Those GM diesels were lousy ....

 

Not sounding like I like Chevy trucks but you take a 6.2 diesel and put a turbo on it and it woul spank the 6.5 turbos butt. My uncle has a 6.2 that we riged a hx-35 ok a 95 dodge onto and it runs great. got it wg to 18pis of boost and because of the higher compression ratio it spools faster than the 6.5 and also runs stronger. Now I have another unlce with a 6.5 turbo that he can't keep an injection pump in for more than 30k miles but when the truck in runnning it really runs nice. it would be equal to a 300hp cummins I would think.

 

Hi dman01,

You know a lot about diesel mechanics, but I am not a mechanic of any kind; therefore, you will have to excuse my ignorance about the finer points of mechanical work. I like Chevy and GMC trucks when they have a good product available. I never did like the 6.2 and 6.5 GM V8 diesels because I could work gasoline engines harder without the mechanical problems associated with those early GM diesels they initially put into their pickup trucks.

Actually, the inline six cylinder gasoline engines in Ford, GM and Chrysler cars and pickups, back in the good old days, were all extremely hard knocking gasoline engines that ran forever under adverse punishment. My son at the present time is drivings a new Chevy Trail Blazer with a inline 4.2 litre six cylinder gasoline engine that produces 275 hp. My wife's GMC 4.3 litre (gutless) V6 in her half ton extended cab pickup only produces 180 hp. GM's small 4.8 litre V8 gas engine only produces 270 hp. My son loves that peppy inline six in his trail blazer. Maybe Ford and Chrysler will return the inline six gas engines in some of their vehicles in the future.

And to think BMW and Mercedes Benz gave up the inline six cylinder engines a couple of years ago and replaced them with V6 engines. They give up the stong bottom end engines and replaced them with engines of the weak bottom end V6 block configuration. Technology is going backward to accomodate new streamlined body styling.

 

Thats a good question I don't know If I have the answer but it might be because of use of space. If you look at cars these days the nose is smaller so theres less room to put a big engine. A v6 engine can fit in a smaller space and still give the same HP. A V6 is wider than a I6 but it is still shorter. The width of the v6 is not big enough to hurt the airodynamics of a car because mose are turned sideways to the car. turn a i6 sideways and it sticks out the side of the car. put it straight in line and the nose is too long. I think that also with newer engines they are useing a shorter stroke to gain back some of that TQ that is lost. This again might be wrong and someone will tell me I'm sure.

 

This is going to be a long message and I will be away for a few days.

You are right with regards to automobiles, but in my wife's GMC pickup the front of the V6 engine block is positioned so far back from the radiator that there is lots of room for a 4.2 litre I6 like is in my son's Trail Blazer and it would give us an extra 95 hp for pulling our two place horse trailer. The way I see it, GM only takes 180 or 190 hp from a pickup's 4.3 V6 because the weaker bottom end would not be reliable under continuous hard use situations requiring additional power.

I was grinding camshafts at an engine rebuilder plant in the city of Edmonton for a few months until I got bored with it. At that plant the number of defunct V6 engine cores that came in for rebuilding told the story that V6 engines break down in the bottom end often.

At a car and light truck show in Edmonton, Alberta Canada I observed the bottom end of a cut-a-way demonstration full size model Cummins engine, model Duramax engine and a model Power Stroke engine. The I6 connecting rod heads were massive and wide compared to the two V8's con rod heads. The I6 had a main bearing on each side of every connecting rod attached to a crankshaft con rod journal. On the V8 crankshaft each one of its con rod journals has to support the twisting shearing force of two opposite forces created by a piston in each cylinder bank. The crankshaft main bearings were on each side of a crankshaft journal containing two con rod heads. The I6 block has much stronger bottom end components and configuration. That 5.9 litre B-series Cummins has been used in trucks, farm machinery, tug boats and other industrial applications for decades. It is a hard knocking engine that takes a lot of abuse, because it is built sturdy. It weights more than the V8s. In some motor homes the same 5.9 litre B-series engine is producing 660 ft lbs of torque.

Now the torque issue explained by me below is just my logic and not necessarily fact. The Cummins I6 has a much longer stroke than either of the V8 diesels from Ford or GM. The Duramax has a shorter stroke than the Power Stroke. A longer stroke requires a longer crankshaft throw; therefore, more leverage is available to produce more torque at low engine speed. That is why the Cummins HO produces 555 ft lbs of torque starts at 1400 rpms and continues at that same rate until 2800 rpm where it looses about 5 ft lbs out to 2900 rpm, and then drops off rapidly. That long stroke makes Cummins no match at high rpms with the V8s and their shorter strokes, but the V8s are no match with the Cummins' higher torque from idle up to 1800 rpm for Duramax and 2200 rpm for the Power Stroke. The shorter stroke is why the V8 diesels can reach such high engine speeds but have poorer low engine speed torque. Duramax is governed (fuel shut off) at 3200 rpm. If I was hauling light loads on level terrain, wasn't bothered about fuel consumption and was in a hurry, then I would choose a V8 diesel to fly down the turnpike. On the other hand, if I was loaded to the limit in mountainous terrain, wanted the maximum fuel economy per trip and was not in a hurry I would choose the I6.

By-the-way, I drove in Canada and the USA from 1990 to about 1998 and every engine in every highway tractor I drove had an I6 block except for one. A Peterbuilt I drove regularly from Edmonton through the mountains to Northern California had an 8V92 screaming Jimmy in it. That two-cycle V8 woud get tired when it saw a slight grade if I did not keep the engine speed over 3000 rpm. The I6 engines lugged over the crest of many steep grades at 1100 rpm. A Mack engine I pulled with could get over a crest dropping to 900 rpm for a short time without me having to down shift by dropping a couple or three gears lower due to the ground speed decreasing rapidly. I6 engines are definitely made to do heavy duty work.

What I consider heavy loads for a pickup to pull is as follows:
In the early 1970s with my 1969 360 CID Ford heavy duty 3/4 ton I pulled a 8 foot wide 24 foot long tri-axle goose neck trailer. A couple of summers I made a couple dozen trips hauling around 400 bales of hay on a load that amounted to around 12 tons. The truck had farm license plates and the 70 mile trips one way did not pass any government weigh scales. There were no hills to pull and I drove much of the way in third gear. The load was so heavy I would park in the hay field while the farmer loaded me with his tractor and then he would pull my unit out of the soft field onto the hard road allowance. The truck did not have enough power to move the trailer in the field. When I left the forage farm west of Edmonton, within five miles I had to enter the four lane highway which was a couple of feet higher than the gravel road. I would not bother stopping at the stop sign and had no problem traveling about 25 miles to Edmonton, then about 20 miles across the city and another 25 miles east of the city to a horse stable. If a fast approaching vehicle on the highway would cause me to have to come to a stop at the stop sign I could not move forward as the clutch pressure plate would slip with a loud bang. I would have to back down the ramp for a hundred yards onto level road before the truck could pull the load for another try at entering the highway. That is just one of the heavy type loads I pulled with that 1969 Ford. I eventually broke an oil control ring on one of the engine's pistons.

My 1976 Ford did a lot lighter work and went a lot less miles before the engine gave out. I junked the truck with 75,000 miles on the odometer because the body was rusted out so badly. The engine was not worth replacing. I have pulled some with other peoples' diesels in the last few years with favorable power especially with the Cummins. A fellow I drove for has a 1996 Dodge diesel pickup that he loads a pallet of paving stones in the box and pulls a trailer with it loaded with equipment and a skid steer loader. The Cummins engine is still running fine but the pickup frame is taking a beating. Last winter he bought a GMC two ton truck with an inline four cylinder diesel engine to replace the Dodge before its frame gave out completely. That Cummins engine is too much engine for the truck and now they have high output engines in the Dodge pickups. :confused

 

If you take a look at their new frames they are a lot stronger than they used to be. But I can't say mine is weak for I have not had problems with my truck at all. ever hauling well over its limits.

 

The stroke theory is very close. In the tow offs the duramax is last. Shorter stroke makes it fast. But it dont pull as well.

The 6.0 is fully capable of making peak torque at 1400 rpm. But for some reason it doesnt make peak until 2000 rpm in the ford application. I believe they did this to incease the hp. Because with peak torque at 1400 rpm The highest rating offered is 230hp. You arent going to win a hp war at 230 hp. When entry level is 300. So they moved the entire torque band up 600 rpm. The vt365 is governed at 2800 rpm. It is down to 464 lb ft at 2600 rpm even tho its rated at 620 peak. It cant hold its torque band too long. So You move the whole thing over 600 rpm. And you have the highest hp diesel on the market. You realise this thing makes more hp than a 3126e cat. And the cat makes 860 lb ft of torque. I thought moving the rpms up like that might be bad. But for the autos it seems its ok. But the owners of the stick shifts say its a bit doggy before 1800 rpm. Ford claims 500 lb ft at 1500 rpm. But it doesnt seem likely. I think this engine will love an auto. And with the kick butt new 5 speed its an easy choice.

 

If the frames were insufficient. We would be hearing about it from the high hp crowd because they are developing frame pretzling amounts of torque. In the very frame your discussing. The sled pullers would definitely be replacing em every run. Ive only read of one frame failure and it was on an 80s suburban.

 

You may want to review your statement. I own an 03 6.0. I also own a 93 chev 3500 6.5 turbo diesel that was new in 96 under warranty. It has 190 hp and 385 lbs of torque. That's it baby. I hoped it was more but 300!!!! no way never did. That's the second post I've seen today with guys claiming massive hp from old technology diesels. The 7.3 right up to 12/31/02 only has 240 hp and 530 lbs of torque. And for the record, the 6.2 chev diesel was an absolute tragedy and ruined GM for some time because of what a failure it was. Worse than a gas engine in every way imaginable. It went bye bye and the 6.5 was much much better but doesn't even compare to duramax, 2nd gen cummins, 7.3 or 6.0 powerstrokes. 3rd gen cummins has 305 hp and 555 lbs torque. Their 2nd gen was far less.

 

The torque values are the twisting force readings taken at the flywheel end of the engine crankshaft. The 6.0 PSD has a shorter stroke than a 5.9 Cummins High Output; therefore, with the same quantity of diesel fuel supplied to both the V8 and I6 it would result in the Cummins producing more foot-pounds of torque from an identical alloted amount of burning fuel. The chemical energy released in the burning fuel in the cylinder produces a mechanical force on the top of the piston. Thus the fuel is converted into mechanical energy and rotates the crankshaft resulting in a twisting force (torque). It stands to reason that in the case of simple levers and when their resultant mechanical advantage is generated that an output force is increased at the loss of speed when there is an increased lever length. Now, the stroke and resultant crankshaft throw lenght is increased poportionally with increased piston travel in the cylinder. The longer the crankshaft throws the greater the leverage or mechanical advantage in an engine with the cylinder bore smaller than the stroke. That is why the Cummins inline engine can produce maximum torque starting at a low 1400 rpm. For the Power Stroke to produce maximum torque at 1400 rpm its volumetric efficency would be very low and much fuel would be wasted to produce that low end torque. If the 6.0 PSD had a longer stroke it could not rev as high, and change engine rpm as quickly like a gas V8 engine. Cummins has a wide maximum torque band of 1500 rpms while 6.0 PSD has a maximum torque band of not over 200 rpms. The 6.0 PSD's rising torque before and after maximum torque is still at high enough values to be useful. Cummins has the advantage that their maximum torque is available soon enough to provide initial low engine rpm grunt for those vehicles with manual transmissions, and it does not start to drop until the engine is reaching 2900 rpms where the gear ratios are set to attain enough vehicle velocity to break the speed limits. We are brain washed to believe that V-type engines are better than inline engines when it comes to reliable efficient preformace in truck work engines.

 

All good reading above - can't argue with very much of it...

Fact is, EPA and other emmissions/tree-hugger legislation is forcing diesels further into computer control and higher RPM as means of reducing air pollution - in doing so, some elements that have long been a diesels strong point are being sacrificed - economy in heavy use and steep grades is down due to the higher RPMs required to stay up in the sweet spot of the power band - and engine longevity has to suffer as rotating mass must spin faster - the newest Cummins is "blessed" with the same "advances" in technology and computer control as Ford and GM - you can't escape it, and that is why I quickly bought an '02 Dodge - still lots of computers, but not as bad as the latest and coming stuff!

As far as which engine is "best" - well it's hard to beat the durability and long life of the Cummins (that's undoubtedly one reason even Ford offers the same Cummins I have in my Dodge in their 650 class Ford trucks) - and the REST of the truck is no slouch, but neither is the Ford, and the Ford offers more body variations. All the popular diesels can be increased in power - the Cummins clearly tolerates those upgrades better due to its extremely heavy construction - but a sane person can only safely use just so much power. All the diesels are sturdy enough to outlive 99% of their owners, or at least last FAR longer than the original owner will keep it before trading it in - so for most, longevity really isn't a meaningful issue.

I like my '02 Dodge 2500 immensely - but my feelings wouldn't be hurt to be driving a Ford either - I did it for lots more years than I have with the Dodge - they're all great trucks in my opinion!

 

Gary. you should get you COMP reprogramed for the Drag COMP. I drove a truck with one and it sure was nice. Nothing like hitting 3k and still pulling like you were at 2k. What clutch are you running? DON"T GET A CENTERFORCE in a gasser good in a diesel not so good

 

Well, I'm nearly 67 years old - my drag racing days are over, and the 6-speed dern sure is NOT built for fast shifting - a little old lady in a wheelchair could probably take me from a stoplite across an intersection...

My main interest for my truck is the power it provides down around 1500-2000 RPM - and it does just fine there in pulling our 5th wheel, which is the main duty for my truck...

Power up at 3000 RPM wouldn't do me a bit of good, and I think that's all the Drag Comp benefits...

 

But its fun to have the power up there when you need it.

 

The highest HP for the auto was 250 and the manual 275. I believe the torque was 525 lb/ft.