hello
I am new to this forum and not good with excel.

this is a brief explaination of what i need to do to kick things off. I
hop somebosy can help

have a calculation for temperature that i have 25 deg figures for. I
need to be able to create a excel calculation for any given value (in
deg). I have a table of values run from a line of best fit basis.

so far my equation is eg

D1=(A1*B1)*C1

F1=D1/ratio in table pre determinded by the temp in E1


Can anybody help

Scott




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sway
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sway Wrote:
hello
I am new to this forum and not good with excel.

this is a brief explaination of what i need to do to kick things off. I
hop somebosy can help

have a calculation for temperature that i have 25 deg figures for. I
need to be able to create a excel calculation for any given value (in
deg). I have a table of values run from a line of best fit basis.

so far my equation is eg

D1=(A1*B1)*C1

F1=D1/ratio in table pre determinded by the temp in E1


Can anybody help

Scott



In Cell D1, enter this formula

=A1*B1*C1

and in Cell F1, your formula will look like

=D1/RATIO FROM TABLE PREDETERMINED BY THE TEMP IN E1

I believe that the "*ratio from table predetermined by the temp in E1*"
can be a value obtained using the VLOOKUP function. I am assuming that
for every temperature in Cell E1, there is a corresponding ratio.
Perhaps if I know how the table looks like, I can give you a more
specific formula to use.

Regards.


--
BenjieLop


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Thanks. Here is a breakdown of the equation and what it represents etc
Its basically to work out a fuel injection ratio for a water/methanol
injection system.

the equation goes

peak fuel useage (petrol)x injector duty cycle (percentage) x AFR (air
fuel ratio)

This part gives the amount of airflow in the same unit as the fuel
injected.

This airflo figure needs to be then divided by the water injection
ratio in a table to give the correct amount to be injected.

The first part i have the equation for but at the moment i have to add
the water injection ratio manually. This is not a problem but i would
like to replace the water injection ratio box with air temperature to
make it idiot proof.
From the look of the Vlookup facility i could get it to referance the
water injection ratio using the air temp as an index. This has moved
the game up a level and again more complicated.

I have the ratios for 0,25,50,75,100,125 etc etc. If i was to use
VLOOKUP i presume it would only be able to give an answer for 0 25 50
75 etc. Ultimatly i would like it to allow the user to input any number
within the range i have figures for (0-300 deg C) and it adds the ratio
to the equation.

Im not sure if i have explained all this suitably. If its possible to
give me any assistance it would be greatly appreciated.

Scott :)


--
sway
------------------------------------------------------------------------
sway's Profile: http://www.excelforum.com/member.php...o&userid=32619
View this thread: http://www.excelforum.com/showthread...hreadid=524115

sway Wrote:
Thanks. Here is a breakdown of the equation and what it represents etc
Its basically to work out a fuel injection ratio for a water/methanol
injection system.

the equation goes

peak fuel useage (petrol)x injector duty cycle (percentage) x AFR (air
fuel ratio)

This part gives the amount of airflow in the same unit as the fuel
injected.

This airflo figure needs to be then divided by the water injection
ratio in a table to give the correct amount to be injected.

The first part i have the equation for but at the moment i have to add
the water injection ratio manually. This is not a problem but i would
like to replace the water injection ratio box with air temperature to
make it idiot proof.
From the look of the Vlookup facility i could get it to referance the
water injection ratio using the air temp as an index. This has moved
the game up a level and again more complicated.

I have the ratios for 0,25,50,75,100,125 etc etc. If i was to use
VLOOKUP i presume it would only be able to give an answer for 0 25 50
75 etc. Ultimatly i would like it to allow the user to input any number
within the range i have figures for (0-300 deg C) and it adds the ratio
to the equation.

Im not sure if i have explained all this suitably. If its possible to
give me any assistance it would be greatly appreciated.

Scott :)

example of table

air temp ................Ratio
25................ 177.5
50................ 62
75 ................ 36.5
100............... 25.6
etc etc

ASSUME that your Air Temp/Ratio table has this range : X2:Y100

Hence, your "ratio from table predetermined by the temp in E1" is
obtained by using this VLOOKUP formula:

=VLOOKUP(E1,$X$2:$Y$100,2)

and, as you stated, this formula is sort of limited as it will only
give you the ratio for temperatures such as 0, 25, 50, 75, 100, etc. It
is a good start though.

I do not know, at this point, how the Air Temp and the Ratio are
corellated in your table. Is there a formula that relates the two
factors? Or, will the ratio at any given air temperature (besides 0,
25, 50,etc.) be interpolated? As soon as we know how the Ratio and the
Air Temp are related, then we can derive a formula that will apply to
your situation.

If you want you can email me directly at

BENJIELOPATHOUSTONDOTRRDOTCOM

and we'll see if we can work out a formula for your use.

Regards.


--
BenjieLop


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