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fuel pumps...



 
 
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  #1  
Old December 30th 04, 06:39 AM
Jeff Davison
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Default fuel pumps...

How many horsepower will a high performance mechanical fuel pump on a
302 support? Would it be better to use an electric pump? Application is
for a crate 302 FRPP 345 HP motor with a 625cfm Grant Road Demon through
Heddman shorties and a Flowmaster dual series 30 & "H" pipe American
thunder system.

JD
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  #2  
Old December 30th 04, 07:22 AM
JS
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Default

Flip through a Summit catalog or something... I'm sure there are mechanical
fuel pumps that will go well into that range. And why not? Stock big
blocks push out more than that... same idea, smaller pump housing.

If you're only looking to push 400 or so horses through this thing, a
mechanical is quite feasible and recommended. The electric system will work
as well, but will cost you a lot more, and for probably remote gains at
best.

JS

"Jeff Davison" > wrote in message
...
> How many horsepower will a high performance mechanical fuel pump on a 302
> support? Would it be better to use an electric pump? Application is for a
> crate 302 FRPP 345 HP motor with a 625cfm Grant Road Demon through
> Heddman shorties and a Flowmaster dual series 30 & "H" pipe American
> thunder system.
>
> JD



  #3  
Old December 30th 04, 07:48 AM
Jim Warman
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Just to temper JS's advice a wee bit..... if you opt for the mechanical
pump, choose it wisely. I have experienced fuel pump float at high rpm....
The pump lever can't follow the pump cam and fuel volume will go down. One
very good thing about mechanical pumps is that when the motor stops, the
pump stops. Electric pumps "should" have some kind of Murphy device to shut
them off in the abscence of oil pressure or rpm..... (think 'can't get out
of the wreck and the fuel pump is still running'....). I like the safety of
the mechanical pump but the consistency of a good electric is hard to
ignore.

Yours is relatively mild compared to some of the grenades I've tried.....
and most of them lived quite well with mechanicals. Watch real close to see
if you're nosing over downtrack or through the traps.

"JS" > wrote in message news:G8NAd.14818$152.14108@trndny01...
> Flip through a Summit catalog or something... I'm sure there are
> mechanical fuel pumps that will go well into that range. And why not?
> Stock big blocks push out more than that... same idea, smaller pump
> housing.
>
> If you're only looking to push 400 or so horses through this thing, a
> mechanical is quite feasible and recommended. The electric system will
> work as well, but will cost you a lot more, and for probably remote gains
> at best.
>
> JS
>
> "Jeff Davison" > wrote in message
> ...
>> How many horsepower will a high performance mechanical fuel pump on a 302
>> support? Would it be better to use an electric pump? Application is for
>> a crate 302 FRPP 345 HP motor with a 625cfm Grant Road Demon through
>> Heddman shorties and a Flowmaster dual series 30 & "H" pipe American
>> thunder system.
>>
>> JD

>
>



  #4  
Old December 31st 04, 05:50 AM
Kathy and Erich Coiner
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Default


"Jim Warman" > wrote in message
news:2xNAd.31163$KO5.7946@clgrps13...
.. Electric pumps "should" have some kind of Murphy device to shut
> them off in the abscence of oil pressure or rpm..... (think 'can't get out
> of the wreck and the fuel pump is still running'....).


A friend used to drive a Chevy Vega that had a fuel pump wired to run only
when there was oil pressure.
One day the wire from the oil pressure sending unit fell off.
The car ran until the carb was dry.
The car stopped.
The fuel pump would not run until oil pressure built.
oil pressure would not build until the engine fired.
Engine would not fire until the fuel pump ran.
Etc.

Cars today use an inertial switch that cuts off the fuel pump if the car is
in a wreck.

Erich


  #5  
Old December 31st 04, 08:59 AM
Jim Warman
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Well, you're right and you're wrong..... Ford uses an inertia switch (not an
inertial switch) to cut fuel pump power. Other marques use various
strategies... oil pressure, ignition signal.... Lord knows what else. What
applies to one car doesn't necessarily apply to the one parked next to it.
The inertia switch requires a specific amount of force to activate..... I
can foresee the day where a mild accident breaches the fuel system but
doesn't trigger the inertia switch... the ambulance chasers wil have a field
day with this one.

I recall the Vega not-so-fondly..... aluminum block with cast iron linders
and a cast iron cylinder head to make sure the motor didn't leap out of the
engine bay. Every year or so we troop down to Circuit City or similar and
buy the latest greatest computer, all the while thinking that the "state of
the art" with autos has been stagnant for 50some years. Just when we think
we have seen it all, the engineers "improve" things.

Please, be sure of your facts before asserting a particular point.... I
would certainly be unhappy if I gave bad advice and the executor of their
will decided to make a test case out of the deal.

User installed, aftermarket pups are usually done with price in mind....
safety devices are often overlooked.....and, getting back to the initial
thrust of this thread - we ARE looking at a consumer installed, aftermarket
pump installation. Sadly, there is no inertial switch premounted with this
modification in mind....


"Kathy and Erich Coiner" > wrote in message
news:NU4Bd.6822$Y57.4212@trnddc08...
>
> "Jim Warman" > wrote in message
> news:2xNAd.31163$KO5.7946@clgrps13...
> . Electric pumps "should" have some kind of Murphy device to shut
> > them off in the abscence of oil pressure or rpm..... (think 'can't get

out
> > of the wreck and the fuel pump is still running'....).

>
> A friend used to drive a Chevy Vega that had a fuel pump wired to run only
> when there was oil pressure.
> One day the wire from the oil pressure sending unit fell off.
> The car ran until the carb was dry.
> The car stopped.
> The fuel pump would not run until oil pressure built.
> oil pressure would not build until the engine fired.
> Engine would not fire until the fuel pump ran.
> Etc.
>
> Cars today use an inertial switch that cuts off the fuel pump if the car

is
> in a wreck.
>
> Erich
>
>



  #6  
Old December 31st 04, 03:53 PM
David M
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On Fri, 31 Dec 2004 07:59:45 +0000, Jim Warman rearranged some electrons
to form:

>
> I recall the Vega not-so-fondly..... aluminum block with cast iron linders
> and a cast iron cylinder head to make sure the motor didn't leap out of
> the engine bay.


My sister used to have one years ago, if I recall correctly,
she hit a small animal and it ripped the whole front suspension
out of that so-called car.

--
David M (dmacchiarolo)
http://home.triad.rr.com/redsled
T/S 53
sled351 Linux 2.4.18-14 has been up 19:11 1 user

  #7  
Old January 3rd 05, 01:09 AM
.boB
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Default

Jeff Davison wrote:

> How many horsepower will a high performance mechanical fuel pump on a
> 302 support? Would it be better to use an electric pump? Application is
> for a crate 302 FRPP 345 HP motor with a 625cfm Grant Road Demon through
> Heddman shorties and a Flowmaster dual series 30 & "H" pipe American
> thunder system.
>
> JD


You'll be surprised at how small of a fuel pump
you really need. It's all based on how much power you
expect to make, regardless of engine size, carb type,
cam specs, etc. A naturally aspirated motor only needs
..4 to .5 lb/hp/hr.
go he
http://216.242.145.16/products/content_p.phtml?pk=11
to the Aeromotive web site for an excellent tutorial
on selecting a fuel pump.

IMO, electric is clearly the best racing pump.
But for a fun street car, it's too expensive and too
complicated. A mechanical pump will work just as well
on the street for a third of the cost and a lot less
work to install properly.



--
..boB
1997 HD FXDWG - Turbocharged!
2001 Dodge Dakota QC 5.9/4x4/3.92
1966 Mustang Coupe - Daily Driver
1966 FFR Cobra - Ongoing project

  #8  
Old January 3rd 05, 08:56 PM
Jack
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Default

Is there ever a risk of oversizing the pump?

Jack

..boB wrote:
> You'll be surprised at how small of a fuel pump
> you really need. It's all based on how much power you
> expect to make, regardless of engine size, carb type,
> cam specs, etc. A naturally aspirated motor only needs
> .4 to .5 lb/hp/hr.


  #9  
Old January 5th 05, 05:41 AM
.boB
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Default

Jack wrote:

> Is there ever a risk of oversizing the pump?
>
> Jack
>
> .boB wrote:
>
>> You'll be surprised at how small of a fuel pump
>>you really need. It's all based on how much power you
>>expect to make, regardless of engine size, carb type,
>>cam specs, etc. A naturally aspirated motor only needs
>>.4 to .5 lb/hp/hr.

>
>


Not really. As long as you set up your fuel
system correctly, whatever fuel isn't used will be
returned to the tank.
But if the pump is too big, it really just a
waste. Costs too much money, makes too much noise,
draws too much power, more difficult to mount, etc.

--
..boB
1997 HD FXDWG - Turbocharged!
2001 Dodge Dakota QC 5.9/4x4/3.92
1966 Mustang Coupe - Daily Driver
1966 FFR Cobra - Ongoing project

 




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