turning up the fuel on a ck27

[MESSMAKER]

Anyone done it? How did it turn out?

 

[K man]

No, but you got my attention. I am curious to see if you get any replies on this.

 

[ritcheyvs]

Anyone done it? How did it turn out?

Do you mean increasing the amount of fuel injected into the cylinders? If so, here's the deal: First, the injection pump (IP) and centrifugal work together to regulate the amount of fuel injected to maintain RPM, based on the "throttle" setting and load. The IP has a maximum amount (volume) of fuel that can be injected, limited by the bore and stroke of the IP plunger. The IP can deliver up to that max volume if needed to maintain RPM but that max volume cannot be increased without modifying the IP, something beyond the capability of nearly all owners.

What would happen if you could, somehow, increase the volume of injected fuel? Probably not much. There is only so much air in the cylinder so you can only burn the corresponding amount of fuel regardless of the amount injected. To get more power you need to put more air into the cylinders (e.g. a turbocharger) otherwise you just get black smoke from unburned carbon. If you could, somehow, cram more air and fuel into the cylinder you have another problem: heat. Typical normally aspirated (non-turbo) engines are not designed to remove so much heat from the cylinders, head, and (especially) pistons.

For example, when Mercedes added turbos to their old 3-liter 5-cylinder (OM617) diesel engines they used a new injection pump AND they added nozzles to spray engine oil against the underside of the pistons to cool the pistons. The new IP sensed the (boosted) manifold pressure and adjusted the max fuel volume accordingly. In other words, the injected fuel volume was limited to correspond with the manifold pressure. To the casual observer the turbo and non-turbo OM617 engines look identical except for the turbocharger and the different IP. But if you put the turbo IP and add a turbo to the non turbo block you can melt the pistons.

 

[gladehound]

Just throwing this out there (I'm certainly no engine tuner!). Since increasing fuel from the pump seems to be a no go, what about adding propane? People do it on trucks all the time. Obviously, if you hot rod any engine the ability to handle a given duty cycle (as % of max hp for given duration) is diminished.

I would never do this to my own tractor but just threw out the idea in case you want to play.

Tractors hold value so well that I've always firmly believed that if you need more power sell what you've got and buy a bigger tractor.

 

[thepumpguysc]

Yes they can be turned up. if you search utube. motorman Matt> Kubota Diesel Mower vid.
The adjustment screw has a TAMPERPROOF CAP on it for a reason..
but can quickly be removed w/ a Dremel tool and a slit cut in it lengthwise and pryed off.
Good luck and don't hurt yourself.

 

[jabelding]

Any older diesel can be turned up to some degree there is plenty of rack left on most injection pumps and the pumps are usually the same in a given engine family say ck 27-ck35 the only difference is usually just the cylinder displacement and fuel amount. So on a 27 you should be able to turn it up a bit before you run out of pump stroke. On my older kubota L275 it would never blow black smoke under heavy load. So removed the cap on the adjuster and I turned it up a bit until I got some black smoke under heavy load. The tractor was fine and I had a bit more power. Probably just brought it back to where it was when new. The Injection pumps do wear and push less fuel over time. If you really want to go crazy just add a small turbo and really jack it up.

 

[SPYDERLK]

Im not familiar whether the CK27 is gear or HST, but if gear it will be easy to judge the effect of turning it up if you have hills and the tractor has a tach.

I turned the adjustment screw in on the 7520, by increments, and kept comparing performance up a hill I had characterized. The effect was marked, but this was a turbo tractor. ... I stopped at 1 full turn.​

Yours is not turbo so you wont get the chain effect of more combustion causing more exhaust causing higher intake boost, giving the potential to burn ever greater amounts of fuel. -- Still, if your [naturally aspirated] tractor wont throw black smoke as it bogs down close to mid rpm, a little more fuel will help. Id guess 1/4 to 1/2 turn will get you the max available power. Itll probably only be a horse or 2. Almost 10%. Should be noticeable.

 

[ritcheyvs]

OK, I understand what we are talking about now.

On these mechanical IPs, there is a fuel limit stop that limits forward movement of the IP rack. It's item #14 in this diagram:



It is a threaded rod and lock nut that is normally set up on a diesel bench when the IP is assembled. Adjusting this stop "out" allows the rack to move further forward, which increases the effective plunger stroke, and that increase the amount of fuel injected. Legal issues aside, a little excess fuel will produce black smoke and a lot of excess fuel will actually reduce power.

 

[thepumpguysc]

Ritchey> you seem to be misinformed. The injection pump is an entity unto itself, and limited by the screw the engine manufacturer installs. Not adjusted on a bench by the injection pump folks. When you send a pump in for service, the screw stays in the engine block.
The pump folks SETS the fuel at full and CHECKS idle and starting. The full load fuel SCREW is set by the engine manufacturer at the factory. Due to gear train wear, fuel quality and injector condition, the fuel may not be getting a complete burn, hence the need to
"turn it up".. I'm not saying this is the correct method to remedy a low power condition, I'm just answering the question asked..
You are correct in the effective plunger stroke.. and too much fuel will actually lower the hp of the engine by flooding it w/ fuel.

 

[ritcheyvs]

PumpGuy is right on and I was wrong. I really need to stop extrapolating my limited automotive IP knowledge to areas where it doesn't apply.

Question for ThePumpGuySC: Are you in the Diesel IP/injector business? If so, do you offer services or parts that may interest folks here? Also, on the subject of IP wear (and correcting for it), do you have any experience or data on when (e.g operating hours) this might become a consideration? I know Diesel auto drivers (including me) with 300+ K miles on the factory original IP although most replace or rebuild injectors about every 100K miles or so (I think 100K miles is like 2000 operating hours). Finally, do you think ULSD has changed IP and injector service life?