Rated engine power
How do manufacturers, presently, determine how to rate their engine's crankshaft horsepower? Is the cooling fan engaged and drawing air? Alternator charging? Power steering pump and A/C installed and working?
Forum Discussion
rjstractor wrote:
4x4ord wrote:
^^^I find that interesting. Do these apps ask for the vehicle weight then time how long it takes for the vehicle to coast in neutral as well as time how long it takes to accelerate?
I'm not sure. I imagine it's a lot more sophisticated than that, using the phone's accelerometer and GPS, as well as data received from the vehicle's OBD2 port. Vehicle weight is part of setup I would think.
I think you're right it probably uses weight and acceleration along with a generic coefficient of drag to determine hp. Unless it involves coasting in nuetral on level ground it is just kind of a best guess. I wonder if these apps you are talking about will draw a torque curve and brake specific fuel consumption map?4x4ord wrote:
^^^I find that interesting. Do these apps ask for the vehicle weight then time how long it takes for the vehicle to coast in neutral as well as time how long it takes to accelerate?
I'm not sure. I imagine it's a lot more sophisticated than that, using the phone's accelerometer and GPS, as well as data received from the vehicle's OBD2 port. Vehicle weight is part of setup I would think.Super_Dave wrote:
I've been bothered by HP ratings being at essentially redline RPM or in a range that I would never ever be driving at. I would want to know max HP at my user range.
This confuses some into thinking their late model V6 minivan, or suv, with say 290 rated hp, is as capable as some older V8s they have owned. Problem is, that hp is achieved at 6500 rpm, which no one would tow at, continuously.
Jerry- I've been bothered by HP ratings being at essentially redline RPM or in a range that I would never ever be driving at. I would want to know max HP at my user range.
4x4ord wrote:
^^^I find that interesting. Do these apps ask for the vehicle weight then time how long it takes for the vehicle to coast in neutral as well as time how long it takes to accelerate?
My Torque app and CTS2 monitor does this. The Torque app requires extra info, but the CTS2 reads it from the ECM since it already monitors engine torque output.
My BMW also has a sports display as one of the displays on the nav screen that shows instant horsepower and torque readings. It is pretty **** accurate.Huntindog wrote:
ShinerBock wrote:
Huntindog wrote:
ShinerBock wrote:
Huntindog wrote:
I would not discount this requirement with "just".
"Certified power" just means that they had a third party SAE licenced person witness them do the J1349 or J1995 test.
If you want real figures that you can rely on..... It is a big deal. Those that do it seem to always perform better, in spite of having lower numbers.
Whenever a company is allowed to self test anything, they always come up with better results.
In my buisiness, I have seen janitorial companies self test the emissions of their equiptment.... Wanna guess how often they fail?
OSHA allows this... What a joke.
On the retail side, we self inspect food safety aspects of the buisiness... Same thing, good scores invariably result. Of course when the health dept shows up..... The truth shows up in their report.. So now we have a independant company show up to do unanounced suprise inspections, in addtion to our self inspections. The outside company is very tough, and our health dept scores have improved dramactically as a result.
This self dyno testing works the same way... It is human nature to want a good score.... It doesn't matter what is being measured. If we are allowed to do it ourselves, our score WILL be better.
No it is not a big deal unless you have some reason not to trust the brand you are buying from. If that is the case then I would question why you are even buying from them.
The certification is just a way for SAE to get more money. SAE sells licences to these certified witnesses (who can work for vehicle manufacturer) and forces the manufacturer to use these witnesses. Without these witnesses, SAE does not receive as much money.
This is all it takes to be a witness.
"Qualifications of a Witness
Witnesses for engine power and torque certification testing shall be registered with SAE. Witnesses shall be competent engineers who are experienced in engine testing and familiar with the requirements of the SAE J1349® and SAE J1995® standards. Witnesses registered by SAE shall meet one of the following criteria:
Prior registration as a witness for European homologation testing and a signed statement acknowledging that the individual has studied and understands the SAE procedures.
Documented and verified experience in engine testing with three recommendations from individuals who are registered witnesses themselves or whose technical training and experience establish them as competent to evaluate the individual's skills as a witness. In addition, a signed statement is required acknowledging that the individual to be registered has studied and understands the SAE J1349® and SAE J1995® testing procedures.
A Bachelors Degree in Engineering or equivalent plus 5 years of related engine testing experience and completion of an SAE-approved training course. Documented participation as an "apprentice witness" in at least three (3) SAE J1349® or SAE J1995® test procedures conducted by an SAE-certified witness who attests to the competency of that individual to conduct witness tests may be substituted for completion of an SAE-approved training course.
Other qualified individuals who are identified and appointed by the SAE Engine Power Test Code Committee. The witness will provide a signed statement acknowledging that the individual has studied and understands the relevant SAE test procedures."
It works the same way with manufacturers when they say a product has to pass a certain standard that they themselves create. The product has to pay the manufacturer to test their product to this standard.
I remember about a decade ago when Cat recommended that coolant for one of their engines had to pass a certain standard number that only their coolant had passed on a certain engine. They built special test equipment for this standard that cost tens of thousands of dollars and tore it down after their coolant passed the standard. This allowed them to sell only their coolant to those dumb idiots who only go by what the manufacturer recommends without any competition.
The other coolant companies had to pay Cat lots of money to rebuilt this test equipment in order to receive this test standard number. Ironically the other coolants passed the test without changing a thing, but they had to be tested per this standard in order to revive the number. Kind of smart on Cat's part because they made lots of money by eliminating competition for many years and forcing the competition to pay them in order to be competition.
Actually I do not trust the manufacturers that do not certify..... One manufacturer in particular has a bad habit of advertising numbers that are not backed up in the real world.
Another manufacturer that DOES certify always seems to do better than the higher rated competition.
Human nature being what it is.... Some will not admit this to keep from losing a debate.
I held the same view when SAE announced this new certification process long before this debate so it has nothing to do with that. Having worked for various engine and vehicles manufacturers, I just don't put any weight into the process especially since the certified witness is allowed to work for the very same manufacturer who is testing their engine. You can even set the test in a way to get the best numbers with the certification. You state this can happen WITH an SAE witness present.... What can happen when one isn't present? We already know from what has been happening.
I know some fanboys like to tout this certification as if it means something, but it just doesn't mean anything to me knowing what I know about the industry from working in it for so long. I can see others outside the industry who don't really know much about really what goes on behind the scenes might be ignorant enough to hold these certifications in high regard, but I don't based on my past experiences. To each their own.
I do not believe that a licensed SAE witness, would go the trouble and expense of becoming an SAE witness just to throw it away by allowing cheating (which is what you are insinuating).
At any rate, your take on it has not been backed up by what we have all seen over the last 19 years or so.
I believe they would no doubt. After all, they are only human and their employer or a manufacturer could offer them more money to do so. They are human and subject to greed just like everyone else. If a manufacturer is posting more horsepower than actual, they will be caught and would likely be sued just like some are being sued for posting higher fuel economy.
What I am also saying is that if you knew more about these test standards(which I posted early and highly recommend to take a look at) then you will see that a manufacturer can still load the best possible conditions to give them 20 or more extra horsepower even with a witness. Just about every condition in the standard has an allowable +/- even the calculated adjustments. This is likely what happen in the past with certain manufacturers who were posting much higher ratings. They never got sued because they were probably still within the standard, but loaded it up with the best scenario for all of the conditions.
So what is the point of an extra witness if a manufacturer can load up the numbers for the best possible scenario and still be legit even with them there? The witness isn't going to cry foul because it is still within the standard.- ^^^^ I found and downloaded one of the phone apps. The one I downloaded wants me to tell it my frontal area and estimate a value for the coefficient of drag. I think my procedure has the potential to obtain more accurate results. In my case the power used to overcome drag and rolling resistence is determined by recording the time required for the RV to slow from one speed to another while coasting in neutral.
4x4ord wrote:
If there is anyone interested in knowing their engine's peak crankshaft horsepower and you don't mind a bit of screwing around, you could provide me with the following data and I would be able to calculate it for you.
I would need an accurate combined weight of your truck and trailer.
You would need to know the speed your truck travels in the most straight through gear of your transmission at rated engine speed.
I would need a measurement of the time it takes on a level stretch of highway for your unit to slow from 2 mph over that travel speed at rated rpm to 2 mph slower while coasting in neutral.
I would need the time required to accelerate from 2 mph slower than rated travel speed to 2 mph faster.
(So for an f350 Powerstroke with 3.55 gears and 20 inch rims you yould would get going 75 mph and shift to neutral. Start your stop watch when the truck slows to 71 mph and stop it at 69 mph. Record that time value. Then select 4th gear and with the skinny pedal matted record the time required to accelerate on level ground from 69 mph back to 71 mph. To increase your accuracy it would be beneficial to perform these tests going one way on the road then turning around and performing them the opposite direction over the same stretch of road. Then average the results).
If the measurements taken are accurate the calculated hp will be very accurate as well.
There are smartphone apps that do the same thing, probably with much more precision and accuracy.- If there is anyone interested in knowing their engine's peak crankshaft horsepower and you don't mind a bit of screwing around, you could provide me with the following data and I would be able to calculate it for you.
I would need an accurate combined weight of your truck and trailer.
You would need to know the speed your truck travels in the most straight through gear of your transmission at rated engine speed.
I would need a measurement of the time it takes on a level stretch of highway for your unit to slow from 2 mph over that travel speed at rated rpm to 2 mph slower while coasting in neutral.
I would need the time required to accelerate from 2 mph slower than rated travel speed to 2 mph faster.
(So for an f350 Powerstroke with 3.55 gears and 20 inch rims you yould would get going 75 mph and shift to neutral. Start your stop watch when the truck slows to 71 mph and stop it at 69 mph. Record that time value. Then select 4th gear and with the skinny pedal matted record the time required to accelerate on level ground from 69 mph back to 71 mph. To increase your accuracy it would be beneficial to perform these tests going one way on the road then turning around and performing them the opposite direction over the same stretch of road. Then average the results).
If the measurements taken are accurate the calculated hp will be very accurate as well. ShinerBock wrote:
Huntindog wrote:
ShinerBock wrote:
Huntindog wrote:
I would not discount this requirement with "just".
"Certified power" just means that they had a third party SAE licenced person witness them do the J1349 or J1995 test.
If you want real figures that you can rely on..... It is a big deal. Those that do it seem to always perform better, in spite of having lower numbers.
Whenever a company is allowed to self test anything, they always come up with better results.
In my buisiness, I have seen janitorial companies self test the emissions of their equiptment.... Wanna guess how often they fail?
OSHA allows this... What a joke.
On the retail side, we self inspect food safety aspects of the buisiness... Same thing, good scores invariably result. Of course when the health dept shows up..... The truth shows up in their report.. So now we have a independant company show up to do unanounced suprise inspections, in addtion to our self inspections. The outside company is very tough, and our health dept scores have improved dramactically as a result.
This self dyno testing works the same way... It is human nature to want a good score.... It doesn't matter what is being measured. If we are allowed to do it ourselves, our score WILL be better.
No it is not a big deal unless you have some reason not to trust the brand you are buying from. If that is the case then I would question why you are even buying from them.
The certification is just a way for SAE to get more money. SAE sells licences to these certified witnesses (who can work for vehicle manufacturer) and forces the manufacturer to use these witnesses. Without these witnesses, SAE does not receive as much money.
This is all it takes to be a witness.
"Qualifications of a Witness
Witnesses for engine power and torque certification testing shall be registered with SAE. Witnesses shall be competent engineers who are experienced in engine testing and familiar with the requirements of the SAE J1349® and SAE J1995® standards. Witnesses registered by SAE shall meet one of the following criteria:
Prior registration as a witness for European homologation testing and a signed statement acknowledging that the individual has studied and understands the SAE procedures.
Documented and verified experience in engine testing with three recommendations from individuals who are registered witnesses themselves or whose technical training and experience establish them as competent to evaluate the individual's skills as a witness. In addition, a signed statement is required acknowledging that the individual to be registered has studied and understands the SAE J1349® and SAE J1995® testing procedures.
A Bachelors Degree in Engineering or equivalent plus 5 years of related engine testing experience and completion of an SAE-approved training course. Documented participation as an "apprentice witness" in at least three (3) SAE J1349® or SAE J1995® test procedures conducted by an SAE-certified witness who attests to the competency of that individual to conduct witness tests may be substituted for completion of an SAE-approved training course.
Other qualified individuals who are identified and appointed by the SAE Engine Power Test Code Committee. The witness will provide a signed statement acknowledging that the individual has studied and understands the relevant SAE test procedures."
It works the same way with manufacturers when they say a product has to pass a certain standard that they themselves create. The product has to pay the manufacturer to test their product to this standard.
I remember about a decade ago when Cat recommended that coolant for one of their engines had to pass a certain standard number that only their coolant had passed on a certain engine. They built special test equipment for this standard that cost tens of thousands of dollars and tore it down after their coolant passed the standard. This allowed them to sell only their coolant to those dumb idiots who only go by what the manufacturer recommends without any competition.
The other coolant companies had to pay Cat lots of money to rebuilt this test equipment in order to receive this test standard number. Ironically the other coolants passed the test without changing a thing, but they had to be tested per this standard in order to revive the number. Kind of smart on Cat's part because they made lots of money by eliminating competition for many years and forcing the competition to pay them in order to be competition.
Actually I do not trust the manufacturers that do not certify..... One manufacturer in particular has a bad habit of advertising numbers that are not backed up in the real world.
Another manufacturer that DOES certify always seems to do better than the higher rated competition.
Human nature being what it is.... Some will not admit this to keep from losing a debate.
I held the same view when SAE announced this new certification process long before this debate so it has nothing to do with that. Having worked for various engine and vehicles manufacturers, I just don't put any weight into the process especially since the certified witness is allowed to work for the very same manufacturer who is testing their engine. You can even set the test in a way to get the best numbers with the certification. You state this can happen WITH an SAE witness present.... What can happen when one isn't present? We already know from what has been happening.
I know some fanboys like to tout this certification as if it means something, but it just doesn't mean anything to me knowing what I know about the industry from working in it for so long. I can see others outside the industry who don't really know much about really what goes on behind the scenes might be ignorant enough to hold these certifications in high regard, but I don't based on my past experiences. To each their own.
I do not believe that a licensed SAE witness, would go the trouble and expense of becoming an SAE witness just to throw it away by allowing cheating (which is what you are insinuating).
At any rate, your take on it has not been backed up by what we have all seen over the last 19 years or so.
