How many GPH do I need
#1
12-07-2009, 02:51 PM
How many GPH do I need
With some discussion on another thread and I see this come up on other forums as well; How much GPH do we need for our trucks for a certain power level? I have seen this posted by Lowfly from FASS:
95 GPH - Good for up to 450-500 HP
150 GPH - Good for up to 650-700 HP
180 GPH and above will feed anything else.
Now from my drag racing gasser info i know you usually you take HP level you want to run and multiply it by .083 and that is how many gph you'll need. But since our engines have extra atmosphere help (turbo) you need to add 25% to that so:
650hp x .083 = 53.95gph x 125% = 67.43gph
That is just a rough figure and to get you an idea. according to that a 90gph pump will safely support 700hp. Over 700hp I would go with the 180gph or 220gph whatever they offer. I know pressure has a lot to do with this as well because as pressure goes up volume goes down so the higher pressures like the P-pump likes 40-45psi that number is probably off. So is there any formula to be used for diesels like that one above? I have seen guys push 500-600hp on a stock LP. How many GPH are those rated for? Is it because the stock LP pressures are lower around 17-30 psi? If so couldn't you lower the pressure on the FASS or Airdog and feed more HP?
95 GPH - Good for up to 450-500 HP
150 GPH - Good for up to 650-700 HP
180 GPH and above will feed anything else.
Now from my drag racing gasser info i know you usually you take HP level you want to run and multiply it by .083 and that is how many gph you'll need. But since our engines have extra atmosphere help (turbo) you need to add 25% to that so:
650hp x .083 = 53.95gph x 125% = 67.43gph
That is just a rough figure and to get you an idea. according to that a 90gph pump will safely support 700hp. Over 700hp I would go with the 180gph or 220gph whatever they offer. I know pressure has a lot to do with this as well because as pressure goes up volume goes down so the higher pressures like the P-pump likes 40-45psi that number is probably off. So is there any formula to be used for diesels like that one above? I have seen guys push 500-600hp on a stock LP. How many GPH are those rated for? Is it because the stock LP pressures are lower around 17-30 psi? If so couldn't you lower the pressure on the FASS or Airdog and feed more HP?
Never really thought about it...
#5
12-09-2009, 11:38 AM
Diesel Bomber
#6
12-09-2009, 12:10 PM
I totally agree....my 90gph FASS gives me 42psi all the time for right now but I don't think it will be enough for my upgrades. Which pisses me off because the person I got it from knew my plans and he told me it would handle it......so i figured I would start a thread like this and see what was required and if there was a formula to get an idea of where you need to start.
#8
12-09-2009, 09:20 PM
Diesel Fan
#9
12-10-2009, 11:02 AM
Duster...
First off,the pump you have purchased is rated for a stock to moderate truck.Now what defines a moderately tuned truck is up to ones own interpetation,however,knowing your shooting for 600's and quick et slips you do not have enough pump.
The 150 in that series like you have is not available so you would have to go to the 200gph which more than be adequate enough.I know from past experiences that a factory lift pump ,if new,may keep up with the demands of a built p-pump but if the system is older and has a few years on it then your really asking alot of it to try and keep up with the demand.
I am in total agreement with 94 12valve on this subject....
You can NEVER have enough lift pump,especially when it comes to keeping up with any built p-pump.Think of the demand at the whack of the throttle and the 90gph pump.The p-pump will suck the supply down so fast and hard it will struggle to get the lines refilled and always work from behind.The 150's and 200's will each have less work to do to maintain the supply,thus creating a more efficent fuel delivery which will stay even from the initial whack of the pedal until you lift off of it.
Recently my FASS 150/180-1010@45psi failed again.While chatting with the FASS tech man I was told it was his opinion that the demand from the p-pump was overworking the FASS while it was under heavy acceleration load.That fact was found to be evident when he had me pull the pump off and look at the 5/8" check ball under the T-block and see where it was.It was found to be sucked down into the block and stuck and when it did that it overloaded the work load of the motor and burned it up.That pump was a 180pgh which has been discontinued by them and will now only be offered as a 200 gph.So I will be replacing the t-block motor assembly with a new 200gph t-block and a upgraded 3/4" check ball to prevent it from being sucked into the pump body again.I am glad this didn't happen last month while it was on the jet and being gassed.All that nitrous,high rpm load and the fuel system taking a crap could have been devastating so I feel very fortunate that it quit while driving to work Monday night.
So in closing,IMO for the average owner who is not a true performance built truck the 95gph may be adequate but for anyone who is planning on their HP quest to keep going,its best to go big now or expect issues somewhere down the road......Andy
First off,the pump you have purchased is rated for a stock to moderate truck.Now what defines a moderately tuned truck is up to ones own interpetation,however,knowing your shooting for 600's and quick et slips you do not have enough pump.
The 150 in that series like you have is not available so you would have to go to the 200gph which more than be adequate enough.I know from past experiences that a factory lift pump ,if new,may keep up with the demands of a built p-pump but if the system is older and has a few years on it then your really asking alot of it to try and keep up with the demand.
I am in total agreement with 94 12valve on this subject....
You can NEVER have enough lift pump,especially when it comes to keeping up with any built p-pump.Think of the demand at the whack of the throttle and the 90gph pump.The p-pump will suck the supply down so fast and hard it will struggle to get the lines refilled and always work from behind.The 150's and 200's will each have less work to do to maintain the supply,thus creating a more efficent fuel delivery which will stay even from the initial whack of the pedal until you lift off of it.
Recently my FASS 150/180-1010@45psi failed again.While chatting with the FASS tech man I was told it was his opinion that the demand from the p-pump was overworking the FASS while it was under heavy acceleration load.That fact was found to be evident when he had me pull the pump off and look at the 5/8" check ball under the T-block and see where it was.It was found to be sucked down into the block and stuck and when it did that it overloaded the work load of the motor and burned it up.That pump was a 180pgh which has been discontinued by them and will now only be offered as a 200 gph.So I will be replacing the t-block motor assembly with a new 200gph t-block and a upgraded 3/4" check ball to prevent it from being sucked into the pump body again.I am glad this didn't happen last month while it was on the jet and being gassed.All that nitrous,high rpm load and the fuel system taking a crap could have been devastating so I feel very fortunate that it quit while driving to work Monday night.
So in closing,IMO for the average owner who is not a true performance built truck the 95gph may be adequate but for anyone who is planning on their HP quest to keep going,its best to go big now or expect issues somewhere down the road......Andy
Last edited by Hammer; 12-11-2009 at 01:20 PM.
The following users liked this post:
PhilipR (01-26-2010)
#10
12-11-2009, 06:54 AM
Thanks Andy and that's what I thought. I am going to have to call FASS and see if I can get the 200gph pump part sent to me so i can upgrade mine. My truck is my DD and I can't have it down for a week waiting for parts. I questioned the guy I bought the 90gph from but he told me it was fine....I figured he's built trucks before he's knows what he's doing......right.....I agree with having more pump than minimum though because it's easier on the pump.....my goal was 600 and he said it woulf fuel 700 easy so i took his word that I had plenty of pump...Maybe this explains why I have to pull the return line on the FASS once in a while and pull the check ball out of the spring.
