Kohler ch14 s

[Drossign 0]

I am new to the command line of engines. I have a kohler k 301 that we put the the # 30 carb from a k341 I am wondering if there is a bigger carb on the ch 15 or 16 that I can put on a ch14. Any help would be appreciated.

[Kelly 1,033]

Is the 12hp/301 stock?? the #30 is a bit big for a stock 12hp, not sure on the CH carb swap

[Jeff-C175 7,206]

For what reason would you want to put on a bigger carb?

[Drossign 0]

More fuel and air mean more hp.

[Jeff-C175 7,206]

Well yes, of course that is true, but how are you going to cause the engine to pump more air?

 

In ANY engine, the amount of air that it can pump at any given RPM is FIXED by the volume of the cylinder and combustion chamber. (only the cylinder, combustion chamber volume only determines compression ratio.)

 

Unless you add a turbo or super charger, or bore and stroke the engine, or modify the lift profile of the camshaft,  you will NOT pump more air by adding a larger carburetor.

Edited July 24, 2013 by Jeffpicks

[Drossign 0]

So are you trying to tell me by up sizing the carburetor will not in crease hp unless I do this.? If this is the case why would people plane the head or deck the block or lengthen the connecting rod to creat more compression. Wouldn't this creat less fuel and air which would create less hp. I'm just trying to pick some brains?

[Jeff-C175 7,206]

Correct... with exception:

 

IF and only if the carburetor in it's original design is somehow RESTRICTING the airflow into the engine... then fitting a carburetor with better air flow which is appropriate for the engine may give a bit more power.

 

In general though, this isn't the case. 

 

Raising the compression ratio by decking or planing or changing rod length won't change the amount of air flow.  The PISTON is still displacing the same amount of air... it's still moving the same distance in the same size cylinder.  It is however compressing that SAME amount of air more, which creates more power.

 

Just as further clarification...

 

Let's say your engine at full RPM was pumping 50 CFM of air.  Would placing a 100 CFM carb on that engine create more power?

 

No, it would not.  Because there is still only 50 CFM flowing through the carb...

 

Forget about the fuel burning and think of an engine as an air pump and it will make sense to you.

 

The only way to cause the engine to pump more air is to change it's displacement, cam profile, or force air into it via a 'charger.

[Fordiesel69 271]

Bottom line:  If you take a regualr K301 that has not been modified, and you slap and bigger carb on it, no you will not get more power.  In fact if too big, it will run worse. 

 

If you send the engine to a shop or do the mods yourself, then absolutly it will be of benefit.  We took it as you are slapping bigger carb on a stock motor.

[Forest Road 594]

Here's some good reading that deals specifically with your situation. I think it was on page 4 or 5.

http://www.kirkengines.com/downloads/KillerKohlerPartII.pdf

You're on the right track but there's more to it than just a bigger carb.

[Jeff-C175 7,206]

 

In fact if too big, it will run worse.

 

Absolutely!  If a carb is designed for a certain CFM of airflow, all the fuel metering passages are calibrated so that the correct air:fuel mix will be delivered to the engine.  The fuel metering depends on having the proper pressure differentials when operating.  Pressure differentials depend entirely on airflow.

 

Slap a humongous carb on a smaller engine and you won't get proper fuel delivery because there isn't enough airflow.

[Kelly 1,033]

I have a 2 barrel carb on my race car, the engine has 11.5 to 1 comp. big lumpy cam, ported polished heads lots of work all over, it is about 450hp it runs strong up to about 7000rpm it's all in tuning, there is hours into tuning my carb. on this car.

            Just putting a big carb on will not give you more power, even thou it is bigger if the engine can't use the fuel or air entering it is a waste, air to fuel ratio should be about 14 to 1 to get top power, put the stock carb on, make sure it is in tip top shape, throttle shaft tight no air leaks, be sure the points are nice and set correctly, new head gasket and a true head not warped most are, clean the piston and valves, set the valves to spec. good quality plug and plug wire, clean fuel system, good working fuel pump, learn to fine tune the carb high and low speed jets, when you have all this the engine will give you all it has to offer in stock form.