Not sure about the 3.5EB but the 2.7EB engines have programming in them that reduces turbo pressure in 1st and 2nd gear. Allowing full boost in the first two gears might just eliminate the need for a tuner. Any Forscan gurus listening?

 

Is boost not a function of the pcm? Forscan doesn't touch the pcm but any forscan setting for the 2.7 would likely be the same for the 3.5. Short answer, buy a tuner

 

Bump. Is this true?

 

Even if this is true, Forscan can't help you. And, perhaps there's a reason why boost is limited... too much boost plus the extremely low ratio of the first gear in these trucks may cause things to break. It's all fun and games until you shear a driveshaft

 

High boost at low rpm generally runs cylinder pressure through the roof....which generally runs rods through the block. Tread lightly.

 

Can't anyone with a Lariat (not myself) confirm this with their oem boost gauge?

 

Forscan has no access to the pcm. For good reason. People would be breaking stuff left and right.

 

I can't see them limiting the psi. Most turbo sports cars (I had a 300zx tt) don't have time for full boost in 1st gear because of turbo lag. By the time they kick in all the way, its time to shift.

Correct me if Im wrong. This is what the purpose of boost launching is when you're drag racing in a 4wd/awd turbo vehicle. You brake stand it to build boost ahead of time and then when you launch- the street light become lines and you jump into hyperspace, lol.

*Im sure anyone here that's running a tune is getting more than the factory setting of psi in 1st gear and they can chime in anytime.

Anyone here ride in a GMC Syclone or GMC Typhoon?

 

You don't build full boost at the line though. Our turbo Pro Mod car was set to 20psi on the 2-step at launch then ramped up to 45psi by 1.1-1.5 seconds into the run depending on track conditions. These were ~4000 hp motors.
The diesels I used to race would launch at 40ish psi and make well over 100psi about the time we hit the converter lock switch in 2nd gear. These were only ~1000 hp motors.
Point is....none of them, even being two extreme opposite ends of racing, made full boost right off the bat.
The tuning will make or break a motor. I don't know anyone that tunes a motor for max boost at low rpm. It's just not safe. You can definitely add a little though....there's just limits for keeping everything inside the block.

 

This man gets it. I too have owned 1k plus HP turbo vehicles, and having damn near full boost down low is a baaaad idea. The idea of turbos is to ramp the boost up progressively not go max right away because you will run out of the powerband real quick.