Cam duration
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Re: Cam duration
Everything is the same other than front carb sits 1inch higher. However before jet change fuel consumption equal.
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Re: Cam duration
Why does a duration calculator take number of cylinders as input?Stan Weiss wrote: ↑Thu Feb 22, 2018 2:03 pm You can play around with this
Estimate Cam Intake Duration Needed @ 0.050" http://www.magneticlynx.com/carfor/calccam.php
Stan
Test it with an input of 1 cylinder.
Engine Size = 375.5ci -- Number of Cylinders = 1 -- Max RPM = 9500
Volumetric Efficiency = 125% -- Head Flow - Intake CFM = 444
The result of your calculation is:
2092.28 Duration @ 0.050" Lift
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Re: Cam duration
Jon,SchmidtMotorWorks wrote: ↑Sat Feb 24, 2018 5:24 pmWhy does a duration calculator take number of cylinders as input?Stan Weiss wrote: ↑Thu Feb 22, 2018 2:03 pm You can play around with this
Estimate Cam Intake Duration Needed @ 0.050" http://www.magneticlynx.com/carfor/calccam.php
Stan
Test it with an input of 1 cylinder.
Engine Size = 375.5ci -- Number of Cylinders = 1 -- Max RPM = 9500
Volumetric Efficiency = 125% -- Head Flow - Intake CFM = 444
The result of your calculation is:
2092.28 Duration @ 0.050" Lift
How many people without thinking about it will know what the size of one cylinder of their engine is verses their engines size?
You are right it does no validation. So GIGO
Stan
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Re: Cam duration
Bore and Stroke would be a better choice of inputs than displacement and cylinders.Stan Weiss wrote: ↑Sat Feb 24, 2018 6:29 pm
Jon,
How many people without thinking about it will know what the size of one cylinder of their engine is verses their engines size?
You are right it does no validation. So GIGO
Stan
Regardless of the inputs, a return in the thousands of degrees indicates a scaling problem.
Helping to Deliver the Promise of Flying Cars
Re: Cam duration
Engine Size = 375.5ci -- Number of Cylinders = 8 -- Max RPM = 9500
Volumetric Efficiency = 125% -- Head Flow - Intake CFM = 444
The result of your calculation is:
261.53 Duration @ 0.050" Lift
?
Volumetric Efficiency = 125% -- Head Flow - Intake CFM = 444
The result of your calculation is:
261.53 Duration @ 0.050" Lift
?
Please Note!
THE ABOVE POST IN NO WAY REFLECTS THE VIEWS OF SPEED TALK OR IT'S MEMBERS AND SHOULD BE VIEWED AS ENTERTAINMENT ONLY...Thanks, The Management!
THE ABOVE POST IN NO WAY REFLECTS THE VIEWS OF SPEED TALK OR IT'S MEMBERS AND SHOULD BE VIEWED AS ENTERTAINMENT ONLY...Thanks, The Management!
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Re: Cam duration
That was the default calculation.
Change the number of cylinders to 1 and the the duration goes to the thousands (which is impossible).
That indicates a scaling problem in the formula.
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Re: Cam duration
The real answer to your question is it's not possible to achieve the result, it is not necessarily a scale issue. 444 cfm cant feed a 375ci engine sufficient to achive 125% VE at 9500rpm. a number greater than about 330 tells you thatSchmidtMotorWorks wrote: ↑Sun Feb 25, 2018 1:45 amThat was the default calculation.
Change the number of cylinders to 1 and the the duration goes to the thousands (which is impossible).
That indicates a scaling problem in the formula.
Last edited by digger on Sun Feb 25, 2018 2:48 am, edited 3 times in total.
Re: Cam duration
I see, I thought it was designed for 8?SchmidtMotorWorks wrote: ↑Sun Feb 25, 2018 1:45 amThat was the default calculation.
Change the number of cylinders to 1 and the the duration goes to the thousands (which is impossible).
That indicates a scaling problem in the formula.
Wouldn't the math be different for 1 cylinder vs multiple cylinders due to lack of scavenge from the other cylinders?
Please Note!
THE ABOVE POST IN NO WAY REFLECTS THE VIEWS OF SPEED TALK OR IT'S MEMBERS AND SHOULD BE VIEWED AS ENTERTAINMENT ONLY...Thanks, The Management!
THE ABOVE POST IN NO WAY REFLECTS THE VIEWS OF SPEED TALK OR IT'S MEMBERS AND SHOULD BE VIEWED AS ENTERTAINMENT ONLY...Thanks, The Management!
Re: Cam duration
The ve tables may help, but to me the more duration equals more ve is flawed.Stan Weiss wrote: ↑Fri Feb 23, 2018 6:31 pm I will have to add a list of different type engines and what a reasonable VE range would be.
Stan
Maybe some limits on duration inputs based on the rpm entered.
By that calculator our emc engine should have been 3% higher ve with the largest cam vs smallest tested. That would be about 20-25 Lbs of tq and it wasn't near that difference, and the smaller cam was the better one.
I just don't think the relationship of cfm-duration-ve is like the calculator shows.
Randy
Re: Cam duration
In pipemax VE seems to be about lift which makes more sense but things are not so simple all the time
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Re: Cam duration
Stan! Is the duration on the valve or on the lifter?
If it is on the lifter what rocker ratio does the equation use?
Erland
If it is on the lifter what rocker ratio does the equation use?
Erland
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Re: Cam duration
Unless they changed the formula on the website, I get 261 for the duration with 8 cylinders. If you change the input to 1, I think you need to divide the displacement by 8, which gives you the same result (261). I get "Invalid Result" with a 375.5ci single cylinder.
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Re: Cam duration
Erland,Erland Cox wrote: ↑Sun Feb 25, 2018 5:21 pm Stan! Is the duration on the valve or on the lifter?
If it is on the lifter what rocker ratio does the equation use?
Erland
This is at the lifter. This is just a basic calculation which will get you close in most cases.
Stan
Stan Weiss/World Wide Enterprises
Offering Performance Software Since 1987
http://www.magneticlynx.com/carfor/carfor.htm
David Vizard & Stan Weiss' IOP / Flow / Induction Optimization Software
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Offering Performance Software Since 1987
http://www.magneticlynx.com/carfor/carfor.htm
David Vizard & Stan Weiss' IOP / Flow / Induction Optimization Software
http://www.magneticlynx.com/DV
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Re: Cam duration
Stan Weiss/World Wide Enterprises
Offering Performance Software Since 1987
http://www.magneticlynx.com/carfor/carfor.htm
David Vizard & Stan Weiss' IOP / Flow / Induction Optimization Software
http://www.magneticlynx.com/DV
Offering Performance Software Since 1987
http://www.magneticlynx.com/carfor/carfor.htm
David Vizard & Stan Weiss' IOP / Flow / Induction Optimization Software
http://www.magneticlynx.com/DV