DIY - Duramax Marinisation
04-21-2016, 04:23 PM
#62
Registered
Thread Starter
I personally don't know anyone running a dry sump right off, but I'm guessing it only requires same volume as a gas engine.
04-25-2016, 09:58 PM
#63
Registered
Thread Starter
After we decide on lift and CP3 pumps, the next thing is injectors and supply line upgrades.
Only a couple points to mention here. If sticking with a stock CP3 pump, there is a couple upgraded fittings you can do to get the most out of it.
High Flow CP3 1/2" Hose Barb Fitting
[ATTACH=CONFIG]554691[/ATTACH]
For those who prefer AN fittings and braided fuel line, they make these clean AN-8 inlet and AN-6 return line adapters.
CP3 Fuel Supply Fittings (AN-8)
[ATTACH=CONFIG]554692[/ATTACH]
After those easy CP3 upgrades, we can increase volume into the fuel rails with this Ported Fuel Rail Fitting.
[ATTACH=CONFIG]554693[/ATTACH]
For the DIY pro's, you can easily drill out your stock fitting and save the $35. I chose to replace mine, and then moved the main inlet fitting over to the secondary rail. Thus increasing the volume of both rails. As you can see in the pic below, the very small [stock orifice left] is all required to supply enough fuel to make 550+ crankshaft HP.
[ATTACH=CONFIG]554696[/ATTACH]
The other "and most important" fitting to replace is also in the drivers side main fuel rail. At the back of the rail there is a pressure bypass valve that was designed to pop open and dump in over pressure situations. When you crank up the fuel pressure, that relief valve is known to pop open when you don't want it to. To resolve the problem, you can shim the stock valve or replace it with this $35 plug, PPE Race Fuel Valve.
[ATTACH=CONFIG]554699[/ATTACH] [ATTACH=CONFIG]554698[/ATTACH] [ATTACH=CONFIG]554697[/ATTACH]
Only a couple points to mention here. If sticking with a stock CP3 pump, there is a couple upgraded fittings you can do to get the most out of it.
High Flow CP3 1/2" Hose Barb Fitting
[ATTACH=CONFIG]554691[/ATTACH]
For those who prefer AN fittings and braided fuel line, they make these clean AN-8 inlet and AN-6 return line adapters.
CP3 Fuel Supply Fittings (AN-8)
[ATTACH=CONFIG]554692[/ATTACH]
After those easy CP3 upgrades, we can increase volume into the fuel rails with this Ported Fuel Rail Fitting.
[ATTACH=CONFIG]554693[/ATTACH]
For the DIY pro's, you can easily drill out your stock fitting and save the $35. I chose to replace mine, and then moved the main inlet fitting over to the secondary rail. Thus increasing the volume of both rails. As you can see in the pic below, the very small [stock orifice left] is all required to supply enough fuel to make 550+ crankshaft HP.
[ATTACH=CONFIG]554696[/ATTACH]
The other "and most important" fitting to replace is also in the drivers side main fuel rail. At the back of the rail there is a pressure bypass valve that was designed to pop open and dump in over pressure situations. When you crank up the fuel pressure, that relief valve is known to pop open when you don't want it to. To resolve the problem, you can shim the stock valve or replace it with this $35 plug, PPE Race Fuel Valve.
[ATTACH=CONFIG]554699[/ATTACH] [ATTACH=CONFIG]554698[/ATTACH] [ATTACH=CONFIG]554697[/ATTACH]
Last edited by kidturbo; 04-25-2016 at 10:05 PM.
04-26-2016, 12:48 AM
#66
Registered
Thread Starter
The primary reason to shim or replace the rail mounted pressure release valve is that when it pops opens, the rail pressure drops far enough below requested to set a P0087 code. When that happens, the ECM instantly goes into "limp mode" and your forced to either turn off the engine for several minutes, clear the code somehow, or limp home at under 2000 rpm. Same thing happens with a fuel filter restriction.
Plenty of good articles out there on the Dmax forums about FPRV mod. Here is one example: http://www.dieselplace.com/forum/3-p...alve-work.html
Another fuel rail piece worth identifying and possibly relocating if needed is the fuel pressure sensor.
[ATTACH=CONFIG]554702[/ATTACH]
GM has moved this sensor several times over the years. On the LB7 it was tucked in the valley behind the pump, the LLY version had it in the middle of passenger side rail, and LMM it was moved to the end of the rail. Here is a good link explaining these locations. http://www.duramaxdiesels.com/forum/...ad.php?t=25040
On my LLY conversion I found the center of fuel rail location conflicted with the crankcase vent tube upgrade kit I installed. On that engine model you can easily move the sensor to end of rail where there is a plug by default. Main thing is to be certain you know where the sensor is located on which ever model you start with.
[ATTACH=CONFIG]554703[/ATTACH]
Plenty of good articles out there on the Dmax forums about FPRV mod. Here is one example: http://www.dieselplace.com/forum/3-p...alve-work.html
Another fuel rail piece worth identifying and possibly relocating if needed is the fuel pressure sensor.
[ATTACH=CONFIG]554702[/ATTACH]
GM has moved this sensor several times over the years. On the LB7 it was tucked in the valley behind the pump, the LLY version had it in the middle of passenger side rail, and LMM it was moved to the end of the rail. Here is a good link explaining these locations. http://www.duramaxdiesels.com/forum/...ad.php?t=25040
On my LLY conversion I found the center of fuel rail location conflicted with the crankcase vent tube upgrade kit I installed. On that engine model you can easily move the sensor to end of rail where there is a plug by default. Main thing is to be certain you know where the sensor is located on which ever model you start with.
[ATTACH=CONFIG]554703[/ATTACH]
05-08-2016, 12:54 AM
#67
Registered
Thread Starter
Injectors. Stick size does matter...
When it comes to power and reliability of the Duramax in a marine setup, choice of injectors plays a huge role. The injectors control how much fuel goes into the cylinder, along with how quickly it gets sprayed in there.
You may have noticed the new diesels keep getting quieter and quieter, this is due to whats known as pilot injection. I like to think of it like MSD ignition for diesels. Rather than the injector shooting one large shot of fuel into the cylinder, they now fire multiple shots per stoke, like the MSD fires on a gas engine. The first few shots are called pilots, and meant start a fire burning smoothly as the piston approaches TDC. Then the primary injection shot hits with the majority of fuel. This pilot injection is what takes the knock out to the diesel..
To make more power in a diesel you add more fuel. Unlike a gas engine, we are not concerned with A/F ratio. You go to lean, you make less power. You go rich you make more power, heat, and typically black smoke. Maintaining Stoichiometric Combustion in a diesel is not a concern, but maintaining safe exhaust gas temperature [EGT] is. Another major difference from a gas engine is when the ignition cycle starts and ends. Modern common rail diesel injection cycles shoot the majority of fuel just a few degrees before top dead center. Then they continue spraying fuel after piston passes TDC. This is where EGT's come into the calculation.
You wanta turn up the power, you turn up the fuel pressure and or injector pulse width. But if you don't advance the timing, you also get more smoke and higher EGT's due to extra unburned fuel injected after the piston has passed TDC. So just turn up the timing along with pulse width right? Yes, the Duramax like her timing, till the point she smokes a hole through a piston... Remember that pilot injection? You've got a nice little flame started on top the pistons, then you shoot a huge shot of fuel to it earlier in the stroke, and that injector tip turns into a plazma cutter. The Duramax pistons and injectors were designed so that main shot of fuel only gets sprayed into the bowl area of the piston. Start spraying fuel to early and you start etching the pistons top or worse. For the details on all this I'll refer again to the Diesel Army article from our piston section.
For the short version, here is some pics of a common rail injector pulse, along with couple pics of what happens when you push the pulse width and timing a bit to far in search of more power... Just Google "Duramax Cracked Pistons" and click Images, you'll find plenty of examples, couple of them mine.
[ATTACH=CONFIG]555111[/ATTACH] [ATTACH=CONFIG]555112[/ATTACH] [ATTACH=CONFIG]555113[/ATTACH]
The correct way to increase the fuel volume and power is to increase the amount of fuel the injector can spray through the tip in the same amount of time. Known as injector flow rate, it's measured in mm3 or liters per minute {LPM]. While old style diesel injectors were measured in HP increase, new common rail injectors are measured in % over stock flow rate. I will cover these options next.
When it comes to power and reliability of the Duramax in a marine setup, choice of injectors plays a huge role. The injectors control how much fuel goes into the cylinder, along with how quickly it gets sprayed in there.
You may have noticed the new diesels keep getting quieter and quieter, this is due to whats known as pilot injection. I like to think of it like MSD ignition for diesels. Rather than the injector shooting one large shot of fuel into the cylinder, they now fire multiple shots per stoke, like the MSD fires on a gas engine. The first few shots are called pilots, and meant start a fire burning smoothly as the piston approaches TDC. Then the primary injection shot hits with the majority of fuel. This pilot injection is what takes the knock out to the diesel..
To make more power in a diesel you add more fuel. Unlike a gas engine, we are not concerned with A/F ratio. You go to lean, you make less power. You go rich you make more power, heat, and typically black smoke. Maintaining Stoichiometric Combustion in a diesel is not a concern, but maintaining safe exhaust gas temperature [EGT] is. Another major difference from a gas engine is when the ignition cycle starts and ends. Modern common rail diesel injection cycles shoot the majority of fuel just a few degrees before top dead center. Then they continue spraying fuel after piston passes TDC. This is where EGT's come into the calculation.
You wanta turn up the power, you turn up the fuel pressure and or injector pulse width. But if you don't advance the timing, you also get more smoke and higher EGT's due to extra unburned fuel injected after the piston has passed TDC. So just turn up the timing along with pulse width right? Yes, the Duramax like her timing, till the point she smokes a hole through a piston... Remember that pilot injection? You've got a nice little flame started on top the pistons, then you shoot a huge shot of fuel to it earlier in the stroke, and that injector tip turns into a plazma cutter. The Duramax pistons and injectors were designed so that main shot of fuel only gets sprayed into the bowl area of the piston. Start spraying fuel to early and you start etching the pistons top or worse. For the details on all this I'll refer again to the Diesel Army article from our piston section.
For the short version, here is some pics of a common rail injector pulse, along with couple pics of what happens when you push the pulse width and timing a bit to far in search of more power... Just Google "Duramax Cracked Pistons" and click Images, you'll find plenty of examples, couple of them mine.
[ATTACH=CONFIG]555111[/ATTACH] [ATTACH=CONFIG]555112[/ATTACH] [ATTACH=CONFIG]555113[/ATTACH]
The correct way to increase the fuel volume and power is to increase the amount of fuel the injector can spray through the tip in the same amount of time. Known as injector flow rate, it's measured in mm3 or liters per minute {LPM]. While old style diesel injectors were measured in HP increase, new common rail injectors are measured in % over stock flow rate. I will cover these options next.
05-08-2016, 02:47 AM
#68
Registered
Thread Starter
So now that I've again scared the bejesus out of ya, let me repeat, if your happy with 500hp or less, none of this stuff matters. Factory injectors will do fine as long as they are in good working order. They can supply enough fuel to power a stock engine well into the 650hp range, in a truck. In a boat, I like to keep that down in the low 500's top due to the pulse width concerns.
If you have any questions about your stock injectors condition, have them professionally tested. The guy who purchased my LLY powered boat actually owns a shop that specializes in nothing but common rail injectors. Call Andy at InjectorsDirect.com and he will clean and test your injectors, return you a full condition report, along with some added piece of mind. Because a leaking or misfiring injector can lead to piston damage also.
If they test ok and you wish to go above 500hp, then you can just change the tips / nozzles to increase the flow rate. That's how I did it. You can have your OEM nozzles extrude honed to a increase the hole size and final flow rate. Below is what they look like outside, and then under a microscope. Depending on the engine model, injectors will normally have 5 to 8 holes in the tip.
[ATTACH=CONFIG]555116[/ATTACH]
[ATTACH=CONFIG]555114[/ATTACH] [ATTACH=CONFIG]555115[/ATTACH]
If you need to buy a complete set of new or reman injectors, then it's a good time to upgrade the nozzle size. With the ECM tuning options like EFIlive, it's about impossible to go too big on the size. For common power upgrades under 800hp a 30-60% over stock nozzle will do the trick. I read a story this week where someone was testing new 500% oversized injectors in a bone stock truck, and it ran great. While I don't suggest doing anything that outragous in the real world, the point is larger injectors allow you to lower the pulse width with tuning to where you get more fuel into that piston bowl without a huge increase in timing. Thus increasing power while maintaining the design parameters of the pistons and other internals as GM built it.
It should also be noted that GM changed the flow rate of the stock injectors with every model update. To calculate and compare flow rates across all models we use the same fuel pressure and pulse width values on each injector to get a correct comparison. These changes in GM's design also means the ECM injection pulse width used on the LB7 does not match up with a LMM or LML engine. Just something to keep in mine if your planning to get into the ECM tuning side of this. Here is a link that talks about the injector flow rate comparison. Basically stock flows rates breaks down like this.
From the link above, at 180mpa fuel pressure and 2800us pulse width stock injectors flow:
LB7 206.3 mm3
LLY 218.6 mm3
LBZ 182.0 mm3
Or in LPM
LB7 - 18lpm
LBZ - 19lpm
LMM - 17lpm
From Thoroughbred Diesel website on oversize LMM nozzles, this is the flow volumes by %.
+ 20% = 23 LPM
+ 40% = 27 LPM
+ 75% = 33 LPM
+100% =38 LPM
A 100% over injector can fuel upwards of 1200hp at the same pulse width or period of time that a stock injector would fuel 600hp. That's how you keep the fuel spraying in the piston bowl and run the engine at high RPM and power levels for extended periods of time without melting it down. Basically when in doubt, go a little bigger and turn it down in the tuning. The only other important thing you need to know about Duramax injectors,,the pointed end goes in the hole...
[ATTACH=CONFIG]555117[/ATTACH]
If you have any questions about your stock injectors condition, have them professionally tested. The guy who purchased my LLY powered boat actually owns a shop that specializes in nothing but common rail injectors. Call Andy at InjectorsDirect.com and he will clean and test your injectors, return you a full condition report, along with some added piece of mind. Because a leaking or misfiring injector can lead to piston damage also.
If they test ok and you wish to go above 500hp, then you can just change the tips / nozzles to increase the flow rate. That's how I did it. You can have your OEM nozzles extrude honed to a increase the hole size and final flow rate. Below is what they look like outside, and then under a microscope. Depending on the engine model, injectors will normally have 5 to 8 holes in the tip.
[ATTACH=CONFIG]555116[/ATTACH]
[ATTACH=CONFIG]555114[/ATTACH] [ATTACH=CONFIG]555115[/ATTACH]
If you need to buy a complete set of new or reman injectors, then it's a good time to upgrade the nozzle size. With the ECM tuning options like EFIlive, it's about impossible to go too big on the size. For common power upgrades under 800hp a 30-60% over stock nozzle will do the trick. I read a story this week where someone was testing new 500% oversized injectors in a bone stock truck, and it ran great. While I don't suggest doing anything that outragous in the real world, the point is larger injectors allow you to lower the pulse width with tuning to where you get more fuel into that piston bowl without a huge increase in timing. Thus increasing power while maintaining the design parameters of the pistons and other internals as GM built it.
It should also be noted that GM changed the flow rate of the stock injectors with every model update. To calculate and compare flow rates across all models we use the same fuel pressure and pulse width values on each injector to get a correct comparison. These changes in GM's design also means the ECM injection pulse width used on the LB7 does not match up with a LMM or LML engine. Just something to keep in mine if your planning to get into the ECM tuning side of this. Here is a link that talks about the injector flow rate comparison. Basically stock flows rates breaks down like this.
From the link above, at 180mpa fuel pressure and 2800us pulse width stock injectors flow:
LB7 206.3 mm3
LLY 218.6 mm3
LBZ 182.0 mm3
Or in LPM
LB7 - 18lpm
LBZ - 19lpm
LMM - 17lpm
From Thoroughbred Diesel website on oversize LMM nozzles, this is the flow volumes by %.
+ 20% = 23 LPM
+ 40% = 27 LPM
+ 75% = 33 LPM
+100% =38 LPM
A 100% over injector can fuel upwards of 1200hp at the same pulse width or period of time that a stock injector would fuel 600hp. That's how you keep the fuel spraying in the piston bowl and run the engine at high RPM and power levels for extended periods of time without melting it down. Basically when in doubt, go a little bigger and turn it down in the tuning. The only other important thing you need to know about Duramax injectors,,the pointed end goes in the hole...
[ATTACH=CONFIG]555117[/ATTACH]
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