At Xtreme we use the Boost a Pump on all 500+ forced air and some Nat Asp,motors.I run 94 Lb. injectors on my 03and have a toggle switch and manually switch the BAP on for hard drivind a must have,as a safety measure alone.Dave S.
Just got my new KB with oil separator
- Thread starter Lomancobra
- Start date
Exactly my point! I plan on using the BAP to provide the extra safety margin. In my case, I'm going to leave it on all the time so I don't have any driveability issues. You can run the BAP continuously as long as the PCM has enough range at the low end to reduce duty cycle enough to maintain proper pressure. The fuel pump can not tell if the bus voltage is at 12 and the duty cycle 100% or the bus voltage is at 13.33V and the duty cycle 90%.
12 * 100% = 12V
13.33V * 90% = 12V
As long as the PCM can reduce the duty-cycle and not hit the lower limit of 20% d/c, there will be no negative impact of running the BAP all of the time (with reasonable voltage boost). Now, if you crank the BAP up too much and the PCM can't physically reduce the d/c enough, then you'll overheat the fuel, prematurely wear the pump, the pressure will be too high and the PCM will pull injector duty-cycle to compensate. Not a good scenario....you just have to be smart about it.
MJ
Im wondering, if the tune is good with no BAP but logging shows the FPDM to be pegging then maybe running the BAP (as opposed to having it installed but set to 0%) would offer some "insurance" or does the tune actually need to created to allow for BAP?
First, to the original poster, congrats on the setup and the work done by Herman, let us know how it goes when you get it tuned!
And now to continue to take this seriously off-topic but seriously interesting tech: Mark your saying your supply voltage to the FPDM dropped below 12v after adding heat exhanger fans? I'm about to install a pair of SPAL 6.5" fans.. what else did you do to put such a strain on the alternator, were the fans enough? Again were it not for you I would never have considered that installing heat exchanger fans would cause me to run leaner but it makes sense.. now..
Jerry
BAP
The Computer does not know if there is a BAP or not. The BAP only supplies additional fuel if needed/required, the Computer sets the fuel pressure by the program.
AMB
The Computer does not know if there is a BAP or not. The BAP only supplies additional fuel if needed/required, the Computer sets the fuel pressure by the program.
AMB
Not sure if I understand your question BUT .....
The bottom line is this: at any given hp level, you need a given amount of fuel. The fuel pump can only provide X lph of fuel at Y pressure where X and Y are inversely proportional. You can empiracally tune a single car and make good power and some might say that this proves that the fuel system is up to the task. However, you really need to look at the big picture and IMO the big picture includes safety margin. Just look what happened to me, bus droop caused my car to run ~ 1pt. leaner on average and have erratic fuel pressure (and erratic air/fuel). If you tune a car on the hairy edge, it only takes a small change to possibly make things go to hell real quick.
So, to quote someone else "it's all in the combo". When it comes to fuel delivery the combo boils down to this:
1. fuel pump (flow vs. pressure curve)
2. FPDM (functional?)
3. buss voltage (relatively constant under varying loads?)
4. PCM (ie. strategy, calibration, etc.)
5. fuel lines (how much pressure drop?)
6. FRP sensor (functional?)
7. Fuel rails and pulse dampener (enough captured volume?, how much pressure drop under high flow?, etc.)
8. injectors (enough flow capacity at a give delta_P, how much heat at high duty-cycles?, any problems going non-linear at high or low duty-cycles?, etc.)
MJ
Re: BAP
Exactly, the PCM has no idea of the BAPs existence. The BAP will not affect the PCMs ability to control pressure unless the BAP causes the PCM output to saturate at either the high or low duty-cycle limits.
MJ
Exactly, the PCM has no idea of the BAPs existence. The BAP will not affect the PCMs ability to control pressure unless the BAP causes the PCM output to saturate at either the high or low duty-cycle limits.
MJ
Hi Jerry,
My problem was caused by the following:
1. underdriving the alternator by 11%
2. running the SPAL fans, IC pump, and high-speed cooling fan in the staging lanes causing the battery to drain to a low level
3. running all of the accessories during the 1/4 as well as having the lights on (night racing) caused the bus voltage at the FPDM to droop.
The bottom line was that the alternator was being underspun and it had a huge load on it during WOT. The fans were on, the IC pump was on, the headlights were on, the battery was being HEAVILY charged, the fuel pump was running at high flow/pressure, the ignition was drawing high current, etc. As a result, the pump/driver just couldn't keep up.
From now on I'm going to be running a BAP for a little extra safety margin and piece of mind.
MJ
P.S. Moderators, should we take this tech stuff out and move it into a new thread? If so, please do it! I feel bad about hijacking this one.
Re: Re: BAP
Under normal circumstances without a KB chip the EEC will cut additional pressure provided by the increased voltage caused by the BAP. KB's chip works around the way the EEC controls pressure and lets the BAP do its job. Now, with a non KB chip like the diablo unit, the system runs fine at all rpms (in my case anyway) with the BAP turned to 0% but as you stated if the FPDM is at full duty cycle you on the ragged edge and run the risk of a voltage drop to the pumps and in turn damage. Since the diablo chip isnt tuned(as far as I can tell) to allow for higher fuel pressure like the KB chip is I am wondering this...... Even though my diablo chip wont allow for increased pressure via the BAP, is it still a good idea to run the BAP at lets say 25% JUST IN CASE so that if the voltage does drop to the fuel pumps the BAP is there?
Okay, I guess that is kind of what I was getting at. Lemme see if I can rephrase a little better.
Under normal circumstances without a KB chip the EEC will cut additional pressure provided by the increased voltage caused by the BAP. KB's chip works around the way the EEC controls pressure and lets the BAP do its job. Now, with a non KB chip like the diablo unit, the system runs fine at all rpms (in my case anyway) with the BAP turned to 0% but as you stated if the FPDM is at full duty cycle you on the ragged edge and run the risk of a voltage drop to the pumps and in turn damage. Since the diablo chip isnt tuned(as far as I can tell) to allow for higher fuel pressure like the KB chip is I am wondering this...... Even though my diablo chip wont allow for increased pressure via the BAP, is it still a good idea to run the BAP at lets say 25% JUST IN CASE so that if the voltage does drop to the fuel pumps the BAP is there?
Re: Re: Re: BAP
Dude, that is exactly what I'm going to be doing. :thumbsup: I plan on running the BAP somewhere in between 10-15% voltage boost *at all times* in order to provide 10-15% safety margin on the pump's flow capacity and also take advantage of the BAPs voltage regulation function to be sure that I always get a fixed and known voltage to the fuel pumps despite electrical load placed on the charging system.
I believe that this is what David does and recommends also (davidmax).
The only thing that I need to monitor is the PCMs ability to control pressure under low flow/pressure conditions with the extra pump driver voltage. If I'm consistently seeing FPDM output duty-cycles bordering on the 20% low limit (10% pwm measured using scan tool) then I may have to resort to using the hobbs switch or some other way to turn on/off the BAP. I would like to try to avoid this for driveability concerns.
MJ
Dude, that is exactly what I'm going to be doing. :thumbsup: I plan on running the BAP somewhere in between 10-15% voltage boost *at all times* in order to provide 10-15% safety margin on the pump's flow capacity and also take advantage of the BAPs voltage regulation function to be sure that I always get a fixed and known voltage to the fuel pumps despite electrical load placed on the charging system.
I believe that this is what David does and recommends also (davidmax).
The only thing that I need to monitor is the PCMs ability to control pressure under low flow/pressure conditions with the extra pump driver voltage. If I'm consistently seeing FPDM output duty-cycles bordering on the 20% low limit (10% pwm measured using scan tool) then I may have to resort to using the hobbs switch or some other way to turn on/off the BAP. I would like to try to avoid this for driveability concerns.
MJ
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Great info guys, thank you!
<----- Notes to self: lower pullies bad... take generator/charger to track for staging lanes.. buy a BAP
<----- Notes to self: lower pullies bad... take generator/charger to track for staging lanes.. buy a BAP
Lower pullies are not bad, just don't be an idiot like me and run the wrong alternator pulley. DOH! Instead of overdriving the alt by 15% I underdrove it by 11%. Also keep in mind that our alternator is only a nominal 110 amp output at 6000rpm alt. speed (Visteon 4G alternator).
MJ
Re: Re: Re: Re: BAP
let me just reiterate it again to double check.
Running with the BAP on will invariably cause in increase in fuel pressure which the EEC will respond to by telling the FPDM to lower voltage to the pumps until the the proper fuel pressure is acheived. On a normal, non BAP'd car at WOT the FPDM will be getting commands from the EEC and in turn will crank out voltage to the fuel pumps and we should log (via scan tool) a duty cycle of 10-51% (which we multiply by 2x for an actual duty cycle). Now, this is all fine and dandy but if we are running high HP we may find that the duty cycle is pegged 51%(ie 100% real). When this happens we run the risk of any small drop in voltage causing a drop in voltage to the pumps and a potentially lean situation.
Now, in a car with a BAP, but without a tune to allow for increased fuel pressure, if we have the BAP on, the initial effect is for the BAP to increase voltage from the FPDM to the fuel pumps which in turn causes an increase in pressure and subsequently causes the EEC to instruct the FPDM to reduce voltage going to the pumps and in turn the FPDM will be consistantly sending less voltage to the pumps based on where the BAP is set.
Now, am I correct in assuming Your concern is that under lower loads the BAP may cause the duty cycle to drop so low as to affect drivability because it is outside of the EEC range of "understanding".
If thats the case, it really shouldnt be a problem should it since the BAP is operated off of boost and wont actually"trigger" the BAP unless we are at least under some boost?
Okay, I think we are on the same page now
let me just reiterate it again to double check. Running with the BAP on will invariably cause in increase in fuel pressure which the EEC will respond to by telling the FPDM to lower voltage to the pumps until the the proper fuel pressure is acheived. On a normal, non BAP'd car at WOT the FPDM will be getting commands from the EEC and in turn will crank out voltage to the fuel pumps and we should log (via scan tool) a duty cycle of 10-51% (which we multiply by 2x for an actual duty cycle). Now, this is all fine and dandy but if we are running high HP we may find that the duty cycle is pegged 51%(ie 100% real). When this happens we run the risk of any small drop in voltage causing a drop in voltage to the pumps and a potentially lean situation.
Now, in a car with a BAP, but without a tune to allow for increased fuel pressure, if we have the BAP on, the initial effect is for the BAP to increase voltage from the FPDM to the fuel pumps which in turn causes an increase in pressure and subsequently causes the EEC to instruct the FPDM to reduce voltage going to the pumps and in turn the FPDM will be consistantly sending less voltage to the pumps based on where the BAP is set.
Now, am I correct in assuming Your concern is that under lower loads the BAP may cause the duty cycle to drop so low as to affect drivability because it is outside of the EEC range of "understanding".
If thats the case, it really shouldnt be a problem should it since the BAP is operated off of boost and wont actually"trigger" the BAP unless we are at least under some boost?
Re: Re: Re: Re: Re: BAP
Your understanding is good. I'm going to try to NOT use the "trigger" (i.e. hobbs switch) due to potential driveability issues.
Also, you can use the BAP to extend the flow capacity (range) of the pump regardless of whether your tune can command higher pressure or not. In fact, pressure control is not highly-dependent on the BAP if the PCM's command to the FPDM remains within it's output limits. The PCM controls the fuel pressure...period (except for when it can't due to exceeding it's control limits).
MJ
Originally posted by Shadowgray03
Okay, I think we are on the same page now
Running with the BAP on will invariably cause in increase in fuel pressure which the EEC will respond to by telling the FPDM to lower voltage to the pumps until the the proper fuel pressure is acheived. On a normal, non BAP'd car at WOT the FPDM will be getting commands from the EEC and in turn will crank out voltage to the fuel pumps and we should log (via scan tool) a duty cycle of 10-51% (which we multiply by 2x for an actual duty cycle). Now, this is all fine and dandy but if we are running high HP we may find that the duty cycle is pegged 51%(ie 100% real). When this happens we run the risk of any small drop in voltage causing a drop in voltage to the pumps and a potentially lean situation.
Now, in a car with a BAP, but without a tune to allow for increased fuel pressure, if we have the BAP on, the initial effect is for the BAP to increase voltage from the FPDM to the fuel pumps which in turn causes an increase in pressure and subsequently causes the EEC to instruct the FPDM to reduce voltage going to the pumps and in turn the FPDM will be consistantly sending less voltage to the pumps based on where the BAP is set.
Now, am I correct in assuming Your concern is that under lower loads the BAP may cause the duty cycle to drop so low as to affect drivability because it is outside of the EEC range of "understanding".
If thats the case, it really shouldnt be a problem should it since the BAP is operated off of boost and wont actually"trigger" the BAP unless we are at least under some boost?
Your understanding is good. I'm going to try to NOT use the "trigger" (i.e. hobbs switch) due to potential driveability issues.
Also, you can use the BAP to extend the flow capacity (range) of the pump regardless of whether your tune can command higher pressure or not. In fact, pressure control is not highly-dependent on the BAP if the PCM's command to the FPDM remains within it's output limits. The PCM controls the fuel pressure...period (except for when it can't due to exceeding it's control limits).
MJ
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Okay, here is a mathematical comparison I made between two systems:
System 1 - KB blower @ 15psi, 55lb/hr injectors, no BAP, stock fuel pressure:
1. Injector range: 620rwhp (10% margin)
2. Fuel pump range: 550rwhp (ZERO margin)
System 2 - KB blower @ 15psi, 39lb/hr injectors, BAP @ 50%, fuel pressure at 60psi:
1. Injector range: 575rwhp (5% margin)
2. Fuel pump range: 563rwhp (10% margin)
MJ
System 1 - KB blower @ 15psi, 55lb/hr injectors, no BAP, stock fuel pressure:
1. Injector range: 620rwhp (10% margin)
2. Fuel pump range: 550rwhp (ZERO margin)
System 2 - KB blower @ 15psi, 39lb/hr injectors, BAP @ 50%, fuel pressure at 60psi:
1. Injector range: 575rwhp (5% margin)
2. Fuel pump range: 563rwhp (10% margin)
MJ
Personally, if (when) I were interested in making a solid 550rwhp I'd run the following:
-55lb/hr injectors @ stock fuel pressure
-BAP at 10-20% boost
In fact, as soon as I do the KB, this IS what I'll be running.
MJ
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ttt
Surprisingly it does not sound as apparent as the eaton did. But when you start banging through gears the whine is definately noticeable and beautiful. You will love it!
steve, glad to see your happy with your car...
The way we treated you is the way everyone gets treated, i am very happy to explain whats going on with the car, not just take the money and run....:beer: I have found that when i fully go over the mods with the customer he comes away from the experience with a better grasp on why things work and can be more informed on whats going on with their car in the future if a problem arises.........glad your experience was a good one! hermann
The way we treated you is the way everyone gets treated, i am very happy to explain whats going on with the car, not just take the money and run....:beer: I have found that when i fully go over the mods with the customer he comes away from the experience with a better grasp on why things work and can be more informed on whats going on with their car in the future if a problem arises.........glad your experience was a good one! hermann
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MJ,
If my thinking is correct, the Hobbs Switch turns on the the BAP at a given boost, correct? My question is...wouldn't it help driveability since you would be starting the car up w/ stock fuel pressure (the BAP not activated yet)? It is my understanding that high fuel pressure during start-ups can sometimes makes it difficult for the engine to initially fire. I'm just curious what drivability issues one would run into when using a Hobbs switch. If my thinking is not off base, I thought most would opt for the Hobbs switch because it allow you not to run a higher fuel pressure during start-up.
If my thinking is correct, the Hobbs Switch turns on the the BAP at a given boost, correct? My question is...wouldn't it help driveability since you would be starting the car up w/ stock fuel pressure (the BAP not activated yet)? It is my understanding that high fuel pressure during start-ups can sometimes makes it difficult for the engine to initially fire. I'm just curious what drivability issues one would run into when using a Hobbs switch. If my thinking is not off base, I thought most would opt for the Hobbs switch because it allow you not to run a higher fuel pressure during start-up.
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