Hey guys,

I had ran a gt3574 on the car for about a day and it felt pretty good... Nice power, everything.. @ about 12 pounds.

I got a new turbo because the gt3574 was bad, and not it feels like I have lost a bunch of power. It is a .69AR rear .70AR compressor...

I have a small exhaust leak @ my midpipe/downpipe junction and it is possible that there is one at the t4 flange, but isn't 14# the same no matter what the leak??

What should I start looking for as far as problems are concerned?

Thanks!

 

If your boost gauge is reading 14psi then that's what should be making the power. Anything AFTER the turbo (on the exhaust-side of the equation) is irrelevant to the cold (read: charge-side).

Manny or slush-box?

I would say check out your clutch, first if it's a manny... LONG time ago I had a 2G GSX (DSM) and had the same exact problem... Finally,, when I got the case open, it looked like a freakin beaver had nested in my trans, built a damn that rivaled the Hoover, the got chewed up and died, leaving only his fur behind as a curse.

 

Its an automatic....

Any other ideas? When a rotary motor goes does it do so slowly?

 

it can gradually lose power as it loses compression or it can go all at once. Only way you can really tell if its about on its way out or gone is with a compression test (search, it's easy)

it could be your tranny slipping from the increased power. Not many people go sinlge turbo and leave the auto in place, it's not known for holding power.

since you've gone single turbo I'm assuming you've got a PFC or something similar, select boost from the commander display and go full boost and see what it says, that'll give you the full boost that the computer is seeing, it can be completely different from the gauge.

check vacuum hoses

 

+1 about the auto trans. My understanding is that they were designed and built JUST beyond the capability of the stock engine, but could be wrong.

If nothing else, with the car warmed up and at idle, try spraying under the UIM with something like starting fluid. If that gets sucked into an errant vac-line, the tach will bog and you'll have a ballpark of where (if) your vac leak is.

I would recommend doing this A) *AFTER* you've checked your compression on all faces, front and rear, and; B) *NOT* in your garage. That **** smells like my uncle's farts after being out all night, drinking, then getting up and having a 4-egg breakfast.

 

pressure test for boost leaks

 

you said your gt3574 was bad, what is your new turbo? the same kind? different turbos make different power.

 

^ exactly, plus thats a tiny turbine housing.

 

Well, if it were bad, the gauge wouldn't be reading 14psi.... If it were bad it WOULDN'T be reading 14psi.... 14psi is the same end result, regardless of where it is in the efficiency map.

If the UIM is seeing 14, there's a separate problem as to why it's not going to the ground.

The size would merely dictate how soon it would reach it's maximum efficiency. It should feel the same, if the replacement turbo is the same as the one that got taken off.... Well, we'd HOPE it felt better, but.... *shrug*

Just out of curiosity: What nipple's your boost gauge run to?

 

Sounds like a leak.PSI and Volume are 2 different things .You can have 14 psi but less total airflow due to the leak.Pressure test with a bottle of soapy water

 

14 psi with a .61 turbine is not the same as 14psi with a 1.06 or 1.15.

the bigger ones are going to make noticeably more power; anywhere from 50-100+ difference based on the system its running in. Pressure and flow are two completely different things, and both affect power output greatly. 14pis means nothing if the air isn't going anywhere.

 

generally ~0.84 A/R in a T4 is the smallest recommended turbine housing to use on a rotary, around 1.00 A/R is even better. Is it choking at higher RPM mostly? If so, then your turbine housing could have something to do with it, but i would first check the obvious things like mentioned above.

 

Hey guys update...

I found out (through noise) that the wastegate was leaking badly. everywhere....

the flange was leaking a **** and the output was ALSO leaking pretty bad.... It was a deltagate, which I now realize is one of the worst gates to be using.

I bought a TiAL knockoff, that I am really happy with so far, hasn't been installed yet, but the internals look good, no leaking and its one of the few new parts on the mobile.

This will be installed tomorrow after I pull ALL OF THE **** OFF AGAIN. (repetition is key they say)

I'm going to weld the V-band on and try again. I also ordered a new T4 gasket, as it was slightly leaking at that spot too (barely).

BUT one thing I do know is that it the guy that was running this turbo in his FC was doing 350 rwhp at 17#, and I know that I am nowhere near that.

Personally I think that elimination all leaks that relate to the turbo "working" will help me a lot as far as where the problem is coming from.

TODO tomorrow wastegate install, leak test, and try to check the compression.

--------------------------EDIT-----------------------------

Should the FD's be able to beat/keep up with a stock LS3 corvette also automatic?

 

Just tell us what kind of turbo you're running now. A gt3574 at 14psi is a FAST car. A gt2554 at 14psi (at least on a 13b) is going to need a tracheotomy. It makes a BIG difference.

Also, I wouldn't think a leaking/open wastegate will effect your power output. It will will simply make your spool terribly slow. Once you hit full boost however, a nice wastegate will feel the same as no wastegate at all.

And an LS3 makes over 400hp and over 400ftlbs stock. They are heavier than an FD but not by much. It'd have to be a cracking FD to keep up. Stock for stock, no.

 

This setup sounds like trouble. What ecu are you running? I haven't counted but I have seen many threads with people saying there motor blew and so they are selling off all their parts and in the list of parts is a knock off wastegate. Best wishes

 

I am not sure how to get the name of the turbo. Its an O trim with a .69 rear and a .70 front, and that is all that I know, oh and it is all garrett parts.

About the me vs LS3..... as soon as the gate opened up I started to catch up again. Maybe it just looked like it to me, or it was hopeful thinking, but I"m pretty sure I started to catch up with him when the boost kicked in.

TBH I haven't seen that problem yet.

I'm running a PFC, my afr's are at 13.5 through the range, and the car pulls like crazy when the gate was wide open, I really think that the problems is that my spool is later (due to the leaks) and to me it seems like something is wrong.

 

*face palm*

You're boosting at 13.5 AFR? You'll be needing an engine soon. And more often than not an O-trim is like sucking through a straw, of course it feels slow.

 

*my god*

 

 

This thread is so full of win.

:sigh:

 

Use one then judge it. They have been used before and found to be exact replicas that are fully swappable with tial guts. It's in now and works great. 11# with no creep or any issues.

about the 13.5 afr..... I was just guessing, it was in the green and it was running rich.

P.s I was asking for info not a flaming.

 

And info we gave. You claimed to like the the tial replica before using it. You claimed to be running the car crazy lean, you claimed to be running a turbo way too small for the engine.

Basically you've proven you have no idea what is going on, how do you expect us to act?

 

Hasn't heard you yet?? I guess keep trying....
Actually it is more fill of lose... I don't see it being a win with a (prior) shitty spool and a (prior) leaky gate. YOU'RE full of win, especially with your "helpful" comment.
Of course, Can I not like something when I look at it??? I guess not according to your logic. I felt that for a *replica* it looked to be well made, and I subsequently "liked" it.
I was guessing, like I said. So deal with it.
Well now.... This is all opinion, yes rotaries like to have more flow, yes I would get more power, but guess what. I DON'T GIVE A ****. If I can make 300 to the wheels with this turbo.... GUESS WHAT?!?!? I'M HAPPY!!!!!!!!!
?????????? If i didn't know what was going on, I would have started a thread that said this:

My old turbo went WOOOSHH and my NEW turbo GOES WOOOSHH but the wooshiness doesn't feel the same WTF ^^ SOMEONE FIX MY CARZ YO.

Instead I gave information REGARDING what I felt the problem was, I gave info when I was asked for it. I had (mostly) correct answers to the questions. Hell I was even willing to take suggestions to see if something was going bad...

So, tasty danish, and anyone else doing this kind of helping, respectfully, blow it out your ***.

 

As an RELATED update:

I put the new gate on, a new gasket at the T4, and some newtome manifold gaskets on, and guess what?!?!? boosting very well, thanks for the ACTUAL help that was given to me.

 

Oh wow you really are dense. Well guess what, you weren't happy, that's why you made this thread so obviously you "give a ****."

but that is pretty much what you asked. "my old turbo was xxx fast at 14psi, my new one isnt WTF!!?? "

You have a great sense of humor. Word of advice, stay the **** out of the lounge.