Measuring Port Length

Indycars

Administrator
Staff member
Will a cylinder head manufacture give you port length and minimum cross sectional
area? I'm looking for a procedure for measuring the port length. I've only found one
idea so far.

https://hotrodenginetech.com/porting-pointers/

Measure the length of the port from the intake mating surface to the valve seat. Do the same for the intake manifold, measuring from the port entry in the plenum to the runner exit. As a rule you want the centerline or average dimension of these two lengths. This is somewhat difficult to achieve, but you can get very close by using a length of string to measure the length of the port floor and the port roof and then average the two lengths. Add these together to establish the existing fixed port length. You can't change this, but you can tweak the cross section and work on the most restrictive areas to increase and improve the quality of flow. The overriding caveat is to do no harm. As soon as you start grinding you begin increasing the cross section which tends to slow the airspeed and raise the effective engine speed requirement where maximum torque and horsepower are produced. Note: Measure the exhaust ports the same way.
 
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Ive always just used a short length of mig weld wire, as its available, cheap, easy to bend and measure
Product-RAD64004177-270Wx270H



to measure the distance between the furthest edge or back of the valve seat (A) and the intake gasket surface, in a more or less straight line (b) consider your measuring intake runners from back of the far side of the intake valve to the runner entrance in the plenum

http://www.wallaceracing.com/runnertorquecalc.php

http://www.wallaceracing.com/intake-runner-length.php

http://garage.grumpysperformance.com/index.php?threads/exhaust-components.361/#post-442

http://www.swartzracingmanifolds.com/tech/index.htm

http://www.bgsoflex.com/intakeln.html

https://www.rbracing-rsr.com/runnertorquecalc.html

http://racehead.com.au/designing-performance/what-size-itb-should-i-use/

volumetric.gif

Varying-Intake-Runner-Length.png

Wave-Pulse-RPM-Chart.jpg


Port-Length-For-Port-Cross-Sectional-Area-Calculations.gif

vgdx4.jpg

and a dial caliper
calipersaa.jpg


ID point out that different cylinder head designs, port sizes and even different cylinder head ports on the same head tend to vary between manufacturers and part numbers for the same engine, and intake manifold runner designs vary even more,


EDL-7501_sSN.jpg

dualp.png


hly-300-110.jpg

singlep.png


WND-8501_AT.jpg


EDL-2925.jpg



Id also point out that cam timing matched to the exhaust scavenging has a huge effect on potential intake flow rates. and changes in displacement,cam timing, compression and header design have a very pronounced effect on intake flow rates
exhaustpressure.jpg

EXFLOWZ4.jpg

pistonposition2a.jpg

http://garage.grumpysperformance.co...spacers-and-related-intake-modification.1038/
 
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Ive always just used a short length of mig weld wire, as its available, cheap, easy to bend and measure

upload_2019-10-14_8-47-51.png

to measure the distance between the furthest edge or back of the valve seat (A) and the intake gasket surface, in a more or less strait line (b)
consider your measuring intake runners from back of the far side of the intake valve to the runner entrance in the plenum

http://www.wallaceracing.com/runnertorquecalc.php

http://www.wallaceracing.com/intake-runner-length.php

http://www.bgsoflex.com/intakeln.html

https://www.rbracing-rsr.com/runnertorquecalc.html

http://racehead.com.au/designing-performance/what-size-itb-should-i-use/
Varying-Intake-Runner-Length.png

Wave-Pulse-RPM-Chart.jpg

upload_2019-10-14_8-46-45.png

Guess I didn't give the purpose for measuring port length. This would be for the pressure wave that moves
thru the port. I don't think it would have trouble turning the corner like air and fuel does. It would not be
hard to shape the wire to approximate the centerline, then straighten it out to measure.
.
 
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Seems Rick’s method would be much more accurate. The all the air can’t follow that line but if the formula is set up with that in mind I guess that would work. Why is this important?
 
Why is this important?
If something don't change my mind, I'm planning on going forward with the SS header design
project this winter. I've purchased a different 16 inch SPAL fan that is about one inch shorter
and will allow me to raise the engine. Need to do this before I mock up the headers.
 
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Like most projects once you get started, it's seems to have the domino effect. This all started with
wanting build headers, but I should raise the engine now if I'm going to, that requires a new fan,
modifying the trans electrical connector, Oh ya the remote filter line will have to change to. There
is probably more that I will discover shortly.

FP01_RaiseEngineInterference01_01540.jpg
 
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