Fuel Dampener installed amazing improvement V8

[92 VP SS]

I always wondered why my SS felt so rough. Ive had a 97 HSV Senator and the same engine felt so much smoother.

Anyway I noticed my SS didnt have a dampener fitted, so today I went to the wreckers and got a dampener from a 3.8L VR, unbolted the mounting tab and installed it near the fuel rail entry just like my HSV had and viola my SS runs smooth similar to my HSV.

Anyway I suspect these little devices improve the fuel delivery by evening out the fuel pressure and they make a big difference to how the car runs. So if anyone elses V8 is running a bit rough I would recomend chucking one on, it only takes 10mins and stinging eyes.

Ps definiatly depressurise your fuel system (there is still pressure after) so, WEAR SAFTEY GLASSES TOO !

I might try installing 2 ? Thoughts anyone

[db_notso]

fuel dampners are normally fitted to cars with big pressure loss when the injectors are firing....
as it "dampens" the loss of pressure by sort of temporarily increasing fuel pressure as it drops to maintain a smoother fuel rail pressure,

its basically like a spring loaded valve that is designed to oscillate with fuel rail pressure fluctuation

basically it oscillates in time with injector pulses, fitting two will make one dampen the other and likely give little change to the rail pressure consistency.... but yeah they were goin to fit a dampner incorporated to the fuel pump on return but decided was too expensive in mass production as not EVERY car showed signs of fuel rail pressure fluctuation...... for whatever reason....

[92 VP SS]

My car must of had significant fuel pressure fluctuation ! It runs so much nicer now. Smoother idle and smoother power delivery I would even say quicker. I was thinking of just having the two dampeners in line but maybe even splitting the fuel line and running them parallel.

When I used to squeeze my fuel inlet line i could feel the pulses they were the same pulses that ran through my car and probably even pulsed into my engine making it run rough. Now when I squeeze the hose after my Dampner it feels smooth like there are no real significant pulses.

So GM were going to fit one on the return line ? Near the fuel tank ?

If you were going to fit 2 where would you put the 2nd one? Also why do you think my SS didnt have one at all ?

Sorry for all the Qs, I have a few avaliable at the moment for free so Im going to try it out. Even if I get 10% of the improvement I got with fitting one it would be worth it !!!

[Pub247]

I always was told they dampn pulses from the fuel pump not anything to do with injectors
If they were to have anything to do with injectors wouldnt make sense to fit them after the injectors not before?

[92 VP SS]

I think they have more to do with the injectors than what yourve been advised. Think about this, the injectors use the pressure in the rail to inject the fuel, if the fuel pressure is fluctuating the injectors pulse will be inconsistant. The dampner smoothes out the fuel pressure by storing pressure and releasing in evenly thus the injector sees consistant pressure.

Im sure there is a better way of describing this.

My car didnt have one so I put one on today and its made a HUGE difference. Now Im thinking if one makes a big difference can 2 make a bit more of an improvement.

[Brett_jjj]

I always was told they dampn pulses from the fuel pump not anything to do with injectors
If they were to have anything to do with injectors wouldnt make sense to fit them after the injectors not before?

Ive heard the same,that they smooth out, or dampen out peak fuel pump pressures..

[Pub247]

I think they have more to do with the injectors than what yourve been advised. Think about this, the injectors use the pressure in the rail to inject the fuel, if the fuel pressure is fluctuating the injectors pulse will be inconsistant. The dampner smoothes out the fuel pressure by storing pressure and releasing in evenly thus the injector sees consistant pressure.

Im sure there is a better way of describing this.

My car didnt have one so I put one on today and its made a HUGE difference. Now Im thinking if one makes a big difference can 2 make a bit more of an improvement.

Umm isnt that what a fuel regulator does stores up pressure in the rail so fuel pressure doesnt fluctuate

[92 VP SS]

From what I've learnt in trying to find out why my car runs so much better with a dampner installed, is the regulator is a relief valve for the overall pressure of the system and the dampner levels out the pressure spikes caused by the pump and the pulses of the injectors.

Im certain the dampner has an affect on the consistancy of the pressure the injectors use. My theory is the more consistent pressure in the fuel rail = more consistent injection of fuel.

Pub247 does your VP have one installed ?

[Pub247]

yes my vp does my old vk efi had 2 aswell one near the pump and another before the rail

[calais24/7]

Can you show me what they look like and where they go lol?

[VK SL 3800]

I might just add, When i converted my car to a v6, the V6 has one behind the throttle body, and the VK EFI pump had one just off the pump, i have since fitted a VS tank and pump without the second dampener and i haven't noticed any difference.

[VK SL 3800]

Can you show me what they look like and where they go lol?

I googled for a pic for you and found a thread i posted lol, so heres a VK EFI pump and regulator:
EFi Pump Question

[92 VP SS]

I definiatly think you need at least one, preferably at the inlet to the fuel rail. But Im going to see if I get an improvement by adding another one.

Pub247 or VK SL 3800

Was the one near your fuel pump after the fuel filter near the tank ? I think my VP SS has 2 pumps, I know one is in the tank but I dont know where the 2nd one is, I think putting one after the 2nd pump may further improve my injection system.

Calais 24/7 the fuel dampner should be on the inlet side of the fuel rail opposite side to the regulator, it looks like a round UFO on the passenger side of the car.

[VK SL 3800]

On a VK EFI its before the Fuel filter straight on the outlet of the pump, fuel system in the earlier girls goes something like this:

Pickup into pump, through dampener 1, through filter , through dampener 2, into fuel rail: Out injectors or through the regulator -return to tank.

My understanding is its main purpose is to stop line shudder or chatter from any sudden fluctuation in line pressure, basically its like one of those thing you buy to stop your pipes rattling in your house when you shut of a tap quickly, except the injector is the tap and your pump is mains pressure.
Older 'batch fire' injection is more subject to it as all injectors fire at once creating a more sudden buildup of pressure once the injectors close, it can create a sudden spike in pressure as the pump is ramming all the fuel up the lines and then the regulator hasnt opened quickly enough to allow pressure to escape.

[92 VP SS]

Ok great thanks VK SL 3800. I will try running two on my SS to see if I get any further improvements when it didnt have one near the rail it was awful in hindsight but I put up with it because I love my old beast.
I assume 1 dampener is critical and the 2nd probably wont have a great affect but I will find out either way when I find where my 2nd fuel pump is located ! Will hit the forums unless anyone readily knows where the VP 5L fuel pumps are located ?

[VK SL 3800]

If its got two it will be up and under the back just follow you fuel lines from the tank, but i thought VP's went to a single pump arrangement.

[92 VP SS]

Yeah I think your right mate, just did a thorough search through the forums and it seems the dual pump setup finished with the VNs, and the VPs have a single high pressure pump in the tank. Well Im going to pop a dampener on there just like you VK had originally.

I think I read somewhere there is a dampener on the pump in the tank but I would say that mine was either faulty or ineffective and with the results I got from putting a dampener before the rail I will be happy if i get a further improvement :-)

Thanks for you help/info. I will post back when Ive put the 2nd one on and let the forum know of any further improvement. But I would strongly recomend at this stage if one is not fitted at the fuel rail to get one on I just used one from a VS 3.8 and have another the same that will go after the pump near the tank.

[Circlotron]

basically its like one of those thing you buy to stop your pipes rattling in your house when you shut of a tap quickly, except the injector is the tap and your pump is mains pressure.

Yeah, I was going to say that too.

[mr calais 5.0]

Does anybody have a pic of it?

[92 VP SS]

Look here for a picture of it Holden 304 Fuel reg

[db_notso]

just looked into this a bit more today embarrising yes
its normally before in side of fuel rail from the pump

and SOME higher pressure systems (mercades and other older models holden etc)
had a dampner EITHER incorporated into the fuel preasure reg.or part of the fuel pump assl'y
there is one i have in the yard at work (old 5 litre??? or it was once )with 2 dampners with v6 stamped on them in parrelel on a v8..... not going to have time to play with it for you nor do i know what they are off....

and the pumps pulsating issues i found came down to three things
pump worn vanes......(pump dead)
fuel FLOW too low (pressure ok at idle but)......(pump dead)
or injectors too big for supply from pump/fuel rail.......(bigger fuel rail)

this is not my forte here obviously..... but from what i can gather if fitting a fuel dampner makes it idle smoother
you may have a fuel pump issue OR the engine is modified and the fuel system cant keep up (normally this would be from strokers)

[yxyx64]

the damper on a vr and vs v8 (not sure about vn or vp but suspect the same) is fitted above the left bank cylinder head on the fuel supply line. It is just a can (bosch part) much like a mini sized swirl pot. You can blow straight through it from one pipe fitting and out the other.

[Andrew426]

I dont think fitting a second one is going to give you any great imporovement, basically it works a bit like a capacitor for fuel - it just evens out high and low pressure pulses. Unless these pulses are actually exceeding the capacity of the first one a second one isnt going to make any difference

[CALAIS94]

pictures of said dampener