Pinfield357

ok i was unaware that it had another place to go i just though that it stoped at the end of the rail i understand now thanx for the help guys.

Matt22

iTrader: (10)

I thought this post could help with a the current Pulsation Damper thread. Late Matt22

RX-7Impreza

here it is circled

dcamcoTII

So will the banjo bolt directly replace the PD?? Does the PD just unscrew and the bolt screw back into its place??

ianbell

If using a banjo fitting YOU MUST put in a new copper crush washer and take great care not to over-tighten as banjo bolts are pretty thin skinned and it is very easy to turn the head right off one - guess how I know!

dcamcoTII

Gracias

dcamcoTII

Dosen't that part include the swivel-seal as well as the bolt?

dcamcoTII

Or is that the only way you can get the 12 X 1.25?
Couldnt you just buy the replacement bolt (Item # 997591)??

rx7sportscar

Hey, I'm just checking.... ya still got that new PD laying around? I might be interested.

Mark
86 Sport Restoration Project.

Thaniel

Yes, Yes.

rx7_turbo2

I used AN fittings.

One that threaded into the fuel rail, and another that made a 90 degree bend into a barbed end. Once the right fittings were found it was pretty easy.

Rotarykid7

hey does anyone know how much to torque the banjo bolt down??? i don't want to snap mine
-Andrew

Rotarykid7

hey does anyone know how much to torque the banjo bolt down??? i don't want to snap mine
-Andrew

sosofast

so will this banjo bolt do the same job as the pd? absorb the forces?

sosofast

why can't i screw in a extension fuel line where the pd goes and put the pd on the other end of the fuel line extension. locating the pd away from the engine but still letting it do its job.

Icemark

No it will not. It is simply a temporary bypass, that forces the FPR and fuel lines to do all the work of the PD

Icemark

you could, but ideally you want a PD as close to the injectors as possible. Any substantial length additions could result in the PD not functioning properly.

RETed

We've found no downsides on running a banjo bolt to replace the leak-prone pulsation damper, especially on stock ECU FC's.


-Ted

Maxthe7man

You can buy a replacement damper that is plug and play from Kemparts or one of their dealers..
Same damper used on 929, 626 ,etc
Kempart #153-730 ...
Max

sosofast

thanks i may go this option, as i dont' know hwo to set up the banjo bolt, even after reading a few threads on it.

also i'm gettin microtect lt8s, ret said wit stock ecu, i dont' wanna be the test with the microtech

WAYNE88N/A

Gotta throw my .02 in...Anybody that's ever done plumbing or lived in an old house knows what the "water hammer" sound is, it's caused by a sudden pressure increase when the taps are turned off...It is solved in modern times by plumbing that includes a 1-2' pipe containing air placed above the water fixture. This air absorbs the pressure shock induced by the water shutoff, so no "hammer" happens, and the plumbing is protected from these pressure pulses...Now, the exact same scenario is playing itself out in our fuel injected rx-7's...We have at least 2 (4 if we're having fun) injectors opening & closing several times each second, inducing those very same pressure pulses I was refering to earlier in the house plumbing analogy, albeit on a smaller scale. Our PD's are there to absorb these injector open/close shock waves. I know guys have said no harm is done installing a banjo bolt, I personally have no proof one way or the other, but I personally wouldn't want several 50 psi "mini-pulses" traveling in my fuel system every second, just as I don't want my house plumbing banging every time I shut off the water. Remember guys- you can't compress liquids (like fuel), the excess pressure has to be absorbed by SOMETHING...

RETed

And this is why I keep offering my counter-argument...
That water-hammer phenomena is caused by the dead-end of the valve.
The fuel system is NOT a dead-end.
The pulse travels into the FPR which, by design, is almost identical to the PD design, and also go through all the rubber hoses and throughout the entire fuel system.
If you haven't heard me the first time, it is NOT a dead-end, and you CANNOT apply this phenomena to the pulsing the fuel system.
What is supposed to happen is the pulsing gets so intense that it affects proper operation of the fuel injectors.
It is NOT the same.

What minimizes this problem is large diameter fuel rails, PD's, things that mimic PD's, shorter fuel rails, fuel injectors that are not run in multi-point or batch mode.

The stock FC fuel rails are around 10mm to 12mm in diameter.
I've heard 1/2" is the magic number, and this is close.

The fuel rails are relatively short - the primaries fuel rail is EXTREMELY short.

The stock ECU runs in full sequential fuel injection mode, so it does not meet the batch mode requirement.

So far, I have heard only ONE person who has claimed their engine was lost due to this.

I know of over a dozen FC owners who run the banjo bolt or removed the stock PD entirely on stock ECU vehicles who have not locked up their fuel injectors to cause engine failure.

I know of at least half a dozen more FC owners who have used my parallel fuel rail diagram using either an SX or Aeromotive FPR, and both companies have explicitly stated their FPR's do not require a PD.  Their engines are not failing due to fuel injectors locking up.

This is a very hot topic in here, and there are good arguments for both.
Personally, I don't feel like paying for something (Mazda wants some serious money for a stock replacement) that caused my car to almost burn down to the ground...


-Ted

WAYNE88N/A

Hmm..Good, solid counter-argument, Ted...Won't make me run out to the car & yank the 6-month old PD out of it to install a banjo bolt, but you're right- the analogy of the home plumbing is a bit off, if only because of the return system on our cars...That doesn't diminish the fact, however, that most (if not all) auto manufacturers use pulsation dampers on their fuel-injected systems...Do they perhaps know something WE don't?

Maxthe7man

One of the best write ups on fuel systems can be found here:
http://www.aempower.com/faq.asp?fid=17&sid=&tid=2

And another at Kinsler.com

Through most of my recent research, I have found that 99.9% of all aftermarket EFI shops, designers, and manafacturers push and condone the use of a pulsation dampener, even the ones that do not actually sell or manafacture a pulsation dampener..
Something I was let onto, in a further discussion with GM's engineering dept, I wondered why some of their vehicles seemed to have no pulsation damper, even some of the original batch fire systems, they were the ones that originally pointed me in that direction, why would they not include them I thought it was the move to sequential as well seems to help knock out some of the harmonics in the fuel systems, but GM does use a pulsation dampener, they however are aware of the possibility of leak,because of one side of the diaphragm having to be open to atmospheric, so they put theirs in the tank, GM says, no matter where it is in the system it will work, its the laws of hydraulics at work, thumbing through my GM truck manual, its incorporated into the sending unit structure..
The S4 pulsation dampener, is in itself not really a failure prone device, the same one is on 626's 929's and protege's right to 2000 and some...I believe its the large injectors, and the higher pulsewidths on the 13bt, leading to pulsations of greater magnitude and speed of occurence that causes the FPR screw to come out and the dampener to fail on large amount of FC's..
Using large injectors at lower duty cycles probably could help reduce the pulsation problem somewhat on some cars to a point. However IMHO using the supply line and such as a means of relieff for the pressure will fatigue hoses, and fittings, increasing the possibility of a leak and dangerous situation, searching the net for a few hours, I found people that had split fuel rails and cracked fuel rails due to fuel system harmonics...
I guess the big question, is how much HP and thus fuel are you moving, and are you a gambling man..... I am not much of gambler anymore....Max

NZConvertible

Ted, I'm going to direct this question at you personally, because evertime I've asked it as a general question, nobody seems brave enough to answer.

So for the umpteenth time, if PD's aren't necessary (as you claim) and there are absolutely no downsides to running without one (as you claim), then why does every single EFI engine out there (including all EFI Mazda rotaries) have one?

I don't care about aftermarket FPR's, or parallel fuel rails, or any other jazz. Stock fuel rails and FPR only, since your no-PD theory seems to cover this situation too.

I know why manufacturers put them there, I just want to hear why you think they're wrong.

BTW, you have posted before that the injectors are only fired sequentially below 3800rpm (i.e. primiaries only), and once the secondaries come on all four injectors batch-fire. This contradicts what you've posted above.

I think saying you won't pay for "something that caused my car to almost burn down to the ground" is a bit emotive. Your PD failed due to age, so that's no good reason to publically recommend against a brand new one. The two can't be compared.