Author Topic: K341 in a Racer  (Read 8623 times)

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Wheelhorseracer

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Re: K341 in a Racer
« Reply #15 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.

Offline Big daddy

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Re: K341 in a Racer
« Reply #16 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.
Bruce Litton

Offline chuckm

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Re: K341 in a Racer
« Reply #17 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
Chuck Moritz
Sutton, Nebraska
age 58


Wheelhorseracer

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Re: K341 in a Racer
« Reply #18 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.

Offline FlatheadPuller

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Re: K341 in a Racer
« Reply #19 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
Dennis Bazzett
Grandville Michigan

Offline outlawmower

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Re: K341 in a Racer
« Reply #20 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.
PUT YOUR GAME FACE ON!!!

Wheelhorseracer

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Re: K341 in a Racer
« Reply #21 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.


Offline FlatheadPuller

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Re: K341 in a Racer
« Reply #22 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.
Dennis Bazzett
Grandville Michigan

Wheelhorseracer

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Re: K341 in a Racer
« Reply #23 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?

Offline Big daddy

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Re: K341 in a Racer
« Reply #24 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.
Bruce Litton

Wheelhorseracer

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Re: K341 in a Racer
« Reply #25 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.

Offline Big daddy

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Re: K341 in a Racer
« Reply #26 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...
Bruce Litton

Wheelhorseracer

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Re: K341 in a Racer
« Reply #27 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.

Offline Big daddy

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Re: K341 in a Racer
« Reply #28 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.
Bruce Litton

Wheelhorseracer

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Re: K341 in a Racer
« Reply #29 on: May 13, 2010, 05:45:48 AM »
Did you replace the seat to accept that large valve?