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  1. #1

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    John Deere 3720

    Default turbo vs non turbo - JD 3x20

    we should get something clear. turbos are fit to smaller displacement engines to produce more power at higher rpms. in so doing they consume more fuel as the inlet air density is increased (much like a high compression engine). the fuel to air ratio is constant, you just have more air so the engine injects more fuel - hence more hp but it is delivered in a range you might not expect (higher). it has been incorectly suggested that 1.) turbos are as reliable as non turbos, 2.) turbos will outlast a non turbo because they are not working as hard. these are flat out false statements and no one should be led astray. a turbo is a complex high speed compressor that has head issues both from the exhaust that drives it and from the fact compressed air gets hot due to increased molecular activity. there is nothing about a 10,000 RPM device bolted to your lower displacement engine that will cause it to work less or be more dependable. that baby is smoking to crank out the hp. it will fail first, and it will cause you more headaches on maintenance than a non turbo. to say otherwise is not only mechanically counterintuitive but just plain false. look under the hood of your turbo and tell me how the serviceablility has changed due to the added plumbing. then consider the added heat running through that plumbing. then consider the fact you are breathing fire through that smaller displacement engine to make it stand up and run. this is not a fuel cooler, you are adding highly sophisticated, complex and expensive gear when you go turbo so you can expect proportionate lessening of the life and low end hp the same as would normally be found on a similar engine of lower displacement, UNTIL the turbo kicks in and then you will get a power curve shift as the boost responds - but only in the range where the turbo is active, otherwise you have the smaller engine as it would normally perform. just wanted to make that clear. if you want or need a turbo and want to futz with it and take the hit on engine life and turbo failure risk, do so with the blessings of all. if you dont understand turbos I reccommend you stay away. there is no such thing as free horsepower. everything comes at a cost.

  2. #2
    Silver Member
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    Default Re: turbo vs non turbo - JD 3x20

    Your whole post was your opinion, and certainly NOT fact. I'll go on to say that your post is a complete distortion to what the effects of turbocharging is and does, and your assertion that turbocharging taxes an engine can't be further from the truth.. I can also tell that you have little to no experience with a modern turbocharged diesel engine, it's lifespan, it's effects, it's maintenence or how it actually works..
    Turbocharging isn't merely slamming more air into the combustion chamber until the engine blows a gasket and tosses connecting rods out of the side of the oil pan as you are asserting..FAR from it..
    I was estatic when I heard the new 3520 and 3720 were going to be turbocharged. Personally, I won't own a diesel engine unless it's turbocharged/intercooled, and now I could get one in a mid sized John deere, AND, it was produced by Yanmar. [img]/forums/images/graemlins/smile.gif[/img].
    A normally aspirated diesel is a fine engine, and it keeps the price down. Isn't that what you seem to be trying to sell yourself on anyway?
    But, it performs nowhere near as efficiently as it's turbocharged counterpart.
    Remember that word "efficiency" because it takes less fuel to make more power on a turbocharged engine. As most know, "fuel" is the heat source (exhaust gas temperature)of a diesel engine. More fuel, more heat. More heat, more problems.
    Turbocharging takes an incomplete, inconsistant air/fuel charge and perfects it "especially" at lower RPMs where a non turbo diesel falls flat on it's face.. Turbocharging makes up for the lack of available O2 and allows the fuel charge to burn completely, instead of ending up in the crankcase as lubrication robbing soot. That alone is worth every cent to move up to at least a 3520.
    It seems that 100% of over the road and off road diesel engines are turbocharged these days. Most carry a full 5 year warranty. Most will run over a million miles before any kind of engine service is needed. Why? Because they are more powerful, more consistant, more fuel efficient, burn cleaner, operate at a more consistant intake heat range, which leads to substantially longer life.
    Caterpillar has just intorduced a twin turbo set up on all of it's C series over the road engines. Ford will be introducing twin turbo technology in 2007 on it's Powerstroke diesel, which I will be ordering to replace my incredible 2003 turbocharged 6.0L PSD. My guess is that these companies feel a little different about turbocharging benefits than you do..
    I suggest that you join the 21st century, and do some research before you try to sell your opinion as some sort of fact.

  3. #3
    Super Star Member RoyJackson's Avatar
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    Default Re: turbo vs non turbo - JD 3x20

    Both of you folks are making some good points.

    Turbo's do add HP, but as they run at extremely high RPM, they can require extra maintenance. More frequent oil changes, for one. It's advisable to let a turboed engine run for a few minutes prior to shutting down to allow a bit more cooling. Otherwise, the bearings in a turbo can wear faster then the design calls for.

    Turbo failures, due to not allowing them to cool prior to shut down, was not too uncommon when turboed engines were introduced to the general public about 20 years or so ago. Unlike large trucks, whose owner/operators maintain there equipment, automotive owners may not have changed the oil or allowed for the extra heat as required.

    Most engines that are turbocharged have reduced compression compared to a normally aspirated engine of the same cubic capacity. The turboed engine will produce less power when off boost. This wouldn't be as noticeable with a large truck engine due to the gearing and very large cubic capacity of the engines. That lack of power (relatively speaking) can be more noticeable in a small displacement engine, such as those in the Deere tractors. Of course, this depends on the design of the engine/turbo and at what RPM the turbo makes most boost. I would guess the turbo in a tractor is designed to make power at low to mid-range RPM's.

    Personally, my situation doesn't have a need for a turboed engine. I just don't have to run my tractor that hard. I do see the need for turboed engines in large trucks and in some industrial situations. My opinion is that most residential (i.e. non-agricultural, non-commercial) users won't have too much need for the turbo. I will suggest that turbo-charged rental units will have a higher failure rate then normally aspirated engines. Only time will tell if that is the case.

    Minor addendum: Seasalt did make a comment about higher fuel consumption on a turbocharged engine. This is true....the engine does have to work harder until it goes on boost (relative to a same dispacement normally aspirated engine) for the same performance.
    And, if you've ever had the opportunity to drive a Porsche Turbo 911...well, they're incredible. That boost is addictive (worse then crack-cocaine!) so one's foot is hard on the throttle as much as possible. That's when the fuel economy takes a serious hit.

  4. #4
    Super Star Member
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    NH TC25D

    Default Re: turbo vs non turbo - JD 3x20

    Welcome to TBN, seasalt! [img]/forums/images/graemlins/smile.gif[/img]

    You've only been a member 7 days and this is your eighth post.

    What prompted this diatribe against turbos?

  5. #5

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    Jul 2005
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    Default Re: turbo vs non turbo - JD 3x20

    Welcome to tractor by net! I am also very new to this forum and it is a very useful website......I just bought a 3520 and I will agree that I was also pretty excited when I heard JD was going to do this. I have worked on diesels for years and I will say that both turbo and non turbo have their place and issues. I have two trucks with 6.5L chev diesels. One with a turbo, one without. The one without a turbo is all stock, puts out about 150 hp/320 ft lbs and gets close to 20mpg. The other is an engine I built that was featured on "The Diesel Page.com" that had about every performance modification and bolt on available that puts out 320 hp/650 ft lbs of torque and gets 20 mpg. Same engines with dramatically different results. Efficiency is the key. The non turbo engine may last a little longer, it may not. My past experience is that both engines will outlive the rest of the truck. I feel the same about these tractors and I assure you that John Deere and Yanmar have done the testing. The Yanmar 3TNV84T is not a new engine to Yanmar, just John Deere. Pop the hood on a 3520 or 3720 and tell me that they are more complicated. I would strongly disagree. Ten years ago, no one bought diesel pick ups, why? They didn't have injection systems and turbos perfected yet for an affordable price. Things have changed and I couldn't be more pleased.

    Thanks

  6. #6
    Elite Member Kyle_in_Tex's Avatar
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    JD 4310,JD5420

    Default Re: turbo vs non turbo - JD 3x20

    From a maintenance and price standpoint, I could see your reasoning. I bet your car is akin to a modern day model T with air conditioning.

    Turbos have been on ag tractors (and others) for quite some time. The bugs have been reduced to a minimum. What they do provide is EXTREME torque at the right rev range right where you need it for heavy pulling or mowing jobs. Many folks pay great amounts of money to increase performance in their cars, boats, motorcycles, etc... A turbo in a tractor is a big plus. I'm not sure what tasks you'll be doing but, if you mow deep stuff, you'll wish you had more oomph. Whether or not a turbo is worth it would depend on what tasks you need a tractor for and if your pocket book can handle it.
    I would trade my 4310 right now for a 3720 if the trade up costs were not so much.

    At any rate, you have posted a fairly opinionated post. There have been some in the past with the same argument. We know which side of the fence you stand on. [img]/forums/images/graemlins/grin.gif[/img]

  7. #7
    Platinum Member
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    Central WI

    Default Re: turbo vs non turbo - JD 3x20

    If you say so...

  8. #8
    Veteran Member
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    Dec 2004
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    western NC
    Tractor
    JD 2320; 4520

    Default Re: turbo vs non turbo - JD 3x20

    Seasalt,

    This is an excellent debate you have! I understand your stance with regard to turbo engines and your reservations. Yanmar has been making industrial engines of all types for many years and are among the best in the world. They WILL NOT produce and market something that has not been proven to provide long service life. The reality is that the mild boost generated by the small turbo in the Yanmar would not appreciably affect engine life, independent of any other factor. When one adds in the fact that the engine revs lower at similar workloads, runs cooler (at least on the top end) and more completely combusts fuel from the more efficient fuel/air charge, the indication is that the turbo will at least have a comparable life to the non-turbo, if not more. Keep in mind also, the Yanmar diesel with turbo has a larger oil volume which enhances lubrication, which also contributes to cooling and to engine livelihood. It also has very simple plumbing, and is not complicated in the least. As for performance, the turbo on these engines is tiny and has a small compressor wheel. With its lower spin up inertia, it actuates at very low RPM. This means there is really no appreciable turbo lag. As someone noted (and myself yesterday) both these engines would last longer than the other components of the tractor, so perhaps we should re-address in about 5000 hours or so, when they are getting tired. I feel the 3120 is a good machine, I feel the 3320 is a good machine, I feel the 3520 and 3720 are good machines with more power and performance. As I mentioned in my prior posts, I feel one should get the most tractor he/she can afford and not compromise on the attachments needed. I have reservations that a 3120, for example, would be able to consistently meet the needs of one who is really working it hard. I have driven one and box bladed with one, and it is pretty weak, but probably slightly stronger than the 4210 that it replaces. I like the 3320, and think it is a good and reliable machine. I would not, though, shy away from a turbo if it is in the budget, simply because it is turbo. Also keep in mind we are dealing with a displacement difference of only 100 cc, slightly more than three ounces. To me this is hardly the same as Formula One, where tiny motors make 900+ horsepower. Also, note that the concept of turbocharging is to prevent overfueling by enhancing a more efficient burn cycle, especially under heavy loads. Of course, if these factors had not been addressed by Yanmar, the argument proposed would have more validity, but they have...

    John M

  9. #9
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    Default Re: turbo vs non turbo - JD 3x20

    Roy said:
    </font><font color="blue" class="small">( Minor addendum: Seasalt did make a comment about higher fuel consumption on a turbocharged engine. This is true....the engine does have to work harder until it goes on boost (relative to a same dispacement normally aspirated engine) for the same performance. )</font>

    Roy, I respectfully disagree.
    The application were talking about (tractor) does not require differing RPM ranges such as a turbo race car. Like an over the road semi, these engines are designed to run, and tuned to achieve peak efficenty at a certain RPM target window to achieve the given task.
    I can tell you another thing, I have had plenty of turbo diesels in my life, and my 3720 has never shown any signs of turbo lag. Quite the opposite, I find if incredibly more responsive and quieter than my prior 4300, no matter what RPM I am using.
    Also, I am a big advocate of synthetic oils. Syn oild have proven themselves not to fail at high temps like a dino oil can. So, if you own a turbocharged engine and somehow forget to allow a minute of proper cool down, syn oil can and will save yer but!

  10. #10
    Super Star Member RoyJackson's Avatar
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    Default Re: turbo vs non turbo - JD 3x20

    "Like an over the road semi, these engines are designed to run, and tuned to achieve peak efficiency at a certain RPM target window to achieve the given task. "

    As I'd mentioned, it really depends on the engine/turbo design. A large turbo has more inertia, hence more lag. That's when one saw the advent of twin turboes on high performance cars. Of course, a smaller turbo has less lag, but less boost too.

    Diesel engines don't rev as fast as a gasoline engine so lag may not be as noticeable. And, of course, our tractors aren't Porsche 911's, so lag doesn't matter as much. I have driven diesel trucks (pickups) that were real dogs as far as acceleration. I drove one turbo diesel pick up that was pretty close to a gasoline engine, but you had to put your foot in it to make it work.

    As I'd mentioned, I just don't see a lot of need for a turbo on a residential tractor. If one is willing to adapt to a turboed engine's requirements...more power to them (no pun intended).

    One rhetorical question...I wonder how much of an increase of power is there on the Deere turboed engines over their normally aspirated brethren?

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