2009 CTS v dyno sheets! :)
12-17-2008, 01:44 PM
#62
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...Gas mileage is as follows. in 200 miles, i was at 16 mpg on the highway. Sometimes 17 at 70mph.. window sticker shows 18.... Well WITH the performance tune on ANY level, i have fixed thier flaws and am now AT LEAST 24mpg. If i drive easy, like i did on the way home i averaged 27.4 mpg for 68 miles straight on the highway...
12-21-2008, 06:11 PM
#63
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While I agree that factory calibrations are what some would call conservative, does anyone bother to understand why? Close coupled catalysts must remain below a certain temperature to not self distruct - leaning mixture (while possibly making more power) will result in catalyst core temperatures exceeding design limits - and will fail. Any mixture alone is rarely the tool to get big "gains". That comes from spark.
Spark tuning from OEM's is done in a controlled environment for determining what max spark for peak power is. Tuning is then refined for 'real world' operation, as even with best knock controll systems used, it is always better to run close to the knock limit, but not over as it requires drastic reduction in spark timing to get rid of knock once it occurs (just look as combustion pressures and temperatures during a knock event to understand).
Comments on turbo motors - very easy with electronic controlled wastegatges to increase boost to engine - but does the tuner ever plot where this modification puts the operation on a compressor map? There are design limits here as well that few tuners bother to even look at, let alone understand.
As far as fuel economy, does anyone really believe in this day of CAFE, emissions and competative advantage, that manufacturers really leave anything on the table for milage improvements? If so, you are dilusional. OEM's spend millions (literally) looking for 0.1 mpg improvements. By what mechanism do you propose that such an increase is coming from? If the engine is still running the same RPM (same gearing), and running stoich (14.7:1), where is the improvment comming from? Think about that one.
Spark tuning from OEM's is done in a controlled environment for determining what max spark for peak power is. Tuning is then refined for 'real world' operation, as even with best knock controll systems used, it is always better to run close to the knock limit, but not over as it requires drastic reduction in spark timing to get rid of knock once it occurs (just look as combustion pressures and temperatures during a knock event to understand).
Comments on turbo motors - very easy with electronic controlled wastegatges to increase boost to engine - but does the tuner ever plot where this modification puts the operation on a compressor map? There are design limits here as well that few tuners bother to even look at, let alone understand.
As far as fuel economy, does anyone really believe in this day of CAFE, emissions and competative advantage, that manufacturers really leave anything on the table for milage improvements? If so, you are dilusional. OEM's spend millions (literally) looking for 0.1 mpg improvements. By what mechanism do you propose that such an increase is coming from? If the engine is still running the same RPM (same gearing), and running stoich (14.7:1), where is the improvment comming from? Think about that one.
My 05 CTS-V with headers, intake, and weighing in around 3600 lbs. can see 31 MPG on the highway.
12-22-2008, 07:23 PM
#64
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Never had a mullet, and just for clarification, it is now the 21st century.
I've worked both sides of the fence (aftermarket and OEM) and can assure you that if you are still running stoich (14.7:1) and have made no mechanical changes (i.e. displacement, gearing, aero, mechanical drag, etc.) there is no way you are going to find this kind of increase in fuel economy. Even if you were to throw emissions out the window, it is unobtainable.
Your 'tuned' V gettting 31 mpg - no way. Go to the EPA web site, find the dyno coeficients for your car (yes, they are published) and calculate road load horsepower for a given speed. Then show me how you increased the total vehicle efficiency to such an extent that you gained over stock.
Changes in driving style - yes, you can make an improvment in fuel economy. Steady-state cruising down a highway (level ground, no wind) requires a change in drag, or increased efficiency either by reduced driveline losses or increased engine efficiency to show an improvment. And once again, you are right in the heart of operating range that OEM's spend the time, money and effort to optimize efficiency for mileage. So unless you are now driving your car in an entirely different manner than before, there is no mechanism for an increase in fuel economy.
I've worked both sides of the fence (aftermarket and OEM) and can assure you that if you are still running stoich (14.7:1) and have made no mechanical changes (i.e. displacement, gearing, aero, mechanical drag, etc.) there is no way you are going to find this kind of increase in fuel economy. Even if you were to throw emissions out the window, it is unobtainable.
Your 'tuned' V gettting 31 mpg - no way. Go to the EPA web site, find the dyno coeficients for your car (yes, they are published) and calculate road load horsepower for a given speed. Then show me how you increased the total vehicle efficiency to such an extent that you gained over stock.
Changes in driving style - yes, you can make an improvment in fuel economy. Steady-state cruising down a highway (level ground, no wind) requires a change in drag, or increased efficiency either by reduced driveline losses or increased engine efficiency to show an improvment. And once again, you are right in the heart of operating range that OEM's spend the time, money and effort to optimize efficiency for mileage. So unless you are now driving your car in an entirely different manner than before, there is no mechanism for an increase in fuel economy.
12-24-2008, 09:22 AM
#66
Mikels, you said it yourself on how mileage was increased. "or increased efficiency either by reduced driveline losses or increased engine efficiency to show an improvement"
Ive already posted that this is a manual transmission 04ctsvfl. My auto trans car is not here yet.
As far as mileage goes. On the v1 it seemed that the car would get more and more gas mileage with the more mods i was doing. I was up to 30 mpg with cam selection, tune, maggy and other minor mods. WAY up from stock. But that all ended when i went to the 454 + bigger maggy.
Ive already posted that this is a manual transmission 04ctsvfl. My auto trans car is not here yet.
As far as mileage goes. On the v1 it seemed that the car would get more and more gas mileage with the more mods i was doing. I was up to 30 mpg with cam selection, tune, maggy and other minor mods. WAY up from stock. But that all ended when i went to the 454 + bigger maggy.
12-24-2008, 03:21 PM
#67
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Yes, increased engine efficiency. What have you done to increase engine efficiency? Changes in spark timing (when a stock cal is running at knock limit already)? Only ways to increase engine efficiency is reduction in pumping losses - OEM's do this by cam phasers, 6-speed (or higher) transmissions, AFM (or DoD) as GM uses which shuts down 4 cylinders on a V8 under light load conditions. All of these lead to reduced pressure drop across the throttle to reduce pumping losses.
Nothing you can do in the calibration can be altered to such an extent to see the claimed 20%+ increase in efficiency.
You are still running 14.7:1 AF ratio, with narrow band O2 sensors, which are not capable of supporting 'lean' burn conditions. Spark timing in cruise conditions is already optimized for FE. Gearing (trans and final drive) are unaltered. There has been no change in driveline losses.
All I am saying is if it were this easy to make such extraordinary gains in FE, OEM's would be all over it. After all, 20%+ would have easily pulled the V from guzzler (or at least reduced it) - and made a tremendous competitive advantage. What OEM in their right mind would have neglected this?
What changes have you made to support such an increase?
As far as the power increases, your tuned values fall in line with every other chassis dyno testing I have done with what the OEM power levels should deliver. 556hp with a manual transmission should be ~15% (if run in 4th gear) or ~472hp. This was value that held true for over 2000 different chassis dyno tests I have personally performed, and in line with industry accepted values - at least for production rear-drive applications.
For an automatic (again run in 1:1 gear, or as close as possible - such as with GM's 6L90E or MYD 6-speed used in the V), the value is 20%.
As far as improvement with a V1 with cam, Maggie, etc. A cam can increase FE by decreasing engine efficiency at lower rpms, resulting in need for higher throttle angle (and therefore reduced pressure drop) to maintain a given power output at lower rpms. Usually this also results in a cam (if fixed timing) that will not meet emissions. This again is reason for advent of variable cam timing - even more effective if dual cam timing (variable intake and exhaust, but separate). Most every other modification will result in a decrease in FE (Maggie included as even with bypass open, there is still an increase in parasitic loss to overall package).
Nothing you can do in the calibration can be altered to such an extent to see the claimed 20%+ increase in efficiency.
You are still running 14.7:1 AF ratio, with narrow band O2 sensors, which are not capable of supporting 'lean' burn conditions. Spark timing in cruise conditions is already optimized for FE. Gearing (trans and final drive) are unaltered. There has been no change in driveline losses.
All I am saying is if it were this easy to make such extraordinary gains in FE, OEM's would be all over it. After all, 20%+ would have easily pulled the V from guzzler (or at least reduced it) - and made a tremendous competitive advantage. What OEM in their right mind would have neglected this?
What changes have you made to support such an increase?
As far as the power increases, your tuned values fall in line with every other chassis dyno testing I have done with what the OEM power levels should deliver. 556hp with a manual transmission should be ~15% (if run in 4th gear) or ~472hp. This was value that held true for over 2000 different chassis dyno tests I have personally performed, and in line with industry accepted values - at least for production rear-drive applications.
For an automatic (again run in 1:1 gear, or as close as possible - such as with GM's 6L90E or MYD 6-speed used in the V), the value is 20%.
As far as improvement with a V1 with cam, Maggie, etc. A cam can increase FE by decreasing engine efficiency at lower rpms, resulting in need for higher throttle angle (and therefore reduced pressure drop) to maintain a given power output at lower rpms. Usually this also results in a cam (if fixed timing) that will not meet emissions. This again is reason for advent of variable cam timing - even more effective if dual cam timing (variable intake and exhaust, but separate). Most every other modification will result in a decrease in FE (Maggie included as even with bypass open, there is still an increase in parasitic loss to overall package).
12-25-2008, 12:38 AM
#68
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...All I am saying is if it were this easy to make such extraordinary gains in FE, OEM's would be all over it. After all, 20%+ would have easily pulled the V from guzzler (or at least reduced it) - and made a tremendous competitive advantage. What OEM in their right mind would have neglected this?...
