Topic: Kohler command head flow numbers

[fordman21]

We have to get this Kohler section lit up on the board here,
 I thought I would post some flow numbers out of a brand new, out of the box stock casting with absolutely no porting at all done to it. Every modification done is with puddy, or done to the valve, the head casting has not been ground or touched. All tests were done at 28WC.
The head is a 30hp Kohler command head.
Stock baseline test on intake port.            88cfm @.500"
The next test was done after the guide was pressed up leaving less then 1/8" exposed in the port:
                                                              89.5cfm@.500"
The next test was done after the stock intake valve was reshaped and swirl polished.
                                                              90.9cfm @.600"
The next test was done after the area around the guide was filled in with puddy on the roof of the port, at first a couple cfm was lost but after trying a few different shapes and removing some puddy it showed a huge improvement. A lot of time was spent here trying different things.
                                                             103.4cfm@.650"

Then the floor was raised and reshaped with more puddy and showed another big improvement.

                                                             108.4cfm@.650"

That is a huge improvement over the baseline readings, I thought it would be interesting to share the results before we start to do some serious port work on these heads.

[leadslead]

wow some one had some time on thier hands  thats a big diffrence

[Gadgit]

wow you want to redoo mine lol

[flatlanderfornow]

Slightly off the topic, but do you know if Kohler ever put the 2-barrel carb on the 18 horse
Commands? I would guess no, but hopefully I'd be wrong.

[FlatheadPuller]

The ones our machinest did for my stepdad flow 122-123 @.600 @28". But I already told you about those Ryan. They fall off alot over .600 lift. Just not enough port material to work with. If you do the mods you did to a open chamber head your numbers go up. Our heads are open chamber heads with larger valves.

Dennis

[fordman21]

That is very respectable Dennis, I can't wait to start playing with these heads. The closed chambers will be opened up a lot and won't look anything like they do now, the intake valve is badly shrouded but there is a lot of material to work with. I think I'll try the other castings and see how they compare with the closed chamber heads stock for stock just for fun. Its hard to believe looking at them with the stock ports half filled in that they picked up so much.

Flatlanderfornow, I don't believe any 18hp engines had a two barrel, but I could be wrong.

Hey Harley, no problem putting one of your heads on the flow bench when it comes back for a refresh over the winter.

[gtpuller]

generally speaking can all of the principles of porting/polishing, valve jobs, cam timing, lift and duration for OHV automobiles be applied to our small single and twin cylinder motors.  I'm assuming so and its probably a stupid question I've found I think some decent discussions on the subject, no experience with this and just trying to learn and understand the concept. Does anyone have any good articles or discussions on the subject? Interested in increasing the flow on a Kohler command single.

Thanks in advance

Tim Johnson

[fx28]

Slightly off the topic, but do you know if Kohler ever put the 2-barrel carb on the 18 horse
Commands? I would guess no, but hopefully I'd be wrong.

As far as I know Kohler only put the 2bbl carb on the 30hp, by the way the manifold and carb will fit the 18hp if rules allow.


Ryan do you have a aspirin bottle holder on your flow bench?  I have a friend that has done a lot of bench work and he always says he has gotten a lot of good info from it along with a migraine or two!  LOL!!!!!!!!!!

Chuck Miller

[George Herrin]

Its mandatory before we start testing we take something for the migrains in advance. LOL

[fordman21]

A lot of what applies to the automotive industry as far as performance improvements does apply to our small engines, especially in the cylinder head department. There should be lots of good articles and discussions available on the web, even a few cool video's of flow bench testing and porting on you tube. There seems to be a lot of interest in the Kohler command single lately I've noticed. Here is some good reading   http://www.modified.com/tech/0009scc_cylinder_head/index.html

I have a couple pain killers on stand by    , I sure can understand how frustrating working with the bench can be, sometimes what you think should make a huge difference makes things worse, and other things make the biggest difference.

[MowRacing]

Cant wait to see what a command single can do for numbers 

[gtpuller]

A lot of what applies to the automotive industry as far as performance improvements does apply to our small engines, especially in the cylinder head department. There should be lots of good articles and discussions available on the web, even a few cool video's of flow bench testing and porting on you tube. There seems to be a lot of interest in the Kohler command single lately I've noticed. Here is some good reading   http://www.modified.com/tech/0009scc_cylinder_head/index.html

I have a couple pain killers on stand by    , I sure can understand how frustrating working with the bench can be, sometimes what you think should make a huge difference makes things worse, and other things make the biggest difference.

cool thats one of the articles that i had found
thanks

Tim Johnson

[leadslead]

whats a flow bench run ??

[gtpuller]

i know almost nothing about this subject probably less than that but i found these

http://www.diyporting.com/flowbench.html

http://performancetrends.com/ez_flow_system.htm

[leadslead]

oh wow thats realy cool good linx just a few desimals from my budjet