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Archive through November 09, 2013
- Thread starter drglinski
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Help Support IH Cub Cadet Forum:
- Joined
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- Allen Schumacher
Marlin, lets see what that engine can handle driving two throwers in deep snow! Could be interesting to watch.
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- Binder 1650
Now that we hashed out HP vs torque with a little side bar on death wobble, I've got a ....
Quick question - Kohler single cylinder engines, RPM vs cooling. I've been told over the years to run my Kohler engines full throttle, 3600 rpms as that gives you max cooling - reason given was air flow is not linear with rpms and the higher rpms you run, the more air flow over the fins to move the heat off the engine and higher rpms give more of a turbulent air flow which is better for forced convection air flow/heat removal. But with higher rpms, isn't there more heat generated?
Also, higher rpms, I've been told, is better for charging the battery.
What is the real story with high rpms vs cooling vs battery charging?
Quick question - Kohler single cylinder engines, RPM vs cooling. I've been told over the years to run my Kohler engines full throttle, 3600 rpms as that gives you max cooling - reason given was air flow is not linear with rpms and the higher rpms you run, the more air flow over the fins to move the heat off the engine and higher rpms give more of a turbulent air flow which is better for forced convection air flow/heat removal. But with higher rpms, isn't there more heat generated?
Also, higher rpms, I've been told, is better for charging the battery.
What is the real story with high rpms vs cooling vs battery charging?
J
jclazar
Guest
Bill, I would run w.o.t maybe for snow blowing, grass mowing, tilling, towing heavy loads, ect. But as far as for pulling a light yard cart or tooling around the property, I set the engine speed below 1/2 throttle, at which the voltmeter on board will display a 13.3 charge at this throttle position. A higher throttle position yields a 13.9 charge. Running a machine faster always produces more friction. I assume in theory, that the flywheel was designed to produce the needed amount of forced air at any given amount of engine throttle providing we don't race the engine above the manufacture's recommendations.
{This is where I'm a real sticker for using Kohler approved engine oil and lubricants.}
{This is where I'm a real sticker for using Kohler approved engine oil and lubricants.}
proessler
Well-known member
Denny, No. I got my Gators from KU down @ C&G. Blew out leaves around shrub beds & decks, then made another pass over the lawn Easy Vacking & pulling my IH #4 cart for 2 more carts full. I make mulch/compost piles to cover wife's flower bed/ flag pole mound. Maybe tomorrow clean out eaves after Packer game. Greased moldboards on the IH McCormick C-20 & parked outside. Fast Hitched McCormick #21 tractor mower to the Super C & parked inside. I need to add more cold storage, maybe a 40x80 hoop building.
Not sure if the stack was the culprit to the valves or not. I had a stack on two tecumsehs that died shortly after putting it on. Always had a rain cap and inside so no rain. Could've been just bad timing on my part or the lack of lead in the fuel of an older motor. Just Leary of doing it. Like I said it killed two of my better running tractors
BILL J. Matt G. posted a chart on the cooling air flow for the K-series engines here years ago. It's straight linear lines directly equal to RPM, so 3600 equals max air flow, 1800 equals 1/2 max air flow. 1200 is 1/3 max.
I run my Cubbies just above the torque peak when mowing, maybe a little higher if I'm in a hurry or I hit a place where the grass is taller. If you read that article from HRM from the link posted here the other day you read that the stress on the crankshaft & conn rod increases exponentially with the increase in RPM. And like John L. said, higher RPM causes more friction and friction causes wear.
If it's really hot and you're working your Cubbie hard yes, you need a lot of cooling air flow, but if you're pushing snow with a blade when it's below freezing, you're actually OVER-COOLING the engine. The gasoline vapor condenses on the cylinder walls and finds it's way past the rings and into the engine oil and the oil never gets hot enough to evaporate the gas & water out. That's why you should change your oil more frequently if you use your CC in winter. And that's also why I explained how the governer works, just because you're running 3600 RPM has NOTHING to do with how much actual LOAD you have on your engine. You have to develope a sense of how much load your actually putting on your engine when you run it.
If your charging system is working, your CC should charge the battery at just above slow idle.
High RPM's just seem to wear things out quicker. How long would your car or pickup last if you drove it as fast as it would go EVERYWHERE?
PAUL - I was going to blow the locust leaves off the driveway today but Mother Nature took care of it for me. Trees lost a LOT of leaves too. Probably mow & aerate late next week.
HARRY - There's a limit to how big you can go over-size on the roll pin holes on those left steerng spindles on NF CC'. You drill out that roll pin hole to 3/8" on a 3/4" spindle and there's not much spindle left. IH even had problems with steering arms on wide frt ends on their BIG tractors if they were used to run loaders or other heavy frt mounted equipment. The steering arms were bolted down on tapered splines and they still worked loose. Carrying too much frt end weight when it wasn't needed aggrivated the problem too. The best "FIX" was the later vintage MTD axles which unfortunately only work on the WF tractors.
I run my Cubbies just above the torque peak when mowing, maybe a little higher if I'm in a hurry or I hit a place where the grass is taller. If you read that article from HRM from the link posted here the other day you read that the stress on the crankshaft & conn rod increases exponentially with the increase in RPM. And like John L. said, higher RPM causes more friction and friction causes wear.
If it's really hot and you're working your Cubbie hard yes, you need a lot of cooling air flow, but if you're pushing snow with a blade when it's below freezing, you're actually OVER-COOLING the engine. The gasoline vapor condenses on the cylinder walls and finds it's way past the rings and into the engine oil and the oil never gets hot enough to evaporate the gas & water out. That's why you should change your oil more frequently if you use your CC in winter. And that's also why I explained how the governer works, just because you're running 3600 RPM has NOTHING to do with how much actual LOAD you have on your engine. You have to develope a sense of how much load your actually putting on your engine when you run it.
If your charging system is working, your CC should charge the battery at just above slow idle.
High RPM's just seem to wear things out quicker. How long would your car or pickup last if you drove it as fast as it would go EVERYWHERE?
PAUL - I was going to blow the locust leaves off the driveway today but Mother Nature took care of it for me. Trees lost a LOT of leaves too. Probably mow & aerate late next week.
HARRY - There's a limit to how big you can go over-size on the roll pin holes on those left steerng spindles on NF CC'. You drill out that roll pin hole to 3/8" on a 3/4" spindle and there's not much spindle left. IH even had problems with steering arms on wide frt ends on their BIG tractors if they were used to run loaders or other heavy frt mounted equipment. The steering arms were bolted down on tapered splines and they still worked loose. Carrying too much frt end weight when it wasn't needed aggrivated the problem too. The best "FIX" was the later vintage MTD axles which unfortunately only work on the WF tractors.
When you put a stack on an engine you are significantly reducing back pressure in the exhaust tract. This causes a lean condition which in time will burn a valve. Readjust the carburetor with the stack on a little on the rich side and you should be good to go. I have custom made numerous stacks and stack/muffler combinations and always richen the carburetor up if the factory muffler has been replaced and or the back pressure has been significantly reduced. Just my 2 cents from my experience.
BRETT - My thoughts on your stack situation was that cool air got down into the stack when you shut the engine off and warped the exh valve which caused it to burn. I have a straight pipe on the K321 in my #72 and I ALWAYS stuff a shop towel into the stack as soon as the engine stops. 150+ operating hours and NO problems!
Letting the engine idle and cool off after running it is VERY important too. The exh valve on gas engines operates around ORANGE Hot under load. You have to let it dissipate all that excess heat before shutting the engine off.
Some engines are just more susceptible to exh valve warping & burning than others. I've had a straight pipe on my Super H Farmall for over 15 yrs and no problems. I also have a rain cap & it's stored inside.
Letting the engine idle and cool off after running it is VERY important too. The exh valve on gas engines operates around ORANGE Hot under load. You have to let it dissipate all that excess heat before shutting the engine off.
Some engines are just more susceptible to exh valve warping & burning than others. I've had a straight pipe on my Super H Farmall for over 15 yrs and no problems. I also have a rain cap & it's stored inside.
nbextermueller
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- May 18, 2007
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- Nic Bextermueller
My opinions on stacks is...
The look cool when done right, but are far too loud if they are just straight off the block. I have a picture of a 128 with a stack, where the stack was adapted to the factory muffler. That's what I may do on mine. It's stored indoors, so no need for a rain flap.
But in the racing world, short stacks (aka: straight pipes, or even shorty headers can and do burn valves. It's due to a lack of "back pressure" on the exhaust. Especially on any single cylinder pipe (picture zoomies on a V-8.)
During the cycle of the engine there is a very short time when the exhaust is still open, the intake starts open, and the piston is traveling downward. Odds are, the flame front is still occurring and without the resistance or pressure caused by a muffler, the flame travels out past the valve down the pipe. But what really gets thing burned is the presence of oxygen in such a short pipe. It will make those exhaust gases, much much hotter. Melting and burning away at your precisely machined valve seats.
Eventually, you lose a good seal at the valve, and things go down hill from there, sucking exhaust gases back in where a fuel charge should be, killing the A/F ratio, losing power, then washing the rings cause it's to rich.... Yadda yadda yadda.
So yes, short pipes can kill valves. We run them on pullers because mufflers do create pressure that can limit RPM's. but at 7,000+rpm, valves, seats, and springs are consumables anyways.
The look cool when done right, but are far too loud if they are just straight off the block. I have a picture of a 128 with a stack, where the stack was adapted to the factory muffler. That's what I may do on mine. It's stored indoors, so no need for a rain flap.
But in the racing world, short stacks (aka: straight pipes, or even shorty headers can and do burn valves. It's due to a lack of "back pressure" on the exhaust. Especially on any single cylinder pipe (picture zoomies on a V-8.)
During the cycle of the engine there is a very short time when the exhaust is still open, the intake starts open, and the piston is traveling downward. Odds are, the flame front is still occurring and without the resistance or pressure caused by a muffler, the flame travels out past the valve down the pipe. But what really gets thing burned is the presence of oxygen in such a short pipe. It will make those exhaust gases, much much hotter. Melting and burning away at your precisely machined valve seats.
Eventually, you lose a good seal at the valve, and things go down hill from there, sucking exhaust gases back in where a fuel charge should be, killing the A/F ratio, losing power, then washing the rings cause it's to rich.... Yadda yadda yadda.
So yes, short pipes can kill valves. We run them on pullers because mufflers do create pressure that can limit RPM's. but at 7,000+rpm, valves, seats, and springs are consumables anyways.
Daniel G.
I gotta disagree with ya on stacks looking dumb.
Bryan's 169 is super cool IMHO.
I gotta disagree with ya on stacks looking dumb.
Bryan's 169 is super cool IMHO.
CHARLIE - Think it was about 1966 I got two VW Beetle exh. resonators for X-mas or my B-day, forget which. Dad brazed up a "T" pipe from large electrical conduit and some 1" pipe fittings and those resonators became Twin Stacks on the old 70. We ran them for quite a few years that way. We had some low hanging branches on some trees so had to have short stacks. I'd tried a longer stack with a rain cap for a while before the twins, but the old K161 didn't have enough Horse Power to open the rain cap.
I know I took some nice pic's of the 70 with the twin stacks, either I have it buried some place or Mom still has it.
I know I took some nice pic's of the 70 with the twin stacks, either I have it buried some place or Mom still has it.
And when I think it might rain I carry a plastic bottle with the bottom cut off to place over the stack. It has never blown off and keeps the water out .PTO handle is where the water bottle sits when not needed.
Hi all haven't been on here in a while, been working too much. I am having a small problem with my 12hp it runs fine for a little then starts to sputter then it will seem to recover then it dies, it does this two or three times then it refuses to start again for awhile. it acts to me as if it is starving for fuel but the tank is full and when I check the float bowl there is fuel in it also, any ideas anyone? Oh I should mention that it does this when its not under load. I don't know if it does it when under a load because it will not stay running long enough to find out.
