The Twin Screw Thread
12-13-2005, 01:37 AM
#121
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Posting some pics here that might help. The first 2 show the the system on my 90 GT. The second 2 are of pretty much the total parts package.
I haven't pulled the motor yet so if you want pics of specific areas from my 90 GT let me know.
I also have an MX424 sitting on my bench if you want pics of the stripped down system
I haven't pulled the motor yet so if you want pics of specific areas from my 90 GT let me know.
I also have an MX424 sitting on my bench if you want pics of the stripped down system
12-13-2005, 05:47 PM
#123
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Ok...this is a long rambling, stick with me..I hope it helps.
The BEGI 2025 that you are running IS NOT SET UP TO DECREASE FUEL PRESSURE. PERIOD.
It may do so ONLY if it presents the largest restriction in your fuel system prior to the fuels return to the tank.
In our cars, the BEGI is not the greatest restriction......its the stock regulators. (unless approaching 0” VAC or under boost when the BEGI unit starts working)
The fuel pressure at idle is dictated by the size of the restriction in the line presented by either
1) 85-86 fuel pressure regulator or..
2) 87 regulator.
3) if you want to split hairs ..you can add the health of your fuel pump and system.
From what i can gather, the 85-86 regulators are LESS restrictive than the 87 regulator, therefore allows for a slightly lower idle fuel pressure. (which is why it may be better to run one with the higher rated injectors...30lbs etc) Correct me if im wrong in any of this..!!!!!!.
The restriction that the BEGI unit provides is and ALWAYS will be less than the restriction that is provided by the 2 stock regulators, unless approaching the transition from VAC to boost.
Now..Im curious for those that have the GTs
1)What are your fuel pressures at IDLE
2)at 0 manifold pressure
3)and under boost…and at what boost
4)What size injector?
I ask as it seems common for the GTs to experience TIP detonation during the transition to boost. While fueling isnt the only cause for this, if you are anywhere shy of the required amount of fuel during the transition from VAC to BOOST , you are not helping things. Im thinking perhaps the ZERO point/transition fuel pressure is set to low??
I haven’t seen or heard any real definitive guidance on how to set the BEGI unit on ANY set up that is out there ....except for something along the lines of..."give the center screw X turns...the needle valve Y turns"
If you set up you car blindly like that, IMHO you are flirting with fueling issues.. You need a fuel pressure gauge and obviously an AIRFULE ratio meter of some sort. The BEGI unit seems to be a pretty mysterious object to many of us in the way it works. It is/was to me also until the last week or so…but I think I have a pretty good grasp on the SOB now.
This is how my car is currently set up (YMMV)
1) I have an after market Adjustable fuel pressure regulator. The ONLY reason I used this is I had it on my car to begin with when it was NA….it worked well then as well so I kept it as it determines the idle fuel pressure..
2) I have the BEGI 2025, which you all have.
3) I’m running all fuel dampers.
4) 24lb/hr injectors
VACUUM-SIGNAL LINES
1) the signal from the manifold goes into the barb on the BEGI UNIT shown in the picture.
2) the check valve goes on the barb that is attached to the NEEDLE VALVE. NO TWO WAYS ABOUT IT. THAT IS HOW IT IS INSTALLED.
3)you must obviously have a stock VAC line running to your pressure regulator
This is how I set up my fuel pressure.
(I have accounted for the fact you all are probably running a STOCK 85-86 or 87 type regulator and not the one shown in my pic.)
1) start the car
2) note the fuel pressure, write it down if you like.
3) keep all vacuum lines and signal lines connected.
4) turn the CENTER HEX adjustment bolt on the BEGI unit until its almost ALL THE WAY OUT…..no fuel will come out, don’t worry
5) at this point the ONLY RESTRICTION IN YOUR FUEL SYTEM IS PROVIDE BY THE STOCK REGULATOR…THIS IS THE LOWEST FUEL PRESURE your fuel system can give you (unless your voltage slips on the fuel pump) …my car, with 24# injectors I see 38-40psi.
6) With the car at idle, pull the SIGNAL LINE off the BEGI unit. You MUST PLUG the signal line as you have now introduced a vac leak to your engine. I just tore of a small piece of paper and let it get sucked onto the opening. The BARB on the BEGI unit is left open to the outside air. Since it is now sensing ambient pressure, it is actually sensing “0” as would be seen on a boost gauge as you drove and transitioned from vac to boost..
Get a hex key and start turning the CENTER HEX KEY back in. In doing this you are setting the fuel pressure you would like to see at ZERO boost…0”hg…whatever you want to call it……or the transition from VAC to boost. I call this the ZERO point for my own reference and I set my car to appx 68-70psi. Write down the fuel pressure you set it to for your own records.
7) once set, place the SIGNAL line back on the BEGI unit and note your fuel pressure afterwards. IT WILL DROP. It should drop to the value you saw in step 2.…my case 38-40psi. It does this as the vacuum being produced at idle is be transmitted though the signal line to the inside of the BEGI unit, pulling up on the diaphragm inside and in doing so moving the piston off the face of the metering port in the BEGI unit. The BEGI is not providing ANY restriction to your fuel system at this point….the stock regulators are again in control..
8) NOW……..this gets to the tricky part and actually requires that you drive the car.
The maximum fuel pressure that you see under boost is dictated by the adjustment on the needle valve and ONLY the needle valve. NOT THE BIG CENTER HEX BOLT.
In a nut shell…needle valve all the way in the HIGHER the ending fuel pressure
Needle valve out LOWER the ending fuel pressure.
To describe what is happening with the needle valve is as follows…..
You are bleeding off pressurized air inside the BEGI unit produced by boost. Its this pressure that forces the diaphragm and piston down on the metering port and restricts the fuel flow inside the unit ….thus INCREASING THE FUEL PRESSURE!!!!!
IF you turn the needle valve all the way out, you are letting that air pressure escape and thus reducing the amount of force it can place on the diaphragm and piston in order increase fuel pressure. If you have the CHECK VALVE ON BACKWARDS, you will never get the settings correct as air will NEVER be allowed to escape.
NOW….If you have the needle valve all the way out and you still have too much fuel pressure you MUST install the small restriction tube in the SIGNAL LINE that goes to the BEGI unit.
To explain what this does is as follows…
The restrictor tube does what its name implies…it restricts the amount of air flow and resulting boost pressure into the BEGI unit. With less pressure inside the unit, the diaphragm and metering piston cannot apply as much force down on the metering port and thus cant restrict the fuel flow as much.
IMPORTANT PRINCIPLE…. For any given setting on the needle valve for maximum fuel pressure, the use of the RESTICTION TUBE, will always lower the final fuel pressure seen under boost.
Example…
In my car I had the needle valve 1 turn in from being all the way out with a ZERO point ( no boost/no vac) fuel pressure set to 68-70-psi via the center hex bolt,
When I drove my car and saw boost (7-8psi) my fuel pressure would go beyond my gauge limit of 100psi!!
This told me that since I basically cant let anymore air out of the BEGI unit via the needle valve, my only other choice is to RESTRICT the amount of air coming in. Therefore I placed the restrictor tube in the signal line. On the next test drive, the fuel pressure stopped in the mid 80’s. with the needle valve un touched from the previous run.
I understand that we all have different size injectors, different set ups, fuel pump health and other variables but the steps in adjusting your fuel pressure to run at idle, 0”hg and under boost when using the BEGI are the same as far as I can gather.
Im sorry if this all reads as confusing, but Ive never had a good understanding of how the BEGI unit worked, what made it tick while it was operating and most importantly a proper way of setting it.
While all this was fresh in my head I decide to
it all up on here…
HTH
clear as mud??
The BEGI 2025 that you are running IS NOT SET UP TO DECREASE FUEL PRESSURE. PERIOD.
It may do so ONLY if it presents the largest restriction in your fuel system prior to the fuels return to the tank.
In our cars, the BEGI is not the greatest restriction......its the stock regulators. (unless approaching 0” VAC or under boost when the BEGI unit starts working)
The fuel pressure at idle is dictated by the size of the restriction in the line presented by either
1) 85-86 fuel pressure regulator or..
2) 87 regulator.
3) if you want to split hairs ..you can add the health of your fuel pump and system.
From what i can gather, the 85-86 regulators are LESS restrictive than the 87 regulator, therefore allows for a slightly lower idle fuel pressure. (which is why it may be better to run one with the higher rated injectors...30lbs etc) Correct me if im wrong in any of this..!!!!!!.
The restriction that the BEGI unit provides is and ALWAYS will be less than the restriction that is provided by the 2 stock regulators, unless approaching the transition from VAC to boost.
Now..Im curious for those that have the GTs
1)What are your fuel pressures at IDLE
2)at 0 manifold pressure
3)and under boost…and at what boost
4)What size injector?
I ask as it seems common for the GTs to experience TIP detonation during the transition to boost. While fueling isnt the only cause for this, if you are anywhere shy of the required amount of fuel during the transition from VAC to BOOST , you are not helping things. Im thinking perhaps the ZERO point/transition fuel pressure is set to low??
I haven’t seen or heard any real definitive guidance on how to set the BEGI unit on ANY set up that is out there ....except for something along the lines of..."give the center screw X turns...the needle valve Y turns"
If you set up you car blindly like that, IMHO you are flirting with fueling issues.. You need a fuel pressure gauge and obviously an AIRFULE ratio meter of some sort. The BEGI unit seems to be a pretty mysterious object to many of us in the way it works. It is/was to me also until the last week or so…but I think I have a pretty good grasp on the SOB now.
This is how my car is currently set up (YMMV)
1) I have an after market Adjustable fuel pressure regulator. The ONLY reason I used this is I had it on my car to begin with when it was NA….it worked well then as well so I kept it as it determines the idle fuel pressure..
2) I have the BEGI 2025, which you all have.
3) I’m running all fuel dampers.
4) 24lb/hr injectors
VACUUM-SIGNAL LINES
1) the signal from the manifold goes into the barb on the BEGI UNIT shown in the picture.
2) the check valve goes on the barb that is attached to the NEEDLE VALVE. NO TWO WAYS ABOUT IT. THAT IS HOW IT IS INSTALLED.
3)you must obviously have a stock VAC line running to your pressure regulator
This is how I set up my fuel pressure.
(I have accounted for the fact you all are probably running a STOCK 85-86 or 87 type regulator and not the one shown in my pic.)
1) start the car
2) note the fuel pressure, write it down if you like.
3) keep all vacuum lines and signal lines connected.
4) turn the CENTER HEX adjustment bolt on the BEGI unit until its almost ALL THE WAY OUT…..no fuel will come out, don’t worry
5) at this point the ONLY RESTRICTION IN YOUR FUEL SYTEM IS PROVIDE BY THE STOCK REGULATOR…THIS IS THE LOWEST FUEL PRESURE your fuel system can give you (unless your voltage slips on the fuel pump) …my car, with 24# injectors I see 38-40psi.
6) With the car at idle, pull the SIGNAL LINE off the BEGI unit. You MUST PLUG the signal line as you have now introduced a vac leak to your engine. I just tore of a small piece of paper and let it get sucked onto the opening. The BARB on the BEGI unit is left open to the outside air. Since it is now sensing ambient pressure, it is actually sensing “0” as would be seen on a boost gauge as you drove and transitioned from vac to boost..
Get a hex key and start turning the CENTER HEX KEY back in. In doing this you are setting the fuel pressure you would like to see at ZERO boost…0”hg…whatever you want to call it……or the transition from VAC to boost. I call this the ZERO point for my own reference and I set my car to appx 68-70psi. Write down the fuel pressure you set it to for your own records.
7) once set, place the SIGNAL line back on the BEGI unit and note your fuel pressure afterwards. IT WILL DROP. It should drop to the value you saw in step 2.…my case 38-40psi. It does this as the vacuum being produced at idle is be transmitted though the signal line to the inside of the BEGI unit, pulling up on the diaphragm inside and in doing so moving the piston off the face of the metering port in the BEGI unit. The BEGI is not providing ANY restriction to your fuel system at this point….the stock regulators are again in control..
8) NOW……..this gets to the tricky part and actually requires that you drive the car.
The maximum fuel pressure that you see under boost is dictated by the adjustment on the needle valve and ONLY the needle valve. NOT THE BIG CENTER HEX BOLT.
In a nut shell…needle valve all the way in the HIGHER the ending fuel pressure
Needle valve out LOWER the ending fuel pressure.
To describe what is happening with the needle valve is as follows…..
You are bleeding off pressurized air inside the BEGI unit produced by boost. Its this pressure that forces the diaphragm and piston down on the metering port and restricts the fuel flow inside the unit ….thus INCREASING THE FUEL PRESSURE!!!!!
IF you turn the needle valve all the way out, you are letting that air pressure escape and thus reducing the amount of force it can place on the diaphragm and piston in order increase fuel pressure. If you have the CHECK VALVE ON BACKWARDS, you will never get the settings correct as air will NEVER be allowed to escape.
NOW….If you have the needle valve all the way out and you still have too much fuel pressure you MUST install the small restriction tube in the SIGNAL LINE that goes to the BEGI unit.
To explain what this does is as follows…
The restrictor tube does what its name implies…it restricts the amount of air flow and resulting boost pressure into the BEGI unit. With less pressure inside the unit, the diaphragm and metering piston cannot apply as much force down on the metering port and thus cant restrict the fuel flow as much.
IMPORTANT PRINCIPLE…. For any given setting on the needle valve for maximum fuel pressure, the use of the RESTICTION TUBE, will always lower the final fuel pressure seen under boost.
Example…
In my car I had the needle valve 1 turn in from being all the way out with a ZERO point ( no boost/no vac) fuel pressure set to 68-70-psi via the center hex bolt,
When I drove my car and saw boost (7-8psi) my fuel pressure would go beyond my gauge limit of 100psi!!
This told me that since I basically cant let anymore air out of the BEGI unit via the needle valve, my only other choice is to RESTRICT the amount of air coming in. Therefore I placed the restrictor tube in the signal line. On the next test drive, the fuel pressure stopped in the mid 80’s. with the needle valve un touched from the previous run.
I understand that we all have different size injectors, different set ups, fuel pump health and other variables but the steps in adjusting your fuel pressure to run at idle, 0”hg and under boost when using the BEGI are the same as far as I can gather.
Im sorry if this all reads as confusing, but Ive never had a good understanding of how the BEGI unit worked, what made it tick while it was operating and most importantly a proper way of setting it.
While all this was fresh in my head I decide to
it all up on here…HTH
clear as mud??
Last edited by Tony; 12-13-2005 at 06:21 PM.
12-13-2005, 06:00 PM
#124
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L-jet and LH-jet up through 86 regulators run 30-36psi. 87+ regulators run 47-55psi. Everybody seems to look for 85-86 US regulators. Any US 80-86 or Euro 84-86 regulator is the same. The 16V cars have two, so they should be easier to find.
Tony, if you have a adjustable rising rate fpr, the BEGI is redundant. You probably just have an adjustable fpr plus the BEGI fmu.
Tony, if you have a adjustable rising rate fpr, the BEGI is redundant. You probably just have an adjustable fpr plus the BEGI fmu.
12-13-2005, 06:05 PM
#125
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Originally Posted by FlyingDog
L-jet and LH-jet up through 86 regulators run 30-36psi. 87+ regulators run 47-55psi. Everybody seems to look for 85-86 US regulators. Any US 80-86 or Euro 84-86 regulator is the same. The 16V cars have two, so they should be easier to find.
Tony, if you have a adjustable rising rate fpr, the BEGI is redundant. You probably just have an adjustable fpr plus the BEGI fmu.
Tony, if you have a adjustable rising rate fpr, the BEGI is redundant. You probably just have an adjustable fpr plus the BEGI fmu.
You see where i have scribbled on the regulator..."38-40psi vac line ON"
if im at idle and pull that line off the regulator, the fuel pressure will only go to 46-47psi max. If i could blow on the port of the regulator and create pressure, it wouldnt change.
Perhasp i used the wrong term describing what the type of regulator it is.
12-13-2005, 06:38 PM
#127
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Originally Posted by heinrich
Tony that is a wealth of information, more than I've ever read anywhere on the subject, thanks 
It was just buggin me that i didnt really know how this key part worked on my car or how to set it...im still not 100% as i have to check the AFR at the fuel pressures i have..
12-13-2005, 07:09 PM
#129
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Originally Posted by mspiegle
Hmm... IIRC, you have a kit from his last run. Your crank pulley setup looks much different than what the majority have. I think most people have a larger anodized crank pulley. Is your stock pulley supposed to go inside of the SC pulley?
I don't know how the this one pulley he sent me is supposed to do complete the groupo, Andy never sent me instructions or comments.
BUT if it were going to go on the outside of the stock crank pulley, what does the v-belt part go to? Maybe the last accesory driven from the crankshaft...?
Q- Is the crank pulley a different offset or diameter for the whipple/autorotor than it is the Eaton/Jag?
12-13-2005, 07:41 PM
#130
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Tony
Are you running 36 to 38 lbs fuel pressure at idle? My idle pressure is 29 to 30 lbs. I understood that 29 to 30 lbs to be the number to strive for.
Are the injectors you are using the same ones that some of us are buying from Summit Racing part #M-9593-B-302 #30? My understanding is that these are actually 24 or 25 lb injectors.
Just trying to clear up misunderstandings as we go here. This is information I got first hand from Andy last Aug/Sept. when I did my install.
Are you running 36 to 38 lbs fuel pressure at idle? My idle pressure is 29 to 30 lbs. I understood that 29 to 30 lbs to be the number to strive for.
Are the injectors you are using the same ones that some of us are buying from Summit Racing part #M-9593-B-302 #30? My understanding is that these are actually 24 or 25 lb injectors.
Just trying to clear up misunderstandings as we go here. This is information I got first hand from Andy last Aug/Sept. when I did my install.
12-13-2005, 08:24 PM
#131
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I need to find out ASAP. If that is the case my 30's are being run on a rear turbo set up and this would be important info for them to have...
Originally Posted by Daryl
Tony
Are you running 36 to 38 lbs fuel pressure at idle? My idle pressure is 29 to 30 lbs. I understood that 29 to 30 lbs to be the number to strive for.
Are the injectors you are using the same ones that some of us are buying from Summit Racing part #M-9593-B-302 #30? My understanding is that these are actually 24 or 25 lb injectors.
Just trying to clear up misunderstandings as we go here. This is information I got first hand from Andy last Aug/Sept. when I did my install.
Are you running 36 to 38 lbs fuel pressure at idle? My idle pressure is 29 to 30 lbs. I understood that 29 to 30 lbs to be the number to strive for.
Are the injectors you are using the same ones that some of us are buying from Summit Racing part #M-9593-B-302 #30? My understanding is that these are actually 24 or 25 lb injectors.
Just trying to clear up misunderstandings as we go here. This is information I got first hand from Andy last Aug/Sept. when I did my install.
12-13-2005, 08:41 PM
#132
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The pressures at which they're rated is different, but I don't think the # rating is that far off. IIRC, Ford's 24lb injectors are closer to 22 or 23 at the Porsche spec. The early 24lb Porsche injectors are rated at 22 by GM.
12-13-2005, 08:50 PM
#134
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Ok, I am just passing on information given to me by Andy. At the time I was in discussion with John Speakes about Fuel pressures and injector size. These are the numbers Andy told me to quote to John.
12-13-2005, 08:53 PM
#135
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I just did some googling. Ford seems to use several different specs, but their 19, 24, 30, and 36 lb injectors seem to be rated at 43.5psi which is the same as the 3bar Bosch uses. The flow rates should be the same, which makes sense since Bosch makes the Ford injectors. If somebody has the Bosch part number for the Ford injectors I can check the Bosch spec.