21,000psi on big tune with lbz regulator

[WolfLMM]

More pressure= better atomization= more surface area of fuel available to burn=more power. When you spray with higher pressure, it hits the piston with more umphh, all other variables being the same.

Only to surface of fuel droplets burns, finer mist means bigger faster boom. This was touched on in James "bigger injector thread" as well.

I'm with Josh, low rail pressure means less power, incomplete combustion, and more black smoke. So I don't believe it could hurt the motor! <that is JMO

 

[Chevy1925]

OP, your missing HP from that drop off in power. you might actually run faster on your tune 4 than tune 5 due to that (but it depends on how rob setup the tunes). if you want to get all your rail pressure back and have max power, you need to start doing some diag. Test injector return rates, check cp3 return rate and then go from there. adding a second CP3 or a bigger single will get your rail back as well but it masks worn parts. Not that that is a bad thing but adding that second pump does not always guarantee that you will get your rail back. if parts are worn enough, you can still have a drop in pressure.

 

[S Phinney]

The goal in the end is to have the truck do as the tune ask. If there is a problem with pressure recovery you should find the issue that's causing it. If the tune is that big that it drops rail that much it just adds unneeded wear and tear on fuel parts. I doubt you can actually measure that wear and tear because there are too many variables that could creat worse wear and tear. I want every truck that I tune to do what I ask of it. When I find those limits I then tell the customer of his options.


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[diesel-don]

OP, your missing HP from that drop off in power. you might actually run faster on your tune 4 than tune 5 due to that (but it depends on how rob setup the tunes). if you want to get all your rail pressure back and have max power, you need to start doing some diag. Test injector return rates, check cp3 return rate and then go from there. adding a second CP3 or a bigger single will get your rail back as well but it masks worn parts. Not that that is a bad thing but adding that second pump does not always guarantee that you will get your rail back. if parts are worn enough, you can still have a drop in pressure.

New to EFI Live and still waiting to hear back from Rob from a data log but im not new to tuning in general.

After looking at the logs my big tune is at 3200pw max and pulls hard just skips out a little bit in 4x4. It feels like a fuel problem but hard to say. Turbo holds 41psi boost with 40%vane position or less. What kinda power would you guys guess this things makes?It blows the tires off at 40mph in 2wd. Im not sure how much more the stock block can take!

Anyone want to take a peek at my 4x4 WOT datalog?

I found a friend selling a dual cp3 kit from PPE so I should be putting it on this weekend.

 

[WolfLMM]

Just a wild ass guess, prolly down 30-40hp...

So if say around 550ish, to the wheels.

 

[NC-smokinlmm]

If desired is 26k and actual is 21k then it's not the tune holding it back. Plus running rail at below desired is not what I would do since atomization would suffer and could hurt the motor IMO.


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Commanded rail means nothing really, you can pull it down with pulse width and duration. Basically, chasing the piston down after tdc...

 

[Chevy1925]

Commanded rail means nothing really, you can pull it down with pulse width and duration. Basically, chasing the piston down after tdc...

He's saying rob did not make the tune hold back power via rail like you suggested. The fact it commands 26k and only hits 21k explains that.

 

[NC-smokinlmm]

He's saying rob did not make the tune hold back power via rail like you suggested. The fact it commands 26k and only hits 21k explains that.

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...

 

[Chevy1925]

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...

Your thinking way too far into it lol

 

[NC-smokinlmm]

Your thinking way too far into it lol

I tend to do that... :spit:

 

[NRA223]

Better to think too much than too little. :thumb:

 

[Dozerboy]

New to EFI Live and still waiting to hear back from Rob from a data log but im not new to tuning in general.

After looking at the logs my big tune is at 3200pw max and pulls hard just skips out a little bit in 4x4. It feels like a fuel problem but hard to say. Turbo holds 41psi boost with 40%vane position or less. What kinda power would you guys guess this things makes?It blows the tires off at 40mph in 2wd. Im not sure how much more the stock block can take!

Anyone want to take a peek at my 4x4 WOT datalog?

I found a friend selling a dual cp3 kit from PPE so I should be putting it on this weekend.

Pretty hard to say how much hp your making. My 3497stg2 at 35psi on 2800us holding perfect rail makes a little less hp then I did max effort with the stock turbo. Guessing it might be 500ish.

You do know your playing with fire now? Add duals and your asking for a catastrophic failure.

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[diesel-don]

Pretty hard to say how much hp your making. My 3497stg2 at 35psi on 2800us holding perfect rail makes a little less hp then I did max effort with the stock turbo. Guessing it might be 500ish.

You do know your playing with fire now? Add duals and your asking for a catastrophic failure.

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Just because of the increased HP/TQ? I was thinking that if I don't change the tune and add duals then i should only get the FP that is demanded (26,000) anyway and since it was written for my truck then it should be what Rob intended anyway. Please let me know there is something else im missing.

I mean if Rob expected the pressure to be lower than he could have set the demanded rail fuel pressure lower in the first place. Unless he loaded the tune for a built motor stage2r and didnt see any issue changing because my stock fuel system couldnt hold that much...

Thanks for all the replies.

Cant wait to hear back from Rob on this. I know he is busy.

 

[Dozerboy]

Just because of the increased HP/TQ?

Yes. I wouldn't add duals if you don't want to build your engine at some point. Most guys thinking is a stock cp3 is a good limiting device to keep from breaking something. After adding duals or a stroker is when most guys break something.


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[WolfLMM]

Adding duals will only provide the fuel the tuning commands. Rob is a good tuner, tell him to make it live. Tuning has come a long ways in last few years.

Good luck.

 

[diesel-don]

Yes. I wouldn't add duals if you don't want to build your engine at some point. Most guys thinking is a stock cp3 is a good limiting device to keep from breaking something. After adding duals or a stroker is when most guys break something.


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I do plan to build it next year.

 

[diesel-don]

Adding duals will only provide the fuel the tuning commands. Rob is a good tuner, tell him to make it live. Tuning has come a long ways in last few years.

Good luck.

Rob has already tuned to demand 26000, so if i add duals i should not have to retune,im i right?

The only reason i ask is because i would like to add 60% injectors within the next couple months so it would be nice to postpone next tune until then.

 

[Dozerboy]

So add duals just to have Rob reduce the power back to what he makes now?

IMO at this power level tuning the lbzs hasn't really changed in the last 7 years....maybe.... other then turbos.


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[JoshH]

If you have tuning meant for a stock fuel system with a lift pump, and you are not achieving desired pressure, you have something wrong. I would recommend fixing whatever is causing your low rail pressure situation rather than covering it up by over-supplying fuel for your current horsepower goals.

 

[Chevy1925]

If you have tuning meant for a stock fuel system with a lift pump, and you are not achieving desired pressure, you have something wrong. I would recommend fixing whatever is causing your low rail pressure situation rather than covering it up by over-supplying fuel for your current horsepower goals.

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