21,000psi on big tune with lbz regulator

[Forever]

I was inferring he did it so that its not obvious what he is doing. I've spoken with rob about this issue and he didnt seem concerned and just about every truck I tuned with his tuning never held more than 22k in a max effort tune but held 24 or better in tune 4. Commanded was always 26k, I will also say all said tuned trucks are still alive and doing well despite being driven hard. It is just a theory of mine, I'm not capable of looking at the tunes myself to figure it out nor do I really care too...

Rob Tuned my truck and I have experienced the same thing.

 

[WolfLMM]

^^this. find the weak point in your system and fix it

Which is most likely a weak cp3. In which case you either replace (nightmare) or add another pump (smaller nightmare:rofl. He already has a race plug, so that leaves excessive injector return rates, or a supply issue to cp3, or a weak cp3.

And yes the tune will only provide the fuel commanded. So right now you are commanding 26k and getting 21k. Adding/fixing what's wrong will net back the 5k. This is no more dangerous than having a brand new truck with a strong fuel system running max effort tuning. You're playing with fire when you tune these trucks no matter what.

Edit: not knocking you James, just used post as reference.

 

[Chevy1925]

Rob Tuned my truck and I have experienced the same thing.

because you have something weak in your system that can not keep up on the big tune


i can see it now "ATP tuning conspiracy 2016, what are we REALLY getting for 3200uS tune!" :roflmao:

 

[Chevy1925]

Which is most likely a weak cp3. In which case you either replace (nightmare) or add another pump (smaller nightmare:rofl. He already has a race plug, so that leaves excessive injector return rates, or a supply issue to cp3, or a weak cp3.

And yes the tune will only provide the fuel commanded. So right now you are commanding 26k and getting 21k. Adding/fixing what's wrong will net back the 5k. This is no more dangerous than having a brand new truck with a strong fuel system running max effort tuning. You're playing with fire when you tune these trucks no matter what.

Edit: not knocking you James, just used post as reference.

no biggy buddy

 

[WolfLMM]

For reference my truck commands 26k and only achieves 25k. On 3200pw. It has been running that way on stock charger for 25k and on the 68stg2R for 10k. Like I said, you're only getting back to where rob thought you would be..

 

[IdahoRob]

I'll explain my experience with the different models and rail pressure vs HP. on a stock CP3 average fuel system in decent shape.

I like to think of a teter-toter. Pulse width on one side and pressure on the other side. You have to find the balance for most available HP.

As was posted earlier; the LB7/LLY trucks will be happy making 19k rail pressure on a big fueling tune. Would it make more HP with more pressure? heck yeah. The LBZ/LMM trucks that low limit of balance is 23,500-24,000. Anything below that and you will start dropping HP fast.

My big tunes 3100-3200us on stock injector/stock cp3 trucks have that as the max and when rail pressure drops, so does the pulse. This way the ecm should fine the balance of pulse to pressure. If the system can't keep up at 3100us than as the pressure drops, the pulse will be pulled back.

I have tested this over many years and many trucks on the dyno and the track. If the truck can't keep this balance of pressure to pulse, then the fuel system most likely needs some attention. Here is a write I did that may help. http://atptrucks.com/blog/fuel-rail-pressure-is-low-now-what

I don't recommend adding a second CP3 without tuning adjustment on a stock engine. This will now make a 3200us tune to run at 26k psi. Big HP, enough to kill a stock block. I will adjust the tuning as per a customers request for HP after explaining the possible failures. Most choose to lower pulse to a more sane level and have the 26k psi.

Hopefully this helps a bit explain how I think of things. Basically I build tuning from many years of experience on what the average truck (and customer) can handle. Fine tuning can be done to optimize each set-up and needs.

 

[Dozerboy]

Thanks for clearing that up Rob. I was starting to wonder if I wasn't being a sissy for not turning my truck up to 3200us.

I was pretty suprised on the power I picked up going from 23500psi to 25kpsi on my old tired cp3.

Sent from my SAMSUNG-SM-G900A using Tapatalk

 

[Chevy1925]

And the tuner takes the myth out of the tuning he does

 

[diesel-don]

I'll explain my experience with the different models and rail pressure vs HP. on a stock CP3 average fuel system in decent shape.

I like to think of a teter-toter. Pulse width on one side and pressure on the other side. You have to find the balance for most available HP.

As was posted earlier; the LB7/LLY trucks will be happy making 19k rail pressure on a big fueling tune. Would it make more HP with more pressure? heck yeah. The LBZ/LMM trucks that low limit of balance is 23,500-24,000. Anything below that and you will start dropping HP fast.

My big tunes 3100-3200us on stock injector/stock cp3 trucks have that as the max and when rail pressure drops, so does the pulse. This way the ecm should fine the balance of pulse to pressure. If the system can't keep up at 3100us than as the pressure drops, the pulse will be pulled back.

I have tested this over many years and many trucks on the dyno and the track. If the truck can't keep this balance of pressure to pulse, then the fuel system most likely needs some attention. Here is a write I did that may help. http://atptrucks.com/blog/fuel-rail-pressure-is-low-now-what

I don't recommend adding a second CP3 without tuning adjustment on a stock engine. This will now make a 3200us tune to run at 26k psi. Big HP, enough to kill a stock block. I will adjust the tuning as per a customers request for HP after explaining the possible failures. Most choose to lower pulse to a more sane level and have the 26k psi.

Hopefully this helps a bit explain how I think of things. Basically I build tuning from many years of experience on what the average truck (and customer) can handle. Fine tuning can be done to optimize each set-up and needs.

Okay so in my logs i am able to maintain between 3100-3200us even at lower than desired fuel pressure. So if i increase the fuel pressure at the rail to the desired 26,000psi by adding a second cp3 will that actually increase the volume of fuel being injected during each cycle?
So if i have you retune the truck with the duals what will you do(without giving away any secrets of course)? Will you back down the pw to compensate for the added pressure? Thanks again.

 

[PureHybrid]

He will probably drop pulse and a touch of timing.

And yes, more pressure= higher volume of fuel for a given pulse width.

 

[diesel-don]

He will probably drop pulse and a touch of timing.

And yes, more pressure= higher volume of fuel for a given pulse width.

Got it. Big thanks to everyone for helping me sort this out.

 

[Forever]

because you have something weak in your system that can not keep up on the big tune


i can see it now "ATP tuning conspiracy 2016, what are we REALLY getting for 3200uS tune!" :roflmao:

I definitely wasn't stating that. I was agreeing with smokinlmm .

 

[NC-smokinlmm]

And the tuner takes the myth out of the tuning he does

How you figure? Rob really didn't explain why at all or say there was a problem. I still think it's a trade secret, like little tricks I do to transducer installs to make them read better, if you catch me and inquire, I play dumb...

 

[diesel-don]

^^this. find the weak point in your system and fix it

It seems like my weak point is my aging cp3. Since I don't plan to get back into the engine until I have time and parts to fully build it (winter 2017) I feel that adding a second cp3 will not only be a purchase towards my goal of 1000whp but it will also provide any demanded fuel pressure giving Rob some flexibility with his tunes.

 

[Chevy1925]

It seems like my weak point is my aging cp3. Since I don't plan to get back into the engine until I have time and parts to fully build it (winter 2017) I feel that adding a second cp3 will not only be a purchase towards my goal of 1000whp but it will also provide any demanded fuel pressure giving Rob some flexibility with his tunes.

as long as you know where the weak point is and know the second CP3 will fix it, i see no issue with that. Its pretty much what i did when i built my engine in 2011. I knew my cp3 was weak based on tests and instead of buying a new cp3 and a second one to throw on top all at once, i figured i would give just a second one a try to see if i could hold rail with 45% over injectors. i had no issues.

Josh and i suggest you finding the issue for sure FIRST though cause you could very well put the dual kit on and still get low rail pressure cause you have a weak cp3 AND injectors or you could have other under laying issues. i have seen trucks not hold rail with stock injectors and dual pumps on good tuning. its not super common but it happens when the owner threw parts at it to fix an issue.