04 SO CA

I just searched other threads and I guess 22psi is about right for an 04. I guess I need to download the aftermarket turbo program in order to accompish boost fooling. Thanks for the info.

dslpwr81

Sorry. Should have looked at the sig. 04. Oopps. Was thinking 06

N.Johnson

For a 03-04 305-555 you should hit 24-25 psi stock....proven. 04.5-07 325-600/610 stock 28 psi minimum wot. Some see up to 32 psi stock for a brief instant and then it bounces off the waste gate.Why the difference? Waste agte set point and they altered the fueling tables, injectors and changed the compressor wheel, mainly the turbo compressor tips. 341 versus the 351 holset turbo. Still since we are all about the numbers we put in mechanical or electronic boost foolers. Great you do! get higher boost numbers but still all that exhaust/drive pressure still has to exit through the same 9cm exhaust housing. That is or does cause a pressure imbalance known as drive pressure. If you do the math a 9 cm exhaust housing equals a id pipe size of 1.3" dia. Since the compressor side of the turbo is spinning radically fast it super heats the air going into the engine. Higher boost numbers on a stock turbo do not give more air volume or hp, just hotter air. This was proven four years ago on a dyno measuring egt's and drive pressure. Simple stuff really TDR did a excellent write up on intake temp versus boost pressure and exhaust gas temps. The tall and skinny is anything over the manufacturer waste gate set point provides no dyno proven gains in hp. YA YA squawk all you want and think about how your turbo is different than all the other stockers....numbers don't lie. Just because your egt gauge says your safe we don't have a drive pressure gauge to compare. What the heck was my point

04 SO CA

Thanks for the info. Makes sense.
I wonder if a small increase in boost would help to gain more power, but still remain safe? Being as I am only seeing 22psi. max.
Now I'm thinking turbo upgrade. "$"

djbikeman

I have one more bit of advice if you are going to run aftermarket turbo software. I have talked to some guys as I travel. The most interesting thing I heard about head gaskets was from John at Floor It Diesel. I was asking him if I needed studs when I installed a new turbo that will spin 45 psi. He said I shouldn't, but just make sure your truck is at full operating temp before you go WOT. He saw a guy pull out of his shop and drive up to the highway. The guy called him 5 minutes later. He had blown the head gasket on a truck that was studded and fire ringed. The motor was cold when he left the shop.

The stock turbo creates a lot of backpressure at high boost levels. It is better to be cautious IMO. I am looking at a turbo in the range of 62/65/14 or 62/71/14. The main reason is to reduce back pressure under high boost conditions. It's not all about intake pressure. Back pressure has to be handled too (Like N Johnson said).

If you are going to run aftermarket turbo software, make sure you get it warmed up before you jump all over it. That is cheap insurance against head gasket failure.

As far as $7k trannies go. I am lucky enough to work in Iowa. Instead of buying a built tranny, I was able to have my 48re rebuilt. It took 6 hours and cost a LOT less than that. I had billet flexplate, Triple Disk TC, Billet Input, Upgraded VB and other upgrades done.

AH64ID

Good advise, and I'd recommend that to anyone... stock or not...

04 SO CA

I'll be adding a turbo to the list just after the tranny. Or, maybe before.
I'm big on warm up and cool down cycles. No heavy foot until warmed. Thanks for the valued info.
How much savings for a rebuild over using mine as a core?

dslpwr81

I would love to have someone throw in a TC, valebody, billet flex, input.... But they all go huh. This is from all the local shops within a few hundred miles. I hear ya on the warm up, cool down. I NEVER let the tach get even close to 2k until the temp guage is way above the 140 mark. I get a little carried away on it, but its my truck and I paid $42k for it so.... I don't know why I want all these mods, I NEVER get on the throttle. Just like knowing I have the power I guess. Besides, a lot of the mods are actually better for your truck under normal driving conditions. They help keep them cool, good fuel pressure and clean fuel, more air, better mileage; the things that should be done from the MFG.