i have a powerdyn bd-11 s/c that i am waiting to put on my 95gt. my car is stock with just bolt ons. trying to figure out what i am gonna need to run 6# and 9# safely. i'm assuming i wouldnt be much over 300rwhp if that so i wasnt sure if i would need new injectors, fuel pump, and all that. it has an fmu with it and i'm gonna use it for now, but i would rather get a tune for it, or at least get it on a wideband to check on a/f. any advice would be great.
extra's needed before s/c install
- Thread starter Finally a 5.0
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- Jul 21, 2005
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IMO I would say you could run the 6 lb pulley with no "issues" but you will ALWAYS benefit from a tune no matter what. I have the stock A9L computer as I assume you do, and running a 5-6 lb pulley I was as my tuner said "runnin dangerous." Some may say that the FMU is not proven to work, which is what my tuner said, (mind you he is really experienced) needless to say, after tuning my car his opinion changed. My point is, a tune is the most important. Secondly, if you wanna do it right, you should get an adjustable fuel pressure regulator, set it to 42 lbs, then get at least 30 lb injectors with a 6:1 calibration in the FMU(and of course your mass air meter matching) and switch your fuel pump. You can go with a 190 lph, but you might as well spend another 20 bucks and get the 255 as the adjustable FPR will regulate that just fine. You always need to provide adequate air and fuel, as you well know, hence I have given you a nice list for starters. Trust me, you will be happy as well as sufficient with this. I just switched from the 3.33 pulley to the 2.87 pulley on my SC and gained 4 lbs. With 30 lb injectors and the proper fmu calibration I had all the fuel and air I needed along with the stock ignition. I have posted enough for one post..Finally a 5.0 said:
so if you have any other questions, feel free to ask.I have a question:
If you're telling him to buy new injectors anyway, then why would you want to also run an FMU?
If you're planning for and have it in your budget to get new injectors, MAF, and a custom tune then get injectors large enough that you do not require an FMU. By the way, if you're only intending to run 6 psi and are going to use a FMU on a basically stock motor then you'll likely be able to get away with the stock 19 lbers with upgrading just the fuel pump. This is not the ideal setup and should be carefully monitored and tune with a wideband. If you're planning to spend the money on a custom tune (around $600 with a chip) then I'd also suggest getting injectors adequate for the job. Your stock meter will be just fine if you're not planning to upgrade your throttle body.
If you're telling him to buy new injectors anyway, then why would you want to also run an FMU?
If you're planning for and have it in your budget to get new injectors, MAF, and a custom tune then get injectors large enough that you do not require an FMU. By the way, if you're only intending to run 6 psi and are going to use a FMU on a basically stock motor then you'll likely be able to get away with the stock 19 lbers with upgrading just the fuel pump. This is not the ideal setup and should be carefully monitored and tune with a wideband. If you're planning to spend the money on a custom tune (around $600 with a chip) then I'd also suggest getting injectors adequate for the job. Your stock meter will be just fine if you're not planning to upgrade your throttle body.
well at first i wasnt thinking i would really need injectors. i always thought that 19# injectors maxed out at 300rwhp, and i thought that would be the max i would get out of my stock motor, and with the fmu and fuel pump i'd be ok. i didnt really plan the injectors and a tune into the budget, but wanted to do the tune shortly down the road. basically i wanted to do a budget friendly blower install, just to get it on there, but still be safe enough to drive around with it while saving up for injectors, tune, maf, and all that good stuff. but if i cant do that safely, it would be too budget friendly if i gotta buy a new motor from blowing it up. let me know what you guys think.
Your current situation is what FMUs were designed for. They are a 'bandaid' for use when the correct sized injectors are not available. Do they work? Yes! Are they the ideal setup? Not by a long shot.
Based on your last post, the FMU solution is probably right up your alley. Extra items aseide from the FMU would be:
Wideband 02 meter
Larger fuel pump or Boost-a-Pump
I tend to lean more towards the Boost-a-pump solution only because it gives you adjustability whereas tossing in only a larger pump does not. A boost-a-pump is also boost activated so that it only kicks in when it sees boost and doesn't affect your part throttle tune. That same feature also heats the fuel considerably less since it's making the pump put out more volume only under boost (unlike an adjustable fuel presure regulator that has the potential to change your fuel curve across the board). The other thing worth of note is that if using an AFPR that adjusted (roughly) outside of 20% then you run the risk of forcing the computer into open loop because the stock 02 sensors will be out of their readable range. The EEC will compensate for fuel pressure changes, but only to a point. The 20% I mentioned is only an approximation.
Based on your last post, the FMU solution is probably right up your alley. Extra items aseide from the FMU would be:
Wideband 02 meter
Larger fuel pump or Boost-a-Pump
I tend to lean more towards the Boost-a-pump solution only because it gives you adjustability whereas tossing in only a larger pump does not. A boost-a-pump is also boost activated so that it only kicks in when it sees boost and doesn't affect your part throttle tune. That same feature also heats the fuel considerably less since it's making the pump put out more volume only under boost (unlike an adjustable fuel presure regulator that has the potential to change your fuel curve across the board). The other thing worth of note is that if using an AFPR that adjusted (roughly) outside of 20% then you run the risk of forcing the computer into open loop because the stock 02 sensors will be out of their readable range. The EEC will compensate for fuel pressure changes, but only to a point. The 20% I mentioned is only an approximation.
i'll have the boost gauge for sure. so with the 255 pump will i have to have an afpr or will it just "know" how much extra fuel to put out with the fmu? also havent heard much about the boost-a-pump, everyone has said get a larger pump, but have heard nothing about this. anyone else have good experiences with this?
- Jul 21, 2005
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The answer to your question is becuase I ran a similar setup to his with just on the light side of 6 lbs and my tuner, Chung, tried to disconnect the fmu, with the 30 lb injecters and a Walbro 255 lph pump and he laughed at how dangerous it was. Said there was NO WAY AT ALL I would be able to run without the FMU. As far as the meter goes, again in my opinion its best to match your injectors with the meter and not try to ride the stock one.Daggar said:
fiveohwblow said:
I understand the need for an FMU in that circumstance however, it's the result of your injectors being too small for the combination. My point is that if you're going to recommend that someone get new injectors for a blown combo, then why not get injectors large enough to handle the job? Particularly if you're also recommending a custom tune.
On the meter thing:
Droves of folks mistakenly think that stock meters are calibrated specifically for 19 lb injectors. That is not the case. It's actually the EEC program that makes the determination of whether or not a meter is in correlation with a given set of injectors. Calibrated meters for X sized injectors are a "work around" developed to use the fuel ramps and tables already in the EEC. If a custom tune is obtained, then those fuel ramps and tables can be properly entered into the EEC so that the correct amount of fuel is given per volume of air. So long as the inducted air volume does not "peg" the meter then it's perfectly acceptable to use the stock meter for the application, particularly when the stock sized throttle body is used (since the throttle body will be the induction bottle neck and not the meter).
It's nuances like this that can either cost or save somone from spending money on things that are not required. The money saved on injectors and meter alone would pay for a good wide band 02 meter.
Just a thought.
- Jul 21, 2005
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Understandable. As far as what I suggested for him though, I did say "at least" 30 lb injectors. I think that they would be sufficient with just 6 lbs, and in fact they were with my 10 lb pull as my tuner was more than capable of utilizing them. However, you would be right to say without the FMU they would not be sufficient. I dont mind using the fmu though, as I only call on it to need it when I am boosting, which I hope is not very often...Daggar said:I understand the need for an FMU in that circumstance however, it's the result of your injectors being too small for the combination. My point is that if you're going to recommend that someone get new injectors for a blown combo, then why not get injectors large enough to handle the job? Particularly if you're also recommending a custom tune.
On the meter thing:
Droves of folks mistakenly think that stock meters are calibrated specifically for 19 lb injectors. That is not the case. It's actually the EEC program that makes the determination of whether or not a meter is in correlation with a given set of injectors. Calibrated meters for X sized injectors are a "work around" developed to use the fuel ramps and tables already in the EEC. If a custom tune is obtained, then those fuel ramps and tables can be properly entered into the EEC so that the correct amount of fuel is given per volume of air. So long as the inducted air volume does not "peg" the meter then it's perfectly acceptable to use the stock meter for the application, particularly when the stock sized throttle body is used (since the throttle body will be the induction bottle neck and not the meter).
It's nuances like this that can either cost or save somone from spending money on things that are not required. The money saved on injectors and meter alone would pay for a good wide band 02 meter.
Just a thought.
I wouldnt suggest utilizing stock injectors though if you are going to put the 9 lb pulley on though...
just4bob50
Active Member
I have a powerdyne with a 6psi pulley,and with a 4" inlet pipe and 90mm mass air it makes 7 lbs of boost at 6200 rpms. I never ran the FMU as i upgraded to the new mass air and 42lb. injectors at the same time. I also had the car tuned with an SCT chip. when i do heads ,cam, and 9psi pulley next year all i need is a retune. As it was mentioned earlier if you have to buy injectors buy big enough to get rid of the FMU. I was going to stick with the FMU, but found that the 4 local tuners didnt really want to tune the car with the FMU on.
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