boost leak!?

[1fast97gsx]

My turbo is an scm61, intercooler is a Precision core with custom piping, and I'm running a 1g head. My boost controller is an hks evc4 and I'm set up for an external wastegate.

My boost controller requires me to do 2 3rd gear pulls to set the learning curve. I did that and it displays the boost it read .... 1.02 bar. This is good since it has a 14.7 spring in it so it's just about dead on. Anyways, i set my high setting to 1.65 bar ( 24 psi ) and my low to around 1.40 bar. First time I do a pass with the high setting ( should be 24 psi ) I'm only hitting around 21 psi. I took the car home and hooked up my leak tester which btw pops off the turbo at anything over 20 psi no matter how tight the clamp is .. so I pressurize it and hear no leaks, although the boost guage almost immediatly starts slowly dropping.

I'm thinking I have a REALLY small boost leak somewhere that only comes into play a higher boost levels? Anyone know how to make a 'heavy duty' leak tester and where to get the parts? Everywhere I go, nobody sells a 3" OD cap to make one that will fit on my 3" inlet and the one I have no just keeps blowing off the turbo.

 

[1fast97gsx]

update: Just for kicks I turned the controller up to 1.90 bar ( 28 psi ) and my boost was hitting around 22-23 now. It's definitly gotta be a small boost leak right?

 

[gixrman]

remember that when you pressurize your system that vavles are open or partially open in one of the cylinders. You have to keep cosistant pressure for this reason. Then you can look, feel for leaks. Your going to have some leak anyway from the rings and carbon buildup on the valves.

 

[1fast97gsx]

yes, exactly. That is what throws me off because usually boost leaks are pretty loud when the system gets pressurized and the pressure drops really fast. With the tester it seems there are no leaks, however my boost controller / guage say otherwise. On the way home from school I set the controller to 2.0 bar ( 30 psi ) and still only got 23-24 on my guage. Did a compression test and it's good so I'm stumped.

 

[gixrman]

what BOV are you using and try a lower pressure or PSI to check.

 

[awdsm drft]

it's not a boost leak. your boost controller is off.

 

[1fast97gsx]

it's not a boost leak. your boost controller is off.

huh? you mean "turned off" or misscalibrated? Either way ... right now I have it programed for 1.75 bar just to run 22 psi. With the boost controller physically turned off I run exactly 14.7 so that's just how it should be. My lower intercooler pipe has 3 tiny pinholes, but I put a coupler over them and a clamp so they "shouldn't" leak. Any other ideas? Oh ... what difference would it make what kind of bov I'm running? It's a Greddy Type S so 23 psi should be no problem right?

 

[gixrman]

Oh ... what difference would it make what kind of bov I'm running? It's a Greddy Type S so 23 psi should be no problem right?

Becuase it could be your BOV leaking under heavy boost. You need to be able to isolate each piece to see were the problem is, presurizing the whole system leaves to many open doors.

 

[1fast97gsx]

but then wouldn't it leak as well when I pressurize the system?

 

[blackgsxrcst]

your bov wont leak on you. think about this..... under WOT, full boost, that vacumm line is putting that same amount of pressure to the bov to keep it closed.

 

[1993eclipseGS]

My type-s leaked when i first got it, At full boost. I didnt have the lower nipple hooked up.
Dont know what your problem is, Goodluck fixing it though.

 

[unlikely hero]

What type of boost controller do you have? For the longest time I tried to find a boost leak because I wasn't getting over .73 when it was set at 1bar. I finally just unhooked the line to the wastegate for shit and giggles and bam first gear run i hit 1.4 easily. Try that but becareful you don't overboost.
=Jason-

 

[1fast97gsx]

What type of boost controller do you have? For the longest time I tried to find a boost leak because I wasn't getting over .73 when it was set at 1bar. I finally just unhooked the line to the wastegate for shit and giggles and bam first gear run i hit 1.4 easily. Try that but becareful you don't overboost.
=Jason-

I have an electronic hks controller. If the wastegate line gets unplugged I get infinite boost, but that doesn't mean there still isn't a little leak or somethng somewhere though. Theres gotta be a reason I'm not getting all the boost I should be getting.

 

[1fast97gsx]

My type-s leaked when i first got it, At full boost. I didnt have the lower nipple hooked up.
Dont know what your problem is, Goodluck fixing it though.

Where is the lower nipple supposed to go to? I have the top 1 going to a source on the intake mani after the throttle body, and the bottom 1 going to my lower intercooler pipe.

 

[1993eclipseGS]

mine is hooked up to the turbo outlet pipe.

 

[1fast97gsx]

ok thanks