im after a ballpark calculation ('cause experts will say it depends on material, temperature, etc) but if i have 60 psi oil pressure and i want to have 1 L/m flow rate, what size restrictor should i use.
it will be measured once installed, but want to have a starting point.
oil flow calculation - for turbo supply
Started by
_brett_32i_
, Jul 18 2008 06:16 PM
15 replies to this topic
#2
_Brewster_
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Posted 18 July 2008 - 09:49 PM
This flow calculator, http://www.flowmeter...wcalculator.php, says 3.7mm, but that might not be right. Looking at it now, one of the calculations is wrong.
Wont a turbo specialist fitting place be able to tell you what you need?
Wont a turbo specialist fitting place be able to tell you what you need?
#3
_brett_32i_
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Posted 19 July 2008 - 09:29 PM
that calculator doesnt allow for pressure?
#4
toryman76
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Posted 19 July 2008 - 09:44 PM
even for a ballpark figure you will need to know some other factor such as temperature...im after a ballpark calculation ('cause experts will say it depends on material, temperature, etc) but if i have 60 psi oil pressure and i want to have 1 L/m flow rate, what size restrictor should i use.
it will be measured once installed, but want to have a starting point.
EDIT: Turns out im wrong and you don't need temperature, you need to know a velocity, but velocity isn't going to be something that you can easily determine
Edited by toryman76, 19 July 2008 - 09:54 PM.
#5
toryman76
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Posted 19 July 2008 - 09:56 PM
im basing my reply on the use of this website:
Pipe Diameter Calculation
I have done similar stuff at uni last year so i should be able to help you out with this
Pipe Diameter Calculation
I have done similar stuff at uni last year so i should be able to help you out with this
#6
_brett_32i_
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Posted 20 July 2008 - 05:54 PM
that calculator wouldnt load for me.
but if temp is necessary, 100 degree is going to be a good average temp.
but if temp is necessary, 100 degree is going to be a good average temp.
#7
_brett_32i_
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Posted 20 July 2008 - 06:17 PM
i found this over at calaiswanker...
a restrictor may need to be used if its a BB turbo as small as 0.6mm but more around the 0.8-1mm mark
oil flow figures arent really availible as they are engine particular so a given restrictor on one engine will vary to another.
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Last edited by theVLguy : 02-04-08 at 22:07.
a restrictor may need to be used if its a BB turbo as small as 0.6mm but more around the 0.8-1mm mark
oil flow figures arent really availible as they are engine particular so a given restrictor on one engine will vary to another.
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Last edited by theVLguy : 02-04-08 at 22:07.
#8
_Baronvonrort_
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Posted 20 July 2008 - 06:19 PM
We use SI units here so why do many still use psi.
Are you sure you have 60psi and is this figure near redline?
Does your volume flow rate only need to be 1l/pm at redline and surely with turbo timers etc there should be reasonable flow at idle when oil pressure is significantly less.
RD of oil =0.9
Mdot (mass flow rate) for 1l/pm =0.015 KG per second.
60 psi= about 486KPA
Pressure head of oil at 486KPA =55 metres.That means if you aim the oil hole vertically the oil will reach a height of 55m.
Using a equation that may or may not suit this application i think velocity should be about 32 metres per second at 486 KPA.
Now Mdot (mass flow rate) = Velocity x Area x Rho (900 for oil since rd is 0.9).
Mdot=kg per second
Velocity in metres per second
Area in metres
You will not need a very big hole to supply 1 litre per minute at 486 KPA yet whether this supplies enough mass flow at idle oil pressure is the question.
What is the internal diameter of your oil supply line?
Are you sure you have 60psi and is this figure near redline?
Does your volume flow rate only need to be 1l/pm at redline and surely with turbo timers etc there should be reasonable flow at idle when oil pressure is significantly less.
RD of oil =0.9
Mdot (mass flow rate) for 1l/pm =0.015 KG per second.
60 psi= about 486KPA
Pressure head of oil at 486KPA =55 metres.That means if you aim the oil hole vertically the oil will reach a height of 55m.
Using a equation that may or may not suit this application i think velocity should be about 32 metres per second at 486 KPA.
Now Mdot (mass flow rate) = Velocity x Area x Rho (900 for oil since rd is 0.9).
Mdot=kg per second
Velocity in metres per second
Area in metres
You will not need a very big hole to supply 1 litre per minute at 486 KPA yet whether this supplies enough mass flow at idle oil pressure is the question.
What is the internal diameter of your oil supply line?
#9
_Baronvonrort_
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Posted 20 July 2008 - 06:23 PM
I came up with a smaller number than 0.6mm at 486 KPA.i found this over at calaiswanker...
a restrictor may need to be used if its a BB turbo as small as 0.6mm but more around the 0.8-1mm mark
How much oil do you want to supply at idle after full boost runs?
#10
_brett_32i_
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Posted 20 July 2008 - 07:41 PM
im pretty sure the measure is taken at idle. i have a .9 welding tip in the fitting at the moment and should be able to measure the flow wednesday night.
supply hose is 8mm id, banjo bolt id is about 4mm
supply hose is 8mm id, banjo bolt id is about 4mm
#11
_brett_32i_
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Posted 20 July 2008 - 08:06 PM
im pretty sure the measure is taken at idle. i have a .9 welding tip in the fitting at the moment and should be able to measure the flow wednesday night.
supply hose is 8mm id, banjo bolt id is about 4mm
supply hose is 8mm id, banjo bolt id is about 4mm
#12
_Baronvonrort_
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Posted 21 July 2008 - 12:59 AM
I stuffed up earlier converting Psi to KPa which puts all the previous calcs way out,too much bourbon before putting brain into gear.
Unless you are running some fang dangled oil pump there is no way you will get 60 Psi at idle and the general rule is another 10psi per 1000 rpm with about 10 psi at idle therefore about 60 psi at 6000rpm.
So 60 Psi = 413 Kpa.
413 KPa should give a pressure head of 46.7 metres and velocity about 30.3 metres per second.
With 4mm diameter pipe this will give a mass flow rate of 0.342 Kg per second
101 Kpa at idle should give a pressure head of 11.4 metres and velocity of 14.9 metres per second.
With 4mm diameter pipe this will give a mass flow rate of 0.168 Kg per second.
1 litre per minute= 0.015 kg per second.
A 1mm restrictor should give mass flow rates of ;
101 Kpa- 0.0105 Kg per second.
413 Kpa-0.0214 kg per second.
Be interesting to hear your flow results and is your pressure guage accurate?
Unless you are running some fang dangled oil pump there is no way you will get 60 Psi at idle and the general rule is another 10psi per 1000 rpm with about 10 psi at idle therefore about 60 psi at 6000rpm.
So 60 Psi = 413 Kpa.
413 KPa should give a pressure head of 46.7 metres and velocity about 30.3 metres per second.
With 4mm diameter pipe this will give a mass flow rate of 0.342 Kg per second
101 Kpa at idle should give a pressure head of 11.4 metres and velocity of 14.9 metres per second.
With 4mm diameter pipe this will give a mass flow rate of 0.168 Kg per second.
1 litre per minute= 0.015 kg per second.
A 1mm restrictor should give mass flow rates of ;
101 Kpa- 0.0105 Kg per second.
413 Kpa-0.0214 kg per second.
Be interesting to hear your flow results and is your pressure guage accurate?
#13
_brett_32i_
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Posted 21 July 2008 - 09:08 PM
i get 'bout 25 psi at idle, so rading will be taken somewhere around that, maybe 40, depends how hot i get it. and the 1l/m is taken at idle not at full revs.
so your revised calculations look about right?
101kpa = ~15psi = theoretically 1 liter per minute
i believe gauge to be accurate, a its brand new and b the readings match u pto all other rb30's
so your revised calculations look about right?
101kpa = ~15psi = theoretically 1 liter per minute
i believe gauge to be accurate, a its brand new and b the readings match u pto all other rb30's
#14
makka
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Posted 21 July 2008 - 10:59 PM
I know this wont help you find out the restrictor size but it will help when you decide on a size or want do do some trial and error testing, a lot of guys use holley carby jets as the orifce for the restrictor, cheap, easy and heaps of different sizes
#15
_Baronvonrort_
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Posted 22 July 2008 - 12:26 AM
25 Psi at idle = 172 Kpa
Velocity should be about 19.5 metres per second at 172 Kpa.
With a 1mm diameter restrictor at 172 Kpa this will give you 0.0137 kg per second and about 0.826 kg per minute and the goal is 0.9 kg per minute.
A little more oil pressure might be needed or just a touch more than 1mm diameter.
101 Kpa gives 0.0105 kg/second so x 60 gives 0.63 kg/minute and oil weighs approx 0.9 kg per litre so way short of 1L/min at 101 kpa.
I am fairly confident with my calcs and curious to see what you get when you test the flow.
Velocity should be about 19.5 metres per second at 172 Kpa.
With a 1mm diameter restrictor at 172 Kpa this will give you 0.0137 kg per second and about 0.826 kg per minute and the goal is 0.9 kg per minute.
A little more oil pressure might be needed or just a touch more than 1mm diameter.
101 Kpa gives 0.0105 kg/second so x 60 gives 0.63 kg/minute and oil weighs approx 0.9 kg per litre so way short of 1L/min at 101 kpa.
I am fairly confident with my calcs and curious to see what you get when you test the flow.
#16
_brett_32i_
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Posted 23 July 2008 - 08:50 PM
so my .9 welding tip turned out to be 1.1mm.
i got
360cc/min at 65psi at 30degrees.
480cc/min @ 43psi @ 53 degress
480cc/min @ 33 psi @ 63 degrees
doubling the flow rate would mean i need a 1.5mm restrictor.
1.3mm
800cc/min @33psi @ 60 degrees
1.4mm
960cc @35psi @ 55 degrees.
so ill stick with the 1.4mm orifice. oil will get a bit hotter, and flow will increase a bit.
i've heard anywhere form half a litre/minute is ok, so im happy with 960cc
i got
360cc/min at 65psi at 30degrees.
480cc/min @ 43psi @ 53 degress
480cc/min @ 33 psi @ 63 degrees
doubling the flow rate would mean i need a 1.5mm restrictor.
1.3mm
800cc/min @33psi @ 60 degrees
1.4mm
960cc @35psi @ 55 degrees.
so ill stick with the 1.4mm orifice. oil will get a bit hotter, and flow will increase a bit.
i've heard anywhere form half a litre/minute is ok, so im happy with 960cc
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