killinfoo666

lets say we get rid of the dampner and replace it with a banjo bolt.

get a marren pd and put it in line between the upper and the lower fuel rails using a tee.

would that be enough to solve the problem?

It would be much easier to rebuild in that spot and you would'nt have to worry about clearance.

SureShot

Go for it..

A long loop of fuel hose would probably work also.

nyt

iTrader: (1)

I have no pulsation damper. I have no problems.

Aaron Cake

iTrader: (1)

It's there for a reason and should be used. Every electronic fuel injection system has a pulsation damper to smooth the shockwaves from the injectors opening and closing.

RETed

I have not seen proof of any downsides to the PD removal, even though there are particular members who offer very strong arguments against it.  A lot of it is regurgitating info and no real-world experience that back up these claims.

I've done it on stock FC's.
I've done it on highly modified FC's and FD's.
None have killed their engine or showed any weird phenomena due to no PD.
This is my real-world experience and not some regurgitated info from references.


-Ted

Aaron Cake

iTrader: (1)

Here we go again...

I am not a fuel system engineer, so unfortunately, there are times when I have to trust the higher knowledge of those actually designing the system. The has to be a reason why 99% of EFI systems have a pulsation damper. Manufacturers don't just put extra parts on without a reason (except, perhaps, for that ridiculous cold-start resevoir). Unless you have specific, real world and lab proof (for example, connecting a pressure transducer to the fuel rail and driving the car under all circumstances while data logging the whole event) that the part is not required, it only makes sense to leave the part in place.

RETed

We've done Haltech tuning on PD, no PD, aftermarket FPR and none of it changes the fuel maps.  That's good enough proof for me.  If there was a problem it will quickly pop up under this condition under the EGT and wide-band.



-Ted

pyrojunkie

I have seen pulsation dampeners used on a carb'd MG Midget. Most people explain the PD's for use in a fuel-injected system. They must not be fuel-injected related though as I have seen them in this carb'd car.

shiftnmadkwik

how much does another banjo bolt cost from mazda, if i wanna yank the dampener? and do they come with crush washers?

fstrnyou

I don't remember seeing any PD's on GM vehicles (camaros/firebirds)

neptuneRX

Ok I'm not going to call my self an authority on PDs, but God knows I've lost sleep over it. I've also spent the last 3 months making a new and improved PD. At anyrate Ted is correct, the PD is much like the Cold Start crap. at most, it really doesnt do anything, other the start fires. Also I was under the impression it smoothed out pulses from the pump, not injectors, but I could be wrong about that.

Solution: Just run some SS line from the fuel filter to the rail and you'll be all good. Or, do what I'm doing, and go all out and changing the all the fuel lines to SS. actually, I'm changing all my lines to Stainless Steel.

-From Nevada!
Christian (see I can't even stop thinking about RX7s while on vacation! )

Icemark

If you were going to do that, and use the Marren PD, it should be attached to the main fuel rail, not between the two. The FP Regulator acts like a PD for the secondary fuel rail.

Rookie84

Can you replace S5 PD with banjo bolt?? If so, what size banjo bolt and what other things would I need for that? Some people said S5 can't use banjo bolt and I want to know if it's true.

Icemark

No, the S5 PD is welded to the fuel rail, if you wanted to replace the PD with a bolt or an adapter for an after market PD you would need a S4 fuel rail

fstrnyou

ok, i have an S4. what are the threads for the fuel rails? 6 or 8mm? i also want to convert all my lines to SS.

when i was installing my motor, i shook the PD and noticed that it rattled. and there is a dirty yellow plastic cover over it. i took it off and a screw fell out. so, i screwed it back into the center of the PD. aparantly, the screw has been out for a while now, even when i was running my old motor. what does that screw do??

Maxthe7man

I guess a set of hammered injectors and a popped motor is not "real world experience"...
give me a break....
I would have to say those that have experienced it, are most likely people that have moved on to a higher output level than most people experience.. I would also say there are alot of people out there have popped a motor and wondered why , how many times have you read," all the a/f's were good, the timing was good, it just let go".... well I think that phenonem is in the fuel rails..
Will it show up on a guage? probably not...
Will it show up on a wideband, probably not, although it might show up on a narrow band, much like the closed loop in that regard, its to fast of an event, and you get an "averaged" readout on most widebands..
Is it there all the time? No, it seems every fuel system has a certain resonance, where the fuel delivery will become unstable...
You can basically corral this occurence to batch injection, in sequential injection, the pulses according to GM cancels each other out.
You can read about this on visteon.com
Kinsler.com
Injector.com
delphi.com

For other rx-7 owners views

http://www.sa22c.org/cat_12/36391/
Bosch shows the puslation damper in all of their fuel injected schematics, even in Teds beloved "maximum boost" its in there as well
The best read is fuel injection installation performance and tuning where there is a significant write up on it, in the design of fuel rails..
Its in alot of SAE the papers on fuel injection and fuel delivery, its in the haynes efi manual, other car manafactures to use it include Honda, Volvo, toyota, nissan, chrysler, etc etc.
How I found about the problem, is dealing with a problem on a buick Grand national, that wouldn't set a code for a misfire, I was given the phone number for GM technical support, in trying to diagnose the grand national, I was enlightened to the injector flow rates changing on batch fired cars, and ijectors having a higher failure rate than sequential fuel injected cars, and the pulsation hammering phenonem. The less rubber you have in the fuel line , the worse it gets...
If you can save a buck on a car, and you make a million cars thats a million dollar saving, they aren't putting the pulsation dampeners in over a million cars, just for kicks now are they...Max

pyrojunkie

RETed posted his own experiences with no pulsation dampener. I would count this as "real world experience".

What you "think" is happening to other vehicles is not "real world experience".

PD's may not be useless, but I fail to see your factual input on this, Maxthe7man. Certainly automakers don't spend money on useless parts, but your guesses on other motors failing is not proof

Since I know PD's have been installed on NON-fuel injected cars, I know the protection isn't only for the injectors. It seems, in some more research, are designed to protect the fuel pump.

If the PD's double as protection for the injectors, I can't say. I have no evidence to say that. I certainly wouldn't go out and say they don't protect the injectors, but thats because I wouldn't overstep the boundaries of my knowledge.

J-Rat

iTrader: (2)

Dude,

Max and Ted are arguing on like 2 different threads... WTF?

Maxthe7man

I am not arguing with Ted, Ted is arguing with the rest of the world on this one, it seems his experience on his mostly stock FC outwieghs what most of the auto manafactures in the world think, along with leading manafactures of efi equipment.. Most of Teds real world experience is unprovable, you don't get 10000 posts working on high output FC's and FD's, you get it by sitting on the internet blowing your own horn..
I know what failed in my car, that is a real world experience, on high output rotary...
If you are gonna chance a 2000.00+ motor, on skimping on a 100.00 dollar part, you deserve what you get...
Maybe Pyrojunkie would like to tell us why they are there, they do not protect the fuel pump, the check valve on the outlet of the the pump would close with a wave of back pressure.
I dunno, I am tired of explaining this, if you are dumb enough to risk your motor when there are nearly a 100 credible sources written by people alot more credible than Reted, then all the power to you...max

pyrojunkie

Since I have seen this questioned a million times I did as much research as I could on the purpose of the pulsation dampener. In other applications, the only protection I can see it designed for is the pump. If the protection was for the injectors, then it wouldn't be found on non fuel injected engines. I have seen for myself though they exist on such engines.

So Maxthe7man, you say your engine problem happened from no PD? That would count as "real world" proof. Strange, you didn't mention your car in the first post.

Rookie84

Max: Dude, no need to attack him personally. If you wanna argue about PD, then do it but no need to attack him like that. Ted has been very helpful to the members here and always kindly answered everyone's questions.

You're just taking this way too far. It's just a discussion about whether you need PD or not. CHILL OUT.

J-Rat

iTrader: (2)

http://www.autoshop101.com/forms/h42.pdf

PULSATION DAMPER:

The rapid opening and closing of the injectors cause pressure fluctuations in the fuel rail. The result is that the amount of injected fuel will be more or less then the desired result. Mounted on the fuel rail, the pulsation damper reduces these pressure fluctuations.

Page 19.

I have a PD, and I intend to keep it. But if you all want to remove it. Knock yourselves out.

Rat

Maxthe7man

To tell you the truth, I have never seen pusation dampener on carbed vehicle, I did just have a carter race mechanical pump part though, and there is a fuel pressure regulator, no dampener by any means though, so I don't know where you got your info from ? Links?

Rookie84, not and attack, just an observance...
J-rat, yep.... I guess you can lead a horse to water eh?,,

J-Rat

iTrader: (2)

Well, now I wouldnt put it like that.

I just present the facts. I respect Ted, and I feel that he provides alot of support to the rotary community. I just disagree on this point. Does that make me right and him wrong? Honestly, I dont think so. Its like the ATF argument, or the E- fan argument, or the fuel pump cutoff switch argument... There are 2 sides.

I run an E-fan (unshrouded too!.)
I run a PD
I wont put ATF in my motor..EVER
And I use fuel pump switches sometimes.

So am I right on those points or am I wrong? I say I am neither right or wrong. I just do what I think is best for me.

fastrotaries

My first TII lacked a PD all together it was an 87. MY current one has one, and it's highly modded. I didn't know the 87 was missing one, until I hit a bridge abutment. Never felt any form of bucking. Flooding, but that's common on those. So? I don't know. I know personally some Automotive Engineers and they're not all there.

YES they're engineers, but just because you're a janitorial engineer doesn't mean you can build a bridge. Or design a kick *** mop either.

Ted offered his personal experience, So Max don't come off and have this "small *****" syndrome. If you disagree then do so, and leave it at that. Seems to me like you came off a little aggresive, for no reason really.