I have a 25hp Kohler CV25 & would like to convert it to a horizontal installation. I'm thinking that can be done fairly easily.... am I right? obviously the intake manifold is different, and the oil pickup tube is needed.  do I need a different oil sump too? I know the heads have to have an oil hole drilled. what else? thanks

ya well, thanks, but I kinda all ready know how to measure them.... mine are unfortunately still in the engine at the moment. I'm just trying to do some planning before I tear it down (or not). anybody have some numbers? aprox is close enough to do some projections. thanks

I guess I should have prefaced this thread like my others....

first.... I'm Alaska.... no tractor racing up here, second, not likely I'll ever get to one of your events to meet people that race (though it's interesting) third,  I'm not building a tractor engine... it's for my hovercraft

and get real.... there are several companies producing long rods and as far as I can tell, no one has posted data on what this product will do all by itself.... removing the effects of the compression increase that comes with the required piston change.

I'm 63, I raced motorcycles in the 70's when the long rod was still a new idea and considered a must have in the day.... you just did it. now.... I'm researching this and there is a lot of different opinion, and some of it makes sense. every mod is a trade off.... I don't want to trade my low RPM power..... I want to increase it, and frankly, the long rod looks like it could be the wrong thing to do. I'm looking for peak power at 3000-3300.... whatever that is, yes I know more RPM means more power, but my props limit the engine speed. anyway,  if I wanted only to increase C/R.... no problem, I know how to deal with that. btw, I'm a licensed aircraft mechanic (40 years) with a machinist background among other industry experience.

---

p.s. - "opening the checkbook and doing the math" is no problem.... I also have an airplane.... that will stress your checkbook, even though I'm licensed to do all work on it

right now the math says there is no reason to pursue the long rod for my application. that based on the fact that no one can show me that it does anything positive at my RPMs (or any RPM for that matter). (bearing in mind that I built long rod motors in the early '70s)

not trying to be a smarty but I specifically asked for data..... not stories from 12 different builders. data comes from testing.... like on a dyno.  it's surprising but there doesn't seem to be much real testing going on that I can find anyway (that people are willing to release). am I looking in the wrong place?

I have already been in touch with Zack. looking for all the data I can lay my hands on

thanks

the long rod idea has been around in auto and motorcycling a long time. Smokey Yunick made a living outta doing it. I was a believer until I started reading (many) threads about what it does and doesn't do. Every mod has trade offs, and now I'm curious... just how much (if any) does it add. Apparently Smokey's success was due to the fact that the head designs of the times were pretty poor, and modern high flow heads eliminate most of the advantage long rods had. like I said, theres a lot of talk, opinion, calculation, and seat of the pants testing... I'm looking for some hard data. it is likely that there is no advantage, and possibly a detriment to using long rods on low RPM engines.

thanks though & keep it coming

I'm going to hop up my CV25 a bit this winter. It runs props on my hovercraft so I need to keep RPM in the normal range. So far I am going to do a port & polish and a good 3 angle on the valves & seats. I have a 27/30 cam to install because that's what my research indicated.... a custom grind would do little at my RPMs.

heres my other possibilities:

long rod conversion.... really thinking I like that idea. I believe the required pistons also bump the compression ratio a bit due to the flat tops, so the question would be, how much? and would the .060 copper gasket keep me in the range to still use regular gas. the other question is the bores.... to provide the right piston clearance, I will need to hone a couple thou (according to Zack.. I believe him) anyway, some are apparently Nikasil, so that would be out. is there any way to tell without pulling the engine apart (like series/build number)?

Roller rockers.... is there any point in doing this on a low RPM engine?

Roller Lifters.... same?

Spark advance..... what is the stock advance on the 25 and on the 27 (since I might use a 27 cam).

What else? is there something I should consider for an engine that can't turn more than about 3300

http://youtu.be/0ZQih6QPiZU

http://youtu.be/B3FKZ91LObo

I know there are roller followers made for the Kohler twin.... how would the roller work with the stock cam? research suggests it might be worse without a cam specific for roller design. what cams are out there? everything I see is aimed at higher rpm ranges. my rpm must be kept below 4000, and 3800 is better because of my propellers (hovercraft)

I was planning on using a 27hp cam in my 25hp Command.