it uses computer for the overdrive. i would use allison 1000t instead. why would anybody drive a heavy boxy body truck over the highway speed limit with a non ABS breaking. this truck are not made for speed.

No, the 700 uses the computer for the tcc NOT overdrive.

 

[rogerm101a2]

hello,
i work at GENERAL ENGINE, if you dont know makes the 6.5L for humvees. Do not add anything to that 6.2 if you want it to hold up. That engine is not meant for horse power!! the only thing i would do is advance the pump. and at that it may not hold for long. the bigest problem on the old engine is the head gaskets leaking and adding anything like a turbo you will blow a head gasket.. just my thought..

 

[bubba_got_you]

the 700r4 with overdrive is the same as the 4L80E it uses computer for the overdrive. i would use allison 1000t instead. why would anybody drive a heavy boxy body truck over the highway speed limit with a non ABS breaking. this truck are not made for speed.

700r4 does NOT need a computer.i have been in all gears with my truck and like i said i only have 3 wires. and no one is suggesting he go over the speed limit but what he wants is the be ABLE to do the speed limit without killing the mileage and redlining the motor.

 

[patracy]

hello,
i work at GENERAL ENGINE, if you dont know makes the 6.5L for humvees. Do not add anything to that 6.2 if you want it to hold up. That engine is not meant for horse power!! the only thing i would do is advance the pump. and at that it may not hold for long. the bigest problem on the old engine is the head gaskets leaking and adding anything like a turbo you will blow a head gasket.. just my thought..

Indeed, the 21 or 22:1 compression ratio of the 6.2 doesn't lend well to turbocharging. At least not over 10psi.

 

[spicergear]

A quick word on the 6.5 turbo diesels in factory form with the computer; the computer was mounted...basically on the engine just above the valve cover and saw a lot of engine heat. A friend of mine was on his third ($$$) computer before he found a company that sold a finned aluminum heat sink for those specific trucks/computers and relocated then computer off of the engine. He had no more problems with his 6.5 whatsoever after that.

 

[jdemaris]

the 700r4 with overdrive is the same as the 4L80E it uses computer for the overdrive. i would use allison 1000t instead. why would anybody drive a heavy boxy body truck over the highway speed limit with a non ABS breaking. this truck are not made for speed.

700R4 rarely uses a computer for anything in diesels. Some of the last 700R4s, called "4L60s" by GM, did use a few computer signals for torque-converter lockup in 3rd gear. 4th lockup was still done with a mechancial pressure switch. A 6.2 diesel that uses any computer signals for the 4L60 will have an RPM sensor on top of the vacuum pump (at engine rear), a MAP sensor, a VRV valve on the fuel injection pump, and a vehicle-speed-sensor on the trans or transfercase. That sort of trans is easy to install with no computer, using the 4th gear pressure switch for lockup.

 

[jdemaris]

I was talking this over with a mechanic friend of mine, since fuel mileage is important to me. He told me that if I intended to keep the old 6.2, or since I'm somewhat of an apocalypse nut an older diesel motor, that I should put an forced induction system on it. The two words that left his mouth actually made me cringe a little. He suggested a twin turbo set up, along with a few other gas saving mods that one can put on a motor but those aren't that big a deal.

In my opinion, anybody telling you to install twin turbos for better fuel mileage has a screw loose in his head.

A turbocharger, better put - and exhaust-driven supercharger . . . was originally introduced to reclaim power lost at high altitudes. Now, it's more often used to make a small engine perform like a bigger one.

Problem with the 6. 2i is -it's a light-duy engine. GM first had it designed to match the power of a 305 gas engine. Thin heads, lightweight block and a cast iron crankshaft.

Why anybody would thing installing twin-turbos would make it more fuel effiicient (and hold up under the boost) is beyond me.

NOTE - Banks did make twin-turbo kits for 6.2s for use on boats when engine life and fuel efficiency was not a concern- just ultimate power. I robbed one of those kits and installed on one of my 6.2s, but left one turbo off.

At sea level, you're not going to see much of a fuel mileage gain with a turbo added. It WILL enable you to turn the pump up, and make more power. Wiith that added fuel delivery, the engine WILL be more efficient, then if you'd done the turn-up with no turbo.

What usually happens when you add a turbo is - you go faster, so it's hard to see overall fuel savings.

6.2 needs to run close to 2000 RPM to make the best fuel mileage. No way around that. Do NOT use big wide tires and get your RPMs down if you want fuel miileage. A beefed up 700R4 or 4L60 works nicely. So can a 4L80 except is needs an expensive controller to install it. If you got a non-lockup TH400, you mgiht get 20 MPG once in awhile with 3.08 axles. If you've got 3.73s or 4.10s - forget it.

If you want manual shift - there are many options. GM sold many 6.2s with four-speed manual overdrive transmissions made by New Process. I have two, and they work real nice. If you' ve got the big HD Munice cast-iron 4 speed - with granny no-synchro low- and not overdrive - you can install a Ranger overdrive unit in front of it. Or insall a later 5 speed.

One of my 6.2 rigs has a small motor-home body on it. It's an 86 K5 Blazer.

When all original - 6.2 non turbo and 3.08 axles and 700R4 trans it got 21 MPG at best.
Same with turbo - it still got a best of 21 MPG but I always climbed hills faster.

When I installed the motorhome body, and weight climbed to 8000 lbs. mileage dropped to 16 MPG.

Trans blew. 700R4 could not handle the turbo power and 3.08 axles. So, I am now in the middle of putting in heavier 3.73 axles and a beefed up 4L60 trans with a custom built 6 lug torque-converter. I am hoping for a slight MPG improvement since the engine won't be lugging so much. Too much RPM s and too low RPMs (with lugging) both hurt fuel mileage.

 

[jones20992]

ok dot know much about the hummer but i under stand that the turbo ones use the same intake as the ambulance this is what i would recommend for the best 6.2 and i like the 6.2 block more then the 6.5 because the biggest problem with the 6.5 is that lack of metal between the cylinders and water jackets so here you go hope it helps

get the intake and exhaust manifolds form a 6.5 turbo ambulance they are top mount

any ihi gm turbo ie; gm-4, gm-6, gm-8

you will want to use a 92-93 waste gate controller as these were not electronic

the ds-4 injection pump is fine for forced induction you will just need to turn the fuel up

water pump and thermstat houseing form 1998+ as it is 110 gpm instead of 90 gpm and the duel thermastats with that will help you keep down the heat

get a 6.5 crankshaft same stroke but its a forged unit

marine injectors

4" exhaust

have fun

i would also recommend a built 4l85-e over a stock 4l80 and if you could find a np-205 out of say a m1028a1 or m1031 it would be killer i would control the 4l85 with this http://www.powertraincontrolsolutions.com/simpleshift.php

 

[jdemaris]

the ds-4 injection pump is fine for forced induction you will just need to turn the fuel up


get a 6.5 crankshaft same stroke but its a forged unit

DS4 is an electronically controlled pump.

GM crankshaft in a 6.5 is NOT forged-steel. It is cast-iron, just like all the 6.2s. In fact, some of the later 6.2s use the same part # cranks as 6.5s. Different rear-main seal setup, but still cast-iron.

 

[jones20992]

DS4 is an electronically controlled pump.

GM crankshaft in a 6.5 is NOT forged-steel. It is cast-iron, just like all the 6.2s. In fact, some of the later 6.2s use the same part # cranks as 6.5s. Different rear-main seal setup, but still cast-iron.

my mistake i was thinking of the Db-2 pump and i dont know where i came up with the 6.5 crank being forged i was very sure of it until i rechecked and you are right its cast just like the 6.2

 

[jdemaris]

my mistake i was thinking of the Db-2 pump and i dont know where i came up with the 6.5 crank being forged i was very sure of it until i rechecked and you are right its cast just like the 6.2

The company that is now making the new 6.5 blocks that are beefed up and heavier then the GM originals now offers a forged-steel crank as an option. Maybe that's what you saw, or was thinking of.

 

[Sharecropper]

I have been running 6.2's in my trucks since GM first offered them in the '80's. Spent a lot of cash on Bank's turbos, wish I had that back. I have found the best way to wake up the 6.2 is to open it up and let it breathe. Port and polish the heads and intake, and install a set of tuned headers from Stans www.stans-headers.com . Then open up the breather or install a direct pipe to the grille knock-out. This will allow you to turn up the pump 1/4 turn. 3" pipes turned out 90 degrees behind the rear wheels will create a negative exhaust presure to pull everything out. The engine will run strong and cool, especially on warm rainy summer nights. My 2 cents.

 

[MudmanHMMWV]

I knew I was forgetting something, the headers were something I thought about but tossed into the back of the pile because it was one of the cheaper things that I intended on doing. Though now that I think about it, it would make sense to do that sooner.

 

[jdemaris]

I have been running 6.2's in my trucks since GM first offered them in the '80's..

So have I and was fooling with other diesels 20 years before that.

My experience with the 6.2 is different.

The 6.2 was originally designed to make equal horsepower and torque as a 305 gas engine - but with better fuel mileage. Thus it was built very light, by diesel standards. Also has a short stroke by diesel standards.

The 6.2 makes its best torque and fuel economy at 1800-2000 RPM which is pretty slow - by gas engine standards. At 2000 RPM, flow is not a major issue.
The engines in stock form get all the air they need to make the stock power ratings. The stock exhaust system is also more then adequate unless someone puts the wrong mufflers on.

If you turn up the fuel, then you DO need more air or you start cracking cylinder heads pretty quick. That's where having a turbo helps a lot.

If you live at high altitudes, a turbo is a must - just get get stock power levels. That's why "turbos" used to be called "altitude compensators."
If you live in the mountains of Colorado, a 6.2 will lose 20% of it's stock horsepower and fuel economy without a turbo installed to make up for the "thin air."

Funny thing is, some early 6.2s had big vales for more flow, and they cracked easier then the small valve heads. Thus the reason why the 6.2s rated for the heaviest work and most power often had the smallest valves. That leaves more metal between them to prevent head cracking.

I've put turbos on many and it really wakes them up, Much more than any port/polish job will ever come close to.

Now, if you're building an engine for running 3000-5000 RPMs (and having a very short life), than things change. Not something I've ever wanted to do with a light-duty engine like a 6.2.

Back in the 70s when tractor pulls were not "big business" I had opportunity to stick many naturally aspirated diesels on dynos to measure power changes with porting jobs, big exhausts, homemade headers, etc. I never found any useful power gains at lower RPMs (below 2400).