GM Muscle

iTrader: (9)

I need to figure out what my new fuel sytem is going to flow in GPM or GPS. I have the Orfice size, fuel PSI, and Specific Gravity but....I suck at math.

Anyone have any equations that can give me a relativly accurate answer? And no, I'm not buying a $300 flow meter.

Thanks,
Andrew

Beaflag VonRathburg

iTrader: (176)

If you post the information you have and I'll try to help you to the best of my ability.

GM Muscle

iTrader: (9)

The orfice size is .056", 60psi, .733 specific gravity. Now I asume SG can be substituted for Density. I ran the numbers through an orfice flow rate calculator I found on a Fluid Dynamics website and it came out to almost 3GPM, seems real high to me.

Any help would be awesome.

Andrew

JL ws-6

iTrader: (50)

If you are running a standalone, the only way to really know what the system is flowing is with a flow guage. Also the only way to really get a good tuneup on it, 1/4 lb of fuel pressure can make a sizable difference.

GM Muscle

iTrader: (9)

I'm just trying to get a general idea of consumption. I'm figuring 60psi on the high side, it will realistically be 2-3lbs lower. Basicly, I think my fuel cell is way to small for going out to street night. Holds less than a gallon and looking at the design, I think I'm going to see cavitation problems on launch once it gets down to a 1/3 full.

Billy the Great

iTrader: (2)

specific gravity is a ratio of the density of the fluid to the denisty of water. Water is 62.4 lb/ft^3 so that means the density of your gasoline is (62.4)(.733)= 45.74 lb/ft^3

JL ws-6

iTrader: (50)

With a 1 gallon standalone, there's really no way that you should be able to use that much fuel up in a night, unless you plan on sparying thru at least 3 full bottles or more.

Out of curiosity, why are you using a high pressure setup with a standalone?

GM Muscle

iTrader: (9)

Thanks for the info.

After doing my home work, I'm doing this all wrong. I'm working with two jets and that gets complicated as per http://www.nescaracing.com/n2o.html . The two jets are .028. So it looks like I need to find the total area of the two.

Here's the formula I found for open flow testing.

Fuel Jet Diameter X Fuel Jet Diameter X .7854 X Number of Jets = Flow test jet area
(Flow test jet area / .7854)SqRt = Flow jet size in thousandths

Now, here's the formula for fuel flow through orfice.

Q = Ao Co (( 2 x Pd / p)SqRt)
Where:
Q - Flow rate in cubic meters per second
Ao - Area of orifice (fuel jet) in square meters
Co- Flow Coefficient of orifice (use .75 as an approximation of Reynolds formula)
Pd - Pressure Differential between inlet and outlet of orifice (6-7lbs)
p - fuel specific gravity (kg/ cu meter - multiply spec gravity by 1000 for metric equiv)

I'll have to sit down and figure this out later when I have the time to do all the conversions.



JL, I have the all the jets I need for a high pressure set up, so I really wasn't going to go with a low PSI set up unless I have tuning issues. I don't see why I would have any issues.

JL ws-6

iTrader: (50)

I understand where you're coming from now. I don't think you'll have issues, I just haven't heard of too many people that go about it that way. You can still adjust the fuel flow with pressure, but at high pressure a 1/2 lb adjustment is probably very hard to get, and with the higher pressure a pressure change probably makes more of a difference.

ATVracr

iTrader: (5)

Pressure change means less at high pressure.

A 1/2lb at 60psi is nothing but a 1/2lb at 10psi is a good sized change.

JL ws-6

iTrader: (50)

actually thar does make more sense, 1/2 a lb at 10 psi it a much larger %. Sorry, I had that backwards.

GM Muscle

iTrader: (9)

Well I came up with .324 GPM using this calculator http://www.efunda.com/formulae/fluid...meter.cfm#calc . So I would probably use about 1/2 gallon a night. I believe my stand alone only holds .8 gallons and, as I mentioned the pump is in the cell, with no baffles, sort of angled twards the front corner of the car. I think I might sell this one and get a 1 gallon sumped tank with an external pump.

Robert56

iTrader: (2)

The meth to find the total area of the two jets can be found in the lead post in the Jetting sticky. Ok, here it is (I didn'd read all of your post though)
(.71 x size of one jet) X = single jet of same area
Then area is a breeze, and am sure you have that math.

Man I love this stuff, but have to go and can't get back for a while.

Robert

98Z28CobraKiller

iTrader: (17)

can this same calculator be used to calculate nitrous oxide consumption? I have been looking for something like this to calculate the actual difference in volume of say a 100 shot(pill/jet) at 1000 psi vs the same 100 shot at 1300 psi. How much more volume do you get from the additional 300 psi? Would it be close to 30% more or is it not that big of a difference?