MY 350 is getting slower now :(
04-09-07, 07:54 PM
#63
Tech Info Resource
iTrader: (2)
04-09-07, 09:43 PM
#64
Nice chart! You should be able to prove your point with it. I completely understand why you believe the better gearbox should generate a higher speed over a given distance, and seeing the gaps where gear changes happen it's obvious the CVT maintains higher acceleration over the course. Isn't the answer a simple integral away?
The only reason I maintain the speed doesn't change is because I haven't seen it happen in the real world. Your CVT gearbox would completely overwhelm any streetable tire with the force it could apply at low speed. This might be the real world reason why lower gears make better ET but not better trap speeds. The mathematical model sure looks like the CVT would win hands down.
A lot of this stuff is counterintuitive. I only know it because I've had these same discussions with people before and had it proved to me (sometimes painfully) in clear, unambiguous terms. I get into lots of "discussions" about airflow where people want me to believe things I know are not true only because they're quite counterintuitive.
The only reason I maintain the speed doesn't change is because I haven't seen it happen in the real world. Your CVT gearbox would completely overwhelm any streetable tire with the force it could apply at low speed. This might be the real world reason why lower gears make better ET but not better trap speeds. The mathematical model sure looks like the CVT would win hands down.
A lot of this stuff is counterintuitive. I only know it because I've had these same discussions with people before and had it proved to me (sometimes painfully) in clear, unambiguous terms. I get into lots of "discussions" about airflow where people want me to believe things I know are not true only because they're quite counterintuitive.
I wouldn't have a clue how to do a "simple integral" using an Excel spreadsheet other than to create a stair-step calculation to add up the area of all the steps for each single MPH. It wouldn't be hard to do, but I don't know how the results would be significant, since the units would be "MPH-LBS".
My thoughts about the CVT overwhelming the tires at low speeds are that the "ideal" CVT ECU would have an intelligent or controllable "max thrust". For example, if the tires couldn't handle 3600 lbs of thrust without breaking loose, then the CVT would maintain a gear ratio and RPM that would not exceed that.
04-09-07, 10:21 PM
#65
Okay, so I did the "easy" integral on the thrust curves above to see what the area under the curves would be. I also capped the peak thrust for the CVT curves to 4000 lbs, since I doubt any streetable tire would hold more than that.
Stock gearing and tires = 208,235 MPH-LBS
Stock gearing and super-low-pro-tires = 214,179 MPH-LBS (2.9% increase)
CVT at peak torque = 224,312 MPH-LBS (7.7% increase)
CVT at peak hp = 252,412 MPH-LBS (21.2% increase)
Stock gearing and tires = 208,235 MPH-LBS
Stock gearing and super-low-pro-tires = 214,179 MPH-LBS (2.9% increase)
CVT at peak torque = 224,312 MPH-LBS (7.7% increase)
CVT at peak hp = 252,412 MPH-LBS (21.2% increase)
04-10-07, 02:40 PM
#69
Tech Info Resource
iTrader: (2)
Okay, so I did the "easy" integral on the thrust curves above to see what the area under the curves would be. I also capped the peak thrust for the CVT curves to 4000 lbs, since I doubt any streetable tire would hold more than that.
Stock gearing and tires = 208,235 MPH-LBS
Stock gearing and super-low-pro-tires = 214,179 MPH-LBS (2.9% increase)
CVT at peak torque = 224,312 MPH-LBS (7.7% increase)
CVT at peak hp = 252,412 MPH-LBS (21.2% increase)
Stock gearing and tires = 208,235 MPH-LBS
Stock gearing and super-low-pro-tires = 214,179 MPH-LBS (2.9% increase)
CVT at peak torque = 224,312 MPH-LBS (7.7% increase)
CVT at peak hp = 252,412 MPH-LBS (21.2% increase)
D=Vo*t+1/2at^2
V=Vo+at...etc...
04-10-07, 03:34 PM
#71
Okay... I did the calculations again to figure out approximate trap speeds at .25 miles. Who knows how accurate they are since I had to fudge the vehicle weight to come anywhere close to realistic speeds. Basically, I'm not taking wind resistance into account, so I had to increase the vehicle weight to 5000 lbs to come up with a 105.X MPH trap speed with stock gearing. Similarly, the CVT running at peak HP came up with a 109.X MPH trap.
04-10-07, 04:29 PM
#73
Just put together a journal of type to compare a few runs I made. Sure enough I found a predicted trend. Higher trap speeds correlate directly with higher Density Altitudes.
I used the following to calculate Density Altitude:
http://wahiduddin.net/calc/calc_da.htm
This site to get weather history information:
http://www.wunderground.com/
I used the following to calculate Density Altitude:
http://wahiduddin.net/calc/calc_da.htm
This site to get weather history information:
http://www.wunderground.com/
Last edited by GOBUCS; 04-10-07 at 06:35 PM.
04-11-07, 02:46 PM
#74
I just got my 3rd Blackstone UOA results for another sample, and something occurred to me about break-in. For you guys that pooh-pooh the idea that engines need to break in for a few thousand miles before they reach their full power potention ... why do so many UOAs during the 1st ~15K miles show such high levels of metal (iron, copper, aluminum, etc.)? I can't think of any reason other than they are products of high friction levels between the moving engine components, and as they "wear in", the friction decreases, and their levels in the UOAs drop off. I would expect power to increase at the same time.
My aluminum and iron are still above average at 13K, but my copper has finally fallen below average. Of course, I did a 3K OCI that time with Mobil 1 10W-30. For the 1st 2 oil changes I went 5K miles.
My aluminum and iron are still above average at 13K, but my copper has finally fallen below average. Of course, I did a 3K OCI that time with Mobil 1 10W-30. For the 1st 2 oil changes I went 5K miles.
Last edited by Gernby; 04-11-07 at 02:52 PM.
04-11-07, 02:53 PM
#75
I just got my 3rd Blackstone UOA results for another sample, and something occurred to me about break-in. For you guys that pooh-pooh the idea that engines need to break in for a few thousand miles before they reach their full power potention ... why do so many UOAs during the 1st ~15K miles show such high levels of metal (iron, copper, aluminum, etc.)? I can't think of any reason other than they are products of high friction levels between the moving engine components, and as they "wear in", the friction decreases, and their levels in the UOAs drop off. I would expect power to increase as at the same time.
My aluminum and iron are still above average at 13K, but my copper has finally fallen below average. Of course, I did a 3K OCI that time with Mobil 1 10W-30. For the 1st 2 oil changes I went 5K miles.
My aluminum and iron are still above average at 13K, but my copper has finally fallen below average. Of course, I did a 3K OCI that time with Mobil 1 10W-30. For the 1st 2 oil changes I went 5K miles.
BTW..How many miles do you have currently? I'm at 20.5k.