where can boost leaks come from besides the obvouis places? i thought i had mine fixed but didn't get it completely. can an exhaust manifold do it?

thanx
James

Short version, anyplace air goes inbetween the intake and the head. I have a huge leak at the intake manifol to head ended up having to replace the gasket twice.

The damn throttle body leaks like crazy and I don't know if there's a cure for it yet.

I wonder if that Modern Performance 60mm one leaks?

Yep, our TB throttle plate shaft likes to leak. Its not a lot, but it does leak, prob not enough to be very concerned with anyway, nor enough to cause any boost fade. You can also leak from the EGR solenoid, and EVAP lines, and also the PCV. Its normal for these places to leak a small amount, and if it does effect your boost(higher boost is more effected), then try running a signal line from your intake manifold vacume source to your wastegate. This way, if there is any pressure loss after the turbo, the wastegate will see the lower boost in the mani, and make up for it. I teed off of my brake booster vac line, and works very well. Holds realy steady boost. Before, my boost would fade in the higher rpm.

i have gone over all my intercooler pipes and they arent leaking.. ive replaced the tb gasket.. my manifold gaskets are faily new, only about 4 months old..

maybe the shaft in the throttle body is leaking.

when i hit full boost, my boost goes up to 20 then falls to about 15 or 16. still trying to find the place(s) that are leaking.

thanx for the info.

James

If you have check the major things like you IC piping, then try running that line from the intake vac source, to the wastegate, or if you have a boost controller, to the inlet of that. I'll bet that will take care of it. Just be sure you have no large leaks first, otherwise its just a band-aid

ok, well i have my egr shit out and the line off the manifold for it capped off and welded..

i have a single line running to my greddy bov.. however.. im remembering that on the greddy type s bov, there are actually two hose connections on it. one on the bottom and one on the top. i have the vaccum line hooked to the one on top but the one on bottom doesn't go to anything.. should it?

also.. below is a pic of my motor.. you know the line that is supposed to go to the intake? (either the stock intake or upgraded ram air intakes). I have an air filter on there which i believe could be letting out pressure out of the head.. what do you think?

EDIT: btw.. these pics are slightly old.. you can see in this pic im still running the cartech fmu and still have my egr shit in..

>also.. below is a pic of my motor.. you know the line that is
>supposed to go to the intake? (either the stock intake or
>upgraded ram air intakes). I have an air filter on there which
>i believe could be letting out pressure out of the head.. what
>do you think?

PCV valve prevents that.

off-topic: you're still using the CarTech regulator?

the pcv valve stops what?

no, im not using the cartech.. read my edited part at the bottom.

James

the PCV valve (if working properly) will prevent positive manifold pressure from entering the valve cover/crankcase.

yeah... i posted that question after your original post, but before you edited it. chances of that are pretty slim!

yeah, well i know i checked the pcv about a month ago and it was fine then. i could take it off and make sure it rattles...

any thoughts on the greddy bov though?

thanx
James

Well that line that your small filter is on, is the breather line. It does just that, it lets the crankcase breathe, and when needed, release excess crankcase pressure, esp under boost. This is why a lot of turbo guys use a "catch can", since that extra pressure can force out oil from the valve cover. The PCV is not a true check valve. It WILL leak a bit of pressure by it. Its ok really, because it just goes out the breather line on the valve cover. It shouldn't be enough to make it fade that much boost. Try what i suggested. Really. And for your BOV, from what i understand, you want to leave the bottom port untouched. But, i'm not 100% familiar with that BOV..

"" intake vac source, to the wastegate, or if you have a boost controller, to the inlet of that ""

i have a bosot controller.. so if i run the vac line directly to the boost controller inlet, then where do i run the line coming from the turbo? to the vac as well?

James

>"" intake vac source, to the wastegate, or if you have a
>boost controller, to the inlet of that ""
>
>i have a bosot controller.. so if i run the vac line directly
>to the boost controller inlet, then where do i run the line
>coming from the turbo? to the vac as well?
>
>James

This is how mine is setup. I took off the line that goes from the turbo compressor outlet, and capped off that fitting on the turbo. It wont be used as a boost source anymore. Now, i used my brake booster vac line, its the larger one that connects directly to the intake mani, and is a great source to use. I cut the line, uses a T fitting, and ran the teed line to my input of my boost controller. Then from the output of the boost controller, to the wastgate actuator. Boost is very steady, no fade, no significant spikes. Be sure to either zip tie or hose clamp your tee fitting, becausae you dont want that to come off..i used hose clamps.

what boost controller do you have?

thanx
James

The diaphram in the greddy and the adjustment screw have been known to leak on the Greddy BOV especially at higher boost. This was happening on my old Greddy.