LB7: What can be expected with stock LB7 Turbo

[KEVINL]

I have the stock turbo back on my truck and I feel like I want to dial back some fuel but I am not sure how much I can do this and stay above 500Whp.

Basically my truck has always poured coal with a big tune on the stock charger. The pic in my Avatar is the PPE on 350hp tune.

I want to reduce the smoke without sacrificing too much power. I don't know what is reasonable expecattion on a IHI of achieving that.

I feel like at some point in the throttle I am just wasting fuel and it isn't producing anymore power.

It seems like with The VVT Turbos you have a lot less smoke at 500+whp than with a IHI

 

[TrentNell]

what pulse width are you running ? i would try a 3000 usec or 3100 usec pulse width and see how it goes .

 

[[email protected]]

I kind of want to know the same thing but with a LLY VVT. I have it to where it hardly smokes on spoolup but once it gets to higher rpms air mass decreases and it starts to smoke a little more.

I don't get how unburt diesel is white but it blows black smoke when its too rich. Ive heard black smoke means the fuel is partially burnt?

 

[KEVINL]

I'm Running 3100usec right now

 

[Whitetail Addict]

cmitchell, the black smoke is partially burnt fuel...the black is carbon if I remember chemistry class correctly

 

[KEVINL]

I have dropped it down to 2900usec smoke is not as bad should I go lower or leave it

 

[[email protected]]

I dropped mine by lowering my maf limiting tables. Instead of it giving 100mm3(3000-3100us) of fuel at under 2.2g/cyl, it gives 90mm3 (2900-3000us) I did not notice any difference but there is still smoke when it revs high(where airmass is decreased).

What rail pressure are you at?

 

[JOHNBOY]

I have dropped it down to 2900usec smoke is not as bad should I go lower or leave it

You should still be able to make 500rwhp with that pulse. For me 2850 always seemed to work. You just need to figure out what kind of timing curve your truck likes.

 

[jason86]

cmitch what are you running on your B0751? i tried for 2 weeks, and i did get it to just a haze of smoke that was great but i could feel (and see in my scans) the table holding me back it was just gutless till around 2.0 G/CYL. like i would floor it and my mm3 would slowly follow 751 until full fueling if you know what i mean (dead pedal). i put my table like this and i can still feel it when i go <50% throttle jump mm3 every time itt changes to another box on the map.

has anyone figured out how to keep the power and throttle response without notifying every cop withing a half mile by smoke signals?

 

[KEVINL]

It is running very strong. I need to get my Turbo horn ported it should run even better then.


I will give 2850 a try


Also the way it is tuned the smoke only is really when I am at WOT.
Am I correct in thinking that at WOT the MAF would be out of its range

 

[jason86]

kevin i have my turbo horn ported and run 2850 and i smoke like a freight train. do you still have good throttle response throughout full throttle movement? i have my TBIQ set high so my throttle is real touchy down low just the way i like it. im wondering with it set higher if its impossible to get back to just a haze of smoke down low, i dont care about smoke at WOT

i dont max out my maf sensor i hit about 58Lbs but i rescaled my B0201 and i still have a little bit till its maxed out.

 

[KEVINL]

I have RDL Uppipes and I think it helped with spool. The only time it smoke signifigantly is at wot and especially if I stand on it from a stop which there is nothing you can do about that.

 

[jason86]

really the only time it bothers me is when i am coasting down to a red light at around 25-30mph then the light turn green and i give it some throttle to get back to speed i belch black smoke everywhere for no good reason. dont get me wrong i think there is a time and place for smoke but not in a situation like that.

 

[[email protected]]

Im the same way I hate smoke, I don't want unesessary attention.

Ive tried to compare spoolup times between maf limiting and no maf limiting. It looked like there was almost no difference, but sometimes it does feel like there is something holding it back.

Here is my MAF limiting table with about a 3100us tune:

One thing that helped me was using finger's AFR pid. It shows in Equivilance ratio and ive found that at about 1 there is just a little smoke and at about .9 is where there is zero smoke. You can find it in a thread here called Air Fuel Ratio Calculation I think its on the next page here in Duramax tuning and logging.

I would like to know how AFR effects power. I think on a gas engine that slightly rich (14-1, 13.8-1) makes best power becuase you are guareenteed that there will be enough fuel so that all the air can combine with it. The only reason you go richer is to control EGTs. But on a diesel I don't know how it is?

I tested timings effect on spoolup the same way by just measuring with efilive how long it took from idle to full boost (about 30psi where the MAP sensor limit is) at WOT. I found about a .3-.5 (3.75 vs 4.1sec.) second difference between about -1-2 degrees, and about 4-6 degrees. It looked like the lower timing helped a little.


I still feel like the maf limiting table might be holding me back, but I dont know.

 

[[email protected]]

The 2.4g/cyl area is where i run into problems. There needs to be a 2.1/cyl cell and a 2.3g/cyl cell. It will be in the 2.4g/cyl cell and really be at about 2.21g/cly and be running to rich becuase it is allowing full fueling becuase it is still in the 2.4g/cly cell.

 

[jason86]

mitch i tried doing the table the way you have it but it gave me terrible dead spots in my throttle, is it doing the same thing to you? probably not because LLY tables have more cells. this is the one that im trying in a few min but i am sure it will not limit smoke too much.

i tried to make a calc smoke and a calc eq pid, i followed all the explanations and copied and pasted and then i could not find the pid to select it. if you could give me 5th grade instructions on how to make and use these new pids it would be much appreciated.

 

[[email protected]]

With a modified pulsewidth table, especially with race tunes and 500rw tunes it makes it really hard to modify this table.

Look in your My Documents/efilive/V7.5(yours might be different)/user configuration.

In that user configuration folder there is a calc_pids.txt you can just replace that with the calc_pid.txt file you found in the Air Fuel Ratio Calculation thread.

I had some trouble with it too. Make sure your efilive is up to date. You also might have two copies of the V7.5 folder (like I did)

You might have My Documents/EFI live/V7.5 and in that V7.5 you might have another V7.5. Just put a copy of the calc_pid.txt in both V7.5/user configuration folders.

 

[KEVINL]

I am down to 2850 usec and have adjusted the throttle based iinjection quanity down by 10% between 80-100% throttle


I copied the maf table from another tune because the tune I was using everything was set to 120 on BO751


The table I am using now is like 145 at 2.4 G/CYL.


The changes I have made cut down the smoke below WOT but WOT is still nasty smoke. Maybe I will try lowering the G/CYL to 90 max.

Living in a big city with tons of traffic I am about to say screw it and get a tow tune bacause I can't go WOT without pissing everybody off and it almost smokes to the point of causing an accident

 

[Turbotug]

How often are you at WOT?

Does the smoke ever clear up while at WOT? If not you will probably need to take more pw out until you are happy with it.

 

[KEVINL]

All the time

J/K


I feel like I can't even use WOT now

It doesn't clear up I can't tell that I have lost any power yet so I am going to take out more pulse width

I need twins