Boost leaks???

Thats honestly what I been thinking I havnt done a smoke test yet but thats really all I can think of.. that would be the most likely reason isnt it ?

Could be a boost leak. Or the blownoff valve needs adjusted

Any chance the old turbo wasn't surge-ported and the new one is? Also why are you using a turbo that size at such a low boost level?

jakk220 said:

Could be a boost leak. Or the blownoff valve needs adjusted

Click to expand...

I loosened it thinking that would make it louder but didn't i did notice that if I have the turbo open not having the headlight induction its alittle louder tho but again only if im getting on it

JusMX141 said:

Any chance the old turbo wasn't surge-ported and the new one is? Also why are you using a turbo that size at such a low boost level?

Click to expand...

Imma be honest not sure wym... but my first one was a 60mm precision turbo and my new one is a gt35r 70mm

JusMX141 said:

Any chance the old turbo wasn't surge-ported and the new one is? Also why are you using a turbo that size at such a low boost level?

Click to expand...

And I'm on 28 lbs of boost now

Another thing I may add i noticed at idle im not at 0 psi im at about 5psi of boost at idle but after letting off the throttle it goes back to 0 then rises to 5 psi roughly

Inkdlyfe said:

Imma be honest not sure wym... but my first one was a 60mm precision turbo and my new one is a gt35r 70mm

Click to expand...

GT35R's are 61.4mm...so it's either a 70mm turbo or a GT35R; it can't be both.

Inkdlyfe said:

And I'm on 28 lbs of boost now

Click to expand...

Still well below where a GT35R or larger compressor would be happy on a 2.0L 4-cylinder. A 60mm compressor wants to be in the mid-30psi range or higher, a 70mm compressor would want to be in the mid-40's coupled to an engine capable of a 5000-9500rpm powerband.

Inkdlyfe said:

Another thing I may add i noticed at idle im not at 0 psi im at about 5psi of boost at idle but after letting off the throttle it goes back to 0 then rises to 5 psi roughly

Click to expand...

Then something is wrong with the gauge...it's impossible to generate boost with the throttle plate 100% closed and no load on the engine.

I just know its stamped .70 AIR and its a gt35r... assuming that means 70mm?..

And I'm 2.0 with .050 over sized pistons 8.8.1 comp, and it seems to wanna build boost about 5000 rpms range at 28 psi peaking around that

And thats what I thought so its time for new lines and gauges it seemsss

Justin is correct. I run a 62mm compressor turbo and above 30psi it really starts to move some air. Ignore the .70 AR on the compressor cover, its the size as stated. I am confused that it has .050 oversized pistons? Most are .020 or .040 ect. Do you have a correct list of all the parts on the car?

I know for a fact its .050 over I just had to get the block done with in the year its Wisco 8.8.1 over sized pistons. But for the most part I do have the list of everything

Inkdlyfe said:

I just know its stamped .70 AIR and its a gt35r... assuming that means 70mm?..

Click to expand...

Not at all...it means the area/radius of the compressor cover casting is .70. There's not a turbo in existence to my knowledge that identifies the compressor wheel size in millimeters on the cover. If you have a GT3582R, it's a 61.4mm compressor.

Inkdlyfe said:

And I'm 2.0 with .050 over sized pistons 8.8.1 comp, and it seems to wanna build boost about 5000 rpms range at 28 psi peaking around that

Click to expand...

Oversized pistons are to fit oversized bores that have been machined to correct bore taper. Adding a half of a millimeter to your bore size isn't going to add any noticeable power increase overall.

So your powerband is going to be based on how far you're willing to rev it out- you wouldn't want a powerband that starts at 5000 then you shift at the stock rev limit of 7200. Even going to 8000 may mean it falls completely out of boost again on a shift....so matching the turbo size to your application is key. It's not as simple as bolting on a larger turbo and going faster- you have to add any two of the following to make a larger compressor worthwhile: boost, RPM, or displacement. The only reason I say this is there's a lot of people out there using turbos that are far too large for their RPM range and power goal and the car is complete turd as a result. You wouldn't want to put a sheet metal intake or 288 cams in a stock engine against a T25 because it's mismatched and would essentially hurt power production...being over-turbo'd is just as bad. There are a lot of cars out there using a turbo that is unnecessarily-large.


But getting back to the original topic at hand- if the old turbo didn't have surge porting on the cover but the new one does, that's why your valve got quieter...it's surge porting doing what surge porting does when the throttle plate closes.

Understandable, like my motor is fully built point blank, cams. Rods. Pistons, valves, I've been building this car for 5 years now dropping every mod I can into it. I've always had 2.5inch ic pipe. But before I was on a 60mm. (Pobally lower then 60mm due to going off compressor stamp) I use to spool fast asf but now its quite long spool.. the lag is insane. Pretty much hitting boost starting at 5k rpms shifting at 7k but I'm able to hit 28 psi in that gap easy probally not holding it as long as needed tho.... I'm starting to think I should down size my turbo .. that should fix my over all issue here for the most part.

I use to be able to "hold" the rpms at 7k and never red line but this new tune done changed everything... and no one seems to be able to tune aem any more