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BV effect on pressure

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wideopen231:
Spud,
   Question. What causes the pressure to be higher with the  K style BV versus the cube style.Is the pressure claculation on your calculator based on in front of BV? If so I can see why it would effect it.
Been wondering this for while and always looking to learn something new.

Spud Miller:

 Yes, it is a bit of a mystery and not easy to understand. Every component in the fuel system affects the flow and pressure slightly. Every hose, every fitting, filter, check valve, etc. The placement of such things all has influence, in most cases very slight. The metering valve has a huge effect on this however. Look at the typical Enderle cube for example...the fuel changes direction many times (90 degree corners in most cases). There's a pressure drop at each point in the system and this causes the pressure to differ depending on where you measure it. The fuel flowing through the system has momentum/inertia and when it hits a corner, it's higher on one side of that point and lower on the other. After several such places, it can change quite a bit.

 If you put a pressure sensor before and another after the barrel valve, you'll see a difference, even at WOT. Sometimes as much as 20 PSI or so. Pressure backs up against things, is relieved in certain places (check valves and passages in the BV that lead to check valves), and the spring loaded poppets in the check valves cause a strange situation with pressure at that point and upstream.

 Pressure reported in the calculator isn't always correct, but it should be fairly close for a given metering valve style. Since putting a box in the calculator for pressure correction would just confuse people and cause endless questions and head scratching, I chose to just use correction factors for each that are typical for what we see flowing systems. It's a ballpark idea to help people choose nozzles.

 When we find big discrepancies in pressure, there's generally something causing it that's easy to identify. For example, running a blank pill in an Enderle barrel valve and running a drop-in style pill in a "main" check valve after the pump can cause actual system pressure at the nozzle to be quite a bit different than what we'd calculate. The system still works great...no problems with doing that and the tuneup is basically the same. But pressure is affected.
 
 Spud

wideopen231:
Thanks Spud,

 I figured the BV had to be a drop. 30 years of air and water flow testing on commercial building systems gives me good in site and always curious.  Drops are reason I always try to run system straight with as few turns as possible. Thats and turbulance.If you see a 90* fitting in my system you know there was no way around it.

 Must have been having brain fart or the path of flow would have answered my question. Cube enters in rear and exits same so 180*.K stly front enter straight to spool then thru when WIDEOPEN.


Any negative to running the K on injected setup? I have both styles. My second injector would require som mods,the enderle hat will work with either.Then second is home brewed using some old enderle parts and the bridgeport,kind of like barn door style.

  Another question. Can I do a dual line deal using my base nozzles total flow at given pressure and going with smaller ones that total the same. Example  running 8-.037's  going with 8-.020 and 8 .031's.  My flow sheets are BASED ON FLOW AT 150 PSI,some stuff from Ralph when I was running blown alky. I have formula or figuring flow rate with pressure change. I normally run new rate for pressure change and compare sizes based off that.  I can see it would add more fittings and some pressure changes.
Don't you hate folks asking for free info.LMAO

ricardo1967:
Good topic. Just to confirm... so generally speaking, a cube style valve is more restrictive than a K-style valve at WOT?

dreracecar:
I would say that the cube is more restrictive if one is running nitro (in volume) and the straight thru design of the K style is mandated, but running alcohol or gas in the type of cars most of us run ,either K or Cube works and would not get rid of a cube and buy a K expecting any big changes. On my "Cube" went from a 1/2" feed line to the dist block down to a 3/8" line. Still more area in the 3/8"id the the total combined area of the nozzels. To me Alcohol is a sloppy fuel compared to nitro or gas and one can get away with a lot little issues and still run great

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