external pumps vs carb mounted pumps??

[junkyardj]

does anyone know the advantages of using external fuel pumps, if there is any?? is it for better fuel pressure? just got some new carbs and just thaught id ask...

 

[#ZERO]

The larger displacement modified engines with more HP require more fuel flow and the single Mikuni SBN body mounted fuel pump will only supply about 35 liters per hour.

Also externally mounted fuel pumps are less susceptible to vibration problems that are associated with carburetor mounted fuel pumps.

 

[junkyardj]

thanks, makes sense.. so the AM external pump push more fuel too? im going to be running a single with 2 outputs, seems kinda sketchy to carbs one pump? is it worth it to invest in two pumps?

 

[#ZERO]

Unless you're running a ported big bore or stroker engine there's no need for any additional fuel flow.

The SBN H-body mounted pump can supply 35 liters per hour which equates to 9.24 gallons per hour and these ratings are at 6000 rpm.

As a rule of thumb 1-gallon per hour is worth 10 hp, so that's 92.4 hp at 6000 rpm and the fuel flow is fairly linear above that, so at 7000 rpm it would be capable of 108 hp.

The SBN I-body carbs have a 40 liter/hour pump which is capable of 123 hp at 7000 rpm.

Also there's only one external fuel pump that flows more than 35 liters per hour and I wouldn't recommend using it for a single carb setup. http://www.mikuni.com/c-fuel_pumps.html

 

[junkyardj]

ya im going to be running a ported big bore with dual 48's, ill find out which pump it is.. thanks for the link..

 

[junkyardj]

looks like the: DF62-702
Outlets: 2
Flow: 65 Liters/Hour

should that be good for dual 48's?

 

[2lick]

looks like the: DF62-702
Outlets: 2
Flow: 65 Liters/Hour

should that be good for dual 48's?

Yes that seems to be the one to use. I am running that one now with some dual 48s as well. Works like a charm, make sure you get those zip ties on good it really pushes the fuel!!!

 

[enzo]

The other advantage to running an external pump is the ability to run a fuel/air separator.

My boat is a 6 mil ABLE with dual 44's. Ski would cut out when ever I would get down to 1/3 of a tank(Surf riding). Tried all kind of things to fix it and finally cured it with the Group K set up. http://groupk.com/sep.htm

 

[Etheraldreamer]

ok next logical question, who sells them the cheapest?

 

[#ZERO]

Mechanical fuel pumps have a problem with the pulse signal diminishing in the higher rpm range for extended periods of time and they only supply around 2.5 psi at idle which can fluctuate drastically.

I've been using an electric in-tank fuel pump with a 1/4-inch flow control valve to adjust the fuel pressure.

It supplies a steady 6-psi of fuel from 11~15 volts at 130 liters per hour and draws less current than a small bilge pump.

It fits directly inside the fuel sleeve tube with a pre-filter installed and it's mounted at the bottom of the fuel tank.

Also no fuel/air separator is needed since it's pushing the fuel out rather then sucking it through a hose from inside the tank.

 

[yamaslut]

where do you get that???

 

[#ZERO]

It's a common in-tank fuel pump that fits quite a few different vehicles.

That one was purchased on eBay a while ago for 20 bucks.

 

[restosud]

what triggers it?
which vehicles use that?

 

[#ZERO]

what triggers it?

I'm using a rotary bilge switch mounted on the dash but might consider triggering it through an Advent T4 ignition with the rpm signal later.

Which vehicles use that?

30 Bucks with free shipping; take your pick. http://stores.shop.ebay.com/AutoPar...dZ104277872QQ_sopZ2QQ_trksidZp4634Q2ec0Q2em14

 

[WaveDemon]

you just blew your chance at selling those for 150 bucks a pop.

 

[#ZERO]

you just blew your chance at selling those for 150 bucks a pop.

If I did, sooner or later someone would say; that's the same pump they sell on eBay for 30 bucks. :icon16:

 

[junkyardj]

lol! nice call demon.. that is a pretty slick setup bro! it looks similar to a motorcycle pump? GREAT IDEA

 

[McDog]

If I did, sooner or later someone would say; that's the same pump they sell on eBay for 30 bucks. :icon16:

Yep, but you would be laughing all the way to the bank from all the sales before we figured it out.

Of course, you wouldn't be laughing for long.....:nutkick:

 

[junkyardj]

how about useing restricter's on the return line to bump up the pressure anyone try that before?

 

[#ZERO]

A Mikuni .60 to .70 main jet works well if your have the restrictors drilled out of the SBN carburetor body.