Craig,
Sounds fair. Next time I'm fiddling with the fuel system I'll do some
experimenting.
I still reckon 1/4" lines would be OK though - at 6.35mm that's still 1.35mm
larger than the pump outlet, so hopefully that would allow enough for
frictional losses. Only one way to find out though....
By the way, I did some testing when I installed the new pump and came to the
conclusion that one of the most important things to watch out for is voltage
drop. Make sure the pump is getting close to it's full 12 volts or flow
drops off markedly... I have the figures if you're interested.
PL
-----Original Message-----
From: [EMAIL PROTECTED]
[mailto:[EMAIL PROTECTED]] On Behalf Of Craig Overend
Sent: Monday, 1 January 2001 17:28
To: [EMAIL PROTECTED]
Subject: Re: FJ Fuel line advice needed
Pete,
one thing to remember is depending on how long the fuel line is, you
will see a pressure loss at the outlet end of the line. Just try blowing
through a short and long piece of same ID hose and you'll definately
notice the difference. So just because the pump will flow 250kW through
its outlet doesnt necessarily mean a line X metres long with the same
internal diameter or slightly bigger will flow the same. Using a line
that is small may flow enough for the engine but is more likely to
overload the fuel pump and overheat/wear it out causing failures.
To do it properly you would do all the fluid mechanics maths, however
alternativly try the following, I have not tested this method as I just
came up with it, I havn't allowed for pump efficiency but the following
might work.
Measure the pump current using an ammetre when loading the pump up to
the required pressure using the pressure regulator directly at its
outlet. Then install the pump on the fuel line and regulator at the fuel
line output and measure the current using the regulated pressure. You
should then be able to tell if the pump is being overloaded from the
current difference and calculate what % bigger flow rate of line you
need.
Say at 12V the pump consumes 7.5A at 60psi with no fuel line.
Say at 12V the pump consumes 10.0A at 60psi with 5mm fuel line 3 metres
long.
Ratio difference = 10.0A/7.5A = 1.333
The flow area of 5mm diam line = 5mm X 5mm / 4 * 3.142 = 19.637mm�
19.637mm� * 1.333 = 26.177mm�
Square_root(26.177mm� / 3.142 * 4) = 5.773mm
So Using a 5.773mm diameter line the pump will be much happier with more
flow potential and last longer at 60psi.
You could alternativly use the fuel pressure difference from the pump
outlet to the fuel line outlet to calculate the % bigger flow rate
required.
Any comments welcome.
With any EFI conversion you should test it using a fuel pressure gauge
at the outlet of the line after you install it.
Craig.
Pete & Kath Liebig wrote:
>
> Bruce,
>
> The outlet on a Bosch EFI pump from the VL turbo is only 5mm in dia. And
> these pumps will support up to 250Kw, so unless he intended getting more
> than this from his engine then 1/4" lines should be fine. I know it seems
a
> bit small, but I really can't see any reason to go bigger than the pump
> outlet. Pump inlet dia is another story...
>
> PL
>
> -----Original Message-----
> From: [EMAIL PROTECTED]
> [mailto:[EMAIL PROTECTED]] On Behalf Of Bruce Ferguson
> Sent: Friday, 29 December 2000 20:35
> To: [EMAIL PROTECTED]
> Subject: FJ Fuel line advice needed
>
> List,
>
> A young bloke I saw at the wreckers today wanted a
> 1600 fuel line for his FJ conversion. (I was securing
> a set of ventilated rotors and twin spots)
>
> I advised him that it was not big enough and 5/16" was
> more on the mark. Was my advise correct and what about
> the return line dia ?? the same ????
>
> Cheers
>
> Bruce
>
> __________________________________________________
> Do You Yahoo!?
> Yahoo! Photos - Share your holiday photos online!
> http://photos.yahoo.com/
>
--membersozdat-------------------------------------------------------
OZDAT Mailing List Please Note:-
Send (un)subscribe requests to [EMAIL PROTECTED]
Send submissions to [EMAIL PROTECTED]
No unauthorised redistribution of this email
http://www.ozdat.com/ozdatonline/index.htm
http://www.ozdat.com/ozdatonline/listindex.html
http://www.mail-archive.com/[email protected]/
---------------------------------------------------------------------
