Ford 6.7L 1050 ft lbs TQ at 1,600 rpm, 475 HP at 2,800 rpm
Ford 6.7L checks in at 1,050 ft lbs TQ at 1,600 rpm, 475 HP at 2,800 rpm
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166 Replies
ShinerBock wrote:
What is the extra step?
The J2723 that GM uses still uses either J1995 or J1349 as their dyno standard, but has an extra validation step.4x4ord wrote:
If our C15 Cat makes 550 horsepower with about 40 psi of boost at 1400 rpm it would seem likely that a 6.7 spinning 2800 rpm would require similar boost to have similar airflow per hp if it were making 475 hp. Is there some reason to think that 38-40 psi should be unobtainable out of a stock 6.7 turbo?
That depends on the efficiency of the turbo which is effected by many things. I don't have a compressor map of a the new PSD turbo to be able say yes or no. It may be able to make 40 psi of boost, but it may be over spinning to do it. Just because two turbos are able to create 40 psi of boost, does not mean they have the same amount of air flow at 40 psi. There is a point where the blade of the turbo is spinning too fast and it is chomping through the air which reduces air flow. A larger turbo will generally have more air flow at 40 psi than a smaller one at 40 psi.
There is also the CFM of the exhaust as well. The big trucks have much larger exhaust and emissions equipment allowing for less restrictions in exhaust flow.- If our C15 Cat makes 550 horsepower with about 40 psi of boost at 1400 rpm it would seem likely that a 6.7 spinning 2800 rpm would require similar boost to have similar airflow per hp if it were making 475 hp. Is there some reason to think that 38-40 psi should be unobtainable out of a stock 6.7 turbo?
4x4ord wrote:
We own some off road but emission compliant equipment powered by Cat C13s. In our applications the engines are factory rated at 543 Hp. These engines work at over 500 hp all day long. We have a highway tractor with a C15 that produces 550 HP and is designed to produce full power and cruise at 1450 rpm. I think the C15s were available at HP ratings of up to 625 hp. When you take into account the higher rpm of the Powerstroke and compare it to a Cat engine it certainly is within reason to think it could sustain its rated power over a long pull. I wonder what the new Powerstroke will be rated at in the new F750s?
There are different emissions requirements for off road and on road engines. So it is emissions compliant, but for less restrictive off road standards. If it is like most nonroad engine from other manufacturers, it likely has a different turbo than the onroad engines.
And again, your calculations do not include air flow/boost of the turbo and how much it increases its effective displacement. You can't have the same size turbo that is on a C13 and put it on a 6.7L power stroke. Well, you probably could, but it would have a very hard time getting that thing to spool at a reasonable rpm which would make it dang near impossible to drive or tow with especially at higher elevations.Huntindog wrote:
4x4ord wrote:
rjstractor wrote:
ShinerBock wrote:
Yeah. If this is sustained power, then it should easily mop the floor with the other two.
Advertisement laws do not require a manufacturer to advertise sustained power numbers. All they have to so is reach a certain power level in a short burst in accordance to SAE procedures which is at low altitudes. Some manufacturers factor in sustained power, and some don't. I wish sustained power numbers was a requirement for the J2807 tow standard meaning you can only advertise the lowest power an engine makes performing the up hill test. I have a feeling that some of the power ratings would drop considerably if it were.
Agreed. I'm not exactly sure how commercial truck engines are rated, but I have a feeling that the early 2000s Freightliner I occasionally drive will put out its rated 515 hp for hours at a time. I'd love to run it up the Ike pulling 60K combined against the new Ford at 40K. I think I know which one would do better...
I think you're right that a 515 hp engine in a heavy duty truck can put out peak power all day long. These pick up truck engines may also be capable of running at peak power all day long. It is possible that the reason they don't make advertised hp on the Ike run is due to the extreme elevation. I wonder if the turbos on the pick up truck engines are capable of pumping enough air at 10,000 feet elevation to allow full fuel to be delivered? Maybe fuel is restricted under those conditions to prevent excessive exhaust gas temperatures?
What it boils down to is the differences in the testing to arrive at the "advertised" HP/TQ numbers. There ARE different parameters. Some require a longer duration of the rated power than others.... This is why some manufacturers always have the highest ratings, but not always the best performance. They likely gain some sales from the high advertised numbers from those that do not look into just how/if that equates to the best performance
I do believe that the HD trucks will be vastly superior in that regard... But I also believe that if they are pushed hard enough they too will reduce power. It just doesn't make sense to let a motor hurt itself when you can prevent it with todays computerized ECMs.
The testing is the same per SAE standards. There are slight difference between the SAE J1349 that Ford uses and the J1995 that Cummins uses. The J2723 that GM uses still uses either J1995 or J1349 as their dyno standard, but has an extra validation step.
There are a lot of tolerance and correction factors that can be fudged on these tests. For example, there are plus or minus factors in the calibration of the equipment used and even the temp. A company can set their test to have the best possible scenario to be able to post the highest numbers. Sure it is sneaky, but it is still legit per SAE standards.
The other thing is that these test are short burst runs and not sustained power ratings as I stated before. The SAE and advertisement law requirements do not force manufacturers to advertise power ratings at their max GCWR up X grade in Y temp at Z altitude for a set amount of time. This is up to the manufacturers discretion just as Cummins does for many of their engines stating that the power level is good up to X altitude(usually 10k ft) in their engine spec sheets. All it states is that they cannot advertise more than what the SAE test and they have to point out the type of fuel used if it is anything other than standard fuel.ShinerBock wrote:
4x4ord wrote:
ShinerBock wrote:
As far as the big diesel versus smaller diesel making the same power, of course the bigger diesel will be able to sustain those power numbers better because it is able to move more air for the amount of fuel needed to make 515hp. Although, 515 hp is about 450 at the wheels which is my level 2 tune. When I was tuned, but had my emissions system, I could barely sustain that power level towing 5k under high load. When I was tuned and deleted, but had the stock turbo, I could maybe tow about 8k-10k sustained at that power level. Now that I have a larger turbo with more air flow, I can easily tow my 14k trailer sustained at that power level.
The industrial diesels move a little more air per HP but when you actually do the math the numbers might surprise you.
A Cat C13 can be speced to produce 520 HP (and we have Cat C13s in some of our equipment where they produce up to 543 HP) The C13s produce peak HP from 1800 rpm to 2100. So it is designed to run all day long delivering 520 HP @ 1800 rpm.
The C13 has a displacement of 12.5 liters. So at 1800 rpm it can produce 520/(1800 x 12.5) = .023 HP/rpm liter. If the Powerstroke were tuned to produce .023 HP/rpm liter it would make 431 HP (.023 x 2800 x 6.7). So although the industrial engine at 1800 rpm produces less power per litre displacement it doesn't pump a whole lot more air per HP produced when compared to the Powerstroke at 2800 rpm.
A C13 did not produce 520 hp. At least not on any stock on road truck. The max the C13 produced was 430 hp. The C15 was the one that created 520 hp and more. You are also not counting for air flow from the turbo (since it changes and engines effective displacement) and compression ratio.
We own some off road but emission compliant equipment powered by Cat C13s. In our applications the engines are factory rated at 543 Hp. These engines work at over 500 hp all day long. We have a highway tractor with a C15 that produces 550 HP and is designed to produce full power and cruise at 1450 rpm. I think the C15s were available at HP ratings of up to 625 hp. When you take into account the higher rpm of the Powerstroke and compare it to a Cat engine it certainly is within reason to think it could sustain its rated power over a long pull. I wonder what the new Powerstroke will be rated at in the new F750s?4x4ord wrote:
rjstractor wrote:
ShinerBock wrote:
Yeah. If this is sustained power, then it should easily mop the floor with the other two.
Advertisement laws do not require a manufacturer to advertise sustained power numbers. All they have to so is reach a certain power level in a short burst in accordance to SAE procedures which is at low altitudes. Some manufacturers factor in sustained power, and some don't. I wish sustained power numbers was a requirement for the J2807 tow standard meaning you can only advertise the lowest power an engine makes performing the up hill test. I have a feeling that some of the power ratings would drop considerably if it were.
Agreed. I'm not exactly sure how commercial truck engines are rated, but I have a feeling that the early 2000s Freightliner I occasionally drive will put out its rated 515 hp for hours at a time. I'd love to run it up the Ike pulling 60K combined against the new Ford at 40K. I think I know which one would do better...
I think you're right that a 515 hp engine in a heavy duty truck can put out peak power all day long. These pick up truck engines may also be capable of running at peak power all day long. It is possible that the reason they don't make advertised hp on the Ike run is due to the extreme elevation. I wonder if the turbos on the pick up truck engines are capable of pumping enough air at 10,000 feet elevation to allow full fuel to be delivered? Maybe fuel is restricted under those conditions to prevent excessive exhaust gas temperatures?
What it boils down to is the differences in the testing to arrive at the "advertised" HP/TQ numbers. There ARE different parameters. Some require a longer duration of the rated power than others.... This is why some manufacturers always have the highest ratings, but not always the best performance. They likely gain some sales from the high advertised numbers from those that do not look into just how/if that equates to the best performance
I do believe that the HD trucks will be vastly superior in that regard... But I also believe that if they are pushed hard enough they too will reduce power. It just doesn't make sense to let a motor hurt itself when you can prevent it with todays computerized ECMs.4x4ord wrote:
ShinerBock wrote:
As far as the big diesel versus smaller diesel making the same power, of course the bigger diesel will be able to sustain those power numbers better because it is able to move more air for the amount of fuel needed to make 515hp. Although, 515 hp is about 450 at the wheels which is my level 2 tune. When I was tuned, but had my emissions system, I could barely sustain that power level towing 5k under high load. When I was tuned and deleted, but had the stock turbo, I could maybe tow about 8k-10k sustained at that power level. Now that I have a larger turbo with more air flow, I can easily tow my 14k trailer sustained at that power level.
The industrial diesels move a little more air per HP but when you actually do the math the numbers might surprise you.
A Cat C13 can be speced to produce 520 HP (and we have Cat C13s in some of our equipment where they produce up to 543 HP) The C13s produce peak HP from 1800 rpm to 2100. So it is designed to run all day long delivering 520 HP @ 1800 rpm.
The C13 has a displacement of 12.5 liters. So at 1800 rpm it can produce 520/(1800 x 12.5) = .023 HP/rpm liter. If the Powerstroke were tuned to produce .023 HP/rpm liter it would make 431 HP (.023 x 2800 x 6.7). So although the industrial engine at 1800 rpm produces less power per litre displacement it doesn't pump a whole lot more air per HP produced when compared to the Powerstroke at 2800 rpm.
A C13 did not produce 520 hp. At least not on any stock on road truck. The max the C13 produced was 430 hp. The C15 was the one that created 520 hp and more. You are also not counting for air flow from the turbo (since it changes and engines effective displacement) and compression ratio.4x4ord wrote:
I think you're right that a 515 hp engine in a heavy duty truck cn put out peak power all day long. These pick up truck engines may also be capable of running at peak power all day long. It is possible that the reason they don't make advertised hp on the Ike run is due to the extreme elevation. I wonder if the turbos on the pick up truck engines are capable of pumping enough air at 10,000 feet elevation to allow full fuel to be delivered? Maybe fuel is restricted under those conditions to prevent excessive exhaust gas temperatures?
Big trucks do lose a bit of power at 10,000' elevation. Even if the turbo has excess boost capacity, it'll be running at a higher pressure ratio to attain the same manifold boost. This means high intake air temperature.
The fan (40 - 50hp) would either run more to move air across the intercooler (much harder in thin air), or run the same, but with hotter air (less O2) reaching the cylinders. Both saps power.
I also doubt the PS or any other pickup engine can sustain full power up the IKE.4x4ord wrote:
The industrial diesels move a little more air per HP but when you actually do the math the numbers might surprise you.
A Cat C13 can be speced to produce 520 HP (and we have Cat C13s in some of our equipment where they produce up to 543 HP) The C13s produce peak HP from 1800 rpm to 2100. So it is designed to run all day long delivering 520 HP @ 1800 rpm.
The C13 has a displacement of 12.5 liters. So at 1800 rpm it can produce 520/(1800 x 12.5) = .023 HP/rpm liter. If the Powerstroke were tuned to produce .023 HP/rpm liter it would make 431 HP (.023 x 2800 x 6.7). So although the industrial engine at 1800 rpm produces less power per litre displacement it doesn't pump a whole lot more air per HP produced when compared to the Powerstroke at 2800 rpm.
You'd also have to factor in boost and volumetric effciency with those calculations. By your math, I'd guess the PS has higher boost as it makes more hp/rpm/L. Plus at high rpm the VE is usually lower, so it needs even more boost to overcome that.
