Heymow - Lawnmower Racing Forum
Engine Help => Kohler Engines => Topic started by: fordman21 on September 20, 2010, 06:15:50 pm
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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.
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wow some one had some time on thier hands thats a big diffrence
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wow you want to redoo mine lol
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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.
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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
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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.
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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
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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
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Its mandatory before we start testing we take something for the migrains in advance. LOL
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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 :D, 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.
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Cant wait to see what a command single can do for numbers :woo:
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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 :D, 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
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whats a flow bench run ??
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i know almost nothing about this subject probably less than that but i found these
http://www.diyporting.com/flowbench.html (http://www.diyporting.com/flowbench.html)
http://performancetrends.com/ez_flow_system.htm (http://performancetrends.com/ez_flow_system.htm)
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oh wow thats realy cool good linx just a few desimals from my budjet
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heres another poor mans flow bench
http://www.4cycle.com/karting/html/flow_bench.html (http://www.4cycle.com/karting/html/flow_bench.html)
I have a question for you guys could you use a vacumn guage to at least get an idea of whats happening with a particular head. so take a reading of the actual vacumn and then a reading at the intake and the exaust ports paying attention to the difference in the readings. Would this give any meaningful results? Silly? Wrong concept? forget the whole thing?
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anyone?
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I would think that a flow bench would give you the best results, and it would be tested at 28WC pretty well the standard of the industry. There are some pretty cheap flow bench kits out there by the looks of it if a guy was serious about doing cylinder head mods. Once the valve opens you are going to loose vacuum with a vacuum guage and you really wouldn't know whats happening at each valve lift interval at a certain point otherwise.
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I would think that a flow bench would give you the best results, and it would be tested at 28WC pretty well the standard of the industry. There are some pretty cheap flow bench kits out there by the looks of it if a guy was serious about doing cylinder head mods. Once the valve opens you are going to loose vacuum with a vacuum guage and you really wouldn't know whats happening at each valve lift interval at a certain point otherwise.
Thanks Ryan I appreciate it.
Tim Johnson
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heres another poor mans flow bench
http://www.4cycle.com/karting/html/flow_bench.html (http://www.4cycle.com/karting/html/flow_bench.html)
http://www.dwyer-inst.com/ (http://www.dwyer-inst.com/)
this is the instrument company used for the above flow bench, the manometers used are less than $200.00. For you gents that have experience in this would this be a good place for a guy to start if he had the inclination to try this! ENTRY LEVEL CHEAP? The above mentioned flow bench uses a 16" and a 24" U tube (8" and 10" WC) respectively, If I understand the material correctly. Standard flow numbers are generally given at 28"WC? would it matter if the "reference" were different just have to set the vacumn up with a pressure that was compatible with what you are working with? dwyer has a larger manometer up to 18" WC didnt see any others.
probably if i look harder maybe find a larger manometer, 28"WC but these are pretty cheap!
Wouldn't be the standard but since only trying to improve the flow of what you have at hand does it have the potential to work?
only gonna look at improvement of what you start with right?
This is what happens when boredom sets in and you cant sleep, surfin the web!
http://www.flowperformance.com/faq.html (http://www.flowperformance.com/faq.html)
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found this interesting
http://www.tractorsport.com/cgi-bin/forum/cgi-bin/ikonboard.cgi (http://www.tractorsport.com/cgi-bin/forum/cgi-bin/ikonboard.cgi)
and i think i answered my own question about using the smaller manometers from this article
http://en.wikipedia.org/wiki/Air_flow_bench (http://en.wikipedia.org/wiki/Air_flow_bench)
Most flow testing is done at 10 and 28 inches of water pressure (2.5 to 7 kilopascals
quote from the above article.
Making a little more sense now. but I have a headache. LoL
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Ryan what flow bench do you use? Is it software driven?
Thanks
Tim Johnson
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Flow Performance, yes it is software driven. It seems to be extremely accurate and consistant.
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I bought a Flow Performance 2.0 kit for testing some karting Tilton carbs. I sent them some carbs and they built an adapter for them and flow tested the carbs for me. Then they sold me the whole setup. I was hoping I could find carbs that flowed more than others, but found they all flow pretty much the same. But what I did discover was that I could improve flow about 10 to 15 percent just by doing a few tricks that cost no money, no modification and hardly any time. I was able to apply these tricks to other parts of the intake and exhaust system. Would never have even dreamed this could be done without a flow bench.
Wally
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thanks yes and its really not that expensive either, and the website for this is in a post above
too much for me right now. I was just tryin to figure out the cheapest way to do it! Honestly at this point the mathematics in converting the readings of the pressure in the manometers, and at the pitot tube to cfm ( flow ) isn,t completely clear to me. Keep readin till I figure it out I guess!!
:bash:
Thanks guys
Tim Johnson
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This one explains things well. I think
http://cid-253920c013930de6.office.live.com/self.aspx/.Public/hyperflow.pdf#resId/253920C013930DE6!200
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Its amazing what little things make a difference, I have new intake manifold and header designs in my head already based on what happens before and after the heads alone.
(http://i144.photobucket.com/albums/r190/fordman21_photos/th_IMG_2484.jpg) (http://s144.photobucket.com/albums/r190/fordman21_photos/?action=view¤t=IMG_2484.jpg)
(http://i144.photobucket.com/albums/r190/fordman21_photos/th_IMG_2476.jpg) (http://s144.photobucket.com/albums/r190/fordman21_photos/?action=view¤t=IMG_2476.jpg)
(http://i144.photobucket.com/albums/r190/fordman21_photos/th_IMG_2474.jpg) (http://s144.photobucket.com/albums/r190/fordman21_photos/?action=view¤t=IMG_2474.jpg)
Here is my set up.
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Have you ever done any flathead flow work?
I am working on a flow bench and wondering how I am going to measure valve lift?
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Have you ever done any flathead flow work?
I am working on a flow bench and wondering how I am going to measure valve lift?
Make a bridge across the top of head with screwable studs use a dail indicator on stud to measure valve lift
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ok, but when it is on the flow bench...I have to have the head on it?
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I would put the head on and pull the air out of the bottom of the cylinder, just need a large diameter flexible hose to go to the flow bench. Just measure how far the retainer or valve stem opens with a set of calipers or make up some spacers to insert in there that are .100" thick once the clearance is taken out. You'll be using really light springs for the testing.
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well DUH, go in through the valve covers, lol...I have been staring and staring trying to make something through the lifters! LOL!
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I've been sick the last couple weeks with pneumonia so I played with the Kohler heads a little bit. With the heads still being stock appearing on the outside with no welding or filler and stock valve seat still able to use the stock diameter valve (undercut stem) I got the numbers up to 124.1cfm@28 at .600, the cool part is that the flow is 122 at .550". Now its time for some bigger valves and seat work.
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Ryan, how does that compare to a Vanny head?
Jack Jones
Hard Case Racing
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Its funny you should mention that Jack, I actually had to model the bowl area after the 09 and up briggs head to get it to show the bigger numbers, they are big on swirl. After that it didn't like the raised floor.
Its got the briggs head with bigger valves and stock seats beat by just a few cfm, but I'm not done yet. The calculator says right now the heads are capable of feeding close to 80hp.
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Ryan that's what our heads are at with .100 bigger valves and port epoxy in special places. That is with a 25hp head. We have to use stock intakes though. Kinda defeats an all out ported race head.
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Yes, the stock intakes are a lot less than desirable, probably the biggest cork for you guys.
I'm going to try another head after this one with the same bowl area and see just how small I can leave the port opening, then flow it. But I'm going to keep going on these heads because they will likely end up with two carburetors on an outlaw engine.
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I have oversize in my heads but still need to get them to Ryan to flow them. I'm curious how well it will turn out.
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http://en.wikipedia.org/wiki/Pressure_measurement
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We have come a long way since this thread was started :D
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:lol:
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fordman the heads you were working on were they for a single cylinder motor? im thinking about doing a single cylinder kohler for my f/x build and just seeing what ya have for hop up parts for the kohler single.
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MidwestsSuper Cub has the go fast parts for the singles. Ryan Kerr can get ya hooked up with head work to get ya running great.
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Those numbers were from a mild twin head, I didn't post any numbers after the serious work was done to them. The single head should really make some high numbers, pretty nice design and some meat there to work with.
For parts, as mentioned Midwest Super Cub has some pretty hard core stuff available for the singles, they are getting into them in a big way......no pun intended lol.