Lets build a K321 torque monster

[Greentored 3,201]

Ok fellas, this new build is getting K321 powered- it runs but is tired. Plans are to overhaul, mill the head, port and relieve, cut the valves, cheater cam, balance the crank (I have a hines balancer and bobweights) etc... Torque is the name of the game, not interested in race gas or buzzing it over 3500-4000, if even that high. Stock rod, stock piston, etc...

Anyone have some good experience with these?  Will the original or any aftermarket stock replacement rod hold up ok? Am told the Magnum rod and piston will fit and are beefier?

Toss me some ideas, Kohler shaker gurus!

[ebinmaine 63,089]

I got no real knowledge of my own but if you check out Brian Miller's site there is a TON of information on there

[WHX?? 46,729]

http://gardentractorpullingtips.com/balance.htm

Since most of us here are content puttputz around at idle... 

Edited May 26, 2020 by WHX24

[Goofey 89]

Biggest piston you can bore the block to. But why not just fit a 341 or 361 complete engine instead? Or a diesel?

 

All the porting and stuff wont do much for torque. Almost only good for rpm and high hp. Better off concentrating on correct timing and fuel mix IMO.

Edited May 26, 2020 by Goofey

[Blackhood Bill 720]

@Greentored might check with @richmondred01 he has been rebuilding these Kohler's for years.

[Tractorhead 8,609]

Huh, i‘m no Kohler expert, but maybe a bit Supercharge will solve your needs,

after Engine is reworked..

 

 

 

 

😎😇

[Skipper 1,788]

Looks like a late nineties toyota blower for a 2 liter engine or so 

 

Small turboes have been fittet to 500cc motor bikes with great success though. But perhaps that's a bit much too 

 

Seriously though, I would put a china 198f diesel in it. Probably could do that close to the cost of an all in all out rebuild.

Edited May 26, 2020 by Skipper

[Achto 26,546]

12 hours ago, Skipper said:

Seriously though, I would put a china 198f diesel in it.

 

If you want torque then a diesel is most definitely the way to go. I have a tractor with a Hatz 1B40 in it. 9.9hp just under 18ft lbs of torque. So far I have yet to work it hard enough for it to pull on the governor. When I drop a 10" Brinly plow in the ground behind it, the engine never changes tone.

 

If you want torque from a gas engine stroke & compression is what you want. These 2 things will increase torque every time. Think big block V8 compared to small block V8.

 

 

Edited May 27, 2020 by Achto

[ebinmaine 63,089]

There's no replacement for displacement

[bc.gold 3,399]

46 minutes ago, ebinmaine said:

There's no replacement for displacement

 

Extreme oversquare engines are found in Formula One racing cars, where strict rules limit displacement, thereby necessitating that power be achieved through high engine speeds. Stroke ratios approaching 2.5:1 are allowed,^[a] enabling engine speeds of 18,000 rpm while remaining reliable for multiple races

[oliver2-44 8,852]

Browsing puller engine build siters in the past, one thing I found several said they do that gains more than porting and polishing is to slightly relieve the top of the block from the valves to the cylinder bore.  Then they talk about welding up the sparl plug hole in the head and weld building up an areas closer to the center of the cylinder for the new plug location.   

[Tractorhead 8,609]

6 hours ago, Skipper said:

Looks like a late nineties toyota blower for a 2 liter engine or so 

 

Small turboes have been fittet to 500cc motor bikes with great success though. But perhaps that's a bit much too 

 

Seriously though, I would put a china 198f diesel in it. Probably could do that close to the cost of an all in all out rebuild.

 

No, this are a300 and a500 charger, can purchased reworked for cheap money.

so between 150$ and 180$ you need for Basic Setup can be used from 50ccm up to 1,2 Litres.

depending on gearratio.

Turbochargers may be bit cheaper, but you need a trusted Oilpump to adapt.

 

I like the sirring running noise, and extrem simply to fit.

If fine Tuned once on the Carb, a simple way to got more torque but if wrong tuned,

a simple Way to blow your cylindrehead to Heaven.

They have the big advantage against Turbochargers, 

they don‘t need pressure oil line like a Turbocharger needs.

drops a bit of the won torque,

but simpler to adapt on a  Engine without Oilfilter  even longterm.

 

 

Also in Mercedes compressor uses this sort of Rootscompressors.

 

 

[tom2p 2,393]

11 hours ago, Greentored said:

Ok fellas, this new build is getting K321 powered- it runs but is tired. Plans are to overhaul, mill the head, port and relieve, cut the valves, cheater cam, balance the crank (I have a hines balancer and bobweights) etc... Torque is the name of the game, not interested in race gas or buzzing it over 3500-4000, if even that high. Stock rod, stock piston, etc...

Anyone have some good experience with these?  Will the original or any aftermarket stock replacement rod hold up ok? Am told the Magnum rod and piston will fit and are beefier?

Toss me some ideas, Kohler shaker gurus!

I believe one or two Kohler engines had a forged rod - it's possible this rod will also work in a K321 ?

or you could go aftermarket (with a rod used by the pullers )

 

some Kohler engines used a better piston (made by Mahle) - maybe one is avail for K321 ?

 

[Greentored 3,201]

 Some of you guys are nuts  I should have noted: the plan is a 'as long as Im in there, lets improve it over stock' type build. Been doing this stuff for 3 decades and always enjoyed compliments and raised eyebrows over "that runs strong...for what it is"....  little 396 chevys giving 454s a run for their money, Vortec heads on a plain old 350 making 325-375hp, a hopped up inline 6 in my coupe turning 6200rpms and blowing the tire off on the 1-2 shift, outrunning the go kart guys fully prepped 212 predators with the same with stock internals, .......ok you get the point.....  Theres nothing I plan to throw at this thing that the stock 321 wouldnt be enough for- but theres always room to improve things a bit while theyre apart, right?

Millers page has enough info to make a persons head spin! It does appear there is, or was, an Alcoa forged rod in the K341, and Magnum had a beefier rod and Mahle piston as well. Email sent to Brian, will see what he comes up with.

Really appreciate the advice and a good discussion, fellas!

[WHX?? 46,729]

Here's another place worth checking out for HP Kohler stuff ….

https://mwsc.co/

[oilwell1415 563]

Torque is how much air you move per engine revolution and power is how much air you move per minute.  It's that simple.  You can mess with efficiency and gain a little, but any significant gain will require more air in one way or another.  To increase torque you have to increase cylinder filling, which higher compression can actually hurt.  You'll have to find the balance between the two if you up the compression.  For low speed flow a good multi angle valve job is probably the best bang for your buck.

Something else to look at are tuned intake and exhaust.  Chrysler did some testing eons ago and found that 86,000/rpm is the tuned length of an intake runner.  That would put you at about 24".  Hard to package, but may help.  Same with exhaust.  A long tube header will help.  It would probably need to be around 40" long to work well in this rpm range.

You can also play with the governor spring rate and preload.  If you set the governor to 3800 it will probably start coming in several hundred rpm before that, maybe 3100-3200.  With a different spring rate and preload you may be able to get it to wait until 3600-3700 rpm before it starts pulling power.  An 8hp Briggs I built in college would only make 8hp if you manually held the throttle wide open against the governor.  With the governor working it would only do about 5 or 6 hp on the dyno.  I was able to get it up to 8.5hp on the dyno with the governor properly holding it at 3800 and the playing with the governor spring was responsible for most of that.  And this engine would pass for stock when it was torn down.

Edited May 28, 2020 by oilwell1415

[Greentored 3,201]

Nothing back from Brian as of yet. At this point, I really want to fly this ship and have plenty on the plate. May very well slap a ring set in it and call it a day til another time.

Only concern is, if it runs good (and it most likely will, murphys law) ill never tear it back down and do the whole job correctly

[ebinmaine 63,089]

5 minutes ago, Greentored said:

Nothing back from Brian as of yet. At this point, I really want to fly this ship and have plenty on the plate. May very well slap a ring set in it and call it a day til another time.

Only concern is, if it runs good (and it most likely will, murphys law) ill never tear it back down and do the whole job correctly

 

 

 

I'm sure we could find a whole bunch of people that would be willing to cajole you into spending more of your money. And ripping things apart for no particular reason.

[Greentored 3,201]

13 hours ago, ebinmaine said:

 

 

......... And ripping things apart for no particular reason.

Judging by what my garage looks like in a few short months, looks like a lot of folks beat me to it.

....and apparently I came along trying to play hero and put em all back together

[Greentored 3,201]

Ok, back to this build. I posted up in the 'pullers' section with cam and rod questions and got some answers there.

Tore down and mic'd rod and journal last night and they are perfect. Piston skirt was cracked, rings and bore are WAY out of spec, and the exploding balance gears were still intact, which will be tossed in the trash.

So, do I reuse the factory Kohler rod, or replace with an unknown aftermarket?

Edited July 8, 2020 by Greentored

[ebinmaine 63,089]

@fast88pu Kyle mentions an upper RPM limit of about 4500 for a stock rod in the other thread.

If you're not going to change the cam, hence not going to change your usable RPM range, I'd stick with the stock rod.

 

 

[oilwell1415 563]

I'm not convinced it isn't worth it to change the cam, but I don't know what is available either.  Looking online real quick it looks like you just get your stock cam reground.  The few companies I looked at talked about lift and duration, but didn't say anything about lobe separation angle, ramp rates, etc.  There is a lot of power hidden in those specs.  Do you know what the stock specs are?  Tightening the LSA if there's room to do it without causing other problems can help more than increasing compression.  How many teeth are on the cam gear?  You may be able to install the cam one tooth advanced and get the same effect.  Like I said in the other thread, these engines spend most of their time on the governor, so you take a different approach to building them.  Lots of things that don't make any difference running wide open make a huge difference at part throttle.

[ebinmaine 63,089]

11 minutes ago, oilwell1415 said:

Lots of things that don't make any difference running wide open make a huge difference at part throttle

That's the part that interests me.

I really don't need any more power. I could actually do with half of what I have on the Cinnamon Horse.

But the whole idea is intriguing.....

[oilwell1415 563]

3 hours ago, ebinmaine said:

That's the part that interests me.

I really don't need any more power. I could actually do with half of what I have on the Cinnamon Horse.

But the whole idea is intriguing.....

 

It's pretty basic.  There are two ways to make more power:  burning more fuel, which means putting more fuel and air through the engine, or burning what you are putting in there more efficiently.  When you are running at WOT the best way to do it is to pump more air and fuel until you've reached the practical limits of doing that.  At part throttle the amount of fuel and air you can pump is intentionally restricted by the carburetor, so your goal is to increase efficiency. Increasing efficiency means you can actually use less fuel to do work.  If you've got the carb at part throttle and can only fill the cylinder half full of fuel and air you have to do things to get the most out of that.  Increasing compression is one way to do it, but you can only go so far with that before it causes other problems.  For example, if you increase the compression ratio from 6:1 to 7:1 you have actually reduced the volume of air that will fit in the cylinder by 17%.  At some point that will cost you power.  You can accomplish the same thing in a low speed engine by closing the intake valve earlier in the cycle.  Another thing you can do to help part throttle efficiency and power is advance the ignition timing.  This is why cars had vacuum advance before computers took over.  I'm not sure you could do that easily on a Kohler, but if you could do it you would get a lot of benefit from it.

[Greentored 3,201]

The crank and rod mic'd out dead nuts, giving me .002, and no I wont be buzzing this thing past 3500-4000, so I will reuse the rod. Stens +.010 piston and +.020 rings on the way so I can file fit a top ring. Also did some research and found guys would ream the 5/16 guides, cut down, shorten and install small block chevy valves which are 11/32 stem, and use the oil seal O ring groove for the keepers.. The GM LS series engines have 8mm stems and I have the ability to cut keeper grooves, so one of those will be here soon as well. Planning to cut it down to 1.500-1.600, leave the 1 3/8 exhaust valve. I believe at .324 stock lift, the valve is the restriction, not the port. Lots of research being done, then putting my own spin on it. A moderate, not radical compression boost is a given. Stay tuned, s**ts gonna get silly

Edited July 8, 2020 by Greentored