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Engine Help => Kohler Engines => Topic started by: Wheelhorseracer on May 03, 2010, 07:10:19 AM

Title: K341 in a Racer
Post by: Wheelhorseracer on May 03, 2010, 07:10:19 AM
With the amount of pulling parts available. What about building a K341 (18hp) Kohler for the Single class. They are making a considerable amount of power in the pullers and I can't see why they wouldn't work in a circle track racer..

The issue is the fact that they are quite heavy over a Briggs or Honda single.
Title: Re: K341 in a Racer
Post by: wayne shaffer on May 09, 2010, 02:46:44 PM
Hopefully I can let you know next year. I hope to have my sportsman done this year and this winter I hope to start building a super mod.
I'm going to use a K321 (14hp). I use to pull so I'm a big Kohler fan.
Title: Re: K341 in a Racer
Post by: Wheelhorseracer on May 09, 2010, 03:57:25 PM
have you looked into a finned flywheel.. the pullers don't have fins..

Title: Re: K341 in a Racer
Post by: FlatheadPuller on May 09, 2010, 05:57:23 PM
Easy fix. If you use a light vogel flywheel or any flywheel for that matter the briggs model 28 plastic bolt on fins bolt directly to a kohler flywheel made for a cub cadet clutch driver. We run a set on a open rpm 14hp. The fins are bolted to a midwest flywheel. It turns 7400 and has for 4 years untouched. Never a problem with the fins.
Title: Re: K341 in a Racer
Post by: outlawmower on May 09, 2010, 06:04:40 PM
Easy fix. If you use a light vogel flywheel or any flywheel for that matter the briggs model 28 plastic bolt on fins bolt directly to a kohler flywheel made for a cub cadet clutch driver. We run a set on a open rpm 14hp. The fins are bolted to a midwest flywheel. It turns 7400 and has for 4 years untouched. Never a problem with the fins.

I have heard of this, but never seen anyone use it before. Interesting how that works...
Title: Re: K341 in a Racer
Post by: Wheelhorseracer on May 09, 2010, 06:48:08 PM
Cool... I'm glad someone figured out what to do.

Maybe an Outlaw K-series Kohler? I like the thought...
Title: Re: K341 in a Racer
Post by: wayne shaffer on May 10, 2010, 04:36:06 AM
I'm going to have Midwest Super Cub make me a billet aluminum one. I have not talked to them yet but it should be easy for them.
Title: Re: K341 in a Racer
Post by: JD Mike on May 10, 2010, 05:26:28 AM
A K341 is a 16 hp not an 18hp.

What mower are you going to  use that is horizontal shaft drive?
Title: Re: K341 in a Racer
Post by: Wheelhorseracer on May 10, 2010, 06:40:09 AM
OOPS ... my bad JD Mike.

It would be in an Outlaw. Or maybe a Super Mod.
Title: Re: K341 in a Racer
Post by: wayne shaffer on May 10, 2010, 03:32:46 PM
I'm going to build a ARMA super mod. single. I'm finally going to get my sportsman done so I can get my required experaince and I'm really
hoping to have 2 Super Mods for 2011.
Title: Re: K341 in a Racer
Post by: Caudy155 on May 10, 2010, 05:19:29 PM
it takes alot to get the power out of a single you would with a command twin and with that much power in them life span isnt the longest and when they come apart you might as well find a whole nother motor... they will turn alot of rpms but they arent made to be in and out of the gas... pulling motors are either idle or wide open... and im not real sure that the blocks are strong enough to turn that many rpms for that long
Title: Re: K341 in a Racer
Post by: Wheelhorseracer on May 10, 2010, 05:40:26 PM
Just like in pulling you strap the cylinder down to the block. They have a ton of meat in those blocks.

Remember you are only on the gas for a few seconds on a straight.. how long do you hold it wide open in a puller... a heck of a lot longer than that sometimes 10 to 15 seconds on the limiter.. If they can stand up to a pullers abuse, they certainly would live in a circle track racer.

When you get to the top classes you are only on and off.. If you try to pedal an outlaw in a corner you will be facing the wrong way.



Title: Re: K341 in a Racer
Post by: Caudy155 on May 10, 2010, 06:51:37 PM
hey if you wanna spend that much for all the machine work on the block and the rod piston and crank and not to mention the motor is gonna weigh a ton and then the gear reduction starter on top of that might be a good idea to try but they are so heavy i dont think it would be practical because for the same weight you could have a twin and more power... im not puttin you or your ideas down so dont take offence you dont have to school me on pullin i have been around it my entire life... garden tractors to boot... its the racing that im new to... just from a weight standpoint dont see it that practical
Title: Re: K341 in a Racer
Post by: Wheelhorseracer on May 10, 2010, 07:07:41 PM
You will spend money on machining no matter what engine you build. If you want to talk about money the single is cheaper because you only have one hole to bore, 2 ports to work on.. only two valves etc..only 1 pistons to buy, one rod...etc.

Weight isn't always the enemy.. left side weight is a bonus if you offset the motor in the chassis.
Title: Re: K341 in a Racer
Post by: Big daddy on May 11, 2010, 04:52:53 AM
What are your engine rules for the class you want to build this engine for? The machining cost for a K341, welded or unwelded would be around $500 or less. Deck, bore, valves. Internals can be pricy depending on which stroke you use. Vogel has a forged crank in 3.25" stroke that is about half of what a billet crank would cost. Depending on what you are allowed to build, one can build something really wicked with a K series. Most of what you are describing about the throttle response is true with the pulling engines. We build them for full throttle and to idle a certain way. I have found that certain carb./cam combinations work much better than others. Kohler type carbs. that have been heavily modified coming from dead idle to wide open can be really sluggish, the Mikuni type carbs. (44mm/52mm) IMO would work better. If you keep them off the idle circuit the Kohler type carbs. are not too bad, but if your engine speed bottoms out and the idle circuit kicks back in then you would have to build up the curve again. I would be really curious to see what one could do with a K341 in this area. I know how they work for us on the pulling tracks, they may work out great for racing, then again they may fall on their faces. If you do decide to build one to race, keep us informed about it. I would really like to see how it fares on the round tracks. I think your biggest enemy will be be getting rid of heat. We run ours down the track, maybe idle them a little then shut them off, they are not run for a long period of time. MWSC sells a fan than can be used on these engines that helps get rid of heat. The issue with relying on the flywheel w/fins is that it is cooling off the side of the block that runs the coolest, air and fuel while the engine is running will cool off that side considerably. Keep us informed, very interesting application.
Title: Re: K341 in a Racer
Post by: Wheelhorseracer on May 11, 2010, 06:47:08 AM
I'm not totally sure what class. I have been leaning towards an outlaw engine. The Kohler carb would be gone and replaced with a Mikuni.

There is so much potential in the K-series and I think that they don't need to be just for pullers.

I agree with the heat issue and with fins on the flywheel and the tins in place a small external fan might just be the ticket for controlling the heat. Also i thought about possibly running a puller pump and routing the oil through an external cooler to control heat. If the oil can stay cool and be reintroduced into the engine it can cut down on heat.

I will be starting on this engine this summer by gathering parts. I'm lucky that I have a mower junkyard with hundred on mowchines only 5 minutes from my house. There are a bunch of old K-series engine ready for the building.
Title: Re: K341 in a Racer
Post by: Big daddy on May 11, 2010, 12:04:23 PM
Back years ago when we were running race gas I almost spend the time and trouble to make a water cooled head, but at the time could not justify it due mostly to the fact that the engine did run that long, but Since you would be making a billet head anyway it might be something to consider.
Title: Re: K341 in a Racer
Post by: chuckm on May 11, 2010, 01:52:19 PM
Hi, k341, They have lot of power when their built (BUT) what are you going to put behind that engine
to with stand the torque! It would shell it out in no time. another thing that comes to mind is k341 that are built vibrate alot even balanced I had a friend that his k341 would break the carb bolts (grade 8) off and only run it for a little while pulling I could not amagine what a 20 lap race would do.
2cents
chuckm
Title: Re: K341 in a Racer
Post by: Wheelhorseracer on May 11, 2010, 02:36:15 PM
It would be run through a centrifugal clutch to a jackshaft set-up much like all horizontal engine mower racers.
Title: Re: K341 in a Racer
Post by: FlatheadPuller on May 11, 2010, 03:57:40 PM
I think if one used a steel crank or even a forged crank from Chuck V. If you then lightened up the rotating assembly, knife edged the crank and such strictly to gain quicker acceleration you would have a decent engine. Small port, big port velocity engine to make sure the idle to off idle transition would be good would be a must. A big valve unless done correctly would kill it for racing. Port velocity is crucial in the roundy round world. I would use a narrow base block with an aluminum pan to cut down on weigh. A block side plate would be a good idea to keep the intake port on it. The 50.5 engine rev quick with the 10lb wheels on them. One would rip with an aluminum wheel on it.

I think it is an idea to try if one wishes. It would be different. there are ways to making the engine lighter as in a flywheel, lighten the crank.

Just my 2 cents

Dennis
Title: Re: K341 in a Racer
Post by: outlawmower on May 11, 2010, 05:29:19 PM
Personally I would use a 10HP K-Series. But thats me due to the fact I have a little more experience with those and just those. I have gotten my puller to run quite well before I sold it. Just takes time, and some R&D to get it right but when you do...hold on.

One thing I think personally is that the smaller the bore the faster you can move the weight of the rod, piston, ECT...

Yes I know, Many people will use a leight weight alternative such as Vogel, or JE pistons. But, When I first pulled I used a factory piston that was .030 Over Sized and A large cam with a lightweight rod and this kept me competitive. One thing about the kohlers is, They make power any way you modify them. So I wouldn't be worried about some other guys trying to outrun me with a Briggs.
Title: Re: K341 in a Racer
Post by: Wheelhorseracer on May 11, 2010, 05:36:03 PM
Flatheadpuller, have you played with reverse flow on the Kohler's. I have seen quite a few reverse port engines and it seems to show quite an improvement in power.
Title: Re: K341 in a Racer
Post by: FlatheadPuller on May 11, 2010, 05:39:17 PM
Reverse port engines are uncharted territory for me. Bruce "Big Daddy" on here would more than likely have input on that subject.
Title: Re: K341 in a Racer
Post by: Wheelhorseracer on May 11, 2010, 07:13:36 PM
Between Vogel and Midwest you can make a ton of power here. Like you said thought the issue with these K-series engines is heat. I think some sort of oil cooling would be a must in a circle track racer to assist in colling. I'm not going to run on alcohol either.

Has anyone given thought to an air to water or air to air intake cooling before the carb to cool the air intake charge?
Title: Re: K341 in a Racer
Post by: Big daddy on May 12, 2010, 10:40:47 AM
 IMO if you can run methanol then I would definately do it!!! Again I think your biggest enemy will be heat. I agree for quick acceleration a lighter flywheel will work out the best. However smaller bore engines are not as efficient as larger bore engines, I don't mean fuel efficient I mean volumetric efficiency, how well the cylinder gets filled with the air and fuel on the intake stroke. The air fuel charge will be cool as it enters the engine and will not gain temperature until the compression stroke. It is not uncommon to have ice form on the intake manifold of a super stock 50 while it is going down the track, so I know the air fuel charge is not heating up. The port support plate that some manufacturers sell is good for classes that you cannot weld up the port or have visible exterior welding. If you put a port support on the side of the block then you must machine that side of the block true, and if you are planning on using a Kohler type carb. that has had the backside bored really big, then you place that carb right on the port support plate then you increase your risk of breaking fhe flange of your carb. due to the fact that you are trying to seal up 2 surfaces with the carb. the and there is more risk of distorting the mating surfaces when trying to tighten the carb. bolts tight enough to seal up both surfaces. If you are using a intake manifold between then you will not have to worry about the carb. flange as much. But if you can weld up the port flange on the topside properly then you will not need any port support plate. I have heard of individuals trying the reverse port on K series engines years ago, everyone likes the port up angle of the exhaust port but what kills it is the side entry angle, the air fuel charge has to change directions right at the valve seat to enter the cylinder which slows down the charge. Aluminum pan, lighter flywheels are definately a good place to start in my opinion. And have the entire rotating assembly balanced, not just the internals.
Title: Re: K341 in a Racer
Post by: Wheelhorseracer on May 12, 2010, 11:33:02 AM
Great info Big Daddy.

I have also seen people cut angles in the deck surface out from the piston side of the valve to help with flow out and into the valves.

Have you every fireslotted a Kohler head? I couldn't do it on my K181 as the head surface is Too thin, but I have seen .040 taken from the 341 head with no issues.
Title: Re: K341 in a Racer
Post by: Big daddy on May 12, 2010, 12:11:32 PM
If I am going to try to build serious power with a K341 I would make a billet head, if the rules mandated a stock appearing head then I would use one of the aftermarket look alikes. Too much cc with a K341 head for a stock stroke motor and too thin to do much with. I relieve the deck surface on the block between the valves and the cylinder bore to help with air flow, but try to be conservative with it. Only remove what you need to and try to leave the deck alone at the cylinder edge, also match the deck relief to the cc area of the head that is in that area, i.e. follow the shape of the head in the area of the deck relief. Certain areas around the valves will make the casting think with a Kohler head especially around the valves parallel with the valve head. Don't want the valve pockets tight around the valves! This will hurt air flow in lower and mid lift of the cam. Although finned head will do better for getting rid of heat.
Will make casting thin, not think. Sorry...
Title: Re: K341 in a Racer
Post by: Wheelhorseracer on May 12, 2010, 01:43:47 PM
Ya.. I don't know of any outlaw club that would allow a billet head.

I have been told that with the offset valve guides you can fit a 2.02 intake valve in the 341/361 Block. Seems quite large but at the upper levels I think it would certainly help in flow.
Title: Re: K341 in a Racer
Post by: Big daddy on May 13, 2010, 05:33:53 AM
I have put 2.000" intake valves in the K341 blocks before without any offset valve guides. Honestly though IMO I think 1.950" is as big as I would go with one. The last K341 engine I built had that size of valve in it using a 44mm Mikuni carb. on it and that combination worked really well. With a Kohler type carb. putting any bigger valve than 1.8-1.9" then you would be porting the engine more than what the carb. can flow.
Title: Re: K341 in a Racer
Post by: Wheelhorseracer on May 13, 2010, 05:45:48 AM
Did you replace the seat to accept that large valve?
Title: Re: K341 in a Racer
Post by: Big daddy on May 13, 2010, 07:35:36 AM
The seats are ground into the block. No hard seats for the bigger valves in a K series. You will need to go with 1.650" exhaust however to get everything to clean up and seat properly, you might get a little smaller exhaust but not much. I have used 1.8,1.88 and 2.00" with a stock stroke 0.060" over 16, for pulling I had much better luck with the 1.8, and 1.88" than I had with the 2.00" for tractor pulling, the 2.00" would wind up really well but no torque. Without welding considerably you cannot maintain a good port volume size to valve ratio with the 2.00" intake size.