Awhile back I tested the PPE stack on my LLY truck. It felt very fast, and ran OK. Dyno was in the low 400's. I took it to the track, and it performed erratically, and did not run quicker stacked than unstacked. The major problem was laying down at the 1/8th mile marker. (I had also tested Edge stacked with various tunes with poor results. But some of that was barking during the shift as well, as well as poor ET unstacked.)

So I blamed it on the PPE Stack. Perhaps prematurely.

Now I went to track test another "good street stack" at the dragstrip. The TTS LLY Level 2 and the VA LLY box. This is VERY streetable and feels vicious, with good shifting. I get 1/2 way down the dragstrip, and BLAH!!! It loses power. I spray some nitrous into it, and it does not pick up speed. You couldn't even feel the nitrous on or off.

My best guess at this point is fuel starvation without the infamous 1093 code. But it's only an educated guess. Is it REALLY starving? Or is the ECM defueling it? Or is something else happening? First I need to work on the fueling to remove that from equation.

I guess what I don't get, is why it works for an 1/8mi before cutting out. The 1/8th ET indicated I should be running mid 13's.

Awhile back I tested the PPE stack on my LLY truck. It felt very fast, and ran OK. Dyno was in the low 400's. I took it to the track, and it performed erratically, and did not run quicker stacked than unstacked. The major problem was laying down at the 1/8th mile marker. (I had also tested Edge stacked with various tunes with poor results. But some of that was barking during the shift as well, as well as poor ET unstacked.)

So I blamed it on the PPE Stack. Perhaps prematurely.

Now I went to track test another "good street stack" at the dragstrip. The TTS LLY Level 2 and the VA LLY box. This is VERY streetable and feels vicious, with good shifting. I get 1/2 way down the dragstrip, and BLAH!!! It loses power. I spray some nitrous into it, and it does not pick up speed. You couldn't even feel the nitrous on or off.

My best guess at this point is fuel starvation without the infamous 1093 code. But it's only an educated guess. Is it REALLY starving? Or is the ECM defueling it? Or is something else happening? First I need to work on the fueling to remove that from equation.

I guess what I don't get, is why it works for an 1/8mi before cutting out. The 1/8th ET indicated I should be running mid 13's.

Does your boost lay down after the 1/8th as well?

I had similar problems until getting the supply from the tank to the cp3 doctored up. Hope this helps.:D

Does your boost lay down after the 1/8th as well?

Hmmm... I didn't think to look. If I can get it to do it on the street, and that's an if, I will glance at the gauge.

This is a guess and only a guess......if your not getting a low pressure code...I am thinkin maybe that the trucks programing is backin down the rail pressure before it sets the 1093? I wonder if the new ts box....the acitivator I thinks its called raises the rail presure? I heard a rumor that it does. I am wondering if this may be a fix to the problem? Tell me if I am out in left field here cause I definitely could be.

I'm going to be experimenting with the TS Activator very shortly. The TS Activator adjusts boost and rail pressure for the LLY. I was going to try it at the track yesterday, but ran out of time. We were bracket racing, and I needed good repeatibility, so I just ran the brackets with the TTS level 2, which produces consistant results. Got second place.

Hmmm... I didn't think to look. If I can get it to do it on the street, and that's an if, I will glance at the gauge. You mean the one zip-tied to the wiper blade?? http://www.dieselplace.com/forum/images/smilies/hihi.gif

Naw, I "deghetto'd" and switched to the Trippin Mount. Pyro didn't work, but with an "official" boost gauge, it still goes past 40PSI stacked.

If I would have left the Hood Mount on it, I probably would have noticed the boost level. Sometimes Ghetto Is Good. ;)

Can you imagine the tech guy's face at the track though? http://www.dieselplace.com/forum/images/smilies/wtf.gif
Is there anyway you can monitor the fuel pressure on a run, Pat? I would imagine someone would have to be driving while a crash test dummy was watching a tech II to see what is going on, perhaps??

A quick snapshot with the Tech 2 should do the trick!



Can you imagine the tech guy's face at the track though? http://www.dieselplace.com/forum/images/smilies/wtf.gif
Is there anyway you can monitor the fuel pressure on a run, Pat? I would imagine someone would have to be driving while a crash test dummy was watching a tech II to see what is going on, perhaps??

What I would REALLY need would be:

MPH
RPM (to figure what gear I was in)
injector pulse duration
commanded rail pressure
measured rail pressure
commanded vane position
inlet fuel pressure/vacuum

With that data, something should pop up as not fitting with situation.

Good to see someone else is making big boost pressures, I made 46psi yesterday with just a predator, how much are you guys picking up with a stack.

I can hit 45 with the TTS+VA.

Whether the stock LLY making 40+ PSI is a good thing or bad thing is left to be seen.

We do not have enough fueling at high RPM to find out yet.

The test would be to find out if you made significantly more HP with the same amount of fuel at 45PSI vs. 40PSI vs. 35PSI vs. 30PSI, and how high the EGT's went. For all I know, when my truck hits 45PSI, it is making less power than 40PSI. I have a boost controller I'm going to be testing soon, and hopefully I'll learn something about boost vs. HP on the LLY stock turbo.

Wow, I did not realize that the LLY turbo went that high...Wonder what the point of no return is for that one?? Juice, you know yet??? LOL

Several people don't believe it, but several people have also seen the same numbers on their trucks. As you know, the LLY's are only at the 440HP level so far, what will happen to these 40-45PSI tunes when fuel is available? Since that is nearly double the design intent of the turbo, I have a feeling that something will give, and it will probably be the turbo.

I imagine you could weld the wastegate shut on the LB7 and see the same boost. And we have heard what happens when you do that. :eek: