Can you remove the Fuel Pulsation Dampner for good?
 

There seems to be alot of talk about this piece lately and I haven't read anywhere that you can just get rid of it all together. I've got all the mods done that you can name....so it isn't needed right?

I know in the Supra's you remove it and it adds HP....it would be the same for the 7 right? I'm just asking because I'm still learning about the 7's moody nature. I don't want to do anything to piss her off if i don't have to....plus i just ordered a shit load of Earls fittings for the whole fuel system from front to back. I'm putting two intank pumps,SX FPR,SX fuel filter moved to the engine bay with all new lines. I want to get rid of everything that i possibly can to make it easier and more efficient.

Thank-you to anyone that can help:D

I was wondering the same thing myself. I'm sure the typical two camps will arise..."Mazda wouldn't have put it in if you didn't need it" and "I took mine out with no problems.."

MastaCow at the disco!!!!!!! lol

great pic.

I am curious if anyone has done this as well, I bet the guys in the single turbo section have done it with their fuel system upgrades. I removed it on my Supra when I made all the SS lines and had no adverse effects at all, other than the car running a bit more rich than before. BTW.. does anyone know what size Earl's fittings are needed in the fuel rails on the FD? I plan on doing SS lines and a relocation of the fuel filter when I actually get to dropping the fuel tank and upgrading the pump.

Matt
93 SSM

well it is used to stop the flow irregularity that causes the fuel pump so i suppose removing it will make the injectors have some high and ups in the fuel pressure. I wouldn't do it personnaly. It might not be that bad but...

puma

I'm going ahead with it anyway...I'll let everyone know how it goes. I changed both fuel rails around so that it's all Earl's fittings w/SS lines. It looks beautiful! It's coming together rather nicely I must say:D

Forgive the newbie-like ignorance, but wtf does the FPD actually do, other than leak and cause engine fires? What's it's official purpose, and how does it work?

Inquiring minds want to know!

Patrick

i think that is pretty much all it is good for.

would it be safe to take it out without any fuel upgrades first?

Well, I would say it would be safe to do so.. not too smart though. By the time you are in there enough to take it off you may as well make some nice SS lines and install an AFPR, otherwise it seems like a waste of time to me. I don't know why I haven't heard of more people doing this, with as hot and the engine bay gets.. on that side especially, it makes perfect sense to me to ditch the stock setup and go with SS lines and no pulsation dampener. I plan on doing this, no engine fire worries for me then.

Matt
93 SSM

SanJoRX7, it's not ignorant. You are looking for information by inquiring rather than ignoring.
The Fuel Pulsation Dampener (FPD) smoothes out the pulses that the Fuel pump generates as part of it's normal operation. By pulses, I'm referring the the peaks and valleys of pressure. The fuel pump does not generate a constant amount of pressure, this means that if you didn't have an FPD then some of your engine cycles will have recieved less fuel then others. This shouldn't really be a problem because the rises and drops of pressure generated by the fuel pump are not great enough to have any significant effect on the engine's performance or operation.
My question is: Why can't you just move the FPD closer to the fuel pump and away from the engine so that you can have the best of both worlds?

The FPD smothes the pressure waves caused by the OPERATION OF THE INJECTORS more than any flucations from the FUEL PUMP. Moving or removing the FPD is a BAD idea.

i thought that you can take out the pulsation damper whe you install new fuel rail, larger injectors and fuel pressure regulator.

Why is it such a bad idea? Does anyone have data to back this up? Any experiences? I am open to anything, I just don't see how the fuel system on the FD is that much different than many other cars I have done. I saw no adverse affects other than running at tad more rich than before at times, but that is what PFC or other electronics are for. At this point I am not convinced that it is a BAD idea, it is in fact probably a restriction just like it is in the Supra's fuel system. What could it potentially harm or cause?

Matt
93 SSM

I can't imagine a FPD being any different from car to car. The more I've looked around the more convinced I am of doing it.....I can't find any reason for it to be there on a modified car with aftermarket electronics. I'm designing my fuel system for a high HP car with aftermarket electronics so it should do OK....if not then I'll let you know. I'm getting more and more excited as I work on my fuel system....it's looking really sweet!:mspank:

If anyone is feeling particularly helpful, would you mind posting with the specific parts for upgrading all the lines to ss braided lines and what in-line fuel filter you used. I'm planning on doing this, but don't know where to start for parts.

I really want to know this..

You can use any of the "quality" fuel filters out there....Paxton,Aeromotive,SX,etc.... also the fittings are the same thing.....XRP,Earls,Aeroquip,Russell. I'm using all -6an lines from front to rear.

I've already removed the FPD....it doesn't really do much of anything....so there's no need to have it (this is only my opinion). I will post some of my pics when I'm done and it all works good..

Just so you know.....it's gonna cost you alot of money to do this. I've got $500 just in fittings right now and I'm not even done.....found 10 more things to change to alum. fittings and SS. I don't want anything but these kind of fittings when I'm done:cool:

I have an idea... how about a write-up ;) If you could make up a shopping list and a short how-to, alot of people would be glad to get rid of the FPD and upgrade their lines.

ok well heres a quick way to make a fpd...

all the fpd is is a space of air so the pulses dont shock the system..like plumbing in your house you have standing air tubes so you dont get that pipe knock
i have-8 an lines so everythign will be 4) -8 lines

youll need 1/4 npt tap
a earls fuel press gauge adater pn# ear-100197
basically its a npt to an adapter with a 1/8npt hole in it for a fuel press gauge
in that 1/8 npt hole youll need a pipe-to an adapter
pn#ear-981662 1/8npt to-6
then yull need a tube nut to cap the new fpd
pn# areoquip aer-fcm3675

tap the inlet side of the primary rail
then thread in the gauge adapter
put the pipe-an in the fuel press gauge hole cap that...
it will be like a big t with a small amt of air in the cap

ill post the stiff needed to hook it up to the stock lines in a bit..if not go to the rob rionetti site and go to his fuel filter section part

What Rob Robinette's site didn't cover was how to connect the SS lines to the stock fuel line or how to run the line back to the tank. The rest of it I have already planned out, just don't know that step.

it kinda does
you need 5/16" hose to 1/4" NPT adapter; one female 1/4" NPT to male -8 an

http://www.rx7turboturbo.com/robrobi...uel_filter.gif

see how he connects the fuel filter to the stock lines



if your runnin braided lines all the way bck just follow that procedure right @ the tank

:ret: duh, if i'd have only paid attention...

Your running -8 an lines from front to back? Is that really needed? I'm running -6 but I've thought about -8....is there a specific reason why you chose -8? Also I'm kinda lost on your FPD explanation......are you replacing it with your own version? Why would you need it? I've talked to alot of people who say it's garbage and useless.....i'm deleting it all together....but would like to know what other people think also that are doing there own system.

-8 lines are overkill IMO unless you are going for something beyond 400RWHP.. and well beyond I would think. -6 is plenty big.

Matt
93 SSM

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

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

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.

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

:withstupi 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.

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:D 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?

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:o: 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.

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

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:D
if its nesicary who knows
but for the 12$ its gonna cost me to add it in...its cheap insurance to me;)

how are you doing that bacon?

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 ;)

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

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 :D

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

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..

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.

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

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

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. :D

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.

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..!

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?

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

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.

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

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