Let's do some bench racing

[Hotrodtractor]

Not to poke fun at you I'm just using your quote as an example, but this is a factor that has probably played into things as well. These engines ain't a 5.9 cummins, there is a lot more displacement to work with. Everyone in the performance world has based everything on a 5.9, what is a large charger on a cummins is nothing more than a modest sized charger on a 7.3. People need to think about it and put a charger on that is speced to work with the airflow requirements of a 7.3. Look at Travis's truck (moormph) hell 5 years ago he was running a hx82 as a single bushed down to 3.0 and lighting it with an auto. If in fact that had the smallest turbine available from holset it was a 130/94, quite a difference from the 96/88 borg wheel that everyone thinks is huge. Good friend of mine street drove a s469 with the 96 turbine for a few years with no problems whatsoever. Truck was "on" the charger by 2300rpm.


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Very true - although I thought it was an HX80 - either way I remember that charger under the hood of his truck in the passenger fender well many years ago. I honestly had forgotten about it until you just said it.... that seems like ages ago.

 

[NyCowboy87]

Very true - although I thought it was an HX80 - either way I remember that charger under the hood of his truck in the passenger fender well many years ago. I honestly had forgotten about it until you just said it.... that seems like ages ago.

So did I but check my thread in the pulling section, he chimed in a couple days ago and said it was an 82.


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[PsdPullerJr]

I'll throw this out for you guys to tell me I'm wrong but I've felt for several years now that big cubic inches is actually a disatvantage in a say the 2.6 class. Is it not more effective to feed a smaller cubed engine with "X" amount of air? I've felt a 7.3 could be competive in a 2.6 class, just not with a 2.6 turbo.

 

[02BigD]

annnd FWIW...we didn't recently invest in 5 axis CNC machining equipment for injection system improvements...

Are you insinuating we may see a billet 7.3 head in the future?

 

[ghohouston]

Are you insinuating we may see a billet 7.3 head in the future?

Gotta be, with 4 valves per cylinder of course

 

[Magnum PD]

Have to used one pushrod for 2 valves.

 

[Countrycar]

Are you insinuating we may see a billet 7.3 head in the future?

Now you got my attention...:thumbup:

 

[TyCorr]

Not to poke fun at you I'm just using your quote as an example, but this is a factor that has probably played into things as well. These engines ain't a 5.9 cummins, there is a lot more displacement to work with. Everyone in the performance world has based everything on a 5.9, what is a large charger on a cummins is nothing more than a modest sized charger on a 7.3. People need to think about it and put a charger on that is speced to work with the airflow requirements of a 7.3. Look at Travis's truck (moormph) hell 5 years ago he was running a hx82 as a single bushed down to 3.0 and lighting it with an auto. If in fact that had the smallest turbine available from holset it was a 130/94, quite a difference from the 96/88 borg wheel that everyone thinks is huge. Good friend of mine street drove a s469 with the 96 turbine for a few years with no problems whatsoever. Truck was "on" the charger by 2300rpm.


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no offense taken. I have no clue in these matters. It just seems like thats a lot of charger.

What you said is simething ive known, loosely, given my own admission of ignorance. The i6 td always seem to do a bit more with a smaller charger. As do the duramax motors. Those guys think an s366 is fairly large. Not to get slugged out by hrt! LOL

 

[97BambiBasherPSD]

Nycowboy87 what size chargers did you run in your triple setup?

How much air does it take to make the big power? Do we need bigger than 400 sticks to make it closer to 1k? What kind of tricks can be done to help out the motor make the power?


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[NyCowboy87]

Nycowboy87 what size chargers did you run in your triple setup?

How much air does it take to make the big power? Do we need bigger than 400 sticks to make it closer to 1k? What kind of tricks can be done to help out the motor make the power?


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I ran 450/400's because that is all that's available. A 450cc injector has the potential to make around 900-950 on fuel, proven on swamps engine dyno. A modded 7.3 generally makes 2-2.2hp/cc of fuel delivered, again proven on swamps dyno. So with that said if we could clean up and actually get that 450cc shot of fuel in above 4k rpm then we would have something.

Cummins trucks are making 12-1300hp with around 600cc of fuel delivery. Now a v8 will take roughly 30% less fuel to make the same hp given that ve is close between the two engines. 30% of 600 puts us at 400cc, hmmm we already have injectors larger than that but we can only inject around 350cc north of 4000rpm which is landing us at that magic 700hp number. Ill say it again, the injection events have to get cleaned up and we have to inject more in the higher rpm's. It will take a larger injector capable of injecting more fuel per ms or it's going to take some electronics that don't pull back pw up high in rpm's


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[97BambiBasherPSD]

Ah now that all makes sense. So basically we need some thing that will flow the fuel up high to make the hp. Now is it possible to make the power under 4k rpm? By your post it seems that's where our injectors can flow all the fuel but after 4k it suffers.

Btw you told me what sticks you ran. I was curious about the turbos.

Would you run twins or triples to make the power? And why


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[NyCowboy87]

You can make 800 down low but that's when blocks check out and $hit hits the fan.

My triple set was done with 3 s472's. The two atmosphere chargers had the small 83mm wheel and a 1.25 housing. The manifold charger had the big 96mm exhaust wheel with a 1.25 housing as well. I'd run triples again in a heartbeat. When you can daily drive the truck and have responsiveness, yet there is a ton of air available like in a big twin set you get the best of both worlds. Also back pressure was stupid low like 80psi boost to 50 drive in the street tunes and in the hot tune it would push 125 psi of boost and just over 100 drive.


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[isootmypants]

You can make 800 down low but that's when blocks check out and $hit hits the fan.

My triple set was done with 3 s472's. The two atmosphere chargers had the small 83mm wheel and a 1.25 housing. The manifold charger had the big 96mm exhaust wheel with a 1.25 housing as well. I'd run triples again in a heartbeat. When you can daily drive the truck and have responsiveness, yet there is a ton of air available like in a big twin set you get the best of both worlds. Also back pressure was stupid low like 80psi boost to 50 drive in the street tunes and in the hot tune it would push 125 psi of boost and just over 100 drive.


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Why did you stop running them, if I may ask.

 

[NyCowboy87]

Had 8 pistons check out due to some inferior machine work and I wanted to pull for points so the truck needs to comply with rules.


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[97BambiBasherPSD]

Good reason haha would you have seen any difference if you went to say 2 s480s? Or is that too much for that setup


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[Hotrodtractor]

I ran 450/400's because that is all that's available. A 450cc injector has the potential to make around 900-950 on fuel, proven on swamps engine dyno. A modded 7.3 generally makes 2-2.2hp/cc of fuel delivered, again proven on swamps dyno. So with that said if we could clean up and actually get that 450cc shot of fuel in above 4k rpm then we would have something.

Cummins trucks are making 12-1300hp with around 600cc of fuel delivery. Now a v8 will take roughly 30% less fuel to make the same hp given that ve is close between the two engines. 30% of 600 puts us at 400cc, hmmm we already have injectors larger than that but we can only inject around 350cc north of 4000rpm which is landing us at that magic 700hp number. Ill say it again, the injection events have to get cleaned up and we have to inject more in the higher rpm's. It will take a larger injector capable of injecting more fuel per ms or it's going to take some electronics that don't pull back pw up high in rpm's


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I agree with with statement except for one aspect - the computer is fully capable of injecting fuel in the window of time needed to make power. We don't need longer PW.... we need faster injectors. Stretching out the PW especially at higher RPMs where piston speeds are higher is just a good way to make a lot of heat and smoke.... put the fuel in in the proper window and you make power.

 

[97BambiBasherPSD]

What can you do to make the injectors faster then?


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[NyCowboy87]

True I'll agree with that Jason but don't injection events have to start overlapping up high? This is where the factory IDM says no and you have to pull pw to avoid the popping and missing.


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[powerstroke95]

I agree with with statement except for one aspect - the computer is fully capable of injecting fuel in the window of time needed to make power. We don't need longer PW.... we need faster injectors. Stretching out the PW especially at higher RPMs where piston speeds are higher is just a good way to make a lot of heat and smoke.... put the fuel in in the proper window and you make power.

Jason I remember years ago you posted a "what it would take to make a 7.3 competitive" thread. It may have even been on PSN, I cant remember, but I would sure like to read that again, and others would as well I'm sure. In the thread you talked about the oil capacity and PSI it would take to inject a "competitive" amount of fuel. Any chance you have this thread saved?

 

[Hotrodtractor]

True I'll agree with that Jason but don't injection events have to start overlapping up high? This is where the factory IDM says no and you have to pull pw to avoid the popping and missing.


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No - injection events should never overlap. I know there was some thinking of that in the past and some testing, but that is completely the wrong direction.

Think of the injection event in terms of crank angle degrees instead of milliseconds (or microseconds depending on your tuning system). Oversimplifying everything and rounding numbers to something easy to talk about - lets say that magic number is something like 60 degrees of engine rotation for an injection event. (Its not). At lower RPMs it takes forever to go 60 degrees of crank rotation, but as RPM increases the amount of time it takes gets less and less..... ie less and less PW to hit that injection event window....

The popping and cracking occurs when the IDM freaks out because it can not interpret the signals it is receiving from the computer... ie the PW is too long to give a good clean signal for each injection event..... when this occurs you have already spent too much time attempting to inject fuel.