RolexNJ

So do I understand correctly that you still have the LR Billet Rail on, but removed the dampner itself? And now, you have "no" knocking, banging, clunking noises coming from anywhere at all? Also, I've never heard LR say that about the 72 lb injectors too, but maybe this is something they found out recently. Thanks for sharing this info.

Tom: Why don't you try what he says, instead of the band-aid approach and see what happens? Can you block off the end where the dampner goes and still use SS lines?

Tms951

Rolex, yes the dampener was simply removed and the end fitting capped off. The slower louder knocking sound is gone a replaced by a faint sound on time with the injectors. It is not dead silent but it also can not be heard with out popping the hood and getting in close to the rail and lines.

Are far as lindsey coming out a stating a spec on the dampener they have not, the fact that the dampener is rated for 55-72lb injectors came from a personal conversation with Wes.

RolexNJ

Thanks again for clarifying that. With bigger injectors, such as 72 or 83, I don't think anyone will ever hear "dead" silence due to the nature of them. But the noise a lot of us were talking about is that loud tapping/clunking/banging types of noises. And to me, it was loud and unaccpetable. And I personally heard it the most when I was inside the car and near or at idle. That's when it was really bad. Anyway, thanks. Let's see if Tom can do it to his car and fix the problem.

blodstrupmoen

Same story with tapping noises.
I will try to replace the braided lines to se if that solves it.

Bump for the part number for the 911 Turbo dampener

Porschefile

Anyone have any issues with their 044's "whining". It's been awhile since I had my 951 running, but I distinictly remember the pump whining, though the whining was a bit inconsistant and would change pitch occasionally. It sounded almost as if the pump was being blocked or receiving inconsistant flow. What's odd is I replaced all the fuel lines, filters, the in tank filter/screen and everything in between so there were definitely no blockages anywhere. On top of that, I recently put a new 044 in my 911 and am experiencing the same inconsistant whining. On both cars, the whining would tend to get louder on longer interval drives (usually 1-2+ hrs straight). I'd assume it was louder as a result of the pump getting warmer or something. I'm used to higher flowing fuel pumps and how they generally make more noise, though the inconsistant pitch of the pump running is what worries me. Checked running fuel pressure too on both cars under operation (well it's been awhile in my 951's case) and everything appears fine so no obvious signs of abnormal pressure levels. I tend to get overly paranoid about stuff that normally isn't an issue but, I was curious if anyone else has experienced anything similar?

As far as knocking, I never experienced that on my 951 or 911.

Tms951

I have mine so it can be turned on with the car off and there is no wining at all but the sound of flowing gas is very audible

Anyone remove thier dampener yet? This is the fix. It is not because of your lines.

blodstrupmoen

Why would you remove and not replace the damper ?

Tms951

Because when it was removed the sound went away and there were no negative effects.

Under Pressure Performance

Fellow Rennlisters,

Sorry I have been a bit idle in the forums lately - I have been VERY busy in the shop and simply have not had the time to chime in here and there as I have in the past.

Anyway, I just stumbled upon this thread and thought I should enlighten those having the knocking/clunking issue...

It is true what what TMS said - The "effect" comes from the dampner, but it is not truly the cause. The cause is the combination of the higher volume pump and/or injectors in conjunction with the LR fuel rail and dampner.

First let me say that I have no issues with the LR rail design, but the Marren dampner does create the effect of a rod knock type noise. This dampner does not have a vacuum line, nor does it adjust/compensate for rising or falling fuel pressures - So, by nature, it simply works differently from the factory dampner. In a constant low pressure system (like a carbuerated application) this type of a dampner would work flawlessly and silently, but in the higher pressure, variable rate systems like you all have, it makes noise (similar, but different to water hammering in your home plumbing)

In TMS's car, the noise disturbed me because it sounded like the onset of a rod knock. It had similar characteristics, it was timed to the RPM, it was mecahnical in nature, and would become a bit more faint with a little throttle, then more pronounced at idle - SO, I wanted to rule out any mechanical issues before we started on a quest for more power. The moment I got the car on the lift I could tell it was coming from the fuel lines, and I immediately decided to dump the dampner - It took me longer to convince TMS that his problem lied there than it did to remove dampner and cap the rail.

In short, if you have the fuel rail/line knocking noise and think it is dangerous, don't worry, the dampner does not restrict the fuel flow whatsoever, so there is no harm in keeping it in place. However, if the noise drives you crazy, do your sanity some good and just remove the dampner and you should be happy to find the noise goes away.

Hope this helps - And again, sorry I have been out of the loop for a while.

Sorry for any spelling/grammar errors - My fingers try to type faster than the ability allows.

Enjoy!

TRP951

is it possible to use some less stiffer diaphram in the dampener.
wouldnt removing the dampener cause some kind of problem though with high hp levels?

Under Pressure Performance

Running the vehicle without the dampner has no ill effects. A dampner is used to mask the hammering/pulsing in the fuel lines/rail, but in the cases cited in this thread, the removal of the dampner will quiet things right up.

The pressure is not an issue as the dampner is not a regulator - It is an isolator of sorts.

The factory dampner was able to mask the relatively minor pulse effects in the rail from the injectors firing, but these pulses are miniscule in comparison to the knocking that others are observing.

Of course, if anyone has any reservations running without a dampner, then by all means, keep it in place.

If it means anything, I can't remember the last race engine that I ran a dampner on - Heck, any remaining rubber lines from the pump, and the braided lines themselves act, in effect, as a dampner of sorts, certainly enough to absorb most of the pulsing effects from the injectors.

hot-J

Interesting........ Looks like I'll give it a shot too... Good Job Scott.

Under Pressure Performance

Hot J,

I'm sure you will have similar results as TMS

By the way, did you ever get around to sending me an email regarding the clutch? If so, I never got it, but you may have sent it to a VERY old email address. The reason I believe this may be true is that you mentioned Clark's Garage during our phone conversation but the section of his site that has my contact information is quite out of date.

Feel free to email me: speedfreak@area951.com or feel free to give me a call 508-989-3970

In fact, anyone that would like to discuss this issue in greater detail, please feel free to give me a buzz.

Talk to you soon.

Tom M'Guinn

Nice to see you around these parts Scott I've been too busy to try bypassing the damper, but will at my first opportunity. I am having this issue with a stock fuel rail and stock damper, with 83lb injectors and the 044 pump -- no LR parts on the car at all in fact.

(and, no, no time yet to assemble the motor or even uncrate the tranny...)

Under Pressure Performance

Tom,

The issue is not isolated to the LR pieces. Nor is it an issue with the pump itself, but there are definitely combinations of pumps, dampers, rails, and lines where this issue manifests.

It is also worth noting that removing the damper will greatly reduce (virtually eliminate) the knocking/clunking noise, but will do little if the noise you have is more of a fast tempo harmonic in the rail/lines - That is related to timing of the injector pulses and pumping effect through the lines - This noise will vary in amplitude at different RPM's as the injector pulses phase in an out of sync with the pumping pulsations in the lines - I hope that makes sense.

If you have a distinct knocking in the fuel lines, then the damper removal should do the trick.

Hope this helps.