I found the hydraulic diagram for the 1989 Honda Accord transaxle. On this page from 3geez.com there is a message from HLW on 12/13/2013 which has a link to the PDF file of the manual.
http://www.3geez.com/forum/3geez-acc...updated-4.html
There is a description of the "Lock-up clutch" starting on page 15-7 and then on page 15-17 there is a hydraulic diagram of five valves that control the lockup clutch and a description of how they work. I still don't completely understand it.
I was playing with some formulas to calculate horsepower requirement and potential MPG at different speeds for my car. This is the result:
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Drag and MPG calculated for 1988 Honda Accord notchback coupe
mph hp (aero) hp (rolling) drag hp mpg if bsfc=0.5 lb/hp-hr
10 0.05 1.2 1.25 100
20 0.4 2.4 2.8 89.3
30 1.2 3.6 4.8 78.1
40 2.9 4.8 7.7 64.9
50 5.6 6 11.6 53.9
60 9.7 7.2 16.9 44.4
70 15.4 8.4 23.8 36.8
80 22.9 9.6 32.5 30.8
90 32.7 10.8 43.5 25.9
100 44.8 12 56.8 22.0
110 59.6 13.2 72.8 18.9
120 77.4 14.4 91.8 16.3
130 98.4 15.6 114.0 14.25
140 122.9 16.8 139.7 12.5
150 151.2 18 169.2 11.1
assumptions:
frontal area: 21 square feet
Cd: 0.32
loaded weight: 3000 lb.
rolling resistance coefficient: 0.015
BSFC: 0.5 lb/hp-hr
fuel density: 6.25 lb./gal
aerodynamic drag calculated using
http://gtechprosupport.com/support/AeroDragCalc.htm
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These numbers might be close to being accurate if using a manual transmission and pulse and glide driving. After making this chart I discovered the Ecomodder tool to make a similar chart. Just click "Tools" on the menu.
For steady speed driving with my automatic transmission I estimated these results:
gear mpg speed range (mph)
1 11.25 0 - 12
2 19 12 - 22
3 27.5 22 - 32
4 40.33 32 - 48
4L 48.4 48 - 65
For this chart I'm assuming that the engine has a light load and the fuel flow is about 25% of full throttle flow. This might be close to accurate for the first three gears. For fourth gear and fourth gear with lockup the engine load is greater and the actual mpg will probably be lower unless I'm drafting a truck. Here is a formula I'm using:
mpg=4*v1k/d
v1k: mph at 1000 rpm
d: engine displacement in Liters
To take into account torque converter slip I multiplied the theoretical speed at 1000 rpm by 10/12 (0.833). This is about the usual slip for my car at low engine speeds. This formula seems to give good results for most V8 powered cars even at highway speeds up to 60 mph. It might not be accurate for unusual engines. To estimate the fuel economy at full throttle you can eliminate the 4x multiplier like this:
mpg(full throttle)=v1k/d
Sorry for the bad formatting. The tab characters don't seem to line things up except when the message is in the editing window. If you copy the chart and paste it into Notepad it will look better.