Threshold for Pain: How much can your diesel take?

[ShinerBock]

Recently Diesel World Mag made a few articles about how much each diesel can handle, but never ended up posting the Cummins numbers. Drivingline, an autoblog owned by Nitto, just finished up a similar series of how much each diesel has been known to handle and what their weak link is. This time, they posted all of the diesels.

***Please note: These power numbers are for engine only assuming all supporting mods(i.e. driveline, trans, fuel delivery) are capable of handling these power numbers. So yes, a stock trans will blow long before you hit these numbers.

What is also interesting, and contrary to what many here believe, is how well a diesel engine will hold up to high power numbers with proper tuning. With the advent of common rail and electronically controlled injectors, many novice tuners added too much fuel and timing down low causing too high of cylinder pressures which is very hard on engine internals. This caused many horror stories and many internet myths. Cutting back on fuel and timing at low rpms and increasing it as the rpms rise is much better for your engines internals as the articles state. And of course these are all rear wheel numbers which are generally about 15% less than crank numbers.

THRESHOLD FOR PAIN: POWER STROKE EDITION

7.3L Forged Rods (94.5-00)
Threshold for Pain: 600 HP (1,100-1,200 LB-FT)
Weak point: Rods

7.3L Powdered Metal Rods (01-03)
Threshold for Pain: 450 HP (850-900 LB-FT)
Weak Point: Rods

6.0L (03-07)
Threshold for Pain: 800 HP (1,300-1,400 LB-FT)
Weak Point: Rods

6.4L (07-10)
Threshold for Pain: 900+ HP (1,500-1,700 LB-FT)
Weak Point: Pistons

6.7L (11-Present)
Threshold for Pain: 700 HP (1,300-1,500 LB-FT)
Weak Point: Rods


THRESHOLD FOR PAIN: DURAMAX EDITION

LB7 (01-04)
Threshold for Pain: 550 to 600 HP (1,100-1,200 LB-FT)
Weak Point: Rods

LLY (04.5-05.5)
Threshold for Pain: 550 to 600 HP (1,100-1,200 LB-FT)
Weak Point: Rods

LBZ (06-07)
Threshold for Pain: 650 HP (1,200-1,300 LB-FT)
Weak Point: Pistons

LMM (07.5-10)
Threshold for Pain: 650 HP (1,200-1,300 LB-FT)
Weak Point: Pistons

LML (11-16)
Threshold for Pain: 700 HP (1,200-1,300 LB-FT)
Weak Point: Rods

L5P (17-Present)
Threshold for Pain: Not yet known since no one has been able to crack the ECU yet


THRESHOLD FOR PAIN: CUMMINS EDITION

5.9L Mechanical (89-02)
Threshold for Pain: 800 HP (1,400 to 1,600 lb-ft)
Weak Point: Rod Bolts
Threshold for Pain (Race Applications): 1,400 to 1,500 hp due to running at higher rpm's

5.9L Common Rail-6.7L (03-Present)
Threshold for Pain: 900 HP (1,800 lb-ft)
Weak Point: Rods

[ShinerBock]

Lessmore wrote:

ShinerBock wrote:

Lessmore wrote:

But for some guy driving around in a street truck...I do not know why.

I guess we are on opposite ends of the spectrum. You ask why someone would even add more power to their truck and I ask why someone would even care what someone else does to their own truck with their own money.

I mean, I can see me wondering why if I payed their vehicle payment and all, but I couldn't care less if some guy wants to buy an $80k Corvette just to drive on roads that he can never go over 75 mph on..... or a Jeep that they will never take off road...... or a truck to only haul groceries. I guess we will both be forever wonder why.

I don't think we are at opposite ends of the spectrum.

I was talking about why someone would take their street car/truck...and would soup up the engine to the absolute 'race' max, essentially rendering it barely streetable ....and where it's always on the edge of grenading.

I don't have an issue with someone building up their engine for more 'streetable' power, improving the cooling, brakes, suspension, associated powertrain (drive axles, drive shafts, transmission, etc.) to handle the extra punch of the engine.

In fact I have an old English motorcycle, a 750cc Scrambler. My plan if I ever get around to it, is to build up the engine with strong street performance parts, uprate the rear shocks, slap modern tires on it, uprate the brakes to discs from drums, etc.

I agree with you, I don't care how much someone spends on anything they have...to me, who cares...if they have the bucks...spend all they want. As you say...it's their money...not mine.

I think you are applying gas engine physics to a diesel. A diesel is regulated by fuel, not air, and therefore how much power it can make essentially depends on how much fuel you can add and how much air you utilize to burn it. If you don't need that much power then just don't add as much fuel. I can switch from a 390 rwhp tow tune to a 515 rwhp performance tune and back as I am driving down the highway.

Now you could make a diesel less streetable if you slapped a huge turbo on it that needs to be spooled a lot to make power, but most that do that are mostly using those trucks primarily for the track pushing out a lot more power. Most guys that are running 750-800 rwhp are not using as big of turbos and if they are then they are running a compound setup with a smaller pusher turbo. As long as you have supporting mods, a diesel can run in these ranges reliably for many miles if tuned correctly and driven right. By driven right I mean not towing heavy on an 800 rwhp and switching down to a tune that will keep your EGT's in check.

I agree with you that upping a gas engine to 750-800 rwhp range will make it less streetable, but a diesel not so much.

[RobertRyan]

Lessmore wrote:
Interesting piece. Not surprising though, every mechanical device has a destructo limit. I must add, that I don't for the life of me know why some guys just have to soup up their engines to the point of quick and eventual no return, given that diesel engines in modern HD pickups offer tremendous power in their stock form.

I can understand that those in the racing industry...would extend their engines as far or farther then they can handle...it's racing and that's a factor in winning...after all that's the bizness they're in.

But for some guy driving around in a street truck...I do not know why.

Fair point. If you want a long life do not veer from the factory tune.

[Lessmore]

Me Again wrote:

Lessmore wrote:


A year or so before...I had a '67 Camaro coupe, RS, red line tires, Muncie, 327 V8, rally wheels, Marina Blue...still think it was a very sharp looking car.

I had a debadged SS350 Camaro. Wish I still had it. It was a 10.25 to 1 compression ratio 295HP fun car with the Bose sound system and Muncie 4 speed and tall 3:23 gears if I remember correctly. Mono leaf rear springs were a short fall that was fixed in 68.

Very nice SS 350. First year of the 350 and first car with the Chevy 350 V8, I do believe. I think you're right that GM dumped that single mono leaf suspension for '68. It didn't take much to get that mono leaf rear suspension to hop around like jackhammer, in my experience. 😄

[Lessmore]

ShinerBock wrote:

Lessmore wrote:

But for some guy driving around in a street truck...I do not know why.

I guess we are on opposite ends of the spectrum. You ask why someone would even add more power to their truck and I ask why someone would even care what someone else does to their own truck with their own money.

I mean, I can see me wondering why if I payed their vehicle payment and all, but I couldn't care less if some guy wants to buy an $80k Corvette just to drive on roads that he can never go over 75 mph on..... or a Jeep that they will never take off road...... or a truck to only haul groceries. I guess we will both be forever wonder why.

I don't think we are at opposite ends of the spectrum.

I was talking about why someone would take their street car/truck...and would soup up the engine to the absolute 'race' max, essentially rendering it barely streetable ....and where it's always on the edge of grenading.

I don't have an issue with someone building up their engine for more 'streetable' power, improving the cooling, brakes, suspension, associated powertrain (drive axles, drive shafts, transmission, etc.) to handle the extra punch of the engine.

In fact I have an old English motorcycle, a 750cc Scrambler. My plan if I ever get around to it, is to build up the engine with strong street performance parts, uprate the rear shocks, slap modern tires on it, uprate the brakes to discs from drums, etc.

I agree with you, I don't care how much someone spends on anything they have...to me, who cares...if they have the bucks...spend all they want. As you say...it's their money...not mine.

[Me_Again]

Lessmore wrote:


A year or so before...I had a '67 Camaro coupe, RS, red line tires, Muncie, 327 V8, rally wheels, Marina Blue...still think it was a very sharp looking car.

I had a debadged SS350 Camaro. Wish I still had it. It was a 10.25 to 1 compression ratio 295HP fun car with the Bose sound system and Muncie 4 speed and tall 3:23 gears if I remember correctly. Mono leaf rear springs were a short fall that was fixed in 68.

[4x4ord]

I think it is incredible as well that people feel it is worth the time and expense to soup up a diesel truck so it can keep up to a Honda civic.

[ShinerBock]

Lessmore wrote:

But for some guy driving around in a street truck...I do not know why.

I guess we are on opposite ends of the spectrum. You ask why someone would even add more power to their truck and I ask why someone would even care what someone else does to their own truck with their own money.

I mean, I can see me wondering why if I payed their vehicle payment and all, but I couldn't care less if some guy wants to buy an $80k Corvette just to drive on roads that he can never go over 75 mph on..... or a Jeep that they will never take off road...... or a truck to only haul groceries. I guess we will both be forever wonder why.

[Lessmore]

FishOnOne wrote:

Lessmore wrote:
Interesting piece. Not surprising though, every mechanical device has a destructo limit. I must add, that I don't for the life of me know why some guys just have to soup up their engines to the point of quick and eventual no return, given that diesel engines in modern HD pickups offer tremendous power in their stock form.

I can understand that those in the racing industry...would extend their engines as far or farther then they can handle...it's racing and that's a factor in winning...after all that's the bizness they're in.

But for some guy driving around in a street truck...I do not know why.

In 1970 you could order a Chevelle with a basic 350 4blr carb or you could order a Chevelle SS with a LS6 454. I owned the later and it was a pure joy to drive. It's what floats your boat.... And mine was HP with good looks to top it off. :B

You could order a '70 Chevelle with a straight six too. That 4 barrel 350 with 300 hp moved out nicely. A buddy back then had a '70 Chevelle SS454 with the LS6..450 hp, 4 speed Muncie. I got the occasional ride in it...twice I think...both times in bumper to bumper traffic...he never got it out of first...dang it !! 😞

A year or so before...I had a '67 Camaro coupe, RS, red line tires, Muncie, 327 V8, rally wheels, Marina Blue...still think it was a very sharp looking car.

[ShinerBock]

FishOnOne wrote:
I find it hard to believe the weak point is not the head gasket failures on two of the engines from the entire list.

Head hasket failures can generally be fixed through reproggramming the fuel/turbo mapping and is not necessarily a weak link in hard parts.

Take the 6.7L Cummins for example. When it first came out it was prone to blow head gaskets more than the previous 5.9L. The 6.7L's longer stroke and quick spooling variable geometry turbo added more low rpm cylinder pressure(torque) and the first thing to give was the head gasket. Add to the fact that the factory ECM's were not as good as they are now which made the fuel maps have timing spikes much like the first fuel map in this LINK.

In order to combat this, you have to alter the fuel timing and boost pressure at these rpms to decrease cylinder pressure( the new ECM's on the 2013+ trucks also helped with better mapping ability). Once this was done then head gasket failures become a thing of the past until you start getting into the really high horsepower which at that point head studs will be needed. I can run my 500 rwhp tune all day long without the need for head studs or head gasket failure.

[ksss]

ShinerBock wrote:

ksss wrote:

ShinerBock wrote:

TakingThe5th wrote:
I'm pleasantly surprised that the Ford 6.0 did so well. I've been told that it's one of the strongest Ford blocks once all the quirks are worked out. So far I've been very pleased with my bulletproofed 6.0.

While the 6.0L did have some issues, some of these issues in the aftermarket world should have been attributed to bad tuning rather than the 6.0L itself. Being one of the first Powerstoke engines that could be tuned electronically, novice tuners would crank up the timing and fuel delivery at lower rpms causing very high cylinder pressures. This would cause head bolts to stretch and gaskets to blow. The same thing happened when the Cummins 6.7L first came out blowing head gaskets left and right.

As tuning software became more sophisticated and tuners became more knowledgeable, these problems became a thing of the past. However, many on the internet don't know this and still contribute these old issues to anything tuned even though they don't even relate. Heck, even the software mapping the OE's used back then has advanced giving them better and more smoother fuel mapping. The fuel mapping on the old ECM's used for the 6.7L Cummins when it first came out are much different with less parameters available than the ECM's used on the current engines. More parameters means smoother fuel mapping and greater ability to control low rpm cylinder pressures.

Actually when you read the entire lawsuit between Ford and IH you see that the 6.0 failed on its own without the help of the tuners. They may have made some issues worse but the 6.0 was a disaster from inception.

I think you read what I stated incorrectly. I did say that the 6.0L had issues. However, on the aftermarket side of things many of the tuners attributed their bad tuning to problems with 6.0L instead of their inexperienced bad tuning. Many of the good tuners were able to make even more power reliably.

Roger, my mistake.

[FishOnOne]

Lessmore wrote:
Interesting piece. Not surprising though, every mechanical device has a destructo limit. I must add, that I don't for the life of me know why some guys just have to soup up their engines to the point of quick and eventual no return, given that diesel engines in modern HD pickups offer tremendous power in their stock form.

I can understand that those in the racing industry...would extend their engines as far or farther then they can handle...it's racing and that's a factor in winning...after all that's the bizness they're in.

But for some guy driving around in a street truck...I do not know why.

In 1970 you could order a Chevelle with a basic 350 4blr carb or you could order a Chevelle SS with a LS6 454. I owned the later and it was a pure joy to drive. It's what floats your boat.... And mine was HP with good looks to top it off. :B

[FishOnOne]

I find it hard to believe the weak point is not the head gasket failures on two of the engines from the entire list.

[Lessmore]

Interesting piece. Not surprising though, every mechanical device has a destructo limit. I must add, that I don't for the life of me know why some guys just have to soup up their engines to the point of quick and eventual no return, given that diesel engines in modern HD pickups offer tremendous power in their stock form.

I can understand that those in the racing industry...would extend their engines as far or farther then they can handle...it's racing and that's a factor in winning...after all that's the bizness they're in.

But for some guy driving around in a street truck...I do not know why.

[ShinerBock]

ksss wrote:

ShinerBock wrote:

TakingThe5th wrote:
I'm pleasantly surprised that the Ford 6.0 did so well. I've been told that it's one of the strongest Ford blocks once all the quirks are worked out. So far I've been very pleased with my bulletproofed 6.0.

While the 6.0L did have some issues, some of these issues in the aftermarket world should have been attributed to bad tuning rather than the 6.0L itself. Being one of the first Powerstoke engines that could be tuned electronically, novice tuners would crank up the timing and fuel delivery at lower rpms causing very high cylinder pressures. This would cause head bolts to stretch and gaskets to blow. The same thing happened when the Cummins 6.7L first came out blowing head gaskets left and right.

As tuning software became more sophisticated and tuners became more knowledgeable, these problems became a thing of the past. However, many on the internet don't know this and still contribute these old issues to anything tuned even though they don't even relate. Heck, even the software mapping the OE's used back then has advanced giving them better and more smoother fuel mapping. The fuel mapping on the old ECM's used for the 6.7L Cummins when it first came out are much different with less parameters available than the ECM's used on the current engines. More parameters means smoother fuel mapping and greater ability to control low rpm cylinder pressures.

Actually when you read the entire lawsuit between Ford and IH you see that the 6.0 failed on its own without the help of the tuners. They may have made some issues worse but the 6.0 was a disaster from inception.

I think you read what I stated incorrectly. I did say that the 6.0L had issues. However, on the aftermarket side of things many of the tuners attributed their bad tuning to problems with 6.0L instead of their inexperienced bad tuning. Many of the good tuners were able to make even more power reliably.

[ksss]

ShinerBock wrote:

TakingThe5th wrote:
I'm pleasantly surprised that the Ford 6.0 did so well. I've been told that it's one of the strongest Ford blocks once all the quirks are worked out. So far I've been very pleased with my bulletproofed 6.0.

While the 6.0L did have some issues, some of these issues in the aftermarket world should have been attributed to bad tuning rather than the 6.0L itself. Being one of the first Powerstoke engines that could be tuned electronically, novice tuners would crank up the timing and fuel delivery at lower rpms causing very high cylinder pressures. This would cause head bolts to stretch and gaskets to blow. The same thing happened when the Cummins 6.7L first came out blowing head gaskets left and right.

As tuning software became more sophisticated and tuners became more knowledgeable, these problems became a thing of the past. However, many on the internet don't know this and still contribute these old issues to anything tuned even though they don't even relate. Heck, even the software mapping the OE's used back then has advanced giving them better and more smoother fuel mapping. The fuel mapping on the old ECM's used for the 6.7L Cummins when it first came out are much different with less parameters available than the ECM's used on the current engines. More parameters means smoother fuel mapping and greater ability to control low rpm cylinder pressures.

Actually when you read the entire lawsuit between Ford and IH you see that the 6.0 failed on its own without the help of the tuners. They may have made some issues worse but the 6.0 was a disaster from inception.