engineermike

ST80 is a great choice, but bigger in size. If the ITS80 is trashed, then consider a PT78GTS to replace. Proven to 1000 hp on even large v-8's. With a 408, you'll just have to keep the rpm range down by using an early IVC.

Mike

DanaliHD

iTrader: (5)

precision recommended a gt4276 with 1.28 a/r. i almost bought it on friday morning but decided to wait until after the new year. Plus i keep hearing so much about the S and ST turbos i wanted to see if one of those is a better choice.

Slowhawk

iTrader: (12)

Since the truck has already pushed 16+lbs of boost back in the day,I would say keep this turbo and rebuild/fix the back pressure problem.

DanaliHD

iTrader: (5)

word, that's what i was saying over on performancetrucks. I gotta wait till jan 2 to talk to jesse again. i must have missed something he said cause it doesn't make sense. hmmmm.

so this brings up the question: could damage to the turbo be causing the backpressure issue?

engineermike

Yes.

Just about ANYTHING wrong with the turbo system will cause high backpressure. Any inadequacy of the system will cause the wastegate react by attempting to maintain the set boost pressure. This causes more exhaust to be routed through the turbine, and more backpressure.

As I stated earlier, TB not opening all the way, restrictive intercooler, restrictive air filter, etc. . . will all cause high backpressure. Likewise, a damaged compressor wheel (again, not difficult to check at all) will produce less boost, wastegate pinches off, boost is restored, but at the expense of backpressure. And so on. . .

lt1s10

iTrader: (2)

Is the shaft spinning freely?? I know it would take alot more backpressure to spin if it was dragging.

DanaliHD

iTrader: (5)

lots of good inut and questions for me to present to w2w after xmas break. thanks guys.

if i were a gamblin man, i'd say it's either a damaged turbo since they did find a friggin bolt inside it, lol, or it's the intercooler somehow.

only time will tell. i'll be calling jesse again on Jan 2 when they get back in the shop.

DanaliHD

iTrader: (5)

99% sure I'm buying a ST80 with 1.25 A/R. Just spoke to Jose and it seems the concensus is my GT80 with 1.15 A/R may get the job done but will be more likely to cause issued related to backpressure down the road. Might as well just dump it off now and try to sell it for whatever i can get for it.

Any offers?

MIGHTYMOUSE

iTrader: (59)

just make sure the tubing flows properly or your investment will not improve the situation.

DanaliHD

iTrader: (5)

gotcha

DanaliHD

iTrader: (5)

direct quote from the Turbosmart Pro-Gate 48mm wastegate instructions

"If you are unable to achieve your desired boost pressure it is normally due to exhaust manifold backpressure forcing the wastegate valve open. To increase your boost pressure further, fit a heavier wastegate spring to increase your minimum boost pressure. If you are still unable to achieve your desired boost pressure ensure that your turbocharger is correctly sized for your application."

This is from the section where it talks about hooking up the wastegate to the eboost solenoid using a 2 port connection method.

"the 2 port connection method(2) is used to achieve the maximum possible boost pressure that your system can develop. it is the most suitable method if you are unable to develop your desired boost pressure due to high exhaust manifold back pressure."


not sure any of that has anything to do with my application but i just read it so i figured i'd post it, lol

MIGHTYMOUSE

iTrader: (59)

yes tubosmart had some very good input on their instruction revisions when a certain someone was having trouble achieving desired boost levels with a v8 application & poorly flowing system

turns out when i put a good turbo system under the hood those issues went away and i was able to hook the control system up the normal way and it works perfectly.

DanaliHD

iTrader: (5)

the system has already made and held 18lbs boost on the street. i was re-reading the posts by slowhawk from when he had my truck a year ago. he was saying how insane it was to drive cause it made so much power etc etc etc.

i need to stay out of these forums and just wait for w2w to reopen, lol. I have tried to stay away from here for the last several months but golf season is over so now i'm bored. hahaha

i made a list over on pt.net of things to be checked.

-turbo(obviously)
-wastegate/bov to make sure they are functioning/hooked up properly
-eboost
-intercooler(looking for blockage, leaks, oil in it again)
-air filter, silicone connectors, or anything else that might be colapsing
-and now it is suggested that the valve springs be checked too

anything else to add to the list?

Superman09

iTrader: (65)

your sanity..... haha. Man Dan, this has been one long road for you, u deserve this truck to be running incredible right now. Keep with it.... you will be happy in the end!

bigtymn

did you take that air filter elbow and filter off and check the back presure just wondering?

DanaliHD

iTrader: (5)

Not sure what they have tested yet. This all just went down a few days before christmas and they are now closed till Jan 2. I'm just compiling a list of ideas etc to throw at them when they get back.

DanaliHD

iTrader: (5)

ok, looks like i need a new turbo afterall.

which one? Precision GT4276 with 1.2x A/R or Innovative ST80 with 1.2x A/R?

pretty sure precision has the 4276 in stock ready so ship. it's a few hundred bucks cheaper than the ST80 also.

8ALTNG

iTrader: (1)

Come on Dan. Just step up and buy the Borg Warner Airwerks S91

DanaliHD

iTrader: (5)

i would but it won't fit.

hellbents10

iTrader: (10)

I recommended listening to the shop that is building the truck!