Does Anybody Really Understand Our RPM Limitation?

Bean

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Tuning a CR with a stand alone is cool. Turning it 7000 rpms is even cooler till the bottom end dont like it.

Very low duration x high injection pressure / pretdc injection = rpms

Problem with the HEUI is the first two items in that equation.
 

Vader's Fury

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I would love to take the same truck with 100's, then 200's. Start with the 100's, then let me switch it to 200's and retune it. It's impossible that you would choose the 100's over the 200's. IMpossible....

I will take you up on this offer if you are serious. I currently am running 250/100's from swamps and have been debating sending them back and having 200's installed. I believe I have what would be a good platform for testing this out. Let me know if your interested.
 

Chris

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Why?

Because the one making 600 on a 100% nozzle will be running more timing, more EGT and higher cylinder pressure. It will blow gaskets, melt/crack pistons and crack the heads much faster.


The relationship between flow achieved from increased pressure vs increased flowable area is not linear. It takes WAY.....WAY....WAY more pressure than it does orifice size to acheive the same flow. You simply cannot make a 100% nozzle flow what a 200 will with any practical amount of pressure. Before it flowed equal the tip would have lodged itself into the piston....


I would love to take the same truck with 100's, then 200's. Start with the 100's, then let me switch it to 200's and retune it. It's impossible that you would choose the 100's over the 200's. IMpossible....

Im assuming noone is understanding im saying IF you could make the same power with the SAME duration on both the 100 or the 200. Of course the 200 will always be capable of more hp than a 100. But what IF a 100 could make 600 w/ xx ms. And what IF 600 is all someone wanted. I capitalized the IF for a reason. Right now we all know a 100 cant make 600 on fuel only without a retarded amount of timing and duration, but what IF it could.

I think Bean understands what im getting at. A common rail motor can make quite a bit more hp than a heui motor by combining short pw and higher pressures to get the same volume of fuel than a lower pressure and a larger nozzle. Dmaxes only run mid 2s for pw, and they make plenty of power on nozzles a lot smaller than a 7.3. Even a 6.0 with 190/100s can surpass 525-550 running 2.5ish ms and a mid 60s mm compressor. A 7.3 would be in the mid to high 400s best case scenario.

The point im trying to make is it just ISNT injection pressure, and it isnt JUST the cam, or head flow, or anything. The whole combination makes for us not being able to burn a great percerntage of the fuel injected into the motor. This is why nitrous helps so much. For now we have to run 200 percent or larger nozzles to make big power, but itd be awesome if we didnt. Sure a 200 percent nozzle is very driveable with correct tuning, but there are a few tradeoffs (yes small).
 

Gearhead

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Dmaxes only run mid 2s for pw, and they make plenty of power on nozzles a lot smaller than a 7.3. Even a 6.0 with 190/100s can surpass 525-550 running 2.5ish ms and a mid 60s mm compressor. A 7.3 would be in the mid to high 400s best case scenario.

Also remember that 3ms on a 7.3 is close to the same injection duration as a 6 liter at 2.5ms or a duramax at 2.2ms or so. The only difference is in the injector delay. This is just something to note and that it doesn't affect anything other than what you are logging for PW. The timing is compensated for in the injection delay table and is not a factor in tuning.
 

Bean

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And also remember that 3ms called for is still 3ms called for from the PCM/IDM and overlapping signals at higher rpms cause bad juju. This is the HEUI problem, you cant have signal overlap so you have to shorten pulse width, shorten pulse width to a duration the PCM can deal with then you have no fuel because of injector delay.

All hand in hand- welcome to HRT hell...
 

Bean

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I think Bean understands what im getting at. A common rail motor can make quite a bit more hp than a heui motor by combining short pw and higher pressures to get the same volume of fuel than a lower pressure and a larger nozzle. Dmaxes only run mid 2s for pw, and they make plenty of power on nozzles a lot smaller than a 7.3. Even a 6.0 with 190/100s can surpass 525-550 running 2.5ish ms and a mid 60s mm compressor. A 7.3 would be in the mid to high 400s best case scenario.

.

Nozzles are still not small to get the duration needed to turn high rpms even with 30,000psi. Just makes it easier and can do a little bit smaller then you can with lower injection pressure.
 

Charles

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I will take you up on this offer if you are serious. I currently am running 250/100's from swamps and have been debating sending them back and having 200's installed. I believe I have what would be a good platform for testing this out. Let me know if your interested.


If you're DAC3 it would be possible. Although it wouldn't be much of a "test" perse, as I've already done it.
 

Charles

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Im assuming noone is understanding im saying IF you could make the same power with the SAME duration on both the 100 or the 200. Of course the 200 will always be capable of more hp than a 100. But what IF a 100 could make 600 w/ xx ms. And what IF 600 is all someone wanted. I capitalized the IF for a reason. Right now we all know a 100 cant make 600 on fuel only without a retarded amount of timing and duration, but what IF it could.

I think Bean understands what im getting at. A common rail motor can make quite a bit more hp than a heui motor by combining short pw and higher pressures to get the same volume of fuel than a lower pressure and a larger nozzle. Dmaxes only run mid 2s for pw, and they make plenty of power on nozzles a lot smaller than a 7.3. Even a 6.0 with 190/100s can surpass 525-550 running 2.5ish ms and a mid 60s mm compressor. A 7.3 would be in the mid to high 400s best case scenario.

The point im trying to make is it just ISNT injection pressure, and it isnt JUST the cam, or head flow, or anything. The whole combination makes for us not being able to burn a great percerntage of the fuel injected into the motor. This is why nitrous helps so much. For now we have to run 200 percent or larger nozzles to make big power, but itd be awesome if we didnt. Sure a 200 percent nozzle is very driveable with correct tuning, but there are a few tradeoffs (yes small).



Let me try again...

IF.... you get enough pressure to a 100 to make it flow equal to a 200.... you just lodged the tip of that nozzle into your aluminum piston bowl...


And yes.... pressure is the only option you have to make a 100 flow equal to a 200 when you already stated in the SAME duration. Here's a hint.... flow is a two-part equation in this case. The components are orifice area and fluid pressure. If you already state the orifice areas and the duration then the only variable left is pressure. And a 100 is just never going to flow like a 200 with any amount of pressure that doesn't blow the tip clean off. Plus, you could never operate the injector at such pressures anyway.


You just can't do it with pressure alone. You might surprise youself to pin out some 600+ fuel only injector nozzles on some CR trucks. They are smaller in comparison, but not tiny. As that power comes up they get right back in the game.

And 12v nozzles make our sh*t look mickey-mouse.


And cams, heads and all the rest...... yada,yada,yada...

It's injection rate. Always has been, always will be. The mech engines out there state this profoundly.
 

Chris

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Youre right, im wrong. Navistar should have put 200 percent nozzles in from the factory and with 400 percent nozzles we are 500 hp ahead of the cr cummins and dmax guys. What was i thinking.

Having less time to burn the fuel and make power per cycle happens in every engine. The common rails just get around it a litlte better. Not because of their pure volume, but of the volume theyre actually able to burn and convert to horsepower.

I never said youd need the same volume out of the 100 to make the same power in the same duration as a 200. the 200 will always flow more fuel into the motor. What im saying is if you COULD burn more of the fuel injected more efficiently, you COULD make more hp with smaller nozzles.

Also youre comment about the 12 valve also proves what im trying to say. Why do motors w/ less air flow and less atomization need larger nozzles to make the same amount of power? thats my whole point. Im not saying the system on a 7.3 will ever be capable of making 600 hp on fuel out of a 100 percent nozzle. Theres a chance itll take more money, time and effort than converting the whole thing to common rail or swapping power plants all together. What im saying is, it would be nice.
 

powerstrokenstang

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so one question on timing, on average how much timing does it take to sound like fuel7? i know there are alot of variable thats why i said average, o and on a stock piston motor. basically i am wondering how much usable btdc time and or degrees we have to inject. also how much return is it to inject alot after tdc? i know you are just adding to the fire but doesnt it take more fuel per hp atdc? or does it help lower cyl press since the main combustion has started.
 

Hotrodtractor

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And also remember that 3ms called for is still 3ms called for from the PCM/IDM and overlapping signals at higher rpms cause bad juju. This is the HEUI problem, you cant have signal overlap so you have to shorten pulse width, shorten pulse width to a duration the PCM can deal with then you have no fuel because of injector delay.

All hand in hand- welcome to HRT hell...

Overlapping pulsewidth isn't completely the answer either because you still have the same number of crank angle degrees to play with for an effective combustion event.

I always knew I would have my own special section of hell. :D
 

Gearhead

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My whole point of this was to help explain to those wanting a 4500 RPM tune for pulling sleds that their 100% nozzles aren't going to cut it. We know what the issues are, now somebody fix them already.......LOL
 

Charles

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Youre right, im wrong. Navistar should have put 200 percent nozzles in from the factory.

Have you ever seen a nozzle from a Navistar DT466 or DT530, which btw are rated at sub 300 freakin horsepower? They DID.



And with 400 percent nozzles we are 500 hp ahead of the cr cummins and dmax guys. What was i thinking.

I don't really understand what you're saying with this. If you would like to scratch-build a 7.3 Heui injector that can keep up with our oil flow needs then you can run a smaller nozzle after you then also redesign the fuel side of the injector so that it doesn't blow apart. Until then, you might want to open up the holes a little if you plan to move any fuel. As far as fuel "quality" goes..... blah..... I try to remember that every time I see a sigma pump cracking 6000rpm with copius amounts of power, but for some reason I just don't care anymore each time I watch the mod class. Just get the damn fuel in the hole however you can.



Having less time to burn the fuel and make power per cycle happens in every engine. The common rails just get around it a litlte better. Not because of their pure volume, but of the volume theyre actually able to burn and convert to horsepower.

What does it take for a CR 5.9 to make 650rwhp on fuel? What injectors? Now go pin them out and tell us the hole count and size. Otherwise, we're referencing fantasy land. We're running somewhere between .011 to .014" x 7 to accomplish this. What are these common rails running to do the same?



I never said youd need the same volume out of the 100 to make the same power in the same duration as a 200. the 200 will always flow more fuel into the motor. What im saying is if you COULD burn more of the fuel injected more efficiently, you COULD make more hp with smaller nozzles.

Yeah. Nitrous oxide has been doing it for years. But if you want to make the power fuel only.... the only way a 100 is going to make 200%+ power... is if you stick it on a CR injector and don't blow it apart.



Also youre comment about the 12 valve also proves what im trying to say. Why do motors w/ less air flow and less atomization need larger nozzles to make the same amount of power? thats my whole point. Im not saying the system on a 7.3 will ever be capable of making 600 hp on fuel out of a 100 percent nozzle. Theres a chance itll take more money, time and effort than converting the whole thing to common rail or swapping power plants all together. What im saying is, it would be nice.


I guess I just don't have a problem with a mechanical 5.9 running 0.020" + nozzles....

Makes good power. Gets sh*t done and doesn't turn pistons into flowers.
 

Hotrodtractor

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Youre right, im wrong. Navistar should have put 200 percent nozzles in from the factory and with 400 percent nozzles we are 500 hp ahead of the cr cummins and dmax guys. What was i thinking.

Having less time to burn the fuel and make power per cycle happens in every engine. The common rails just get around it a litlte better. Not because of their pure volume, but of the volume theyre actually able to burn and convert to horsepower.

I never said youd need the same volume out of the 100 to make the same power in the same duration as a 200. the 200 will always flow more fuel into the motor. What im saying is if you COULD burn more of the fuel injected more efficiently, you COULD make more hp with smaller nozzles.

Also youre comment about the 12 valve also proves what im trying to say. Why do motors w/ less air flow and less atomization need larger nozzles to make the same amount of power? thats my whole point. Im not saying the system on a 7.3 will ever be capable of making 600 hp on fuel out of a 100 percent nozzle. Theres a chance itll take more money, time and effort than converting the whole thing to common rail or swapping power plants all together. What im saying is, it would be nice.

I get it Chris - you're trying to relate injection quality to tip size. It is true that on the HEUI injector that someone just slaps a tip on that it is much easier to get a quality injection spray out of a 100% tip than a 200% tip - this goes along with the "some minor concessions" comment and is most likely referring to some minor additional smoke on initial spool up, a bit more smoke on a cold startup (less likely in Texas than say Ohio...), etc... There is just so much more to having a quality injection event possible - especially as tip size increases. This is one aspect that I have spent a LOT of time and effort on for my new sticks - I want a chit load of fuel - but I want it to be high quality fuel with refinements in control resolution so it can sit and idle like stock and be able to easily and smoothly transition from from idle to cruise to WOT without the need for the injectors to act like on/off switches..... that's something that is a bit of a challenge when you can empty a 400cc injector in 2.5ms using a 400% tip. Once the last couple of mechanical control resolution quirks are ironed out to my liking - then I will show you how nice and smooth a 400% tip can be.
 

Charles

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To reitterate for anyone lost on the main point here...


Our high rpm hinderance is oilflow. If you and Dan Schied were standing next to one another, and each of you wanted to move 500cc of fuel in __ms, he would start working on how to flow 500cc through the pump. If you were using a Heui, say with a 5:1 injection ratio.... you would however need to figure out how to move 2500cc of ROTELLA instead... Oh, you still have to move the 500cc of diesel..... but you ALSO have to move 2500cc of 15w40 in the same amount of time... Like B codes better? Well then you'd better figure out how to move 3000cc of Rotella for those bastards. A codes float your boat??? Then better make it 3500cc of engine oil. Meanwhile.... ole Dan's just working on that 500cc of diesel, and that's it...

Gee, I wonder why we have such a hard time?
 
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Hotrodtractor

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To reitterate for anyone lost on the main point here...


Our high rpm hinderance is oilflow. If you and Dan Schied were standing next to one another, and each of you wanted to move 500cc of fuel in __ms, he would start working on how to flow 500cc through the pump. If you were using a Heui, say with a 5:1 injection ratio.... you would however need to figure out how to move 2500cc of ROTELLA instead... Oh, you still have to move the 500cc of diesel..... but you ALSO have to move 2500cc of 15w40 in the same amount of time... Like B codes better? Well then you'd better figure out how to move 3000cc of Rotella for those bastards. A codes float your boat??? Then better make it 3500cc of engine oil. Meanwhile.... ole Dan's just working on that 500cc of diesel, and that's it...

Gee, I wonder why we have such a hard time?

Additional reading for those that are interested:

http://powerstrokenation.com/forums/showthread.php?t=18566

http://powerstrokenation.com/forums/showthread.php?t=33513

http://powerstrokenation.com/forums/showthread.php?t=62966
 

JAP

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To reitterate for anyone lost on the main point here...


Our high rpm hinderance is oilflow. If you and Dan Schied were standing next to one another, and each of you wanted to move 500cc of fuel in __ms, he would start working on how to flow 500cc through the pump. If you were using a Heui, say with a 5:1 injection ratio.... you would however need to figure out how to move 2500cc of ROTELLA instead... Oh, you still have to move the 500cc of diesel..... but you ALSO have to move 2500cc of 15w40 in the same amount of time... Like B codes better? Well then you'd better figure out how to move 3000cc of Rotella for those bastards. A codes float your boat??? Then better make it 3500cc of engine oil. Meanwhile.... ole Dan's just working on that 500cc of diesel, and that's it...

Gee, I wonder why we have such a hard time?
Requoted for awesomeness and effect.
 

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