Technical > Spud Miller's Cave

BV effect on pressure

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ricardo1967:

--- Quote from: dreracecar on July 16, 2015, 08:24:12 AM ---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

--- End quote ---

Thanks Bruce. It makes sense to me.

wideopen231:
Cool I will throw one of the K's laying here on and start with it.I'm not much on super high pressure system,but no reason to add restriction if don't have too and it cost nothing  to avoid. I like to run system around 100# and have jet between 110 and 130 using nozzle sizing to get it in that area.Maybe because I have run them like that for while seems to respond to tuning better for me.

Paul New:

--- Quote from: wideopen231 on July 16, 2015, 07:20:25 AM ---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.

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I would not want to run nozzles that small .020 unless you run a filter...... Still sounds like an easy place to get a plugged nozzle

wideopen231:
always have filter in system.Plus filter fuel twice before it goes into tank. On plugging nozzles .036 is still very small opening.I do pull it down and blow system out and check during week between races. With the way the smaller nozzles are in hat above open plenum if one got plugged it would have little effect on system.Now if two or three get trash yes it becomes issue.It does give big cooling effect to incoming aircharge,which it may do as well with nozzle only at intake flange just have never found away to check air temp in intake port.I have taken readings entering hat and half way down runner. Found as much as 20* differance. Does that make more power?Seems it should,but never been able to do A-B-A testing.

Spud Miller:

 I was not suggesting that everyone junk their cube metering valves just because they present more restriction than a K-valve.

 A restriction is a problem only if you can't get enough fuel out the other end. If your pump is less than 13 GPM, you're not going to see any difference at all running a cube or a K-valve, regardless of fuel type.

 There's a pressure drop, but the point was there's a drop with almost anything you do. Your motor won't care a bit.

 Spud

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