AFC spring gauge

[jbolt]

I've been curious what the AFC spring travel is at different boost pressures so I cobbled this together.



I took measurements of the Diesel dynamics spring today and I'll do my stock spring tomorrow. I'll post the results of both.

 

[jbolt]

Update

The first setup did not work as I expected so I took measurements of the AFC housing and made a mock-up to the same dimensions. This enabled me to take measurements using the diaphragm.

 

[jbolt]

Here is a closeup of the mock-up. I used spacers below the spring to simulate different star wheel positions.

 

[jbolt]

Here are the results of the stock spring measurements. All measurements are in thousands of an inch. (0. 000")



The file was too large to post here so is in my ACF album



I'll post the DD spring when I finish the chart for it.



Jay

 

[BushWakr - RIP]

Jay,



... . way over the top bud... ... someone needs to give you a VE to autopsy..... great stuff !!!!!!!



Let me see if I'm interpreting this graph right Jay... . If we look at the starwheel with "0" turns up (basically bottomed out, with stock spacer washer) then at approx. 2 psi we start to see the diaphram beginning to deflect downward, and at approx. 8 psi we have max deflection of the diahpram resulting in "cone" down as far as it will go..... yes??



If that is correct then... . I notice that (with the stock spacer) the spread between zero deflection and max deflection is about a 5. 5 psi spread. Now looking at the other extreme... again with stock spacer... . if we start with starwheel 6 turns up, we have deflection beginning at about 5 psi (+-) and the max deflection at about 14. 5 psi ... ... that is nearly 10 psi spread, as opposed to the first which, was about 5. 5 psi.



That's quite a bit of difference between the two extreme's..... is this attributable to the "spring rate"????

Was 6 turns up, as far as the adjustment range would let you go??

I'm really interested to see the next set of graphs Jay.....

Is there any way to correlate these figures with the guide pin travel using different cones, or am I pushing our luck here .



Again, good stuff .....





Bob. .

 

[HFletcher]

jbolt, you're a real scientist!!!!!!!! Beautiful work!!!!!!

 

[jbolt]

Bob- you're interpreting it the same as I do. What I found interesting is in my first setup using an air cylinder the spring is very linear but the work involved in converting it to real world numbers was impossible. With the diaphragm the rate of travel is very fast at first and then rapidly drops off. At the transition point (fast to slow) you can hear the diaphragm pop. I believe as soon as the diaphragm has expanded most of the additional pressure is used to expand the diaphragm itself and not the spring. Like blowing up a balloon. At 30 psi the gains are only 0. 001" per PSI. With the star wheel at 6 turns I took it up to 60 psi and the diaphragm was still moving but ever so slightly. I stopped in fear of blowing up the diaphragm itself. I have not checked to see how many turns the star-wheel will go. I made 1, 2, & 3 turn spacers which gave me a range of 6 turns total.



I should note that all measurements were taken with the smoke screw backed out to neutral.



On my AFC 0. 060" for the min spacer thickness I can get before the guide pin gets hit.



Henry- Nothing special here. Just spent a lot of time writing down numbers. Excel makes it look nice. The most fun was making the rig.



More to come...



Oh and I'll gladly take a VE pump to dissect. All we need is a willing donor.

 

[Philip]

Outstanding work jbolt.



It will be interesting to see the DD spring results.

 

[RDBuck]

Outstanding!

This kind of hard data really helps us to better understand what we are doing-or need to do. The expertise of some of you guys really astounds me. Thanks!

 

[Old Smoky]

Pretty cool, Jay. Thanks.



Mike

 

[Lil' Dog]

Jbolt, Nice Work!!! Oo.



Now to pick on the data . . LOL... Was that a hickup or is it true that the 3T rate goes to full travel where the others don't?



I am curious as I like to use the smaller spacer (I am assuming the nylon spacer on the pin) and would like to get the full travel fuel rate. It seems the other settings don't go to full travel till well over 25 Psi. .



Thoughts?

 

[Old Smoky]

It would be interesting to see the results of the silver spring compared to the colored spring as they are said to be slightly different.



Mike

 

[jbolt]

Originally posted by Old Smoky

It would be interesting to see the results of the silver spring compared to the colored spring as they are said to be slightly different.



Mike

Get me a silver spring and I'll measure it



Lil' Dog- I've wondered too about the #3 turn numbers. When I did the measure ments I would first run the pressure up to +30 psi then back off to zero. This sets everything tight. Then I would add 1psi and recored the travel up to 30psi I did this twice and then took recordings at every 5psi (5,10,15 etc) all this was entered into a spread sheet and then averaged.



I have since gotten a better air psi gauge with a smaller error factor . 5% vs 2. 5% so I'll do it again and we will see if the results differ greatly.



Jay