Fuel pressure drop over bv

Anyone recall roughly what the fuel pressure drop is through the barrel valve? eg. fuel pressure at pump is 100psi, what is fuel pressure at the port? Was thinking it was only around 2-3 lbs....

Josh

 

I think it may be relative to your pump/nozzle/flow but I just checked on my RacePak and at 8263 RPM I had 155 at the pump and 132 on the other side of the barrel valve going to the nozzle block at full open throttle.

 

Hey thanks for the info! That's more than I thought it would be, however that is at a higher rpm and higher pressure.

Thanks again

 

There are many variables but 20 psi is a starting point.

 

Mike is right.. an Enderle K valve is 1/2" straight through, the high flow valve is bigger again.
There is virtually no pressure drop from the barrel valve. I measured 2 pounds on my flow bench with a K valve and standard fittings.

But there is a drop from lines and fittings.. before and after the barrel valve, and I think this is what people sometimes call the "barrel valve drop".
A high volume fuel system can definitely lose 30 pounds or more between the pump and the nozzles.

 

I agree that the number I gave seems high. The pump pressure comes out of the block on top of the Waterman and the nozzle point is on the lower back port of the barrel valve. I have the fuel shutoff, two 90 and one 120 degree -10 fittings in there in addition to a System 1 -10 filter. When I get the car back from the chassis shop, I'm going to double check the filter but I just cleaned it a bit ago. I forget what micron rating of the filter is.

 

Its GPM dependent, the more GPM the more pressure drop.

Off the top of my head on my flow bench,,,

About 10 GPM thru square barrel valve I read 220 psi before BV and 200 after.

Switched it to a K valve and the psi dropped to basically 0.

 

So if you only have 6 GPM going thru the BV or if you have 20 GPM, you think the PSI loss will be the same?

It might be a % of the actual PSI reading, but the increase in PSI comes from the increase in GPM.

Regardless, there is very little restriction in a K valve

 

I forgot about the fuel filter. That'd definitely make for more pressure on the pump side.

I figured the barrel valve isn't a solid run through with the spool and exit ports, this would cause an interruption in flow and cause more pressure on the back side then the front.

Found some old data when I had psi sensor on pump. I was about 35 lbs (120 pump, 85 on port dist block)

 

what if the port ck is subtracting from the total? eg. 100 before bv, 95 after bv, 75 in dist block due to 20lb port ck

 

Yeah just to clarify, my sensor was in the port block behind the ck valve. pump sensor was in the pump.

 

If your reading pressure before the barrel valve and after there would be a pressure drop that is a variable number depending on your main jet and high speed. Your main jet pill in the barrel valve is taking fuel and pressure away from the system past the barrel valve and also if you have a high speed coming off you barrel valve. If you had had a blank in the main jet and no high speed coming off the barrel valve they you probably wont have a pressure drop but in real life application you will see a pressure difference between the two sides.