Turbo's for Dumbies

[Pit Bull]

Newbie questions

I have a 2000, 215 HP 420 lbs torque. Stock engine (see sig). what Turbo comes on my engine? I think they changed in 2001 when they went to 235 HP 460 lbs torque. How dependable are these Turbo's in a stock configuration? When my warranty is up and I start to BOMB, at what point do you need to change out the Turbo? I know you guys are way ahead of me on this knowledge, I kinda feel like a 5th grader asking questions in a collage class room. But I have to learn some where. If you have any sites that you can refer me to on "Turbo's for dumbies" that would also be helpful. I have never had a turbo before, even on a car. Care and maintance suggestions would also be helpful

Thanks

These threads on Turbos blowing up kinda have me concerned.

 

[HC]

Just to start the discussion, I'd say your first BOMB should be a pryo, especially since you mentioned "care and maintenance" suggestions and seem concerned about turbo reliability. Watching your Exhaust Gas Temperature and bringing it down to ~300 degrees before shutting off your engine is the #1 way to extend your turbo life. While you can do almost the same thing by following the idle times suggested in the owners manual, I've found that often you don't need to wait nearly as long as the owners manual says. But sometimes, like when you've been running hard, you need to wait LONGER than the manual says. The pyro takes all the guesswork out of this equation.

 

[Lsfarm]

Turbo Primer

Big Toy, If you want to learn about your truck and turbo, buy a factory service manual, and read it cover to cover. The manual costs about $100, and is available right from DC.



As far as your turbo is concerned, don't worry, the turbos you read about here that blow up are usually non stock turbos put on to increase performance, and reduce high EGT's [exhaust gas temperatures]. The factory turbos work just fine and will last virtually forever if you take proper care of the engine and it's lubrication needs. The turbo shares the lubrication oil with the engine.



Get a set of guages, a turbo boost guage, an exhaust gas temp. and a fuel pressure guage for a minimum.



By letting the engine idle until the temp [EGT] drops to about 300 degrees before shuting off the engine will prolong the turbo life. What kills the turbo is when it is still very hot, and the engine is shut off, which stops the flow of lubrication to the turbo. The little remaining oil in the turbo is cooked by the heat, and turns to carbon and coke, which ruins the bearings and seals. Then the turbo dies a premature death.



Sorry about the long reply, but the complete answer is rather long.



Hope this helps. Greg L

 

[jimnance]

Boost

I am seeing 29 lbs of boost and 1100 EGT pulling the hills. Is 29 lbs too much for the engine and/or Turbo?



I am changing oil every 5-6 K miles with DELO or equivilent.

 

[Briar Hopper]

Big Toy, you asked how dependable these turbos are in a stock application. Very. The Hx35 is tough.

The reason you're seeing these Hx40's pop like this, is many have been altered, modified, abused... . It's the turbo that comes stock on an 8. 3 Cummins, and wasn't designed for what some of us have thrown at it. You can find plenty in the archives about the Hx40. It's all been hashed out before, you newcomers need to catch up on your reading.

It's simple... you hear about the popped turbos here, because some of us are trying various things, and sharing the information. The alternative is to cough up big bucks to buy a mystery turbo or twin turbo package from someone else that has quietly popped a bunch of turbos/head gaskets/intercoolers in developing the optimum setup. Some of us want to see how far we get on our own, it's more fun that way.

 

[Lsfarm]

Too much boost?

Jimnance: 29# of boost and 1100* is about right for your truck with the EZ installed. 1100* is just fine, from all that I've read on this site, our engine can take 1100* all day long.



The engine can TAKE a lot more boost, but won't MAKE a lot more boost until you feed it more fuel. the relationship between boost, fuel and engine power is a circle, like a dog chasing it's tail.



If the engine is fed more fuel, it will make more power, and have more hot exhaust that spins the turbo faster, developing more boost, which helps burn the extra fuel which makes more power and hot exhaust and around it goes again. So the limiting factor is fuel. To make more power, add more fuel. This in turn creates more power and heat.



The EGT or pyro gauge pretty much tells us how hard the engine is working, more heat = more power. The only thing that changes this is boost, which is air. If you add more air [more boost] to the engine it cools down the EGT. So if you were to return your turbo wastegate to the original factory setting of 20# maximum, then your EGT's with no other changes will be higher, probably by about 100-150*. This is what my truck did when I experimented.



This may seem really confusing, but it will make more sense as you read more and more on this site.



Sorry again about the long post, but it seemed like an explaination was needed.



Merry Christmas, greg L

 

[jimnance]

Boost

Thanks, makes lots of sense to me.

 

[jimnance]

boost

LSFARM,



You are correct of course. More fuel equals more exhaust equals more boost. Without a waste gate to prevent over boost you run a very real chance of smoking the engine.

 

[Lsfarm]

Max boost

Jimnance, there is no limit to boost, the limit is fuel. More boost cools the EGT's which is GOOD for the engine.



Let me try this explaination: When I first put on my EZ, I was in too big a hurry to go out and play, so I didn't do anything to the boost elbow or wastegate. With factory wastegate settings, I would get 19-20 psi boost, and 1250 degrees EGT. Then I PLUGGED the hardline boost elbow: no wastegate at all. The boost ran up to 29-30 psi, and the EGT DROPPED to 1050 degrees!! The amount of fuel was the same, but with the added air, the EGT's dropped drasticly. The extra air COOLS the combustion.



The reason that everybody [who are looking for more power] are going with bigger turbos, twin turbos etc. is that if you can add more boost to cool down the EGT's, then you can add more fuel which is power. You can always add the fuel, but at the risk of melting pistons and exhaust valves. Adding boost reduces the temperatures, thereby saving the engine, not harming it.



With my wastegate elbow plugged, I never saw more than 30 psi boost until I added the stage 1 injectors, now I see 34-36 psi max boost, and about 1100 degrees max.



If I were to add a bigger turbo, the temps would drop, and the power would stay pretty much the same.



So the only way to make boost is to add fuel, you almost can't make too much boost for the engine, but you may blow hoses off the intercooler and turbo though.



I hope the above makes sense, but the pressures inside the combustion chamber are huge, the boost pressure doesn't make for too high pressures, only adding fuel to the combustion will create greater pressures and temps.



Clear as mud right? Greg L

 

[Lsfarm]

Max Boost round two

Jimnance, I forgot a few things in the last post. The engine won't be harmed by lots of boost, but the turbo itself can be harmed if it spins too fast and therefore creates too much boost.

The high boost from a small turbo like my HY 35 turbo is wasted boost because it is very hot boosted air. If I were making the same boost pressures with a bigger turbo like a HX 35 or one of the bigger ones, then the air would be cooler, and the turbo rpm would be lower.



I will have to unplug my boost elbow and add a turnbuckle and spring to my wastegate arm to limit the boost to 34-35psi, any higher is just overheated air and excessive turbo rpm. I could overspeed my turbo.



Then I need to think about a Piers or Kwikkurt turbo before I add more fuel to the fire.



Greg L

 

[jimnance]

Boost

Clear as muddy water. I am more familiar with Turbocharged Aircraft Engines.



I am familiar with the concept of adding extra air to the mixture to run what we refer to as lean of peak EGT. In essence, you get such a lean mixture that combustion temperatures are reduced.



If you run a very ruch mixture you get the same effect because not enough oxygen is present to have complete combustion.



However, my understanding is that with increased boost you increase combustion pressures, increase horsepower, etc. The net effect is that you make more power. Along the way you increase the "stress" on the engine. All things being equal, the more horsepower produced by an engine of the same displacement it is likely to influence the durability of the engine. Granted, I am talking about aircraft engines which are somewhat different, aircooled, and gas burners, but they are still internal compustion engines. Also, they tend to be large displcement, slow RPM engines that make max power at about 2600 RPM. Sound familiar?



With aircraft engines, turbo or non-turbo, there is a very clear link between HP/Cubic inch and the length of engine life. Also, Turbocharged engines that operate at high boost levels almost always suffer from shorter service lives than those with less boost.



My point is that we cannot be ignorant of the fact that no matter how good an egine the Cummins 5. 9 may be, every increase in horsepower WILL DECREASE the life of he engine. The only question that remains is how much. It is my observation that this is not a linear decrease in engine life, but more like a curve which trends gently downwards and then falling precipitously as HP to displacement exceeds about 1 HP per cubic inch. We see the same effect in aircraft engines but it happens much sooner, around . 75 HP per cubic inch. The difference is largely because of the difficulty cooling high horsepower engines with air.



There is no absolute number that cannot be exceeded, but I suggest that above 30 lb of boost engine life will tend to fall more quickly. Naturally, incorrect mixture settings producing high exhaust gas temperatures will hasten the process.



I am not really saying anything that hasn't been said before, but hopefully coming from a differently background having a little different view point.

 

[Lsfarm]

Diesel vs Gasoline

The Boost vs TBO life on aircraft engines is as you described. And I fully understand your concern about prolonging the life of our Cummins engines. I think that the Cummins engines in our trucks are using only a fraction of the power that the engine is capable of producing continously, kind of like running a Lycoming TIO540 [350HP] in a Cessna 172, and only using 180 horsepower from it.



When I had my first flying job, I worked for the cheapest SOB who ever walked. But I learned a lot from him: he would look at the logbook and fuel receipts when I returned from a trip, and chew me out if I hadn't burnt enough fuel!! The first time he did this I though I was working for a nut-case and though about quitting. He then expained that fuel was cheap, engines and cylinders were expensive. He felt the same about oil, changed it every 20 hours even though the recommended interval was 50 hours.



But anyway, the killer to the aircraft engine was heat, and running the engine rich of peak not only added power, but kept the combustion temps down. Or you could run very lean, to get the same effect. [you should have heard the a** chewing I got when I tried that!]



The big problem with turbo'd gasoline engines is that they don't like extra air forced into the cylinders because then the compression temps approach the ignition temps of the fuel air mix, and if exceeded then you get detonation, and a big hole in a piston and maybe a bent connecting rod. Making the mixture richer cools the combustion temps reducing the danger of detonation, but also makes the engine less effecient [sp?] because it uses fuel to cool the cylinder temps.



This problem is made even worse by the fact that aircraft engines are air cooled and don't have the reserve cooling capacity that water cooled engines have. And because of weight limitations, an aircraft engine can't be overbuilt with extra strength and cooling reserves like our Cummins engine has.



The diesel engine loves extra air in the cylinders because the fuel is what governs the power output, not [fuel/air mixture] throttle opening. The diesel is wide open all the time. This is why it is so effecient[sp?].



The combustion pressures were quickly exceeded in the Lycoming engines I used to fly, and if on a cool day the boost exceeded the maximum, [you had to be carefull] the engine could [and did] blow a cylinder occasionally. [email me about that experience!!]



Our cummins engine can take a lot of boost, and produce a lot of power, [burn a lot of fuel], as long as there is enough boost to cool it down and not exceed 1250-1300 degrees EGT continously.



There is a thread going right now started by Zman asking what EGT's and boost totally stock trucks are running under heavy towing conditions. The results are that the temps can exceed what we consider the limit, but the boost is limited by the factory wastegate, if it was higher, the temps would be lower.



Check out the towing pages for the turbo experiments going on, they are adding cool boost with bigger slower spinning turbos to control EGT while towing heavy loads.



Take care, have a safe New Years's, Greg L

 

[Pit Bull]

Stock Turbo is built for the stock towing limit?

Lsfarm and others

Thanks for the information. When I started this thread I did not know I would get such a good education from it. So is what you are saying? The Cummins engine in our stock trucks have a Turbo setup that is built around the trucks working as a "system" and not running over the factory recommended GCVWR? As has been indicated by the feed back in the Towing thread that has been asking for EGT's generated by stock trucks pulling limit rated or better loads (to big of a load and not enough air equals high EGT and engine life shortening wear or damage/failure). So when it comes to upgrading the power on our trucks everyone needs to take a "system" approach to these enhancements. If you upgrade the injectors then you need to look at the Turbo being upgraded and the fueling system being upgraded and the driveline being upgraded. If all of these things are not done then one enhancement can cause a failure in another system and have a life shortening affect on the other parts. So a stock Dodge Cummins that is used within factory recommended limits may give good dependable service for 500,000 miles where a truck that is modified by larger injectors and a fueling source enhancement but no upgrades in other systems like the Turbo, transmission etc. will have a much shorter life span. I can see this causing owners that upgrade in a hit and miss fashion and then when they have problems, coming away with the view point that the Dodge Cummins is not a great truck (because of their own actions) and their lack of understanding the truck as a "system" that has to be balanced to have long life and dependablity. Am I all wet here or is this what is happening to some of the members? With these Turbo upgrades what I see some of the members are doing is using their trucks as a test bed for upgrading that system (which is great as long as it leads to a complete truck upgrade). How the big question is when do we get to the point that for, say a power out put of 350 - 375 hp with 550 - 600 ft. lbs of torque some one can say you need X Turbo and Y injectors and Z fueling enhancement box and W transmission and driveline upgrade and the system will tow Q weight with the same dependability and long life as the stock truck can pull within the factory recommended limits? Or are we already there? Sorry for the long post and rambling but I just want to see if others are thinking the same way I am.