Since there's been so much controversy over the dome displacement of the PCT pistons, I went out and cc'd one of the pistons.

Procedure:
1.) Filled the valve pockets with Play-doh and flushed them with the crown as well as possible with a credit card and my finger.

2.) Greased the cylinder walls about an inch and a half below the deck and then set the piston-to-deck height = 1.000" +/- a few ten-thou.

3.) Greased the cylinder sleeve edge and set the plate.

4.) Started filling the chamber with a light dish washer soap-water mixture. I used a 10mL +/-.1mL pipette with pipette bulb. We use them in Microbio lab all the time to distribute aliquots of nutrient and bacteria solutions all the time, so I'm pretty good with them. It would have been a little harder to set up a buret b/c I didn't have any table space to get it next to the block...not to mention that I didn't even have a buret and stand.

5.) Filled it until all the air bubbles have escaped out the ports I drilled in the plate. On one of the trials, I wasn't able to get a really small bubble out (probably a tenth of a cc)...that's why you're supposed to do as many trials as possible to help average the numbers. I was only able to do two trials.

Anyways, enough of the procedures and controls, I just wanna state the results and error.

Results:

Theoretical volume (piston-deck height = 1.000") = 131.69532cc

Volume with valve pockets filled
Trial 1 = 122.15cc
Trial 2 = 121.3cc

Volume with valve pockets unfilled
Trial 1 = 125.7cc

Volume of valve pockets = volume (pockets filled) - volume (pockets unfilled) =
125.7cc - 122.15cc = 3.55cc
125.7cc - 121.3cc = 4.40cc

Avg of the volume of valve pockets = 3.975cc

Volume of positive dome displacement = theoretical volume at 1.000" - volume with valve pockets filled =
131.69532cc - 122.15cc = 9.54532cc
131.69532cc - 121.3cc = 10.39532cc

Avg of the above = (9.54532cc + 10.39532cc)/2 = 9.97032cc

Total dome displacement = 9.97032cc - 3.975cc = 5.99532cc

END RESULT = 6.00cc

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Error sources:

The biggest source of error was that I had to reset the piston-to-deck heigh clearance back to 1.000" when I came back to cc the displacement with the valve pockets unfilled. It was 1AM when I stopped after cc'ing it with the valve pockets filled, so I didn't even think twice about having to do it again with them unfilled...I just started cleaning up.

On a wider scale, the biggest error I made was not having done more trials and on all the pistons....and with good reason too....it's PITA time-consuming. As much as I like seeing and comparing the end results, getting there really sucks.

Then there's the occasional drop of fluid that would escape the pipette before it made its way into the hole.

There's also a bit of error in reading the meniscus. After having to fill a 10cc pipette 13 times to get to 120.0+cc's, you just wanna get it over with sometimes.

All the little bits of error add up after a while.

P.S. That was a shitty lab write-up. I really rushed it, but I hope it gets all the points across and not just the end result. I always hated writing them b/c their so tedious, even if they are helpful in the sense that they help you reflect on the experiment and help to control the flow of information to the public....so I hope it wasn't too crappy for any standardization ****'s out there.

 

In comparison to the other number I've heard (+6.15cc), I'm even more inclined to say that c-speedracing.com's +8.63cc displacement number is not the correct one to be using.

 

Nice work. Thanks.




Modified by b19coupe at 11:17 PM 2/1/2004

 

WoW

Good write up

 

Great work IN VTEC!