My Kubota was a dirtbag!
- Thread starter Wildfire
- Start date
Wildfire
Active member
Equipment
Kubota L5740 HSTC3 and a Kubota ZG222Z, 2013 BX25D,Custom Toyota fork lift.
Willdfire,"gas eng needs backpressure"?? I've heard that for years but no one has been able to explain why. Can you??
Wildfire
Active member
Equipment
Kubota L5740 HSTC3 and a Kubota ZG222Z, 2013 BX25D,Custom Toyota fork lift.
A gas engine is a whole different beast. Cut the muffler off a gas engine and you'll feel the engine loosing power. I see it in the shop all the time. timing, engine temp can be affected by no back pressure causing a loss of torque and power.
You know, if you think about it the back pressure really doesn't make since if you look at drag cars. One with zoomy headers on it can't have hardly any back pressure on it and those tipically are the highest performing engines on the track.
Wildfire
Active member
Equipment
Kubota L5740 HSTC3 and a Kubota ZG222Z, 2013 BX25D,Custom Toyota fork lift.
So true but I'm referring to a fuel injected every day automobile. With technology being what it is today you can rework a piston and a head to do what you want it to do. Plus you have to take into account the type of fuel that's being used.
Wildfire
Active member
Equipment
Kubota L5740 HSTC3 and a Kubota ZG222Z, 2013 BX25D,Custom Toyota fork lift.
The way technology is changing so fast these days what we consider to be right today will be changed by tomorrow.
aquaforce
New member
Equipment
L245DT FEL, JD450 Track loader, 5' scrape blade&mower, 5x10 trailer, Dump truck
Nice job on the exhaust!!!
I flared the tip on my exhaust like the diesel after treatment systems use to knock down exhaust temps. It deflects the air into multiple directions to mix the heated exhaust with cool ambient temps. The benefit I like is that the deflection also keeps the exhaust from kicking up dirt, grass and loose items on the ground.
The exhaust hardly stirs anything at all around the tractor and it is diverted so well there is no odor to have to smell.
I flared the tip on my exhaust like the diesel after treatment systems use to knock down exhaust temps. It deflects the air into multiple directions to mix the heated exhaust with cool ambient temps. The benefit I like is that the deflection also keeps the exhaust from kicking up dirt, grass and loose items on the ground.
The exhaust hardly stirs anything at all around the tractor and it is diverted so well there is no odor to have to smell.
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Wildfire, you still haven't given the technical reason. I'm takeing an eng block to a place that builds race engines tomorrow to ck for cracks. I'll try to remember to ask them...
my fix to the exhaust on the loader of my L3940 also added a turbo under the hood
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Wildfire
Active member
Equipment
Kubota L5740 HSTC3 and a Kubota ZG222Z, 2013 BX25D,Custom Toyota fork lift.
Yours look very nice as well. Cool tractor!
Give Google a try. There are so many mixed opinions about the subject you'll have to judge for yourself. http://answers.yahoo.com/question/index?qid=20100623171834AAIftI1
When I went to do mine I bought the stack and even machined a few parts to do what you did there but I decided not to because I didn't want to put a hole in the hood of the tractor for one and if I did that meant the hood couldn't open easily so It was easier for me to extend what was there and doing that I never had the other two issues. How do you get you hood open now? Do the stack impair your visibility?my fix to the exhaust on the loader of my L3940 also added a turbo under the hood
Wildfire
Active member
Equipment
Kubota L5740 HSTC3 and a Kubota ZG222Z, 2013 BX25D,Custom Toyota fork lift.
Ask 10 people about anything and you'll get many different opinions. A Back pressure question is a tough one because of all the factors that has to be considered such as type of fuel and type of engine. It's not something I've been terribly concerned with. Mostly all my engines are all stock.
Kubota Newbie
Active member
Equipment
M4500, New Idea Cut-Ditioner, JD 14T Baler, IH "Plow Chief" plows, Oliver Rake
Guys,
Backpressure, no back pressure, gas, deisel... It's all about the manufacturers intended design parameters. It impacts deisel engines to a lesser extent because they are not dependent on a carbueration/fuel injection system that draws the fuel air mixture in through an intake manifold/carb and/or throttle-body assembly. Deisel power is largely a function of how much fuel you want to inject into the cyl because you're not metering the air flow (within limits of course, which is where turbo chargers step in).
Now... In a gasoline engine the power output relative to the amount of exhaust restriction is a function of the design of the camshaft and how lobe separation and intake/exhaust overlap are designed (yes, both valves are open at the same time to varying extents depending on the cam/engine design). This has an impact on the scavenging effect of the exhaust system in the cyl., (blown and turbocharged engines not withstanding, which is why these engines have radically different cam profiles). Cam/engine designers attempt to try to get the exhaust flow out of the ex valve to help scavenge the burnt gasses from the cylinder and start to help pull the intake charge into the cylinder during this overlap period before the piston even really starts to move down on the intake stroke, thus resulting in a greater air/fuel charge in the cyl, and more power. Radical departures from the design combination either by adding restriction, or removing it, alter this balance and can result in reduced power output. In a true high performance application there is a delecate balance between intake and exhaust tract length, desired power band and camshaft design specs. Messing with any one of the parameters impacts output somewhere in the power band. You can also change output significantly by changing the relationship of the cam to the crank (called degreeing). Then, you can also extend the "dwell" time of the piston at top dead center by using a longer connecting rod thereby giving the cam profile more "time" to work in the overlap period. Want to get really confused? Start fiddling around with a twin cam design where you can change all of the cam opening/closing/overlap variables independently.
Sorry you asked yet????????????
Backpressure, no back pressure, gas, deisel... It's all about the manufacturers intended design parameters. It impacts deisel engines to a lesser extent because they are not dependent on a carbueration/fuel injection system that draws the fuel air mixture in through an intake manifold/carb and/or throttle-body assembly. Deisel power is largely a function of how much fuel you want to inject into the cyl because you're not metering the air flow (within limits of course, which is where turbo chargers step in).
Now... In a gasoline engine the power output relative to the amount of exhaust restriction is a function of the design of the camshaft and how lobe separation and intake/exhaust overlap are designed (yes, both valves are open at the same time to varying extents depending on the cam/engine design). This has an impact on the scavenging effect of the exhaust system in the cyl., (blown and turbocharged engines not withstanding, which is why these engines have radically different cam profiles). Cam/engine designers attempt to try to get the exhaust flow out of the ex valve to help scavenge the burnt gasses from the cylinder and start to help pull the intake charge into the cylinder during this overlap period before the piston even really starts to move down on the intake stroke, thus resulting in a greater air/fuel charge in the cyl, and more power. Radical departures from the design combination either by adding restriction, or removing it, alter this balance and can result in reduced power output. In a true high performance application there is a delecate balance between intake and exhaust tract length, desired power band and camshaft design specs. Messing with any one of the parameters impacts output somewhere in the power band. You can also change output significantly by changing the relationship of the cam to the crank (called degreeing). Then, you can also extend the "dwell" time of the piston at top dead center by using a longer connecting rod thereby giving the cam profile more "time" to work in the overlap period. Want to get really confused? Start fiddling around with a twin cam design where you can change all of the cam opening/closing/overlap variables independently.
Sorry you asked yet????????????
How about a coles notes answer?
Only applicable to gas engines.
A muffler creates pressure as the exhaust spits out.
That pressure helps to draw the exhaust out of the cylinders on the exhaust stroke.
Without back pressure, the exhaust would not be fully sucked out of the cylinders.
It also helps to draw fuel and air in on the intake stroke.
I've heard that a diesel engine does not need back pressure...
Only applicable to gas engines.
A muffler creates pressure as the exhaust spits out.
That pressure helps to draw the exhaust out of the cylinders on the exhaust stroke.
Without back pressure, the exhaust would not be fully sucked out of the cylinders.
It also helps to draw fuel and air in on the intake stroke.
I've heard that a diesel engine does not need back pressure...
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" that pressure helps to draw the exhaust out of the cylinders on the exhaust stroke"
meanjean, I know you didn't wright that. But whoever put that to pen is an idiot. Pressure pushes. It can only draw if the air or liquid is moveing over or passing a venturie.
meanjean, I know you didn't wright that. But whoever put that to pen is an idiot. Pressure pushes. It can only draw if the air or liquid is moveing over or passing a venturie.
Wouldn't doubt if I was the idiot.
A cat with a smalller opening will increase the velocity of the burnt gas.
Increased velocity means better scavenging.
Some pressure is needed to allow for scavenging.
Back to eating paint chips.
A cat with a smalller opening will increase the velocity of the burnt gas.
Increased velocity means better scavenging.
Some pressure is needed to allow for scavenging.
Back to eating paint chips.