Not offense taken and i understand what you are saying and of course the truck is a little different but...but surge is surge. And a turbo,boost, wastegate, back pressure, drive pressure, a/rs all function the same to a degree when talking airflow.Surge can happen under accleration obviously ( which is the worse kind) and it can happen when going from going WOT under boost to totally 100% letting off as well. The force is on the shaft is obviously more when under full boostand switching gears under load, but its still harmful when letting off as well because as i said before, the boost is going backwards and slamming into the wheel(shaft) all at once. Which will over time ( could be weeks, could be years) will cause bearing failure and you will start to have in/out shaft play and get so bad the side to side shaft play will start digging into the compressor housing. And teh more boost you throw at it, the worse it will get. And oif on stock turbo and start pushing over 25lbs, you are past the flow chart for that wheel -a/r and at the choking point which will compound everything that is going on. A ported housing as i said before will help since it gives the air somewhere to go and you will hear it exiting but still imho a different sound the the OP. Not sure if the OP had or not a ported housing when he was stock turbo before his mods, but if he didn't he was getting some severe surge when just letting off the throttle. I have NEVER heard a stock turbo truck make that sound...and with work trucks and family that is about 10 of them.

There comes a point where you need to figure out boost, what a/r you need, how much your turbo flows etc to figure out a perfect scenerio. Which is hard to do.....running the Motec on the drag car i monitor EVERYTHING with more pressure sensors then you can ever find and its still hard to get equal. I was just stating that the OP's truck definitely is not acting normal. On a side note without looking at his vids, what boost was he hitting when its doing all that noise when letting off?

 

Oh, so you did what quikkordead did? I see... yeah, I was just gonna screw it in all the way. From the last post I read, the stock Garrett is only good for 25psi? Where'd you get those specs, BTW? I just don't wanna kill the turbo... I guess I've said that several times. I just would like to fix my lag... what would y'all recommend MAX boost to be? 25psi? That's kinda what I'm thinking...

 

over 25 on a stock turbo you are making too much back PSI and making hotter air...put a 1.00 exhaust housing on it you can run up to about 30...

 

1.00 housing... that's basically a van turbo, right? Will adjusting the actuator rod all the way in make more than 25psi?

 

van turbo has a 115... it will help build a little more boost....but the main thing it does is makes it spool a little faster...if you want more boost you need more fuel and a turbo that can take it..a stock turbo just doesnt push enough air...a 38R is 1 to 1 at 30 psi but its also flowing 33% more air then the stocker....boost doesnt make power..air does...corse more air means higher boost...

 

Right, all I want is quicker spool-ups... so, just tinker with the rod until I can hit and/or stay under 25psi?

 

thats how i would do it on a stock turbo...or un hook and keep a good eye on the gauge..

 

You shouldn't make much more than 25 anyway with a WW on it. I was hitting 26-27 with the stocker & WW tops. That's my experience, anyway.

And the wastegate doesn't "blow off" boost. It opens and lets some of the drive pressure around the exhaust wheel instead of through it. Maybe I'm splitting hairs here, but it's totally different that a "blow-off valve" that seems to be described above.

FWIW, I'm getting 36-37 psi out of my van turbo right now & about 450 rwhp. Been that way for better part of a year so far...

 

So, what would y'all suggest I do? I want to keep the wastegate functional without destroying my stock components...

 

Good info, had no idea, Im always learning everyday.

 

450 at the RW's,nice izzy..