Well, not quite. Supercar1of1 and I, on page 9 of the original Piston Poll thread, were discussing the SRT chat sessions as a possible means to bring the "Ram 10" engine concerns to the fore front or at least ask the SRT gurus to look into any known issues.
Well, I went and scoured some of the other forum sites where the sessions were/are conducted. I stumbled upon several Viper specific chat sessions that were conducted on a Viper forum. I apologize to the ADMIN staff of this forum if I broke any rules for posting the below information. Also, the below is not meant to start any arguments or bash anyone involved with the tuning of these engines, aftermarket or otherwise. So please don't start any of that.
The below questions were raised by the populous and the SRT engineer's responses to each. I think y'all may find some of this information interesting, especially the next to last question/answer concerning the pistons in the 2008 Viper engines. I haven't had time to dig further but older sessions may reveal a similar response for the 03-06 engines. IMO, if the 08's are known to be designed at the limit for stock purposes, then I assume the same thing applies to our engines as well. The only advise I can offer up is becareful with your mods, keeping in mind the original platform may not be designed to handle what you throw at it.
Happy Reading:
SRT-10 Viper Chat Session Sep. 19, 2007
QUESTION: Can you please list the Gallons Per Minute per 1000RPM (GPM/1000RPM) of the new 2008 oil pump Versus the 03-06 pump, and also the 92-02 pump?
ANSWER: No, but I can tell you the 2008 oil pump flows 20% more than the 03-06!
QUESTION: Nadern 4) Getting back the tuning, one of the benefits of the performance tune is it leans out the mid range. The stock program at times felt a bit sluggish in mid ranges bursts. Now with the new program, it is instant power and really screams.
Is there a reason why the car is programmed to run rich in the mid range from the factory?
ANSWER: Nader - Several variables are part of the equation when calibrating the fuel curves. Things like knock sensitivity, catalyst temperatures, valve temperatures, piston temperatures and spark plug temperatures are all dramatically impacted by fueling. We calibrate the engine as lean as we can in order to satisfy all of our durability requirements for all of the engine components. It is true that leaning out the mixture at some (but not all) conditions will produce more power but at the cost of component durability! Also, keep in mind that there are other enrichment factors that can come into play, especially on a chassis dyno, that can give you more fuel than you might otherwise normally have if things like air and water temperatures are not controlled well. Also, chassis dyno noise can be interpreted as knock by the ECU and it will pull out spark and add fuel so don't always believe what you see there!
QUESTION: Nader - "5) There have been many posts here about the computer in the Gen III being adaptive and able to adjust fuel, timing etc. to compensate for better breathing via performance modifications, whether intake or exhaust. Is that true? If so, what is the approximate time or miles needed so that the computer fully recognizes and compensates for the changes or modifications?"
ANSWER: Nader - The ECU will adjust for closed loop fueling - i.e. when running part throttle at stoichiometric mixtures (based on what the O2 sensors see). When the ECU says the engine should be closed loop, it will always adjust the mixture regardless of any engine changes. We call this adaptive fuel. We do not apply adaptive fuel trims in open loop or WOT therefore if you make you engine breath better, it will lean out. Depending on how much things change, it could run dangerously lean and possibly damage the engine. The ECU does not "adapt" spark at all. On the 2004 - 2006 engines (and the 2008) the knock system will reduce spark if it "hears" knock. It will never add spark or adapt for engine changes.
SRT-10 Viper Chat Session May, 2008
QUESTION: since I am no engineer, does this mean the computer always is adjusting or compensating in closed loop no matter the modifications? And, the inverse, in open loop or wide open throttle it does not change adjust the fuel mixture therefore tuning would be required? My Edit: this question pertains to a 2006 model year.
ANSWER: The ECU will always try and adjust fueling to the proper mixture (14.6:1 air fuel) when in closed loop conditions (generally part load and speeds less than about 4000 rpm) - always as long as the O2 sensors are switching. When in open loop (higher loads and speeds over about 4000 rpm) there is no adaptive fueling - period. So yes, tuning would be required to compensate for engine modifications.
QUESTION: 5. I understand that the pistons for the '08 engine were not intended for use beyond the stock application and that if someone wants to mod the engine a piston change out is adviseable. Is this true? If so do you have any specs on the preferred pistons to use?
ANSWER: The 2008 engine is a highly tuned and highly stressed engine. We left few stones unturned in the development or calibration process. Achieving 600 HP required that many of the parts be stressed to their limits and the pistons are one of the most highly stressed components in the engine. If the customer modifies the engine to increase the output by any significant amount (more than just say headers, i.e. supercharger, turbo, NOS), a quality forged piston would be a good idea. We don’t currently offer a replacement piston but many of the aftermarket suppliers could probably offer a good replacement part. Follow their recommendations for fit. Also be careful to make any adjustments for balance if the weight is much different than the stock piston. Don't forget to use a good engine builder and make sure the calibration matches the modifications!
And My Personal Favorite:
QUESTION: How come we have ESP and traction control on a 1500 Ram truck but not on the 08 viper.There are a lot of folks out there that couldn't drive 400 hp much less 600.
ANSWER: Every Viper has both traction control and ESP....just look straight down.......
Well, I went and scoured some of the other forum sites where the sessions were/are conducted. I stumbled upon several Viper specific chat sessions that were conducted on a Viper forum. I apologize to the ADMIN staff of this forum if I broke any rules for posting the below information. Also, the below is not meant to start any arguments or bash anyone involved with the tuning of these engines, aftermarket or otherwise. So please don't start any of that.
The below questions were raised by the populous and the SRT engineer's responses to each. I think y'all may find some of this information interesting, especially the next to last question/answer concerning the pistons in the 2008 Viper engines. I haven't had time to dig further but older sessions may reveal a similar response for the 03-06 engines. IMO, if the 08's are known to be designed at the limit for stock purposes, then I assume the same thing applies to our engines as well. The only advise I can offer up is becareful with your mods, keeping in mind the original platform may not be designed to handle what you throw at it.
Happy Reading:
SRT-10 Viper Chat Session Sep. 19, 2007
QUESTION: Can you please list the Gallons Per Minute per 1000RPM (GPM/1000RPM) of the new 2008 oil pump Versus the 03-06 pump, and also the 92-02 pump?
ANSWER: No, but I can tell you the 2008 oil pump flows 20% more than the 03-06!
QUESTION: Nadern 4) Getting back the tuning, one of the benefits of the performance tune is it leans out the mid range. The stock program at times felt a bit sluggish in mid ranges bursts. Now with the new program, it is instant power and really screams.
Is there a reason why the car is programmed to run rich in the mid range from the factory?
ANSWER: Nader - Several variables are part of the equation when calibrating the fuel curves. Things like knock sensitivity, catalyst temperatures, valve temperatures, piston temperatures and spark plug temperatures are all dramatically impacted by fueling. We calibrate the engine as lean as we can in order to satisfy all of our durability requirements for all of the engine components. It is true that leaning out the mixture at some (but not all) conditions will produce more power but at the cost of component durability! Also, keep in mind that there are other enrichment factors that can come into play, especially on a chassis dyno, that can give you more fuel than you might otherwise normally have if things like air and water temperatures are not controlled well. Also, chassis dyno noise can be interpreted as knock by the ECU and it will pull out spark and add fuel so don't always believe what you see there!
QUESTION: Nader - "5) There have been many posts here about the computer in the Gen III being adaptive and able to adjust fuel, timing etc. to compensate for better breathing via performance modifications, whether intake or exhaust. Is that true? If so, what is the approximate time or miles needed so that the computer fully recognizes and compensates for the changes or modifications?"
ANSWER: Nader - The ECU will adjust for closed loop fueling - i.e. when running part throttle at stoichiometric mixtures (based on what the O2 sensors see). When the ECU says the engine should be closed loop, it will always adjust the mixture regardless of any engine changes. We call this adaptive fuel. We do not apply adaptive fuel trims in open loop or WOT therefore if you make you engine breath better, it will lean out. Depending on how much things change, it could run dangerously lean and possibly damage the engine. The ECU does not "adapt" spark at all. On the 2004 - 2006 engines (and the 2008) the knock system will reduce spark if it "hears" knock. It will never add spark or adapt for engine changes.
SRT-10 Viper Chat Session May, 2008
QUESTION: since I am no engineer, does this mean the computer always is adjusting or compensating in closed loop no matter the modifications? And, the inverse, in open loop or wide open throttle it does not change adjust the fuel mixture therefore tuning would be required? My Edit: this question pertains to a 2006 model year.
ANSWER: The ECU will always try and adjust fueling to the proper mixture (14.6:1 air fuel) when in closed loop conditions (generally part load and speeds less than about 4000 rpm) - always as long as the O2 sensors are switching. When in open loop (higher loads and speeds over about 4000 rpm) there is no adaptive fueling - period. So yes, tuning would be required to compensate for engine modifications.
QUESTION: 5. I understand that the pistons for the '08 engine were not intended for use beyond the stock application and that if someone wants to mod the engine a piston change out is adviseable. Is this true? If so do you have any specs on the preferred pistons to use?
ANSWER: The 2008 engine is a highly tuned and highly stressed engine. We left few stones unturned in the development or calibration process. Achieving 600 HP required that many of the parts be stressed to their limits and the pistons are one of the most highly stressed components in the engine. If the customer modifies the engine to increase the output by any significant amount (more than just say headers, i.e. supercharger, turbo, NOS), a quality forged piston would be a good idea. We don’t currently offer a replacement piston but many of the aftermarket suppliers could probably offer a good replacement part. Follow their recommendations for fit. Also be careful to make any adjustments for balance if the weight is much different than the stock piston. Don't forget to use a good engine builder and make sure the calibration matches the modifications!
And My Personal Favorite:
QUESTION: How come we have ESP and traction control on a 1500 Ram truck but not on the 08 viper.There are a lot of folks out there that couldn't drive 400 hp much less 600.
ANSWER: Every Viper has both traction control and ESP....just look straight down.......
