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mike01s4's Audi fitment Diverter Valve Testing Part 2:
by Mike Shimon (VAST Performance)

Did some more BPV checks....some interesting/conclusive info... thanks KENT L & LOSGATOSS4!!!!!!! for sending the samples for my destruction :) last time I posted about all the different valves (bailey excluded) and the only thing we couldn't talk about was the internals of the bosch valves. So the point of this is to compare three Bosch DV's and note their constructional and material differences and similarities and qualities.

So here it goes,
Valves checked:
  • Bosch. 110 (Porsche)
  • Bosch. 114 (VAG. 710N)
  • Bosch. 108 (VAG. 710A)
  • I sawed off the top (piston chamber side) of each of the above valves.

    From my previous post, all signs indicated that the 110 and 114(710N) were the same exact valve due to the exact same spring rate, max displacement and piston seating, etc. Now, I also noticed that the diaphragm was made of the same exact polymer material with the same exact thickness and the same construction with the same brass stopper. So, even though there are two different part #'s, they are totally the same.

    I cut away sections of the diaphragm and mic'd them up. The diaphragm thickness for the 110 and 114(710N) is as follows: 0.0200" - 0.0205" bosch 110 bpv

    I then took apart the stock 108(710A) valve and analysed it in the same manner. The brass piston stop is taller, (hence, the lower displacement value as noted in my first tests). Also, the diaphragm material is thicker: 0.0240" - 0.0245". This is substantially thicker than the valves that we are all upgrading too, and it mislead me for a moment. But, as I pulled away sections of the diapragm for testing, I noticed that the stock material tore very freely, while the 110 & 114(710N) was more elastic and resisted tearing even along an initial cut. I then applied the same force to the piston hats for each valve and noticed that the stock valve diaphragm just gave way very easily and I was able to rip it right off while I was struggling to tear the 110 & 114(710N).

    Also, with the upgraded valves, Bosch cut some costs with reducing the thickness of the brass stopper and most likely reduced costs with using a thinner, but stronger diaphragm material. The last difference is, of course, the higher spring rate and larger piston displacement with the 110 & 114(710N).

    (shorter brass piston stop for the 110 & 114/710N allows ~0.050" more travel) bosch 110, 114/710N bpv stopper comparsion

    (thicker, but weaker stock material on top compared to the 110 & 114/710N thinner/stronger material on the bottom) comparison of bypass valve diaphragms

    (valves disassembled. note how i was able to rip the diaphragms right off with the stock valves) image of open bypass valves

    So that's it folks, you don't have to guess anymore, when buying these valves, I hope!

    05/13/02

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