Fuel tank mod - Version 2

[R0162]

I took my fuel tank down to open up the return and to try and solve the noisy fuel pump problem, i then remembered that i had already overcome this problem in the past by filling the sills with sound insulation, but this all got removed when i was doing the rebuild.
The sills act like a amplifier, and empty chamber which resonates, i know this only too well since i moved the air filter in there, the whoosh -pssstt sounds great.

So i don't want to lose that sound but i also don't want to hear the fuel pump buzzing, so i came up with this design, i modified the fuel tank again so that i can put the fuel pump and filter underneath whilst also improving on the anti- surge design on the tank.

The fuel pump is wrapped in sound insulation and another blanket of sound insulation is separating the side pod from the engine bay but still leaving the air flow gap between tank and chassis bar.

Hopefully this should also cut down a bit of transmission/engine noise, fingers crossed when i start it up tomorrow it will have worked.

Sorry for the poor pictures i was working late to get it finished.





Below is a photo of one of the home made baffles, it doesnt look like a big gap underneath but its amazing how fast you can fill a compartment with fuel through these gaps, in fact pouring fuel into one compartment seems to fill them all at the same speed about 4" up on the sloping face there is a horizontal strip approx 80mm, this is tack welded with a gap all around, and is to stop fuel from flowing too high up the sloping face under heavy acceleration when the fuel is very low(best to have it and not need it), the gauge shows empty when fuel is approx 4" above the bottom of the tank.

The design should allow the outlet to always recieve fuel under heavy driving even when the tank is showing empty.





People kept on saying to me to use baffle foam but how do you weld the tank with foam inside?

[GTO600]

Chris, if you want the foam you need a removable plate like l had on the tank l had made.

Tank is shorter & has fuel return & breather in the top with outlet on the left side.

[R0162]

Thats what i thought Kevin, some sort of bolted top design, creating an access panel it is definately the best way to design a tank imo.
Very nice tank design.

[wessexrfc]

Would be careful your pump doesn't over heat as they run quite hot.

[R0162]

I had my worries about this, so i asked my mechanic about this before wrapping it, he said the fuel running through keeps it cool.
I really need confirmation on this before i seal it all up tomorrow.

[andygtt]

cant really see what you are trying to achieve from the pictures.... filling with foam is simple, you make the tank but leave the top off... fill with foam and then weld up.

No baffling or foam will solve the noise from your pump, you need to feed the pump more effectivelly, you could use your original pump to feed the 044 or go whole hog and have a swirl pot like me.

My 4 pump arrangement (2 lifters and 2 044's) is much quieter than the single 044 setup similar to yours that I used to have.

[XLRONYX]

It's hard to tell from the pics, but it looks like the path to the pump is a bit uphill. I've always read that these high flow pumps don't inhale very well and so there should be a gravity feed to the inlet (all downhill from tank port to pump). I wonder if the noise is happening because the pump is trying too hard to suck and is cavitating.

Jeff

[spoed]

The cars built in South Africa at the factory [ours came fully assembled] all have the fuel pump wrapped up in a closed cell foam for noise. Probably about 2 inches of the stuff. What the factory guys did tell me, was that the fuel filter must be well maintained , or alternatively get a bigger filter set up which doesnt easily restrict the fuel flow. Also a restricted fuel flow makes for a noisy pump.

[R0162]

Hi Andy , i'm not trying to solve the noise from fuel pump with baffling, i had the fuel tank down to sort the return issue and decided to modify it for better anti surge, i also modified it to suit the new fuel pump location, so it was dual purpose.

While i was on with it i decided to sound insulate the fuel pump, that linked with new location is the only part of the mod which is to reduce noise.

I tried it out today and total success, i'm very happy with the results, it is so silent i could not hear it prime

[R0162]

XLRONYX said:

It's hard to tell from the pics, but it looks like the path to the pump is a bit uphill. I've always read that these high flow pumps don't inhale very well and so there should be a gravity feed to the inlet (all downhill from tank port to pump). I wonder if the noise is happening because the pump is trying too hard to suck and is cavitating.

Jeff

Hi Jeff

there may be 10mm difference in height between centre of pump and centre of fuel outlet, but the fuel pump will always be lower than the fuel level.
I mounted the fuel pump at its lowest possible point, that sound insulation is only 9mm thick and the pump basically touches the engine underpan.
Because of what you are saying is the reason i made the tank get smaller as the fuel level goes down, this creates pressure naturally and helps the pump.

I thought i would take a risk and see if the anti surge design really works, so with only 5 litres of fuel i did some heavy acceleration and gave it a bit of lateral g, it was a bit tense not knowing, but everything was good, not that i will ever be running it that low again intentionally

But i have definately found a solution to the noisy fuel pump problem, the cabin seems to be missing something without that buzzing sound, plus i now have a completey empty side pod ready and waiting for another oil/air cooler.

[anonymous-user]

R0162 said:

i made the tank get smaller as the fuel level goes down, this creates pressure naturally and helps the pump.

er, no it doesn't!


However, it is a good idea and helps prevent fuel "slosh"....... (assuming you can live with the reduced fuel capacity)

[R0162]

Max_Torque said:

er, no it doesn't!


However, it is a good idea and helps prevent fuel "slosh"....... (assuming you can live with the reduced fuel capacity)

why doesnt it help increase pressure? The weight of fuel/airpressure above pushing into a smaller space naturally increases pressure doesnt it?

If you were to put fuel in a big cone the height and size of a house, then put a small hole at the bottom, the pressure of the fuel at the point at the bottom would come out so powerful you could spray it for a long distance.

It is the theory of point loading or the pyramidial effect in reverse, if you take the weight of something above and bear it onto something smaller, then the localised load increases, best way to imagine it is to exagerate the situation, imagine an upside down pyramid, the loads increase and become more extreme as you go towards the tip, and it is reversed the other way round, thats why we still use the pyramidial effect in order to "spread" loads.