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Holden 6 fuel pump flow rate

Started by _rb3torana_ , Aug 01 2014 05:10 PM

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34 replies to this topic

#1 _rb3torana_

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Posted 01 August 2014 - 05:10 PM

Just wondering if anyones tested the stock blue or red fuel pump flow rate? Obviously they're rpm dependent. Or what are the limits of the stock pump? Cheers

Edited by rb3torana, 01 August 2014 - 05:11 PM.

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#2 _judgelj_

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Posted 01 August 2014 - 06:52 PM

Isn't it like 5psi or there abouts?

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#3 _rb3torana_

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Posted 01 August 2014 - 09:28 PM

I was more after a LPH or GPH value or a HP rating. Cheers

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#4 _judgelj_

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Posted 01 August 2014 - 09:53 PM

That's what i was thinking, but in the absence of an actual answer i thought i'd give you some irrelevant info

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#5 EunUCh

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Posted 01 August 2014 - 10:26 PM

Have never measured it but according to the HK workshop manual it should be 1 pint in one minute @ 500 rpm @ a pressure of between

3-41/2psi.

I pint is what i drink beer out of or about .473l/min....at the same rate as a holden six...lately anyway..the way things have been going.

Hope that's some help

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#6 warrenm

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Posted 01 August 2014 - 11:19 PM

Don't want to be picky, but a 1 imperial pint is 568ml, 473ml is a US pint.

Edited by warrenm, 01 August 2014 - 11:22 PM.

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#7 _rb3torana_

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Posted 01 August 2014 - 11:52 PM

So does that mean at 1000rpm it will be around 1L per min?

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#8 red6

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Posted 01 August 2014 - 11:53 PM

Would also be interesting to know the difference (if any) between the original glass top fuel filter and a later blue/black type fuel pump.

Edited by red6, 01 August 2014 - 11:53 PM.

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#9 EunUCh

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Posted 02 August 2014 - 07:41 AM

Your right about the pint measurement,my mistake,being a GMH publication for Australia it would be in imperial.

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#10 _oldjohnno_

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Posted 02 August 2014 - 11:50 AM

A rule of thumb that incorporates a generous 20% safety margin is 400ml/hp/hr

So a 300hp engine would work out to 120l/hr or 2l/min.

Another way to state it would be 1 litre per minute for every 150hp.

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#11 MustardGTR

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Posted 02 August 2014 - 01:18 PM

I'd say this demo this will stretch a standard red motor fuel pump for flow rate!

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#12 ls2lxhatch

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Posted 02 August 2014 - 03:46 PM

A rule of thumb that incorporates a generous 20% safety margin is 400ml/hp/hr

So a 300hp engine would work out to 120l/hr or 2l/min.

Another way to state it would be 1 litre per minute for every 150hp.

I setup this Fuel Calculator using the formulas from the Aeromotive Techinical Bulliten #501

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#13 EunUCh

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Posted 02 August 2014 - 04:44 PM

Just guessing here, but if at 6krpm does that mean that a serviceable stock fuel pump will pump 204l/hr?

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#14 _oldjohnno_

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Posted 02 August 2014 - 04:46 PM

I setup this Fuel Calculator using the formulas from the Aeromotive Techinical Bulliten #501

Nice! Have bookmarked.

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#15 _oldjohnno_

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Posted 02 August 2014 - 04:57 PM

Just guessing here, but if at 6krpm does that mean that a serviceable stock fuel pump will pump 204l/hr?

In theory yes, but in practice it'd be a bit less. As the rpms rise the valves and passages would become more restrictive, and because the pressure is limited by the spring tension there'd be some levelling off at the top end. I don't know how much; you'd have to test. SBC pumps are the go for a six - cheap as dirt and enough flow for any 202.

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#16 gtrboyy

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Posted 02 August 2014 - 07:22 PM

Chev hi-vol pump is easily best way to go about it.

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#17 _Bomber Watson_

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Posted 03 August 2014 - 06:12 PM

While were on the subject, i have an open querie i've been pondering for a while.

Before my LJ's cylinder head decided cylinder 3 needed water injection, I was having one issue with the carbs.

It has an edelbrock 140gph sbc fuel pump, aeromotive 4 port bypass fuel pressure reg, -6 from the tank to a filter to the pump to the reg then -6 all the way back to the tank. Pickup is in the bottom of the tank return is at the very top. -4 from the pressure reg to the HS6's (pressure reg acts as a distro block)

All was fine except for at idle, around 1000rpm (as low as i could get it in neutral so it would idle in gear) where the fuel pressure would fluctuate wildly, jumping between 0 and 6psi or so in time with the engines revolutions, with the reg set at 2.5psi. Just off idle it would even out and all was fine.

Obviously the one pump per revolution was pumping more than the reg could handle, but just off idle when the pump was working a bit faster it settled down.

After about 30 seconds or so of idling it would start spitting fuel out of the float bowls in time wiht the pressure fluctuation.

Has anyone else experienced this issue? Currently wondering what to do...

Cheers.

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#18 _judgelj_

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Posted 03 August 2014 - 06:30 PM

sounds like the reg wasn't regulating the fuel supply?

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#19 _Bomber Watson_

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Posted 03 August 2014 - 06:56 PM

.........

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#20 _oldjohnno_

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Posted 03 August 2014 - 07:32 PM

Has anyone else experienced this issue? Currently wondering what to do...

Cheers.

If you look closely at a mech fuel pump you'll notice a couple of things. One is that the diaphragm isn't connected positively to the rocker arm - the rocker can pull on the rod to fill the pump chamber but the only thing that pushes the diaphragm (and hence the fuel) back is a spring. The rocker arm is still moving, but the diaphragm rod is just floating in the hole in the rocker.

This is a really nice setup. Most of the time, especially under idle or low load conditions, the diaphragm barely moves at all, maybe a few thou. If it's a high output pump it probably still only moves a couple of mm at full throttle. The beauty of this is that the pump doesn't do any more work than it has to, so everything tends to last a long time plus the pump doesn't take any more power than it needs.

The other nice thing is that the fuel pressure is determined by the spring under the diaphragm, so it's a regulator in itself. Need more pressure? Just shim the spring. Need less? Use a softer spring. There's no need for an external reg if the pump has the right spring fitted. A reg with a bypass return is the worst type to use with a mech pump because the pump will be working flat out all the time just circulating fuel. Pump life will be badly reduced and the pulsation from the fully stroking diaphragm will give the reg a conniption. If you have to use a reg use a standard dead-heading one, it'll let the diaphragm float the way it was meant to.

Edited by oldjohnno, 03 August 2014 - 07:34 PM.

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#21 _Bomber Watson_

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Posted 03 August 2014 - 07:37 PM

AHA. So it IS something i did wrong.

Now i need to ponder the ultimate question, change the whole setup and run a dead head, or just go frOck it and fit an electric pump like everyone else does

Edit, option 3 i suppose, plug the bottom of the reg, keep it there as a distro block, and hunt around for a suitably soft spring.....

Cheers.

Edited by Bomber Watson, 03 August 2014 - 07:39 PM.

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#22 _oldjohnno_

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Posted 03 August 2014 - 07:49 PM

Mech pumps are quiet, simple and reliable, and they don't chuck a tanty if they swallow some air. Plus they don't have the wank factor of $1000 worth of stupid anodized shit in the boot. Just fit a standard reg and forget about it.