12valve vs. common rail power questions

[AMassaro]

Why are 12valve Cummins able to produce more power (aftermarket) than the newer common rails??? Is it just because they have been around longer, therefore guys have more time/troubleshooting invested?

 

[ROADWARRIOR]

The injector pump on the 12 valves is able to dump in quite a bit more fuel than the pump on the common rails. The common rails are also limited in rpm.



Dan

 

[BigGunZ]

Why are 12valve Cummins able to produce more power ?

Are you referring to HP, TQ, or both? I would think that a 12 valve couldn't match the HP of a HPCR.

 

[Forrest Nearing]

Are you referring to HP, TQ, or both? I would think that a 12 valve couldn't match the HP of a HPCR.

see above, a modded p7100 is capable of pushing a lot more fuel than the common rail pump...



fuel = power

 

[BigGunZ]

see above, a modded p7100 is capable of pushing a lot more fuel than the common rail pump...

fuel = power

I get that, but power comes in 2 forms. What can a modded 12 valve see horsepower-wise assuming just airflow and fuel mods (no cam)?

 

[AMassaro]

So it all comes down to the injector pump... . Makes sense. Has nothing to do with 12 vs. 24valves then... Ok, next question is who is working on common rail injection pumps and can they be made to dump more fuel?



Thanks for all replies. I'm absolutely obsessed with my truck. Never thought this would turn into the "hobby" of my life.



also, hp is a derivative of torque and they cross paths at 5250rpm's so why wouldn't a 12valve give equal hp figures to a comparable common rail???

 

[Forrest]

I get that, but power comes in 2 forms. What can a modded 12 valve see horsepower-wise assuming just airflow and fuel mods (no cam)?

Over 800 ... Jim Fulmer did it.

 

[Forrest Nearing]

I get that, but power comes in 2 forms. What can a modded 12 valve see horsepower-wise assuming just airflow and fuel mods (no cam)?

"power" actually only comes in one form... torque... torque at speed = horsepower...



more fuel and more RPM = more power...



a stock cammed 12v w/ just fuel and turbos can make more than an HPCR can



add a cam and it'll make even more

 

[JCleary]

So it all comes down to the injector pump... . Makes sense. Has nothing to do with 12 vs. 24valves then... Ok, next question is who is working on common rail injection pumps and can they be made to dump more fuel?



Thanks for all replies. I'm absolutely obsessed with my truck. Never thought this would turn into the "hobby" of my life.



also, hp is a derivative of torque and they cross paths at 5250rpm's so why wouldn't a 12valve give equal hp figures to a comparable common rail???

I saw BigBadDodge do 859 a couple of weeks ago. I think the highest 3rd gen was in the 500's.



ATS has a modded CP3. $2750, and it comes with a throttle-activated 120psi pusher pump. I've never heard of anyone running it, though.



Industrial Injection is also working on one, and rumor has it that it will be a LOT cheaper than the ATS unit.

 

[Rams-n-Hogs]

Is it just because they have been around longer, therefore guys have more time/troubleshooting invested?

That's a big part of it. There is a learning curve for everything. Having BOMBED both, I will go out on a limb, and say, I personally think it's easier to get big Hp, (to a point, i. e. 500-600) out of the common rail, than the 12V, but the 12V is more fun, sounds better, and smokes more. There's no telling where a modded CP3 will take us, yet.



Jim

 

[Devan Manis]

I think that in the future the common rail is gonna blow the p7100 pump out of the water. As much as i love the p-pump.

 

[Forrest Nearing]

it certainly has the potential to if they can get the fuel out of it!

 

[catoiler]

Twin CP3's!!

 

[JVolpe]

I think the ECM computer programming is also a factor. It is a two edged sword, easier to make a few fuel map changes or fool a sensor than put in cam and change injectors, but I am also fighting torque management and rev limits with mine. When someone gives us full control of the computer and programming then it will be a lot easier.

 

[BigGunZ]

"power" actually only comes in one form... torque... torque at speed = horsepower...

more fuel and more RPM = more power...

a stock cammed 12v w/ just fuel and turbos can make more than an HPCR can

add a cam and it'll make even more

That's argueable. 2 engines can produce equal torque and have vastly different HP numbers, which was the reason for my question. Just saying "they can make more power", doesn't tell the whole story. As someone else pointed out, I'll bet the HPCR's have a lot of untapped potential.

 

[Forrest Nearing]

That's argueable. 2 engines can produce equal torque and have vastly different HP numbers, which was the reason for my question. Just saying "they can make more power", doesn't tell the whole story. As someone else pointed out, I'll bet the HPCR's have a lot of untapped potential.

horsepower is a function of rpm... the p7100 trucks can turn 5000-6000rpm and put out more fuel...



the p7100 at this time is capable of more power than the HPCR...



it also is capable of more torque

 

[Msilbernagel]

I think the ECM computer programming is also a factor. It is a two edged sword, easier to make a few fuel map changes or fool a sensor than put in cam and change injectors, but I am also fighting torque management and rev limits with mine. When someone gives us full control of the computer and programming then it will be a lot easier.

On a different forum, there was a fellow (since moved to South America) who had programmed the ECM to remove the extra events, changed timing, etc. Since his move, I've talked to one of the fellows who benefitted from that work, and he told me that while that person was tight lipped about what he'd done, it did include programming a marine ECM. Makes sense, since I think that puts you back into the Cummins arena rather than Dodge.



So - if there is anyone out there bold enough to dive in, I believe it can be done. It could also be possible with the Dodge ECM, but perhaps more difficult.



My guess as to why the CP3 won't make RPM is that the frequency demanded of the injectors (up to three events for one 'fire') is probably a factor. You only have so many milliseconds to get the various jobs done, and given response-time capability of the injectors (open, close, and fuel-flow) there ceases to be sufficient time to get it all done above a certain RPM...



Unless, of course, you reduce the number of events to ONE.



Sounds like we need to apply some talent to this job. :-laf



Mark

 

[BigGunZ]

horsepower is a function of rpm... the p7100 trucks can turn 5000-6000rpm and put out more fuel...
the p7100 at this time is capable of more power than the HPCR...

it also is capable of more torque

HP is a function of quite a bit more than RPM.

That said, I'm not arguing your point about the P7100's making more power. I was merely asking to quantify the statement that "12 valvers make more power". I was not disputing it... . nor would I, as I know little about them.

To some, power implies torque... . to others it implies HP. When someone tells me that powerplant "A", makes more power than powerplant "B", ..... I like to hear specifics about the HP/TQ and even like to see dyno sheets.

I'm a gearhead... I can't help it.

 

[LDobie]

HP is a function of quite a bit more than RPM.

Actually, according to physics, Power, defined as a time rate of doing work, is quite simply a function of Torque and RPM. The dyno measures the torque or twist of the output shaft and the RPM and from that it calculates the power. The equation is HP = (Torque in ft-lbs * RPM) / 5250



HP is kind of a voodoo theoretical number, for example, the 5. 7 Hemi makes 345 hp, but there is no way in hell that it would ever out work our beloved CTD, which is around 325hp. I could imagine Huge HP numbers from a CTD if you were able to push that torque curve to a much higher RPM, like 4000-5000 rpm and lighten everything up and get her to hold together

 

[JEpling]

I just had to replace my cp3 pump wish i could have found a better pump instead of having to buy a stock pump!! 2005 3500 single wheel truck 373 gear, 6 spd with #3600 dd 12cb south bend clutch, tst power max, crazy larry power pup, fass with filters,afe air box, htb2 turbo, toyo 325/70/17 tires, have edge hot juice with aditude in the closet. Truck dyno at 563hp and 1101 torque with egt backdown set at 1300. but still like to know why pump went down with a fass system on the truck from day 1 of upgrading performance?