Taking the grill out of the hood isn’t going to help anything. In fact, that allows larger debris into the engine bay. I would have left the hood mounted grill alone. It sounds like it’s performing as designed. Lift the hood and blow off the engine and surrounding area with compressed air or leaf blower, after each use. Use SAE 30, SAE 40, 10W40 or 15W40 oil. Put the grills back in place and keep them clean.
Kohler Command 21 Running too hot? 280-300 degrees
- Thread starter Gasbuggy
- Start date
What do you mean octane on itself? We are not talking about gasoline sitting on the bench here. The speed gasoline is burning in an engine has direct effect on engine temperature and egt. Your modern engine has the ecu to control the reaction, but that is not the case in this thread.
I have CHT and EGT sensors on my air cooled carbureted motorcycle and have personally observed that octane rating does have an effect.
Let it idle for at least 30 sec. before turning off to eliminate the backfire. That lets exhaust cool down so unburned fuel doesn't pop off. Carburetor means unburned fuel will go through the motor to the hot exhaust with or without a solenoid cutoff carb. .
Most owners manuals say to let it idle before turning key off..
Most owners manuals say to let it idle before turning key off..
Back fire when shutting down, turn down the engine speed to a slow idle before shutting down.
Speed of burn is the same regardless of the octane rating. And what I mean is that there are many ways to achieve an apparent octane rating.
There is a lot of misconception about what octane rating means and what it does not mean. The Internet is full of these misconceptions.
Low octane gasoline=more pre ignition/detonation=higher CHT.
Every engine has some detonation if tuned properly, higher octane reduces it.
This is not misconception.
Bitog is full of misconceptions and people keep repeating them without any personal experience on the subject...parrots!
All of which is completely different than the speed of burn. Again, many misconceptions.
Are you claiming that octane ratio has no effect on CHT And EGT?
I’m not sure what octane ratio is, but in and of itself the octane rating of a fuel does not affect those. But again as I’ve noted there are a plethora of ways to achieve a fuel’s octane rating. There are also many ways one engine is able to compensate for or adapt to the rating. But the rating itself does not affect those values.
By octane ratio I meant octane rating, 87 vs 93.
Please tell me how this Kohler engine would adapt to low octane fuel or bad fuel?
You are claiming that octane doesn’t affect CHT and EGT, I suggest you are dead wrong.
Your engine is not running too hot.
The Kohler engine most certainly does not, that’s correct.
You can suggest anything you want.
Now tell me what are going to be the effects of said fuel on said engine?
I honestly have no idea what you’re asking at this point. As I repeated multiple times in this thread, the octane rating in and of itself will have no effect. If the engine has a problem with preignition then a fuel with a higher octane rating will help that. But if it doesn’t and the fuel is being ignited by the spark plug, then in and of itself the octane rating between different fuels will make no difference.
Octane molecules have the same BTU and burn rate regardless of the branching. The difference comes in the resistance to preignition.
Cover gets removed (in post 12). I ran 93 because I was under the impression it spec'd 91+.
Good idea, it would be a good idea to remove all of the shrouds and clean the fins. My 16hp Command looked clean but was PACKED underneath but I couldn't see it with all shrouds in place. Would be some time well spent. I also concur on the 93 octane...no need to run higher than 87 or 89. Pure gas would be even better.
This is where you don’t understand the concept. Properly tuned engines do have some pre ignition/ detonation. If they don’t, they are not optimized. Over time, this Kohler engine will start to wear and have blow by and will start to accumulate carbon. The additional oil blow by does lowers the octane in the mixture and the carbon deposits increase pre ignition, this leads to higher CHT and lower EGT. Higher CHT increase pre ignition even more and so on, that is why many call detonation ”cancer”, you have to deal with it before fatality. Using higher than recommended octane gasoline compensate for these issues by resisting to preignition (which you agreed), therefore lowering CHT and increasing EGT.
It is true that higher octane doesn’t burn slower. This is misconception because higher octane does affect the combustion timing, which give the APPEARANCE of a slower burn. Backyard mechanics who dont really know the difference would just say that is burn slower because it kinda does make sense to them. Now, bitog parrots would just keep repeating the same thing over and over trying to police the facts, unfortunately they don’t understand the concept, context and why people say that.
It is true that higher octane doesn’t have more power. This is misconception because higher octane prevent excessive ignition retard from ecu, which give the APPEARANCE of more power. Again, people who don’t know the difference would just say that premium gasoline have more power because it kinda does in specific context. A brand new Focus RS had 350hp on 93, but had less power with 91 because the ecu pulled timing, same thing with STI and other high performance cars.
Many people have experienced an old engine that would run better with premium gasoline.
That being said, if someone has an engine running poorly with very high CHT, premium gasoline will not save him, but the concept is still valid.
In this thread, 300f is far from hot and I bet he could run 87 octane without issue because the engine doesn’t experience too much pre ignition/detonation, but the concept is still valid.
If someone wants to experiment, CHT sensors are cheap and take seconds to install while changing the spark plug.
What you stated pretty much confirms everything I said. And like I mentioned, there are many misconceptions about what the octane rating means and what it does not mean. Especially if you have an understanding of the many ways an octane rating can be achieved
One thing I didn’t see, unless I missed it, was the engine speed that you run. Higher engine speed will help cool the engine better than low to medium speed. At least this is true in my experiences.
L8R,
Matt
L8R,
Matt
You falsely claimed the opposite in this thread and multiple other threads.