Disregarding variations in internal leakage, a positive displacement pump will discharge a specific volume of fluid per revolution.
That is irrespective of discharge static and dynamic head pressures. ¹⁾

But what is the flow rate in gallons per minute (GPM) for both the feed and return sides of the pump?
One way to find out is determine how much oil one full tooth cavity holds and then do the math for revolutions.
We can find the area of a square / rectangle / triangle box easily enough using line measurements and math.
But the gerotors in the oil pump are not straight lined and cornered.
The process below is the same as finding the volume of a combustion cylinder or head.
It's commonly known as CC'ing the chambers. Although in this instance, we are CC'ing one gerotor cavity and doing the math based on the results.

✘ - Basically, a homemade burette was originally used in this testing but the error factor was too wide.
A burette is a graduated glass tube with a tap at one end, for delivering known volumes of a liquid, especially in titrations. ²⁾
It is a long, graduated glass tube, with a stopcock at it's lower end and a tapered capillary tube at the stopcock's outlet.
The flow of liquid from the tube to the burette tip is controlled by the stopcock valve.

The “burette” used here was a 3 ML syringe graduated in 10ths of a ML. The tube is 1/8“ medical air tubing with 3 internal runners up and down the tube.
The internal runners make it difficult to use since that stops you from making a tight seal if attaching the tube onto a nipple.
So the tubing used here was attached inside nipples to allow the tubing OD to create an air tight seal.

^{3) 4)}

✔ - Testing with .5 ml SYRINGE USING THE INCLUDED PLUNGER TURNED OUT WITH TIGHTER RESULTS.

Two plexiglass plates were cut app 1-3/4 square with a Dremil cutting tool.
These didn't turn out the exact same size once filed and the edges sanded but as long as the are bigger than the gerotors, that's what matters.
A center hole was drilled thru both plates 3/8” with a drill motor and the edges file (drilling speed melts plexiglass and goops up around the hole).
The center hole is for a 5/16“ bolt washers and nut to keep the plates snug against the gerotors (not to tighten against, just snug).
Tightening the center of the plates will make the ends of the plates flex outward and ruin the seal.
To keep from melting and gooping up the edges, the small holes were drilled with a “pin vise” (available at hobby stores) that doesn't melt the plexiglass.

The small holes were drilled to fit inside the gerotor cavity (1 for tube insertion and 1 for air to escape).
The .070” hole fits the tip added to the end of the tubing. The air hole was drilled .116“.
^{5) 6)}

The valve was homemade from a scrap aluminum block.
A small hole was drilled thru the face of the aluminum for the tubing and a hole was cross dilled in the side to intercept the small hole.
3/8”x16 threads were then cut in the side for a tubing pincher.
A short piece of threaded rod was “balled” on one end to pinch the tubing.
The other end has a 3/8“ nut that was staked in place to turn the rod by hand. A 9/16” wrench is used to turn the rod into the tubing to pinch the tubing and throttle the liquid.

The white grease is to seal the plexiglass plates around the tooth cavity and keep the liquid from migrating across the faces.
The putty (electrical conduit putty from Lowes) is to block off adjacent cavities to keep the liquid in the cavity being tested.
A Q-tip is useful to clean the tooth cavity after pressing in the putty on each side (some may squeeze into the large cavity thru the clearance between the teeth).
The gerotors and plates need to be disassembled and cleaned before each test.

⁷⁾

^{8) 9)}

The accuracy of these measurements requires precise measurement of the liquid. However, precision is not something you can completely control.
Some things you can control (human errors, construction errors)and some you can't control (liquid sticking to the syringe).

Errors at the syringe / tubing:
Syringe accuracy itself cannot be changed and has to be accepted as a “margin of error”.
Typically in a glass burette the uncertainty is ±0.15 cm^3 (0.15ml in a 25ml tube). ¹⁰⁾
The initial reading is said to be potential ‘out’ by ±0.05 cm^3 (liquid sticking to the sides)
The final reading is said to be potential ‘out’ by ±0.05cm^3 (liquid sticking to the sides from top of beginning to top of ending level)
And also there is said to potentially be a drop and the bottom of the burette, of a volume ±0.05cm^3 (liquid sticking to outside of the tip).

• Testing by others has shown a 4%-5% error margin when delivering liquid thru a syringe (using the plunger).
  The plastic tube syringe has more wall friction than a glass tube also.
• The markings on the syringe can be easily misread. One way to misread the volume is by looking at the measurement on an angle.¹¹⁾
  From above, it can seem like the volume is lower, while from below, the apparent volume looks higher.
• Another source of measurement error is looking at the wrong spot.
  When the liquid in the syringe forms a concave curve, the bottom of the curve is used to measure volume.
  If the reading is taken from the higher sections of the curve, the volume measurement will be in error.
• The graduations between the markings have to be guessed at (halfway between markings is easy to call a 1/2 of a mark but may be 1/3 of a mark).
  Deciding between the 2.5 ML mark and the 2.55 ML mark on the 3ML syringe used here places you somewhere between 2.40 and 2.65 mL actual volume used (4% accuracy).
• All air bubbles have to be removed or they will cause errors in the results. A small amount of displaced air will change the final reading.
  The syringe used here was valved off with continuous water running thru it at the same time time to remove all air bubbles.
  Then the green dye was added and the syringe topped off while running green liquid down to the tip.

Errors at the valve:

• The homemade valve used here isn't the best way to strangle water. But it does strangle water.
  Having to use two hands instead of one and still keep eyeballs on the level in the gerotors is tedious.
• A small valve made for a burette or lab testing is a better choice for smooth one handed operation.

Human error:

• Mathing is unforgiving and inaccurate results can be easily inputted due to individual perception of the level and markings.
• You have to trust your eyes looking for bubbles in the tooth cavity, fiddling with the valve, watching for leakage and at the same time watching the level.
• Mistakes are easy to make. Then the test has to start all over again and patience is key to good results.
  If in doubt, disassemble, clean and retest. Repetition builds confidence.
• Loading too much grease on the plates ends in squeezing grease into the test cavity and tainting the results.

^{12) 13)}

^{14) 15)}

Errors in construction:

• The plexiglass plate on top is important as is the two holes to the cavity.
  As a test, two more holes were drilled into each other to see if a bigger single hole might work better.
  Result was the initial liquid drop sat on top of the big hole and blocked the cavity allowing it to remain dry while the gerotor face flooded.
  The bulb of water coming out the end is the same size each bubble and are bigger than the holes in the plate.
  So a big glop lands on the hole instead of in the hole.
  The tapered end of the tube has to go into the small hole so the bulb lands inside the cavity.
  So the 2 holes work better than a single big one. Pics shown below of that test but the single hole is not recommended in this instance.
• Drilling holes in the plate, you have to make sure the edges are flush (no flashing left underneath to add plastic to the volume in the cavity.
  The holes drilled here were carefully done and scrubbed to ensure straightness across the hole.
• The inner and outer gerotors have to be the same height during the test or leakage will appear on top and bottom faces.
  Leakage can also occur on the bottom but not the top.
  So always check for leakage on both sides before recording results.

^{16) 17)}

The 3 ML syringe is graduated in .1 ML increments (liquid between these marks has to be guessed or approximated)
Return gerotor height is 2.785515320334262 times taller than feed gerotor height (0.5“ / .1795” = 2.785515320334262).
So the feed height (.1795“) x 2.785515320334262 = return height (.500”).
The gerotor pattern is exactly the same for feed and return gerotors.
You can fit the feed inner into the return outer with no space difference between the teeth.
The only difference is in the height of each.

Therefore, the volume of 1 feed tooth cavity x 2.785515320334262 should be equal to the volume of 1 return tooth cavity.
Doing the math, the testing didn't match those ratios very well.
Feed volume (.1 ML) x 2.785515320334262 = (0.2785515320334262 ML) but 1 return tooth volume was .3 ML.
A difference between overall volume and overall height of 0.0214484679665738 was present.

¹⁸⁾

Feed Set

• Gerotor height = 0.1795“
• Gerotor volume = 0.104 GPM at engine speed of 1000 RPM (pump speed 500 rpm):
  
  1. One tooth cavity holds app 0.1 ml of volume or (0.1 cubic centimeters) or (.006 cubic inches).
     0.1cm³ = .006 ci³ volume (0.1 / 16.387064).
  2. Volume of eight tooth cavities per 1 pump revolution = 0.048 cubic inches (.006 ci³ x 8)
  3. Total pump volume at engine speed of 1000 RPM = 24 cubic inches per minute (.048 ci³ x 500 RPM pump speed)
  4. Feed pump volume = .104 gallons per minute at engine speed of 1000 RPM (24 ci³ per minute / 231)

^{19) 20)}

Return Set:

• Gerotor height = 0.500”
• Gerotor volume = .312 GPM at engine speed of 1000 RPM (pump speed 500 rpm):
  
  1. One tooth cavity holds app 0.3 ml of volume or (0.3 cubic centimeters) or (.018 cubic inches).
     0.3cm³ = .018 ci³ volume (0.3 / 16.387064).
  2. Volume of eight tooth cavities per 1 pump revolution = 0.144 cubic inches (.018 ci³ x 8)
  3. Total pump volume at engine speed of 1000 RPM = 72 cubic inches per minute (.144 ci³ x 500 RPM pump speed)
  4. Return pump volume = .312 gallons per minute at engine speed of 1000 RPM (72 ci³ per minute / 231)

^{21) 22)}

The 3 ML syringe was discarded and a .5 ML syringe with the included plunger was used instead.
The .5 ML syringe is graduated in .01 ML increments which takes a lot of the guessing out as to actual liquid level.
The tighter resolution with this syringe kept the guessing at the liquid level to a very minimum.
The results were much closer when comparing the two 1977-1985 gerotor set volumes together.

Using the smaller syringe, both cavity results changed slightly and the ratio between them squared up more.
Feed volume (.12 ML) x 2.785515320334262 = (0.3342618384401114 ML) and return tooth volume was .33 ML.
Now the difference between overall volume and overall height is 0.0042618384401114 which is a tighter margin of error.

Volume of a cube is the total cubic units occupied by it, in a three-dimensional space. ²³⁾
A cube is a 3d-shape, that has six faces, twelve edges and eight vertices. Hence, the volume of a cube is the space enclosed by it's six faces.
Therefore, the volume of cube is equal to the product of its length, width and height.
It is measured in (as) cubic units. The more the value of it's dimensions, the more is the volume of it's cubic area.

Since the gears and gerotor teeth are not straight (compound angles and shapes), doing the math gets more complicated.
So instead of drawing lines and doing multiples of mathing, the act of determining volume between the teeth is done here by liquid volume.
The volume of the liquid in a tooth cavity is the result of overall geometry of the cavity and represents the length width and height of the cavity.
Therefore, the volume is automatically represented as in cubic units.

• To find volume of one tooth cavity, measure the area (L x W x D) (or in this case, find the volume in cubic inches (CI³).
• To convert milliliters to cubic centimeters, the ratio is 1 to 1 (1 ML = 1 cubic CM (CM³)).
• To convert cubic centimeters to cubic inches, divide cubic CM by 16.387064 (IN³ = CM³ ÷ 16.387064).
• To determine total volume of 1 pump revolution in CI³, add up the number of tooth cavities in 1 pump rev (8 cavities) and multiply that by volume of 1 tooth in IN³.
• To determine total pump volume per/ X RPM, multiply total volume in CI³ of 1 pump rev by RPM measured (RPM x total volume of 1 pump rev = total pump volume per minute in CI³).
• To convert cubic inches per minute to gallons per minute, divide the total volume by 231, US method, (total pump volume in cubic inches per minute / 231 = GPM).
• To convert gallons to ounces, multiply gallons by 128 (1 gallon = 128 ounces)
• To convert from centimeter of mercury (cmHg) to pounds per sq. inch (psi), multiply cmHg x 0.19336721269578

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^{26) 27)}

1. Determine the volume of oil that one full tooth cavity contains in cubic inches (CI³).
2. Determine the volume of oil that is delivered for one full pump revolution in CI³ (total volume of tooth cavities per 1 pump rev).
   
3. Multiply that figure by pump speed in RPM to get total volume of oil delivered in CI³.
   The Sportster oil pump (except XR-750) operates at 1/2 engine speed.
   So idle at 1000 RPM for the engine is only 500 RPM for the oil pump.
4. Divide that figure by 231 (US) to find total gallons per minute the pump cavities are capable of delivering (GPM per RPM).
   
5. Subtract pumping loss (internal leakage / slippage) to find total GPM pump is delivering.
   Internal leakage through the clearances is an evolving figure based on clearance widths and viscosity.
   Determining the amount of slippage has to be done with other experiments per pump.
   A pump with tighter or looser clearances will yield different results.
   Oil at room temperature (high vis) will produce less internal leakage than oil at operating temp (low vis).
   So for the purpose here, we'll leave pumping loss for another day.
   You have to be careful reading literature on pumping loss as centrifugal pumps will have more pumping loss than tight clearance rotary pumps.
   And worn rotary pumps will have more slippage than rotary pumps in spec.

…….* Click Here for a chart containing these figures plugged into the full RPM range per gear set.

Again, these numbers are absolute (as long as the volumes were calculated properly) in the fact that The Pump Won't Flow Anymore Than What is Listed Per RPM.
Figures are 100% pump efficiency at best and these pumps do not run at 100% pump efficiency.
The greater the RPM, the more flow will be achieved.
This does NOT take into account normal or excessive internal oil leakage within the oil pump.
So real world GPM will be lower than what is listed here.

• 1977-1985 Gerotor Volumes
  • Overall Feed Volume = 0.121 GPM (US) (or 15.49 oz/minute, US) at engine speed of 1000 RPM (pump speed 500 rpm)
  • Overall Return Volume = 0.346 GPM (US) (or 44.29 oz/minute, US) at engine speed of 1000 RPM (pump speed 500 rpm)
• 1986-1990 Gerotor Volumes
  • Overall Feed Volume = 0.185 GPM (US) (or 23.67 oz/minute, US) at engine speed of 1000 RPM (pump speed 500 rpm)
  • Overall Return Volume = 0.346 GPM (US) (or 44.29 oz/minute, US) at engine speed of 1000 RPM (pump speed 500 rpm)
• 1991-1997 Gerotor Volumes
  • Overall Feed Volume = 0.185 GPM (US) (or 23.67 oz/minute, US) at engine speed of 1000 RPM (pump speed 500 rpm)
  • Overall Return Volume = 0.346 GPM (US) (or 44.29 oz/minute, US) at engine speed of 1000 RPM (pump speed 500 rpm)
• 1998-2006 Gerotor Volumes
  • Overall Feed Volume = 0.185 GPM (US) (or 23.67 oz/minute, US) at engine speed of 1000 RPM (pump speed 500 rpm)
  • Overall Return Volume = .485 GPM (US) (or 62.08 oz/minute, US) at engine speed of 1000 RPM (pump speed 500 rpm
• 2007-Present Gerotor Volumes
  • Overall Feed Volume = 0.180 GPM (US) (or 22.99 oz/minute, US) at engine speed of 1000 RPM (pump speed 500 rpm)
  • Overall Return Volume = 0.782 GPM (US) (or 100.090 oz/minute, US) at engine speed of 1000 RPM (pump speed 500 rpm)

Using 0.5ML syringe (graduated in .01 ML increments);

Comparing height vs volume of feed and return gerotors:
The cavities in both feed and return gerotors have the same geometry with the only difference being the height.
The feed gerotor height (.1795“) x 2.785515320334262 = the return height (.500”).
Feed volume (.12 ML) x 2.785515320334262 = (0.3342618384401114 ML) with the return tooth volume being 0.33 ML.
The difference is a volume over-result of 0.0042618384401114 ML when comparing height vs volume of the two gerotor sets.

Gerotor Height = 0.1795”
Gerotor Volume = 0.121 GPM (US) (or 15.49 oz/minute, US) at engine speed of 1000 RPM (pump speed 500 rpm):

1. One tooth cavity holds app (0.12 ml) of volume or (0.12 cubic centimeters) or (.007 cubic inches).
   0.12cm³ = .007 ci³ volume (0.12 / 16.387064).
2. Volume of eight tooth cavities per 1 pump revolution = 0.056 cubic inches (.007 ci³ x 8)
3. Total pump volume at engine speed of 1000 RPM (500 RPM pump speed) = 28 cubic inches per minute (.056 ci³ x 500)
4. Feed pump volume at engine speed of 1000 RPM (500 RPM pump speed) = .121 gallons per minute (28 ci³ per minute / 231)
5. Feed pump volume in ounces at engine speed of 1000 RPM (500 RPM pump speed) = 15.49 (.121 gallons per minute x 128)

^{28) 29)}

Gerotor Height = 0.500“
Gerotor Volume = 0.346 GPM (US) (or 44.29 oz/minute, US) at engine speed of 1000 RPM (pump speed 500 rpm):

1. One tooth cavity holds app 0.33 ml of volume or (0.33 cubic centimeters) or (.020 cubic inches).
   0.33cm³ = .020 ci³ volume (0.33 / 16.387064).
2. Volume of eight tooth cavities per 1 pump revolution = 0.16 cubic inches (.020 ci³ x 8)
3. Total pump volume at engine speed of 1000 RPM (500 RPM pump speed) = 80 cubic inches per minute (.16 ci³ x 500)
4. Return pump volume in GPM at engine speed of 1000 RPM (500 RPM pump speed) = .346 gallons per minute (80 ci³ per minute / 231)
5. Return pump volume in ounces at engine speed of 1000 RPM (500 RPM pump speed) = 44.29 oz per minute (.346 gallons per minute x 128)

^{30) 31)}

Using 0.5ML syringe (graduated in .01 ML increments);

Comparing height vs volume of feed and return gerotors:
The cavities in both feed and return gerotors have the same geometry with the only difference being the height.
The feed gerotor height (.265”) x 1.886792452830189 = the return gerotor height (.500“).
Feed volume (.175 ML) x 1.886792452830189 = (0.3301886792452831) with the return tooth volume being 0.33 ML.
The difference is a volume over-result of 0.0001886792452831 ML when comparing height vs volume of the two gerotor sets.

Gerotor Height = 0.265”
Gerotor Volume = 0.185 GPM (US) (or 23.67 oz/minute, US) at engine speed of 1000 RPM (pump speed 500 rpm):

1. One tooth cavity holds app (0.175 ml) of volume or (0.175 cubic centimeters) or (0.0106791552165781 cubic inches).
   0.175cm³ = 0.0106791552165781 ci³ volume (0.175 / 16.387064).
2. Volume of eight tooth cavities per 1 pump revolution = 0.0854332417326252 cubic inches (0.0106791552165781 ci³ x 8)
3. Total pump volume at engine speed of 1000 RPM (500 RPM pump speed) = 42.7166208663126 cubic inches per minute (0.0854332417326252 ci³ x 500)
4. Feed pump volume at engine speed of 1000 RPM (500 RPM pump speed) = 0.1849204366507039 gallons per minute (42.7166208663126 ci³ per minute / 231)
5. Feed pump volume in ounces at engine speed of 1000 RPM (500 RPM pump speed) = 23.6698158912901 (0.1849204366507039 gallons per minute x 128)

^{32) 33)}

Gerotor Height = 0.500“
Gerotor Volume = 0.346 GPM (US) (or 44.29 oz/minute, US) at engine speed of 1000 RPM (pump speed 500 rpm):

1. One tooth cavity holds app 0.33 ml of volume or (0.33 cubic centimeters) or (.020 cubic inches).
   0.33cm³ = .020 ci³ volume (0.33 / 16.387064).
2. Volume of eight tooth cavities per 1 pump revolution = 0.16 cubic inches (.020 ci³ x 8)
3. Total pump volume at engine speed of 1000 RPM (500 RPM pump speed) = 80 cubic inches per minute (.16 ci³ x 500)
4. Return pump volume in GPM at engine speed of 1000 RPM (500 RPM pump speed) = .346 gallons per minute (80 ci³ per minute / 231)
5. Return pump volume in ounces at engine speed of 1000 RPM (500 RPM pump speed) = 44.29 oz per minute (.346 gallons per minute x 128)

^{34) 35)}

Using 0.5ML syringe (graduated in .01 ML increments);
Both the feed and return cavities have the same volume ratios as 1986-1990 gerotors.
Feed sets are the exact same except for a smaller inner gear ID for the gearshaft.
Return sets are the exact same between the gears but the OD of the outer return gear is smaller and the smaller inner gear ID for the gearshaft.

Comparing height vs volume of feed and return gerotors:
The cavities in both feed and return gerotors have the same geometry with the only difference being the height.
The feed gerotor height (.265”) x 1.886792452830189 = the return gerotor height (.500“).
Feed volume (.175 ML) x 1.886792452830189 = (0.3301886792452831) with the return tooth volume being 0.33 ML.
The difference is a volume over-result of 0.0001886792452831 ML when comparing height vs volume of the two gerotor sets.

Gerotor Height = 0.265”
Gerotor Volume = 0.185 GPM (US) (or 23.67 oz/minute, US) at engine speed of 1000 RPM (pump speed 500 rpm):

1. One tooth cavity holds app (0.175 ml) of volume or (0.175 cubic centimeters) or (0.0106791552165781 cubic inches).
   0.175cm³ = 0.0106791552165781 ci³ volume (0.175 / 16.387064).
2. Volume of eight tooth cavities per 1 pump revolution = 0.0854332417326252 cubic inches (0.0106791552165781 ci³ x 8)
3. Total pump volume at engine speed of 1000 RPM (500 RPM pump speed) = 42.7166208663126 cubic inches per minute (0.0854332417326252 ci³ x 500)
4. Feed pump volume at engine speed of 1000 RPM (500 RPM pump speed) = 0.1849204366507039 gallons per minute (42.7166208663126 ci³ per minute / 231)
5. Feed pump volume in ounces at engine speed of 1000 RPM (500 RPM pump speed) = 23.6698158912901 (0.1849204366507039 gallons per minute x 128)

^{36) 37)}

Gerotor Height = 0.500“
Gerotor Volume = 0.346 GPM (US) (or 44.29 oz/minute, US) at engine speed of 1000 RPM (pump speed 500 rpm):

1. One tooth cavity holds app 0.33 ml of volume or (0.33 cubic centimeters) or (.020 cubic inches).
   0.33cm³ = .020 ci³ volume (0.33 / 16.387064).
2. Volume of eight tooth cavities per 1 pump revolution = 0.16 cubic inches (.020 ci³ x 8)
3. Total pump volume at engine speed of 1000 RPM (500 RPM pump speed) = 80 cubic inches per minute (.16 ci³ x 500)
4. Return pump volume in GPM at engine speed of 1000 RPM (500 RPM pump speed) = .346 gallons per minute (80 ci³ per minute / 231)
5. Return pump volume in ounces at engine speed of 1000 RPM (500 RPM pump speed) = 44.29 oz per minute (.346 gallons per minute x 128)

^{38) 39)}

Using 0.5ML syringe (graduated in .01 ML increments);

Comparing height vs volume of feed and return gerotors:
The cavities in both feed and return gerotors have the same geometry with the only difference being the height.
The feed gerotor height (.265”) x 2.641509433962264 = the return gerotor height (.700“).
Feed volume (.175 ML) x 2.641509433962264 = (0.4622641509433962) with the return tooth volume being 0.462 ML.
The difference is a volume over-result of 0.0022641509433962 ML when comparing height vs volume of the two gerotor sets.
The resolution between the final marks is very difficult to measure. Clearly there was more volume than the (4.6) mark in 4 separate tests.
Each time it was just a tad over. The best pics were used to show the results. The margin from .460 - .462 is left to interpretation here.
But .462 ML is used for the calculations below.

Gerotor Height = 0.265”
Gerotor Volume = 0.185 GPM (US) (or 23.67 oz/minute, US) at engine speed of 1000 RPM (pump speed 500 rpm):

1. One tooth cavity holds app (0.175 ml) of volume or (0.175 cubic centimeters) or (0.0106791552165781 cubic inches).
   0.175cm³ = 0.0106791552165781 ci³ volume (0.175 / 16.387064).
2. Volume of eight tooth cavities per 1 pump revolution = 0.0854332417326252 cubic inches (0.0106791552165781 ci³ x 8)
3. Total pump volume at engine speed of 1000 RPM (500 RPM pump speed) = 42.7166208663126 cubic inches per minute (0.0854332417326252 ci³ x 500)
4. Feed pump volume at engine speed of 1000 RPM (500 RPM pump speed) = 0.1849204366507039 gallons per minute (42.7166208663126 ci³ per minute / 231)
5. Feed pump volume in ounces at engine speed of 1000 RPM (500 RPM pump speed) = 23.6698158912901 (0.1849204366507039 gallons per minute x 128)

^{40) 41)}

Gerotor Height = 0.700“
Gerotor Volume = .485 GPM (US) (or 62.08 oz/minute, US) at engine speed of 1000 RPM (pump speed 500 rpm):

1. One tooth cavity holds app 0.462 ml of volume or (0.462 cubic centimeters) or (.028 cubic inches).
   0.462cm³ = 0.028 ci³ volume (0.462 / 16.387064).
2. Volume of eight tooth cavities per 1 pump revolution = 0.224 cubic inches (.028 ci³ x 8)
3. Total pump volume at engine speed of 1000 RPM (500 RPM pump speed) = 112 cubic inches per minute (.224 ci³ x 500)
4. Return pump volume in GPM at engine speed of 1000 RPM (500 RPM pump speed) = .485 gallons per minute (112 ci³ per minute / 231)
5. Return pump volume in ounces at engine speed of 1000 RPM (500 RPM pump speed) = 62.08 oz per minute (.485 gallons per minute x 128)

^{42) 43)}

Using 0.5ML syringe (graduated in .01 ML increments);

Comparing height vs volume of feed and return gerotors:
The cavities in both feed and return gerotors have the same geometry with the only difference being the height.
The feed gerotor height (.200”) x 4.25“ = the return gerotor height (.850”).
Feed volume (.170 ML) x 4.25 = (0.7225) with the return tooth volume being 0.740 ML.
The difference is a volume over-result of 0.0175 ML when comparing height vs volume of the two gerotor sets.
This could easily be due to using two syringes instead of 1 plus eyesight but a 10 ML syringe was also used on the return set with the same results (app.740“).
So with multiple testing and syringes, the results were about the same.

The same syringe as for previous year sets was originally used on the 07 feed pump gerotors.
However, the return gerotors required 2 syringes and a different brand scale was used for them.
So the test was repeated for the feed side using a new syringe matching that used for the return gerotors.
The result was the same for the feed side using the 2 different syringes.

Gerotor Height = 0.200”
Gerotor Volume = 0.180 GPM (US) (or 22.99 oz/minute, US) at engine speed of 1000 RPM (pump speed 500 rpm):
2007-up gerotors have wider teeth profiles than previous years.

1. One tooth cavity holds app (0.170 ml) of volume or (0.170 cubic centimeters) or (0.0103740364961045 cubic inches).
   0.170 cm³ = 0.0103740364961045 ci³ volume (0.170 / 16.387064).
2. Volume of eight tooth cavities per 1 pump revolution = 0.0829922919688359 cubic inches (0.0103740364961045 ci³ x 8)
3. Total pump volume at engine speed of 1000 RPM (500 RPM pump speed) = 41.49614598441795 cubic inches per minute ( 0.0829922919688359 ci³ x 500)
4. Feed pump volume at engine speed of 1000 RPM (500 RPM pump speed) = 0.1796369956035409 gallons per minute (41.49614598441795 ci³ per minute / 231)
5. Feed pump volume in ounces at engine speed of 1000 RPM (500 RPM pump speed) = 22.99353543725324 (0.1849204366507039 gallons per minute x 128)

Original .5 ML syringe:
^{44) 45)}

New type .5 ML syringe:
^{46) 47)}

Gerotor Height = 0.850“
Gerotor Volume = 0.782 GPM (US) (or 100.090 oz/minute, US) at engine speed of 1000 RPM (pump speed 500 rpm):

1. One tooth cavity holds app 0.740 ml of volume or (0.740 cubic centimeters) or (0.0451575706301019 cubic inches).
   0.740 cm³ = 0.0451575706301019 ci³ volume (0.740 / 16.387064).
2. Volume of eight tooth cavities per 1 pump revolution = 0.3612605650408151 cubic inches (0.0451575706301019 ci³ x 8)
3. Total pump volume at engine speed of 1000 RPM (500 RPM pump speed) = 180.6302825204076 cubic inches per minute (0.3612605650408151 ci³ x 500)
4. Return pump volume in GPM at engine speed of 1000 RPM (500 RPM pump speed) = 0.7819492749801193 gallons per minute (180.6302825204076 ci³ per minute / 231)
5. Return pump volume in ounces at engine speed of 1000 RPM (500 RPM pump speed) = 100.0895071974553 oz per minute (0.7819492749801193 gallons per minute x 128)

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• 1991-1997 Oil Pump
  • Feed Volume at pump speed of 660.3 RPM: 30 ounces per minute
  • Return Volume at pump speed of 660.3 RPM: 60 ounces per minute

On low speed, the oil pump robbed about 3 RPM from the drill press during operation tested with a photo tach from Harbor Freight.
^{57) 58)}

Comparing the flow test to the previous calculations (CCing the gerotors);
Volume of eight tooth cavities per 1 pump revolution = 0.0854332417326252 cubic inches (0.0106791552165781 ci³ x 8)
Total pump volume at pump speed of 660.3 RPM = 56.41156951605242 cubic inches per minute ( 0.0854332417326252 ci³ x 660.3)
Feed pump volume in GPM at pump speed of 660.3 RPM = 0.2442059286409196 gallons per minute (56.41156951605242 ci³ per minute / 231)
Feed pump volume in Ounces Per Minute at pump speed of 660.3 RPM = 31.25835886603771 Oz (0.2442059286409196 gallons per minute x 128)

Actual Pump Feed Flow Test:
The video below shows about 30 ounces per minute into the container at 660.3 RPM.
(which is very close to 31.26 Oz from recalculating volume at 660.3 RPM as previously done on these gerotors).
The video was cut at the 1 minute mark (easier than trying to line up marks and times and stuff when viewing)
The pump started at the 18 sec mark and the video was cut at the 1m-18sec mark.

Screenshot at the 1 minute mark (660.3 RPM) 59)	Video: Feed Volume at 660.3 RPM 60)

Comparing the flow testing to the previous calculations (CCing the gerotors);
Volume of eight tooth cavities per 1 pump revolution = 0.16 cubic inches (.020 ci³ x 8)
Total pump volume at pump speed of 660.3 RPM = 105.648 cubic inches per minute (.16 ci³ x 660.3)
Return pump volume in GPM at pump speed of 660.3 RPM = 0.4573506493506494 gallons per minute (105.648 ci³ per minute / 231)
Return pump volume in Ounces Per Minute at pump speed of 660.3 RPM = 58.54088311688312 oz per minute (105.648 gallons per minute x 128)

Actual Pump Return Flow Test:
The video below shows about 60 ounces per minute into the container at 660.3 RPM.
(just over the 58.54 Oz from recalculating volume at 660.3 RPM as previously done on these gerotors)
The video was cut at the 1 minute mark. Oil hit the bucket at the 18 sec mark and the video was cut at the 1m-18sec mark.

Screenshot at the 1 minute mark 61)	Video: Return Volume at 660.3 RPM 62)