lag, then boost drops off= teh suck
 

so i know alot of my problem is that i'm usin way too small of a turbo for my set up, but there's still one thing that i can't figure out. i've got a .42 .48 on my b16 runnin uber w/ 450's, bmc log mani, 2.5 mandrel dp w/ 2.5 all the way back, 2.5 mandrel charge pipe, and turbo xs mbc. the damn thing doens't hit full spool until almost 4500 rpms!!! then almost right after it fully spools, the psi starts to drop as well. i'm workin on that though. is all my lag comin from that mani, or what?

Re: lag, then boost drops off= teh suck
 

boost leaks.

Re: lag, then boost drops off= teh suck
 

all couplers were tightened w/ a socket, bov won't leak (hks ssq). i dk where else to look

Re: lag, then boost drops off= teh suck
 

could be exhaust leaks too.

also loose vacuum hoses. split in a coupler that you're not noticing.

Re: lag, then boost drops off= teh suck
 

I wish I could help but I have the same problem with a similar setup but I have a b18.mines spools at like 3500 and dies at 5500.I thought with the boost controller it would have held boost longer but thats not happening.I dont think its the header,I have the same one,same turbo but running 21/4 exhaust and piping.Ive checked for leaks but I find nothing.I wished I would have kept my t25 setup cause kicked in at 2500 and died at 5500.if u figure it out post what it was so that I could try the same thing

Re: lag, then boost drops off= teh suck
 

i had a problem similar to that a while back when my wastegate was opening too far. id spool up, hold it for a while, then it'd all blow out and id have to start spoolin up all over again. shimmed the gate a bit and it went away.

Re: lag, then boost drops off= teh suck
 

i'm runnin external

Re: lag, then boost drops off= teh suck
 

Did you always have this problem ?
Gasket between mani and turbo ?

Fook is right does sound like a leak.
You using a mbc btw ?

Re: lag, then boost drops off= teh suck
 

yeah, it's had this prob since i got it runnin w/ the turbo. yes, i'm usin a turbo xs "high performance" mbc, and yeah i have a gasket between the mani and turbo. i dk why my couplers would be leakin since their less than a month old from stealthmode, so i'm leanin twards exhaust leak. i'm gonna pull the mani off tomorrow and see what's up. anything else i should look for? cause this really sucks. my car's slow as balls

Re: lag, then boost drops off= teh suck
 

1.) Build a proper boost leak tester, pressure test your entire intake.

Re: lag, then boost drops off= teh suck
 

How do you do that? Smell that? WRITE-UP!!! :o :P


JP

Re: lag, then boost drops off= teh suck
 

a 42/48 getting full boost at 4500 on a b16 ??? id think theres something up with your charge pipes. i dont see how this has anything to do with your exhaust. just un hook it and run it open down pipe

Re: lag, then boost drops off= teh suck
 

it would affect it if there was an exhaust leak before the turbo

Re: lag, then boost drops off= teh suck
 

Take off the mbc and see if the boost is steady.

Re: lag, then boost drops off= teh suck
 

it wasn't even before the mbc was on, and took just as long to spool too :-[

Re: lag, then boost drops off= teh suck
 

is there? its not hard to find out ::)

Re: lag, then boost drops off= teh suck
 

i'm pullin everything apart today when i get back from fishin to find out what's up. i'll let ya'll know tonight

Re: lag, then boost drops off= teh suck
 

Make sure there isnt any hidden holes on your welds.

Re: lag, then boost drops off= teh suck
 

alright, i went out and started taking stuff apart. i found a small exhaust leak where the wastegate bolts onto the mani. cleaned it up, and bolted the fucker on as tight as i could, and it's still the same. i'm not using the gasket that came w/ it because everyone says that they just burn off. so i dk what to try next ???

Re: lag, then boost drops off= teh suck
 

what wastegate are you using, sounds like its poop.

Re: lag, then boost drops off= teh suck
 

knockoff tial 35mm

Re: lag, then boost drops off= teh suck
 

Yahtzee!

That is most likely your problem. I have the same problem as you except mine is an internal wastegate.

Re: lag, then boost drops off= teh suck
 

pull it apart, chances are the set screws inside have all backed out and everything is just flopping around in there

Re: lag, then boost drops off= teh suck
 

Already been done, long long ago:


http://www.vfaq.com/mods/ICtester.html

Re: lag, then boost drops off= teh suck
 

I haven't been here that long and still a n00b. So, thank you kind sir. ;) ;D


JP