FastX7

I was going to go with -8 lines, I have plans for something above 400rwhp though.

mjw

iTrader: (1)

Cool, planning ahead is a very smart idea.. -8 gives you gobs of headroom for power production. I still give a thumbs down to the FPD though.

Matt
93 SSM

silvr94r2

iTrader: (3)

I'm going for over 600rwhp.....but I'm putting twin pumps with 2 -6an lines to the front that y's into -8an into the rail. I'm still debating on whether to change to a fuel cell and run -8an.....I haven't checked to see if it's legal in the street class. I think -6an will easily flow 600+ won't it? I'm still looking into everything.....if I change my mind I can always put this one on my girls car.

Tim McCreary

Using larger diameter fuel lines will reduce in-line friction of the fuel traveling through it. IE: If you have 75 psi at the pump, you will have closer to 73 at the hose end on a larger pipe compared to 70 on a smaller pipe. This is just an example, not necessarily actual figures. Remember that fuel is at a dynamic pressure, not a static pressure. Your tires are at static pressure. There is no volume change of air in the tire and assuming standard temperatures don't change, the pressure remains constant. Fluid in motion reads dynamic pressure. If you were to hook a pressure gauge to the end of an air hose and put a 1/4" nozzel on the end of the line and open the valve, the pressure reading will drop from the static pressure to the dynamic pressure of the line. If you were to change to a 1/8" nozzel, the dynamic pressure will change. Using this example, think of a longer distance and different pipes. If you use a 1" pipe at 1 mile long and a 1/8" pipe at 1 mile long and put a pressure guage at the end of the line and a 1/8" nozzel, the dynamic pressures would be different. Even though the nozzel is the same, the pipe itself acts as a reservoir and the larger the pipe, the less surface area per cubic inch for the fluid to drag against to resist the flow.

Now back to the pulsation damper (or dampner not sure). I read that the intention of this was for high cycling of the injectors. Every time you turn on the injector, the pressure in the fuel rail drops suddenly and when the injector closes, the flow stops suddenly and the pressure rises again. Cycling this way causes pulsation pressure waves in the fuel in the lines. This resonance then can be amplified just like a tuning fork vibrating. Given enough resonance, the energy in the wave can cause damage. If a low pressure resonance hits at the fuel injector when it opens, then you will be starving the engine of fuel and going lean. If the resonance continues too long, the high pressure waves can exceed pressure ratings of some components and connectors.

Mazda installed the Fuel Pulsation Damper to prevent these things. It is like a shock absorber for the fuel lines. Would you drive your car with just springs only and no shocks? One option for those concerned would be to place a fuel line extension from where the FPD mounts to a more easily accessible and less thermal place and mount the FPD on the end of that line. Although less efficient than the fuel rail mouning point, it should still serve the purpose.

FYI The same pulsations were used in the intake design change from 1988 to 1989. The intake runner length and design was taking into consideration the opening and closing of the intake "valve". They had it timed so the high pressure wave would hit the intake opening to the combustion chamber just as the rotor passed the opening. This forced the higher pressure and higher volume of air into the combustion chamber to give better performance.

Tim

Mindphrame

Damn Tim. Man knows his stuff. Thanks for clearing that up, I had a mechanic get into an argument with me about that its a dampner (sp) not a regulator. He says I call it a regulator. Dont know why they call it a dampner. I told thim there are 2 diff things. Then what the hell is the point of this "Dampner"? I coulden't explain why, but now I can. Thanks.

silvr94r2

iTrader: (3)

Tim: I'm having a little trouble understanding the FPD.....I can understand it has to be there in a stock system but if you change everything from front to back wouldn't you have to take that into consideration? By the way, are you an engineer? You seem a little too smart or this is your field of study You kinda blew me away with all the dynamic and static pressure stuff....I understand it somewhat....just wasn't expecting such a scientific breakdown. You need to speak my language....(caveman voice) FPD good? FPD bad? grunt grunt. Since were in this deep then what about alum. fuel line vs. steel braided line?

silvr94r2

iTrader: (3)

also on the fuel lines.....you can go too big and lose velocity right? I'm tired right now so please excuse me if this sounds ignorant Wouldn't it be the same concept as intercooler pipes and exhaust? You want less restriction but still keep velocity up....too big and it's just huffing.....too little and it creates backpressure. Where would someone find the limitations of the different size lines? I would be interested in finding some kind of chart for this.

Bacon

iTrader: (12)

im shootin for over 500@ 22psi so -8 is only saftey and looking to future

the reason im making my own indestructable fpd is (as explained so nicley above)
its like a shock for a fuel system..
ok a bad demo but ...take you garden hose with squirt nozel on it...squeez it on-off--on--off--on--off
see how much hose moves, it can cause unnesicary pulsations and stress on the pump
so i just fabed up a foolproof model
if its nesicary who knows
but for the 12$ its gonna cost me to add it in...its cheap insurance to me

rx7speed811

how are you doing that bacon?

Bacon

iTrader: (12)

doin what 500rwhp?

prob t-87
haltec
ito ports-best ports money could ever buy IMHO
all the acomanying toys


its all in the tuning and the ports
i may end up with a t04s wich is good for abt 500@ 22..t-78 should be abt 550@ 22..
but well see

Trout

Bacon,
I think he's asking and I would like to ask, where are you getting a FPD that works with -AN lines?

I'm just starting to research upgrading of the fuel lines so this has been a very interesting thread.

For those of you running -8AN lines, are you running one or two lines from the tank?

I was thinking of one -8AN from the tank splitting into -6AN to each fuel rail than -8AN return to the tank. Although I like the idea of two lines from the tank with independent pumps so you have some redundancy.

TIA,
Jack

Bacon

iTrader: (12)

ohh ok well jack if you read on the first page of this thread i go into how to make it...i even listed the pn# so its a call summit but it and assemble it deal

very easy imho..but its not for the faint of heart...prob would cost 20$ if you just wanted to replace the stock and just hook into the stock lines right under the manifold

daiSho

the way it was explained to me was that the FPD could be eliminated if you were adding a secondary inline fuel-pump, mine has been gone since i did a large fuel system upgrade (including surge-tank) and went single..

FastX7

I think the surge tank would eliminate the need for a pulsation dampener then. Since the FP is pumping into the surge tank (?) and then the lines pull it from the tank. That's my understanding on it, please correct me if I'm wrong.

puma

iTrader: (2)

how is the fuel going from the surge tank to the engine then? I supose there must be a pump in the surge tank?

maxpesce

Tim- Thank you for the excelent explanation - I trust you agree with me that completly removing the FPD is a bad idea.

maxpesce

No, the FPD has LITTLE OR NOTHING to do with the fuel pump and the delivery of fuel to the engine (Fuel Rails) and EVERYTHING to do with DAMPENING PRESSURE WAVES caused By the cycling of the injectors PLEASE RE-READ TIM'S POST.

FastX7

Ha ha, yea, i read it once and I think I shorted something out. I guess I need to read it again and take what I can get out of it.

daiSho

probably should have detailed my fuel-system mods, i don't pretend to understand the workings here, just what i'm told..!

Inline/External fuel-pump (between gas tank & surge-tank)
Custom surge-tank
-8 fuel lines
modified fuel rail w/ 1600cc secondaries
aftermarket fuel pressure regulator

...w/ this setup, from what i have been told, the FPD is unnecessary. if this is incorrect, i'd love to be forwarned..!

silvr94r2

iTrader: (3)

That is almost the same setup that i'll be running Daisho.....i've also heard from quite a few sources that the FPD would not be needed. That was my question in an earlier post.....would it be needed on a completely custom fuel system?

the_glass_man

iTrader: (2)

Does anyone know if the aeromotive fpr has a built in fpd like the sx ones do?

InsaneGideon

The SX unit is rather large in volume and has a lightweight diaphragm. From what I've heard of it, it has no actual separate FPD inside. The characteristics of the regulator itself is what allows it to act like a FPD as well. In actuality, it may not provide as much damping as the stock FPD. Just something to consider with the aeromotive as well.

But then again the stock FPD may not be necessary in all cars. It may have been included in the stock design as a "precaution" to keep the 1 out of 5000 cars out of the factory succeptable to oscillating due to the luck-of-the-draw in combined parameter variances.

If in doubt, you can always tell with a fuel pressure gauge. If you ever notice wild fluctuations not related to boost, you're getting oscillation. I had another car with an mechanical FP gauge that would experience fluctuations spanning 70psi! The gauge felt like it was going to vibrate itself into total destruction. The car would go totally lean at full boost and buck like someone was hitting the brakes. A new pump fixed the issue.

manatecu

iTrader: (6)

I have completely ripped apart my fuel system and replaced it with a totally custom system. The first problem with the fuel system is the pump. The pump has two setting high and low. I think the pump shifts at 4k to the high setting. I can sometimes see this shift as the fuel pressure rise a little, kinda like a spike. I am Using an SX regulator. The nice thing about the regular is I can set the exact pressure I want to run at. The more pressure the more fuel is delivered. This is my substitute for running -8an lines. I also think that the FRD has something to do with the fuel configuration of primaries to secondaries in a series. When the secondaries kick in they begin to drop the line pressure significantly this does cause a surge. In order to deal with that I split the single line coming out of the fuel tank, added the filter before the split (By the drivers wheel), and then ran the two fuel inputs into the solid lines, leaving the third line for return. At the front of the car I ran one in line to the primaries and one to the secondaries. On the output side of each rail I ran each line to a seperate side of the SX FPR. This allows for dampening on both lines and allows for the High and low pulse to be dampened. I have been using this setup for about 1 year with no problems. I am putting down about 420 to the wheels and I havn't had one single problem with my car since I went this way.

I don't recommend tapping the rails. This can weaken the rails and cause a rupture, i have seen this several times. I recommend going with aftermarket rails (Keiths rails) They are both top loading and work great. The last thing you want to happen is to have a fuel leak that will trap fuel on top of the engine (Between the Lower Intake Manifold and the engine itself, very hot). This is a fire waiting to happen.

If you are going to do it do it right the first time.

Chris

j9fd3s

iTrader: (3)

http://www.k2rd.com/products/fuel/1743100.html

ghostrx7

I have those two for sale 50 bucks shipped anywhere, brand new never installed....