DynoJet results: Accufab 'X' pipe & SCT Tuner
- Thread starter 632C2
- Start date
tmcphail
GT Owner/Vendor
richardhead
GT Owner
- Sep 19, 2006
- 169
Correction to Second Paragraph!
Let us get directly to what is happening when the dynamometer is measuring horsepower and torque. The output of the engine is directly related to the dynamics of its engine management system. This includes the computer, its management instructions to the engine controls, and all the sensors providing feed back on the subsequent engine operation. The management instructions are generated from a multi-dimensional data base stored in the computer’s memory, which essentially is determined by the design engineer’s specifications based upon laboratory testing of the engine assembly. In a production engine covered by a factory warranty, the final programming adjustments are based upon protecting the engine’s durability quotient by assuring it always runs in a range which respects the component’s individual durability ranges. For the most case, the objective is to prevent pre-ignition/detonation and excessive compression pressures. In the case of our GT engines, the management system receives feedback from a number of sensors and position monitors, as well as a pre-cat and post-cat sensor to monitor A/F ratios and adjust for emissions. The power/torque output curve is directly related to ability of the engine management system to react to the feedback sensors. The response time associated with any adjustment made by the system is directly related to the feedback sensor’s ability/response time to convert physical data to an electrical impulse for the computer program to map against the multidimensional data base and pick an instruction to send to its management controls. The response time associated with this process can vary, and the computer will substitute a “safe mode” command if the input is thrown at it too quickly with a lot of variation. “Safe mode” typically involves a combination of timing retard and engine enrichment, until the computer picks the appropriate commands from its operational data base algorithm. This shows up as jaggedness in the horsepower/torque curves, with the degree dependent upon the operating conditions sensed by the engine management system. Typically, the variations are so small the driver never notices them. The faster the sensing and response times are for the feedback and adjustment devices, and the larger and faster the computer processor is, the more quickly the adjustments are made and the smoother the output curves appear.
Typically, OEM settings richen at near redline since this is where cylinder temperatures are highest, and the possibility of detonation the greatest. It is also where spark strength is under stress due to the higher air gap resistance present under extreme pressure. It is also where the plug runs hotter, and could use the cooling effect of a richer mixture to avoid pre-ignition. Take all this into consideration, and the reason for the OEM program should be obvious. In addition, it is very conservative since all engines are not identical under the same conditions of operating stress. When a tuner modifies this programming, it pays to keep all this under consideration lest the new parameters go beyond limits and cause momentary safety issues…and don’t forget the parameters are slightly different for each engine, so a standard program set at the limits for one engine may cause trouble in another engine.
The less data the computer has in its mapping database, and the slower the computer is, the more conservative the engine operating parameters will be. Changes made to a slower simple system will have a much higher risk factor associated with them than those made to a more complex and faster system.
So…be cautious with any tuner modifications you make if you don’t have the tools to measure your particular engine’s responses.
tmcphail said:
Let us get directly to what is happening when the dynamometer is measuring horsepower and torque. The output of the engine is directly related to the dynamics of its engine management system. This includes the computer, its management instructions to the engine controls, and all the sensors providing feed back on the subsequent engine operation. The management instructions are generated from a multi-dimensional data base stored in the computer’s memory, which essentially is determined by the design engineer’s specifications based upon laboratory testing of the engine assembly. In a production engine covered by a factory warranty, the final programming adjustments are based upon protecting the engine’s durability quotient by assuring it always runs in a range which respects the component’s individual durability ranges. For the most case, the objective is to prevent pre-ignition/detonation and excessive compression pressures. In the case of our GT engines, the management system receives feedback from a number of sensors and position monitors, as well as a pre-cat and post-cat sensor to monitor A/F ratios and adjust for emissions. The power/torque output curve is directly related to ability of the engine management system to react to the feedback sensors. The response time associated with any adjustment made by the system is directly related to the feedback sensor’s ability/response time to convert physical data to an electrical impulse for the computer program to map against the multidimensional data base and pick an instruction to send to its management controls. The response time associated with this process can vary, and the computer will substitute a “safe mode” command if the input is thrown at it too quickly with a lot of variation. “Safe mode” typically involves a combination of timing retard and engine enrichment, until the computer picks the appropriate commands from its operational data base algorithm. This shows up as jaggedness in the horsepower/torque curves, with the degree dependent upon the operating conditions sensed by the engine management system. Typically, the variations are so small the driver never notices them. The faster the sensing and response times are for the feedback and adjustment devices, and the larger and faster the computer processor is, the more quickly the adjustments are made and the smoother the output curves appear.
Typically, OEM settings richen at near redline since this is where cylinder temperatures are highest, and the possibility of detonation the greatest. It is also where spark strength is under stress due to the higher air gap resistance present under extreme pressure. It is also where the plug runs hotter, and could use the cooling effect of a richer mixture to avoid pre-ignition. Take all this into consideration, and the reason for the OEM program should be obvious. In addition, it is very conservative since all engines are not identical under the same conditions of operating stress. When a tuner modifies this programming, it pays to keep all this under consideration lest the new parameters go beyond limits and cause momentary safety issues…and don’t forget the parameters are slightly different for each engine, so a standard program set at the limits for one engine may cause trouble in another engine.
The less data the computer has in its mapping database, and the slower the computer is, the more conservative the engine operating parameters will be. Changes made to a slower simple system will have a much higher risk factor associated with them than those made to a more complex and faster system.
So…be cautious with any tuner modifications you make if you don’t have the tools to measure your particular engine’s responses.
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analogdesigner
GT Owner
Black2003Cobra
Well-known member
Great discussion! But for what it’s worth, maximum cylinder pressures occur at peak torque – not at peak power. (MEP = 4πTQ/Vd). From the dynograph, peak torque looks to be somewhere between 4.5 and 5 krpm…not at redline.
Also, reducing the AFR doesn’t reduce the air charge temperatures within the cylinders (from the vaporization of the fuel when it is injected) as much as one might think. For example, using Lv = 340 kJ/kg (the latent heat of vaporization for gasoline), richening the AFR from 12:1 to 11:1 would only change the air charge temperature by about –2.6 °K (or °C). Even richening the AFR to 10:1 (from 12:1) would only result in a change in temps by about -5.7 °K. Compared to typical temperatures at the intake ports under full boost at WOT, (which depending on boost pressure, SC isentropic efficiency, intercooler efficiency and ambient temps can easily be in the neighborhood of 400 °K, or more), or compared to the combustion temperatures after the spark, (which are on the order of 2500 °K!), that reduction of a few degrees just isn’t that significant. A richer AFR does help reduce knock (post-ignition), but it is by a different mechanism…not from cooling the intake charge.
Edit: BTW, π = pi = 3.141592.......And MEP = mean-effective pressure, and Vd = displacement
Also, reducing the AFR doesn’t reduce the air charge temperatures within the cylinders (from the vaporization of the fuel when it is injected) as much as one might think. For example, using Lv = 340 kJ/kg (the latent heat of vaporization for gasoline), richening the AFR from 12:1 to 11:1 would only change the air charge temperature by about –2.6 °K (or °C). Even richening the AFR to 10:1 (from 12:1) would only result in a change in temps by about -5.7 °K. Compared to typical temperatures at the intake ports under full boost at WOT, (which depending on boost pressure, SC isentropic efficiency, intercooler efficiency and ambient temps can easily be in the neighborhood of 400 °K, or more), or compared to the combustion temperatures after the spark, (which are on the order of 2500 °K!), that reduction of a few degrees just isn’t that significant. A richer AFR does help reduce knock (post-ignition), but it is by a different mechanism…not from cooling the intake charge.
Edit: BTW, π = pi = 3.141592.......And MEP = mean-effective pressure, and Vd = displacement
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tmcphail
GT Owner/Vendor
Anyone that wants to get their vehicle tuned properly needs to find someone they trust and stick with that person. Competency is key in this field. I am lucky enough to do this for a living so I rely on myself.
I have mountains of sensor data on my own TTGT that I continue to collect and refine its calibration. But in the end when you have a vehicle that has great power and drivability the smile on your face tends not to go away !
_________________
Mr. Torrie R. McPhail
2005 Black Twin Turbo Ford GT 1046rwhp / 892rwtq
2005 Silver Viper 610 rwhp / 760 rwtq
2006 Silver Jeep SRT-8 12.4@109.6
I have mountains of sensor data on my own TTGT that I continue to collect and refine its calibration. But in the end when you have a vehicle that has great power and drivability the smile on your face tends not to go away !
_________________
Mr. Torrie R. McPhail
2005 Black Twin Turbo Ford GT 1046rwhp / 892rwtq
2005 Silver Viper 610 rwhp / 760 rwtq
2006 Silver Jeep SRT-8 12.4@109.6
richardhead
GT Owner
- Sep 19, 2006
- 169
Black2003Cobra said:
My apologies, Black2003Cobra...it was late at night and I typed pressure instead of temperature in the first sentence of the second paragraph. Thanks for drawing my attention to this! I have edited same to correct. For those not wishing intensive engineering detail, a very simple uncomplicated explanation of the fundamentals of internal combustion engine operation (including torque and horsepower relationships), using a Chevy 350 CI engine as the example, is presented at this link:
http://mb-soft.com/public2/engine.html
Additional references are also provided in and at the end of the link
Well said, I couldn't have put it any better myself.
I get that same smile on my face everytime I make a good dyno run. It's addicting.:biggrin
Steve
I get that same smile on my face everytime I make a good dyno run. It's addicting.:biggrin
Steve
tmcphail said:
RWTD
Member
First off, I realize I'm using a company name to post under, and tho I'm not meaning to intrude here, I have contacted both the Admins about becoming an advertiser (we have multiple Ford GT customers across the country, and in our area, as well as Australia now [OzGT on here]!). Unfortunately I have not heard from either one yet, so I apologize if I'm stepping on any toes here.
Okay, now to the issue of COT. The main reasoning behind the COT, in almost any manufacturer, is to protect the cats, definitely. There's several temp models in a Ford. There is the Cats, the Exhaust Flange, and the HEGO Tip (Heated Exhaust Gas Oxygen sensor, aka O2 sensor). There's also two stages to each, meaning that it starts to add fuel once they reach a certain temp (it's "predicted", like is in the GMs). On an '03 Cobra, with the YDH1 calibration, the pcm will add fuel if it deems the cats get to 1650 F, if the Flange gets to 1500 F, and if the HEGOs get to 1600. It will exit those strategies generally about 50 to 100 degrees less than that. There is also a Min and a Max Lambda used. For the cats it's 0.937 (from stoich) Max (13.7739) and 0.70 (from stoich) Min (10.29 afr). However, most Cobras will go below 10.0 when the COT strategy kicks in (due to a variety of factors).
p.s. Shoulds out to tmcphail, black2003cobra, and OzGT!
Kind Regards,
James
Okay, now to the issue of COT. The main reasoning behind the COT, in almost any manufacturer, is to protect the cats, definitely. There's several temp models in a Ford. There is the Cats, the Exhaust Flange, and the HEGO Tip (Heated Exhaust Gas Oxygen sensor, aka O2 sensor). There's also two stages to each, meaning that it starts to add fuel once they reach a certain temp (it's "predicted", like is in the GMs). On an '03 Cobra, with the YDH1 calibration, the pcm will add fuel if it deems the cats get to 1650 F, if the Flange gets to 1500 F, and if the HEGOs get to 1600. It will exit those strategies generally about 50 to 100 degrees less than that. There is also a Min and a Max Lambda used. For the cats it's 0.937 (from stoich) Max (13.7739) and 0.70 (from stoich) Min (10.29 afr). However, most Cobras will go below 10.0 when the COT strategy kicks in (due to a variety of factors).
p.s. Shoulds out to tmcphail, black2003cobra, and OzGT!
Kind Regards,
James
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tmcphail
GT Owner/Vendor
Indeed !
_________________
Mr. Torrie R. McPhail
2005 Black Twin Turbo Ford GT 1046rwhp / 892rwtq
2005 Silver Viper 610 rwhp / 760 rwtq
2006 Silver Jeep SRT-8 12.4@109.6
_________________
Mr. Torrie R. McPhail
2005 Black Twin Turbo Ford GT 1046rwhp / 892rwtq
2005 Silver Viper 610 rwhp / 760 rwtq
2006 Silver Jeep SRT-8 12.4@109.6
632C2 said:
RWTD
Member
To continue on my previous post (#49), in regards to the COT, I also wanted to show you a Cobra before/after once the COT was toggled off. FYI, the biggest gain in upper rpm power, on the 2nd graph below, came from the added JLT 12" CAI system (he previously had the stock airbox w/ drop-in K&N filter), but toggling the COT to OFF also contributed, and also smoothed out his upper rpm power delivery, as you can clearly see.
Before COT was disabled:
After COT was disabled:
Before COT was disabled:
After COT was disabled:
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BlackICE
GT Owner
Does turning off COT destroy the CATS, thus really only usefull in cars that don't need CATS?
BlackICE
BlackICE
RWTD
Member
BlackICE, hello sir.
I have *never* seen an '03-'04 Cobra, nor any '99-'04 Mustang for that matter, lose a cat due to COT being disabled. I have seen some GM cars lose some cats (mainly the Camaros/Firebirds, but their orientation in the exhaust was suspect too), and have "heard" and "seen" only less than a handful of Lightnings. I have not heard of any of the GTs I've tuned lose a cat due to this being disabled.
So if you turn COT off, and the cats die, just reflash your pcm back to stock and take it in to the dealer.
They are warrantied by Ford for I think 60k miles, or more, due to environmental regulations.
Sincerely,
James
I have *never* seen an '03-'04 Cobra, nor any '99-'04 Mustang for that matter, lose a cat due to COT being disabled. I have seen some GM cars lose some cats (mainly the Camaros/Firebirds, but their orientation in the exhaust was suspect too), and have "heard" and "seen" only less than a handful of Lightnings. I have not heard of any of the GTs I've tuned lose a cat due to this being disabled.
So if you turn COT off, and the cats die, just reflash your pcm back to stock and take it in to the dealer.
They are warrantied by Ford for I think 60k miles, or more, due to environmental regulations.Sincerely,
James
BlackICE
GT Owner
There are rumors that even if you reflash your prom back to the factory configuration, that the dealer can tell that it was modified. Is there any truth to this?
BlackICE
BlackICE
RWTD
Member
BlackICE said:
Those are just that, rumors. Rumors serve nothing more than to scare the masses, and should be given a BIG :thumbsdow . Don't believe the hype, kind sir. Ford's dealers do not have any capability to determine if the pcm has been flashed from and to stock.
So feel safe to have your car custom tuned by any company who specializes in what they do. I would *highly* recommend only hardware and tuning via SCT products. Tho there are other products form other companies that can also get the job done, SCT's hardware is foolproof, especially when flashing your pcm, and their software is literally AMAZING! However, the software is only as good as the tuner who uses it, hence why I recommended a specialist in the field of tuning.
Sincerely,
James
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Black2003Cobra
Well-known member
FlorIdaho Chris
Yeah, I've got one.
RWTD said:So if you turn COT off, and the cats die, just reflash your pcm back to stock and take it in to the dealer.
Sincerely,
James
I'm sorry, I've got to cry foul here.
Let me get this straight...you are advocating making a fraudulent warranty claim for a problem caused by a non-factory tune? This kind of thinking just sucks. Do you advocate committing insurance fraud as well? :thumbsdow
Ever heard of taking responsibility for your own actions?
RWTD
Member
Florida Chris said:
One should and must take responsibility for their actions, absolutely!
I am adamantly opposed to aggressive driving, such as exhibitionism of speed, abrupt lane changes in front of others, street racing (despicable!), and I 100% certainly do not condone insurance fraud, or any other form of illegal activity. And, FYI, I still run cats on all the vehicles I own, even my 700+ rwhp '03 Cobra.
Would it be fair of others to ask you if you have ever broken the speed limit, spun your tires, raced another vehicle on the street, or cut in front of another vehicle? Littered out your window? Would it be fair of anyone to question an individual's disdain of liberals by what some may consider hypocrisy in regards to potential unfair tax cuts within a particular income bracket (re your signature)? Now I don't know you from the man on the moon. However, your post could have come across with a bit more tact, now don't you think, sir?
My post count here may not reflect it, but I can assure you that I am one of the most respected individuals in the aftermarket industry. My image to everyone is one of the most important aspects of my life, and I am certainly not going to let anyone potentially insinuate to others that I'm some sort of rogue and unlawful citizen, especially over what some may consider a poor choice of words, which mine were, I admit. Now, with that being said, I will somewhat defend what I said previously, albeit in a variance of such:
We all know that manufacturers/dealers will do anything to cut warranty costs, and I am certainly not any newb to the wrath of a bullying manufacturer/dealer. On my initial '03 Cobra, after 2 sets of warranty replacements on my cats, within the first 3k miles of ownership, I was then told that my warranty was null and void due to the catback that I had put on the car (which came AFTER the cats went out). I was told that they caused the cats to overheat. Now, we all know that's absolute BS, and if anything freeing up the exhaust will actually promote and improve cooling. FWIW, the car didn't have any tune, period. Cats shouldn't just fail prematurely, and certainly not on a near stock vehicle. I went with aftermarket Magnaflow cats, at the time, and never looked back (Mags just don't fail).
Lastly, for those who may run into warranty claim issues, please see here, as you may find it useful:
http://www.sema.org/main/semaorghome.aspx?ID=50096
http://www.ftc.gov/bcp/conline/pubs/buspubs/warranty.htm#Magnuson-Moss
http://www.magnusonproducts.com/magnusonmoss.htm
I hope that helps!
Now, if everyone doesn't mind, let's get back to talking tech!
Very Sincerely,
James
jaybnve
GT Owner
Hmmmmm....
Sorry, but I personally am with Florida Chris on this one. You advocated what many would consider to be a dishonest approach to the warranty issue. Your personal reputation, or Ford's response to any prior warranty claim you may have had, is not relevant. If you modify the car, you shouldn't expect to get free warranty service on a part that breaks as a result of the modification.
FWIW, I just spent a bunch of money replacing the clutch in my GT. I drag raced the car for a week, and burned it up. I paid for the replacement out of my own pocket, because drag racing is not covered under the vehicle's warranty. Yet its amazing to me how many people asked if I was going to take it to Ford for warranty service. No wonder the warranty claims people at Ford can be a little suspicious...
Sorry, but I personally am with Florida Chris on this one. You advocated what many would consider to be a dishonest approach to the warranty issue. Your personal reputation, or Ford's response to any prior warranty claim you may have had, is not relevant. If you modify the car, you shouldn't expect to get free warranty service on a part that breaks as a result of the modification.
FWIW, I just spent a bunch of money replacing the clutch in my GT. I drag raced the car for a week, and burned it up. I paid for the replacement out of my own pocket, because drag racing is not covered under the vehicle's warranty. Yet its amazing to me how many people asked if I was going to take it to Ford for warranty service. No wonder the warranty claims people at Ford can be a little suspicious...
RWTD
Member
Again, I did not mean to imply that someone should advocate abusing the warranty, nor unlawful behavior. I thought I have made all that pretty clear in my previous post (#58). I've already stated that my previous use of words in post #53 were a poor choice, and I apologize that those words came across poorly.
Again, let's get back to the tech, and not clutter this thread up in unnecessary friction.
Sincerely,
James
Again, let's get back to the tech, and not clutter this thread up in unnecessary friction.
Sincerely,
James
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