Turbo Charged Engines - Avoid or Buy?

[Grateful11]

Am I missing something here? Doesn't a tractor tend to run at one speed? Unless throttled up or down? If this is true then the exhaust is steadily flowing and the turbo is spinning at the same speed unless you bog the engine down. Engine speed doesn't change because you are driving around or running your PTO.

But more on point, turbos are old news and are reliable if the machine is maintained. Turbos generally require no maintenance unless something breaks.

As for the car comparison, personnally I think it has no bearing on this topic as these machine are not throttled up and down like cars and run on diesel.

Our L3940 has a foot throttle connected to the Hydrostat pedal and we love
it. It's a really different experience than our other 5 tractors. My son helped
load round bales with it today and had a blast, it's the first he's used a FEL.

 

[Redneck in training]

You can't just add fuel and get more power. That's like saying I'm going to run a mile sprint and breath normally. To get the fuel to burn you need more air. The stroke of an engine will pull in only so much air(the volume of the cylinder). The balance is in the air/fuel mixture. Change the amount of air by adding a turbo which forces or compresses in more air by volume, you can inject more fuel, which means more power.

If you are just driving around the yard with no or little load, the turbo isn't doing anything to help the engine....not enough heat being produced. If you are on the hwy next to a big rig, you'll hear the turbo kicking in that whine going up a hill. Going downhill nothing because the load is taken off. If you watch the exhaust temp, it will rise and fall a lot.

Turbos are great, but if you are not a heavy user of your tractor, I'd probably get the tractor without it if possible. Remember all those HP ratings are at peak load, not pulling a 6' finish mower in 4" grass. Put on a 6 row disk or subsoiler and find out what she will do!

Rob

Diesels operate with excess O2. There is not throttle in suction tract therefore the engine gets more O2 than necessary to burn all the fuel. So you can add fuel up the limit of minimum O2 fuel ratio allowing complete fuel burn. More power also allows the engine to run faster etc. That is why I am saying that unless limited by fuel delivery (in ex. speed governor limits fuel delivery when speed SP is reached) many diesel engines can develop enough power to self-destruct. Especially turbocharged engines can easily develop power way beyond mechanical limits of the engine. You can increase air pressure to such a degree that the engine will blow the head off after fuel injection.

 

[medicshawn]

I'm not at our station 1 but here's a newer version of your truck.

http://www.virginiafirefighters.com/aerials/HenricoCountyJackSullivanTruck1.jpg

Henrico County outside of Richmond Virginia

 

[RobJ]

Diesels operate with excess O2. There is not throttle in suction tract therefore the engine gets more O2 than necessary to burn all the fuel. So you can add fuel up the limit of minimum O2 fuel ratio allowing complete fuel burn. More power also allows the engine to run faster etc. That is why I am saying that unless limited by fuel delivery (in ex. speed governor limits fuel delivery when speed SP is reached) many diesel engines can develop enough power to self-destruct. Especially turbocharged engines can easily develop power way beyond mechanical limits of the engine. You can increase air pressure to such a degree that the engine will blow the head off after fuel injection.

Your statement earlier that you can just keep adding fuel to increase power is incorrect. Sure diesels operate with extra o2, but the o2 will run out, the fuel will not burn and the engine will fall on its behind. And this is way under the engines design limits. So a turbo is added to pump in more o2 to get the most out of an engine. The amount of boost is regulated to keep it within the engine design specs...or in some cases the design limits of what the engine is powering!

When I was rebuilding diesels we put every one on a dyno to test it and since I worked for a dealer, I got to test some limits(read...let's try and break it). We saw 2 things when you overloaded and over fuel a diesel. Keep in mind these are not highly modified diesels, regular old tractor, generator, etc diesels. 1) The engine would hit a certain point and simply fall off the power curve. HP, torque would just drop way down. And 2), if you held it just under this drop off point, the engine would overhead and start to melt pistons(after some time). Nothing ever flew apart like you see on a tractor pull. Those engines test the design limits of the engine on every run, and they don't last very long and don't really apply to this topic IMO. . Fun to watch them blow up though huh!

 

[RobJ]

Even tho it may run at one speed [set by you and maintained by the governor] it runs at different loads. More load requires more fuel to hold the rpm, which makes more exhaust which increases turbo speed causing more air to enter the cyls which causes more exhaust -- etc. The turbo does very little when the engine is idle regardless of the speed the engine is turning. As soon as load is applied ... see the second sentence, and post#32.
larry

Larry if I can just add one point. The key to the turbo is the heat and hot gasses created by more fuel and load. Exhaust temps may go from 300 degrees to 900 degrees. The fast expanding hot gasses get that turbo spinning.

An exhaust temp gauge is a interesting thing to watch if you have a diesel pickup or can stick a sensor in the tractors exhause manafold.

Many times when I was pulling wrenches some company would stick our engine on a unit they designed and made. And they would get the load wrong. Bring a motor in and it would be wet stacking, want some warrenty work. From across the parking lot we could see the problem. Factory paint still on the muffler. We'd pull the motor, stick it on the dyno, bring it up to max hp, and within 60 seconds the exhaust temps would go from a couple hundred to 900(I forget the exact numbers), and the paint would burn off in another 30 seconds. Fun to watch and display the load numbers to the customer. We'd usually run it for an hour then give it back to them.

I forget the numbers but we could simulate their load by watching the temps and the paint. Then put the temp gauge on the machine when running their load and sort of guess how much HP they are really using.

 

[Builder]

What is the consensus about tractors with turbos? I tend to be a little cynical about turbos on tractors ... but they can be fun in fast cars :thumbsup:.

The preference is for a tractor with at least 48 HP to the PTO.

Are turbo charged tractors less reliable and expensive to maintain? I expect to use dealer service departments except for fluids and filters which I will do on property (home). My preference is to buy used (less than 400 hours) and find a great buy/price from a seller with tractor, implements, appropriate trailer, etc. I am flexible, but this approach seems to be a good opportunity, or I will buy from the rental fleet of a great Kubota dealer and servicer here in North Texas.

I can shorten this to say that I like the M6040 HST, M7040 HST and M59, but they are quite heavy and large for working relatively close to the landscaped areas, animals, barn, out buildings, and homes on our property. I have noticed that I could buy a slightly smaller/lighter turbo charged tractor (Grand L40 series) or a slightly larger/heavier M series.

After spending 40 hours at night reading reading the TBN posts and spending untold hours looking at the wish books/catalogs, online classified ads ... I am ready to stop the fantasy, pull the trigger and buy our first tractor ... as the TBN gang says, I need seat time and decided it will be a Kubota. :drool: :drool:

Before describing our intended uses, animals, land, hobbies, construction projects, etc ... let me be honest (with myself) and say that our needs are modest, my ambitions/desires large, and we can generally hire out most of anything. We live on 12 acres with a desire to expand to 30-40 acres. Today, if I had to admit, this tractor will be a want a little more than need. But, I like projects, tools, material handling, and to stay busy improving the property (construction projects) and working with the land (for the "hobby" animals).

I appreciate the opinions of the TBN members. Thanks so much.

I bought the last year ('07) M7040 before it became turbocharged to meet new emissions specs. One thing I like is not listening to the turbo whine. My new Holland backhoe is turbo charged and the whine kina gets old after 5-10 hour stints in the seat.

Either way, turbo or NA, they're fine machines.

 

[Charlesaf3]

minor point - the new hst kubotas have variable throttles like a car.

My m59 has no noticeable turbo whine. But it might just be it gets lost in the truly awesome level of noise trapped under the fops..

 

[TripleR]

minor point - the new hst kubotas have variable throttles like a car.

My m59 has no noticeable turbo whine. But it might just be it gets lost in the truly awesome level of noise trapped under the fops..

I can't hear turbo whine on my M8540 either.

 

[funwithahoe]

12 acres? Anything bigger than a Craftsman should do it. No need to worry about Turbo.

Thx.

 

[KubieTwo]

12 acres? Anything bigger than a Craftsman should do it. No need to worry about Turbo.

Thx.

You are probably close, but don't take away his fun. (How many guns do you have?) If he can afford it, he probably needs a BIG toy... He even states that it may be WANT more than NEED. I can't even guess what size tractor I might add if I could afford it, and I only have 33 acres. Can you say JD 9030 series? For 12 acres he needs to be looking at M8540's... LOL

On another note, a lot was discussed regarding turbo HP or not, but nobody really discussed the torque rise improvement of a turbocharged diesel. If you look at the torque curves for NA and turbocharged similar engines, that is where you see the big improvement. Turbochargers were added to diesel locomotives in the 1930's if I am not mistaken and it had nothing to do with EPA, but it did have something to do with torque gain.