# Duramax diesel

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#### K-Rigg

##### Well-Known Member
It wasn't already posted, and you've been a bearer of great news with each post, looking forward to more.

Wow! That is great, and you can get that from simply switching the chip, you don't need to add any heavy duty parts to it?

If you can bypass all the emissions parts and the EGR it sounds like you can run an essentially 'bare' engine and don't need the complex wiring harness from the vehicle to be hooked up to it in order to run like alot of gas cars do. So basically all you might need is the alternator and charging circuit + power to the fuel pump, the computer which runs the injectors, and a crank angle sensor. Does that sound possible? If so then it could be a real easy job wiring it, and you would be able to eliminate most of the accessory drive belt so Bruce will like it better too.

Also, I read that they will be starting to build a new 4.5 liter version soon. It looks like GM started selling the 6.6 Duramax in 2001. Here's a link to the Duramax forum: Duramax Diesel Discussion Forums
here is more info on the chips, edge is probably the best out there for this specific applications, also it comes in an interface, which means you change the power settings on the fly. Edge Products: Product

I haven't really dove into the electronic parts of the engine and truck, but if they still keep the engine computer separate from the chassis computer, then yes this is very possible.

Also a neat thing is the newer diesel are throttle by wire which means you don't have to worry about throttle cable.

here is a link describing all the sensors and goodies of the engine.
Duramax Diesel Electronics | Chevrolet Silverado Enthusiast at Automotive.com

#### K-Rigg

##### Well-Known Member
also try to avoid the newer duramax models, they had injector issues, but they should all have been taken care of by a recall, but i still see trucks that haven't had the injectors fixed from the early years.

#### PTAirco

##### Well-Known Member
As far as the electrics go; most modern Diesels are just as complex and computer dependent as gasoline engines. Some can have as many as 20 sensors attached to their harness and disconnecting or by passing any one of them will mess with something. I have looked for a stand-alone, programmable diesel injection system but so far without luck. I like mechanical systems, but the advantages of electronically controlled injectors are overwhelming - they fix a great many of the Diesel's previous shortcomings.

##### Well-Known Member
It wasn't already posted, and you've been a bearer of great news with each post, looking forward to more.
A friend of me is chiptuning and turbo-ing Hayabusa's and so on; he used the rule of thumb that a 25% increase in power (over rated power) cut the endurance in half. I must say that most of the guys indeed came close to that number; one blew up his 380HP Hayabusa after just 5000 miles..

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#### Dan Thomas

##### Well-Known Member
A friend of me is chiptuning and turbo-ing Hayabusa's and so on; he used the rule of thumb that a 25% increase in power (over rated power) cut the endurance in half. I must say that most of the guys indeed came close to that number; one blew up his 380HP Hayabusa after just 5000 miles..
And I suspect even a stock Duramax would wear out or blow up if it was asked to run at 60 or 75% power for any length of time. It's just another Detroit horsepower-hype machine, like any other auto engine, and I bet it's heavy, too. It might be OK if it's expected to produce a reasonable amount of power, but I sure don't take any automaker's HP figures at face value. I've been looking at auto conversions for more than 35 years now, and there are still very, very few that have overall, tinker-free success.

Dan

#### Starman

##### Well-Known Member
Remember, these engines aren't like the kind that are advertised for muscle cars or sport motorcycles. These diesels are made to haul heavy loads from sea level over a high mountain passes all day, running at full power all day. They are work horses, and are severely 'detuned' from their potential. I think running one at 250 to 300hp for cruise will definitely not break it, since the stock units are rated at 360hp, and using 500hp for climb is used fairly briefly. It might TBO at 2000 hours instead of 4000, but who cares, it won't break it, and when it does get loose just throw it away and get a new slightly used one for another few thousand dollars.

The most important part of this is that they are low reving. You increase power by increasing the torque and without increasing the rpm so you hardly strain the parts since most of them are heavy and are rpm limited due to inertia.

#### K-Rigg

##### Well-Known Member
And I suspect even a stock Duramax would wear out or blow up if it was asked to run at 60 or 75% power for any length of time. It's just another Detroit horsepower-hype machine, like any other auto engine, and I bet it's heavy, too. It might be OK if it's expected to produce a reasonable amount of power, but I sure don't take any automaker's HP figures at face value. I've been looking at auto conversions for more than 35 years now, and there are still very, very few that have overall, tinker-free success.

Dan

there is a saying that goes "when you reached 100,000 miles, you just broke in the diesel"

#### Starman

##### Well-Known Member
Dan, have you ever had your engine go into limp mode? and is there a return fuel line from the pump to the tank to send warm fuel back to the tank ?

#### K-Rigg

##### Well-Known Member
Dan, have you ever had your engine go into limp mode? and is there a return fuel line from the pump to the tank to send warm fuel back to the tank ?
my truck has gone in to limp mode because a clogged fuel filter, but you can restart the engine and it gets out of it. In my vision you would have two fuel filters, one for use and one for back up to switch to. Also i think the aftermarket chips allow you to bypass that function.

I was looking at the lycoming website at there 720 series "400 hp" for torque numbers to try to compare it to the duramax. The HP ratings of an engine don't really matter but the torque does when turning a prop. I suspect the duramax would beable to turn a big prop compared to the O-720.

#### Jan Carlsson

##### Well-Known Member
The HP matter just as the torque, but I guess you mean if a engine have 100% power at 4000 rpm and you turn it 2750 (in direct drive) how many hp it can turn out at 4000 isn't interesting, (until you put that engine in a Formula 1)

On the other hand, if you put in a diesel that have a flat max power curve from 3000 to 4000 and max torque at 2000 and gear it down to 2000-2500 at the propeller, it can turn a fixed pitch propeller with higher static and take-off/climb rpm then the direct drive engine will.

Adding a diagram of the Continental A-65 / A-75 engine, the difference between them is that the A-75 is allowed to reev more due to some minor internal changes, Comp ratio and all rest is the same. We can see that the A -65 have 65 hp at 2300, and A-75 at 2600, but still haven't reach its peek HP OR peek torque.

also look at the 80 HP Eco-motor power over the Rotax 80 HP, the eco motor is operated between its max HP and Max torque, giving much better take off and climb performance with a fixed pitch prop, and that the diesel have 75% power at 18000 feet, vv. Rotax at 8000 feet.

Jan

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#### EFILiveTuner

##### New Member
I have been working with and tuning Duramax motors for about 4 years now. Here are some pictures I can share regarding the tuning software I use (EFI LIVE). There are stand alone wiring harnesses available. An airboat I have been tuning is pictured below. It has a factory harness from a duramax in it that the owner modified to work with his application. Most model years of a duramax can be used as stand alone, however the operating systems from the 07.5-10 duramax LMM have been not tried as a stand alone unit as far as I know. One company makes a stand alone that comes to the top of my head is PPE in California. A factory duramax based ecm is used in the PPE stand alone setup with the factory wiring harness utilized for the injector control and sensors to work on the motor. The rest of the PPE harness is made to simplify all BCM and under hood/in cab fuse panels. I have used a PPE harness on a stripped down pull truck. I did not have time to make my own harness, so the PPE unit was the next best thing. It has a push button start and manual transmission. We use a computer and EFI Live data logging software to monitor the engine parameters via a cable that connnects from the computer to an EFI Live control box. From the EFI box there is a cable that connects to the OBD port for the ECM.

Here is a break down of the model year designations of the Dmax and a few details from the top of my head about them:

01-04 LB7 static charger w/wastegate, no EGR or CAT converter, internal injector lines and injectors located under valve covers controlled by FICM, high psi fuel system opperates at 23,000psi.

04.5-05 LLY VVT charger by Garret, EGR, Cat converter, external injector lines and injectors controlled by FICM,
high psi fuel system operates at 23,000psi.

06-07 (LLY)LBZ VVT charger
by Garret reworked for new EGR function, early model 06 was LLY based Bosch ecm(also used in van and manual trans ZF6 trucks) and later was LBZ bosch, no FICM,upgraded rods and lower end to handle higher base power on LBZ. Larger EGR and Cat converter, new high psi fuel system operates at 26,000psi with external injector lines and injectors.

07.5-current LMM VVT charger by Garret reworked for DPF and new EGR, same upgraded internals as LBZ, new 5 hole injectors for emissions, big EGR, Cat converter and DPF regen system for low emissions. No manual ZF6 trans offered. They do offer the LMM with a 4L80e trans option in a van(ie..Ambulance pkg) vs. the Allsion offered in the trucks, high psi fuel system opperates at 26,000psi with external injector lines and injectors.

EFI Live tuning offers switchable tuning on the fly with the choice of 2 or 5 tunes to choose from. This switchable tuing is called Duramax Switchable Programming or DSP. The hardwired DSP5 switch works by selecting different voltages for the ECM to measure, from these voltages the ECM can determine which program you wish to run. A The DSP2 switch works the same as the DSP5, through a single toggle switch.

That is all I can share for now. I'll try and point you all in the right direction for any further info you have. I do own and drive a built up LLY based Duramax with twin turbos and all the goodies under the hood. It makes just under 800 rwhp on a load cell dyno and 1480 ft-lbs of torque. Hope this info was a bit of help to you all.

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#### Starman

##### Well-Known Member
Thanks that is good news. Do you have any ideas about when the little Duramax might start production?

#### PTAirco

##### Well-Known Member
Any more details/pictures of the Duramax in the airboat? How is the prop driven?

#### pepsi71ocean

##### Well-Known Member
That would rule out switching to a mechanical injection system. I heard they will run on whiskey too.
NO NO NO! Running ethanool, whiskey and Kerosene will destroy that Common rail, even gasoline. The high pressure that are involved in modern diesel will destroy the careful crafted internals. ULSD has almost no lubrication to begin with, and assuming your Kerosene was ULSD, if not then your engine will throw a fit.

Back in the days of world war two with the low pressure 2 stoke diesels whiskey and gas worked fine, even into the P7100 pump era. but it has become an issue and a serious no no. I run Kerosene, a little of gas, but mostly 2 stoke oil in my VP-44. Depends on how cold it is.

That is another issue, temperature, diesel fuels can gel some ULSD can gel at 40 degrees out.

The 6.6 (IMO has much left to be desired) and is to computer program heavy. Plus with those EGR valves and re circ vents ide be afraid to drag that on as an airplane engine. And as such, look into the 6.7L Cummins reliable motor, but once the EGR and other Blue Tec stuff was installed to meet EPA regulations it became an issue.

Diesel engines are a different world. Plus what about the torsional vibrations on the airframe?

You need to bore out those oil galleries first to increase the reliability if you want to get the motor to last at high rpm. and throw in heavier rods. ide hate to think of that motor shooting a rod at 3,000 rpm. Yea you can get 3,000 rpm out of the motor, but for how long can you get it to run at 75 or 80% power.

But on the reliability scale Diesel are way up there, especially the old 2 stoke Diesels. or maybe a P-Pumped Cummins, that would be a reliable beast.

Im not picking out Duramaxes, but if you want to run a diesel engine that weighs in at 900 lbs, you need a really big airplane to run it. And on top of that you would need to upgrade that Diesel to run reliably past 30-40 hours of flight time, or else expect a TBO.

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#### pepsi71ocean

##### Well-Known Member
Might i ask for what HP and at what altitude your looking at.

To make that Dmax produce 600HP reliability at say 8,000 feet would take alot of money, but your mileage i think would be worse then it would be if you left it stock. Not to mention the weakness of the connecting rods when it comes to adding reliable 600HP at 3,000rpm.

If you wanted to get a good 600 HP at 10,000 i would assume right off the bat you would need a triple of not at least a twin turbo to get the boost for the altitude.

#### Starman

##### Well-Known Member
Hi Pepsi, I don't know that much about the specifics of different car/truck engines, but it appears that these engines have a better reliable power to weight ration than gas engines and the best thing about them, for me, is that they can be direct drive.

I've decided against this kind of engine for now because it is simply too heavy and would take too much material to build a plane for it, but I think the weight can go well below 700lb, it's not 900 in aircraft form. Also, I would be happy with 300hp and I don't need high altitude performance.

Also, keep in mind these things are made for working trucks and they are made to run at full power or nearly full power continuously. I've seen how they test engines at car factories, in person.

It may not last as long as an airplane engine but I wouldn't be surprised if it lasts longer, and when it wears out you go down to the junk yard and get a new slightly used one for $5000, the same as an intake valve for an airplane engine costs, uninstalled. #### pepsi71ocean ##### Well-Known Member Hi Pepsi, I don't know that much about the specifics of different car/truck engines, but it appears that these engines have a better reliable power to weight ration than gas engines and the best thing about them, for me, is that they can be direct drive. With the Exception of the powerstoke, i do agree the Duramax does have a better reliability rating when you compare the two. And Direct drive can also add to the Torsional vibrations hitting the propeller. Out of interest did you make any plans for how you would attach the propeller to the motor? I've decided against this kind of engine for now because it is simply too heavy and would take too much material to build a plane for it, but I think the weight can go well below 700lb, it's not 900 in aircraft form. Also, I would be happy with 300hp and I don't need high altitude performance. Trying to shave 300lbs out of a motor that is already tuned up for lightness would be tough, considering you would have to add weight to in order to make it reliable to run at 70% power. Also, keep in mind these things are made for working trucks and they are made to run at full power or nearly full power continuously. I've seen how they test engines at car factories, in person. Ive never towed with my truck at anything over 70% power(actually even when running i never exceed 2,200RPM, which is still 68% power band, and that is only for acceleration. neither does my buddy with a Chevy3500, hes blow one duramax running it on high rpm's. When i took it apart, i diagnosed it as an lubrication issue being the main reason, but he did drop a valve, one of the connecting rods was elongated, and im not sure if it was that way at the factory or weather it stretched due to over heating, and so the second Duramax we put in i bored out the oil galleries, and he hasn't had an issue yet. it Seems to fit the other issues as well, from what ive scene. But then again he towed a good deal, and often hit the GCWR when towing. It may not last as long as an airplane engine but I wouldn't be surprised if it lasts longer, and when it wears out you go down to the junk yard and get a new slightly used one for$5000, the same as an intake valve for an airplane engine costs, uninstalled.

Ide never get a junkyard motor and put it back into the airplane, that is taking a risk to begin with. But im a paranoid freak when it comes to taking risk in the air.

As for TBO, ide expect it to be close, since there are no other flying Duramaxes, you would kinda have to go with the flow and check everything, or if you had the money you could simulate the Motor running at full or 3/4 throttle under 70+% load.
I would think that in terms of reliability its a GREAT idea using a diesel, but unfortunately you would be loading that motor the minuet your start it up, you would need pre lube pumps on that so you wouldn't cause wear issues on start up.

But more importantly, you would be using it at full rating, that is 300 or 360HP at 100% boost, ie max boost you can run, that is the only way diesels make power.

For example i have a 220hp Cummins, during acceleration i have found that the motor will use about 180HP (at 2,200 rpm) under load, as its accelerating, but once your are at speed your turbo boost backs down and your running on 80 HP.

You would have to run at 180HP balls to the wall from the motor in an airplane and so your load would be constant, expect to see worn rings, and connecting rods etic. Plus expect to have bad mileage, because your runnign boost, and the only issue with diesel and fuel economy is their boost level, especially once that waste-gate opens up.

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#### Starman

##### Well-Known Member
It looks like you have a lot of experience with these things. I looked at the Cummins diesel as a possibility too, but couldn't get anyone on their forum to say how much one weighs. Anyway, if the Duramax (and it looks like the others) put out such low power and have the reliability problems I'll just use a gas engine direct drive. To be honest, the test engines I saw running at the factory were at the Chrysler factory since my dad used to work for them. I did too for awhile, running test engines in the emission labs there.

Anyway, the drive method I would use (this design is on a back burner now), is for a pusher with a driveshaft so you couldn't use it for your tractor. The plan is for direct drive with a torsional vibration dampener on the crankshaft that is like a clutch dampener, except that instead of using the springs it will use rubber bushings. Then the driveshaft will be a rear axle from a car, with a self aligning bearing at the prop end. my original plan was to use a torsion bar, and a rear axle is also a torsion bar, but it might be too stiff. Adding the rubber bushings will make it certain to remove all torsional resonance problems.

#### pepsi71ocean

##### Well-Known Member
It looks like you have a lot of experience with these things. I looked at the Cummins diesel as a possibility too, but couldn't get anyone on their forum to say how much one weighs.

Depends on the block size and configuration, the 5.9L with heads turbo etic is about 1,200 lbs, the newer 6.7L's tip the scale at 1,350ish.

A bare bones Cummins 5.9L block is 900ish.

The main advantage of a Cummins over a duramax in this situation is that the higher the RPM the smoother the motors become, as Inline 6's are inherently and secondary balanced by their own movement, unlike V-8's.

Anyway, if the Duramax (and it looks like the others) put out such low power and have the reliability problems I'll just use a gas engine direct drive. To be honest, the test engines I saw running at the factory were at the Chrysler factory since my dad used to work for them. I did too for awhile, running test engines in the emission labs there.

The Issue isn't the diesels, its building/modifying that Diesel to run full boost continuously. Even my Cummins never sees a full 24psi (ie 215HP)of boost, even when accelerating. and that is where you must then modify the engines to accept the boost, and the off set effects of running such. ie higher egt's, more wear and tear, more heat to dissipate.

Anyway, the drive method I would use (this design is on a back burner now), is for a pusher with a driveshaft so you couldn't use it for your tractor. The plan is for direct drive with a torsional vibration dampener on the crankshaft that is like a clutch dampener, except that instead of using the springs it will use rubber bushings. Then the driveshaft will be a rear axle from a car, with a self aligning bearing at the prop end. my original plan was to use a torsion bar, and a rear axle is also a torsion bar, but it might be too stiff. Adding the rubber bushings will make it certain to remove all torsional resonance problems.

Why not cast in a gear reduction on the output side of the motor, and keep the harmonic dampener on the other, and then add heavier valve springs, bigger turbo, and enlarged exhaust, should fix that direc drive issue.

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#### Starman

##### Well-Known Member
My plan for this engine was to cruise it at around 200hp and use 300hp for occasional use.

I think you must be talking about a different engine than I am because others have said the Duramax weighs around 800lb (post 14), and can put out 600hp absolutely stock with only the addition of an aftermarket chip. I find it difficult to believe your claim that one will only cruise at around 80hp.

In any case, I will not modify a car or truck engine internally to run in an airplane, only remove all possible emission components and switch to carburetor if it's a gas engine. I will not invest in a reduction gear, even for a gas engine. (except possibly in an ultralight)

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