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What Small Engine Is Easiest To Modify For Performance?


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#1 boostedbuick OFFLINE  

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Posted September 08, 2012 - 09:54 PM

Rather generic question, I know. But I'm looking to repower a mini dozer and need input. Looking in the neighborhood of a 10-14hp horizontal shaft single cylinder gas engine. Most of that criteria can be ignored, but it HAS to be able to fit inside the frame of the dozer (haven't measured yet). I'm no stranger to adding power to engines, but never tinkered much with small engines. Didn't know if I needed to stay with one certain brand/model/era to have off the shelf options for hop up parts and be able to do it on a reasonable budget (no multi-thousand dollar ideas please).

I like the originality of the dozer, but that 7hp tecumseh is lame. Needs freshened anyway, might as well shelve it and build something fun. Something high compression. Really high compression. Leaded racing fuel compression. What do those junior dragsters run for engines?

I'm brainstorming at this point so feel free to reality check me. But SOMETHING is going to happen to it.

#2 Dieselcubmike OFFLINE  

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Posted September 08, 2012 - 10:35 PM

Alrighty well if your using an engine for a dozer i'd go with a kohler flathead 16hp and put a high compression head on it. Here's a few companies to look at for power.
http://www.nicholsperformance.net/
http://www.midwestsupercub.net/
http://www.vogelmanu...uring.com/shop/

I always run kohler gas engines because there a good hard working brand and theyve never left me down. There very easy to upkeep and are heavy duty. No carb tuning or high idles or any sorts of problems that ive encountered.

#3 Tennblue59 OFFLINE  

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Posted September 08, 2012 - 11:06 PM

I would say either the kohler flat heads, or the honda clone engines (much as it pains me to say that.... :orangecool: )
I base this statement on the fact that these two engines are arguably the most hopped up engines around, and there are plenty of sources and knowledge on how to rod them.

The kohlers are bulletproof and the rigidity of the block is often used by the pulling folks. But the head design doesn't breath as well as an ohc design. For an example of what can be done, go to Brian Miller's cub cadet site.

The honda clone motors are widely used by the go-kart folks. You can buy ANYTHING to up the power of these if you have the wallet... The engine design makes more efficient power than the kohler design. But I don't think they have the longevity of the heavier overbuilt kohlers.
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#4 Dieselcubmike OFFLINE  

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Posted September 08, 2012 - 11:24 PM

I would say either the kohler flat heads, or the honda clone engines (much as it pains me to say that.... :orangecool: )
I base this statement on the fact that these two engines are arguably the most hopped up engines around, and there are plenty of sources and knowledge on how to rod them.

The kohlers are bulletproof and the rigidity of the block is often used by the pulling folks. But the head design doesn't breath as well as an ohc design. For an example of what can be done, go to Brian Miller's cub cadet site.

The honda clone motors are widely used by the go-kart folks. You can buy ANYTHING to up the power of these if you have the wallet... The engine design makes more efficient power than the kohler design. But I don't think they have the longevity of the heavier overbuilt kohlers.


Very well said in my opinion. :thumbs:

#5 wvbuzzmaster OFFLINE  

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Posted September 08, 2012 - 11:42 PM

Definitely the Kohler K series will sit right in there. The one you will want is the 12 horsepower K301 as they are easier to find and I have had no issues with the 12 HP. The 14 HP is a lot tougher to work with in my opinion.

#6 JDBrian OFFLINE  

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Posted September 09, 2012 - 06:01 AM

The Kohlers and Honda clones couldn't be more different but both suggestions are good ones. The Kohlers are built strong and are easy to rebuild and work on. The 12,14 and 16 share the same block and it seems to me that the 12's seem to hold up better perhaps because they do not produce as much heat and have more metal left in the block. I've seen a lot of people searching for 14 and 16 hp Kohlers up here including myself. I have one with a cracked block which seems to be a common problem if the engine cooling fins are not kept cleaned out. It may come down to space considerations. The 2 designs are different shapes and the Kohlers are tall while the Hondas are lower and deep front to back due to the almost horizontal cylinder layout. They make big HP by revving them up to much higher RPM's than the rated 3600.

#7 GTTinkerer OFFLINE  

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Posted September 09, 2012 - 06:15 AM

The junior dragsters are usually limited to the 5 hp B&S horizontal engines and there are several companies that sell aftermarket high performance parts but they don't come cheap..

Folks are getting over 50 hp out of the Kohler K341 engines. There are turbochargers and even superchargers built for them but the big horsepower numbers come with very high prices. A couple of companies, Jones is probably the best known, that machine steel blocks for the K341 with no cooling fins that can cost over $5000 for a used one.

#8 LilysDad ONLINE  

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Posted September 09, 2012 - 06:19 AM

I see more and more of the B&S Intek engines being used for tractor pulling. I have no direct experience with them, but I believe they are way better than the clones.

#9 Toolpartzman OFFLINE  

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Posted September 09, 2012 - 06:38 AM

Near you in Columbus,MO is Brian Miller http://gardentractor...s.com/index.htm
He builds with the Kohler L's also.

#10 KennyP ONLINE  

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Posted September 09, 2012 - 06:41 AM

In your search for 'more power', don't forget the drive train of the the crawler. Too much power can be a real bad experience.

#11 olcowhand ONLINE  

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Posted September 09, 2012 - 08:02 AM

In your search for 'more power', don't forget the drive train of the the crawler. Too much power can be a real bad experience.


Yes, way worse than not enough power! Low power doesn't eat up the drivetrain!

#12 boostedbuick OFFLINE  

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Posted September 09, 2012 - 08:29 AM

Thanks for all input so far. LOTS of help. I am going to go digging. I know of at least 3 places to go small engine hunting around here, so this gives me ideas. These kohler engines being mentioned. How old are they? Virtually all of my small engine selection is going to be old engines. Thought about putting a "crate motor" brand new engine in it, but I can freshen an old one for much less and add more power later if I still need more. The belt drive system in the dozer is going to be the eventual limit. Once I lose ability to transfer the power, adding more of it won't help me any. Think of this as a "strong foundation I can add to later, if necessary" engine search.

#13 Gtractor ONLINE  

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Posted September 09, 2012 - 08:39 AM

My Struck mini dozer has a 14 horse K series Kohler. There is no need for that much power although the cool factor is way up there. :laughingteeth:
I can, and have snapped the drive chain finding an immovable object under the surface. The K321 is a very tight fit in the frame. I didn't build mine - bought it already converted. If I were to do one and leave the drivetrain stock, an 8 horse K series would be my engine of choice.
Good luck!
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#14 Cvans ONLINE  

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Posted September 09, 2012 - 09:46 AM

These guys are giving you some excellent advise. All the power in the world will do you no good if you just keep breaking the drive train. If you really want high compression and increase the kool factor put a small 6hp.diesel in there. Also if you decide to go with the Kohler I will second the notion of using the 12 hp. When you go to the 14hp and up the vibration factor increases quite a bit.
Black diesel smoke and an old Cat just go together though. :thumbs:

#15 boostedbuick OFFLINE  

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Posted September 09, 2012 - 10:14 AM

Yeah but where would I find a cheap diesel? I'd love a small diesel, TORQUE is what I really need here, the ability to keep itself from bogging down under load. Once the RPMs drop under load this tecumseh just gives up.

The drive chain that was snapped, is that the 40 series chain in the back that drives the track sprockets?




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