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I have a fogger set up on my SBF and I need to know the best way to purge the air out of my fuel system after i turn on the fuel pump. I am runnig a dead head system. HELP the few brain cells I have left can`t seem to find a solution.
 

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The nitrous guy
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I run small [.018] bleed jets on all my sytems. Some I install at the reg, some directly at the solenoid. My RacePack graphs show VERY steady fuel pressure readings with the bleeds and no pressure creep before the hit. Can't see a downside.

Monte
 

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The nitrous guy
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Well, I don't want my pressure to creep up high. I want it where I flowed it, when I drop the button. I was recently tuning a IHRA Top Dragster, with a belt drive pump, with the system set at 25psi of fuel pressure. Nitrous regulators flowed at 5 psi. On the RacePak, it was .8 into the run, before the pressure on the regulators got down to set pressure and the car was a turd and black smoking in 60ft because of it. The fuel pressure was just on a slow desent from 25, down to 5 and it took well over a half second to get there. I put the bleeds in and the pressure was dead on target, from idle to full throttle. You do get a "check" in the fuel pressure graph when the systems first activate, but that is why we all use Holley regs, because they recover instantly and return to set pressure. This was a car with a belt drive pump, but you get the same scenario with big electric pumps as well.

Monte
 

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The nitrous guy
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It is not really an "air bleed" , it just simply bypasses some fuel back to the tank, to keep the regulator from dead heading and creeping. Very simple. On one outlet of the reg, I use a 3/8 pipe x #6 fitting with a gauge port in it. I put a 1/8 pipe jet holder (same as in a plate) in the gauge port, install the .018 jet, screw a #3 line on there and run that back to the cell. This is for a fogger, for a plate you could simply put the bypass jet on the side of the reg you are not using.

Monte
 

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It is not really an "air bleed" , it just simply bypasses some fuel back to the tank, to keep the regulator from dead heading and creeping. Very simple. On one outlet of the reg, I use a 3/8 pipe x #6 fitting with a gauge port in it. I put a 1/8 pipe jet holder (same as in a plate) in the gauge port, install the .018 jet, screw a #3 line on there and run that back to the cell. This is for a fogger, for a plate you could simply put the bypass jet on the side of the reg you are not using.

Monte
If you have multiple systems do you need to bleed off all or just the first system ? You mentioned the datalogger shows .8 before the deadhead set up clears and most second kits and or third kits etc etc come on later...So bleading off the other regs may not be needed? I want to add this bleed off to my system
asap.......just askin
 

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monte ive got a two stage system and both systems have a .022 bypass jet in them and my racepak is not smooth on the fuel pressure it does have a check when i launch and when the second system hits but it is a rough line all the way though and its higher then where i flow it put on new regs and the only other thing i can think of doing is putting a larger jet in bypass
 

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The nitrous guy
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If I have 3 kits, I bypass all the regs. It may not be required on multiple kits, but I do it.

Red, the reason your fuel graph is jumpy, is likely the sample rate of the RacePak being set extremely high. You can right click on the pressure panel and slide the "smoothing" bar to the right and get the graph smoothed out. There is always a "check" when the system activates, but if you look at the actual time it takes to recover, it is very quick. Your RacePack sensor will very seldom read the same as your flow tool. That is a very high resolution, accurate sensor and your flow tool is not. I never worry about the difference personally. I always use the same flow tool and know where I am at. I look at the pressure on the RacePak graph as a reference and to see how steady it is, not really to read the exact pressure.

Monte
 

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Monte,
Did the dragster your were talking about above have a 12-803 on it ?? I have never seen one that took .8 to level out ??

RED.
Your set up could need some smoothing ?? Or is your regulator mounted rigid to the engine ?? Are your transducers mounted rigid ?? many times I see these solid mounted the engine harmonics shake the regulator or transducers so much they are unstable.... SJ
 

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The nitrous guy
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Yeah Steve, those were 803s. I thought the first time was a fluke, but the graphs were mirror images for 3 hits before we made the change.

Red, Steve brings up a good point. I see some cars that solid mounted regs cause no issues, on others the graph is crazy.

Monte
 

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on a fogger the race pac will not read the same fuel pressure as what you flowed it at,because you had a single jet in the flow tool ie-79 and the fogger has 8 jets ie-32 so the race pac will see a diffrent pressure.if you did this with a plate system and had a 79 fuel jet and flowed it with a 79 fuel jet the race pac should be real close
 

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I gotta wonder if slow recovery on the dragster was due to alcohol fuel gumming it ( the reg ) up or due to the belt driven pump changing pressure during the launch.

He didn't buy that reg from Tyler Texas :smt071did he?


Richard Gavle
 
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