weird boost issues on b18a1...
 

I just helped my buddy finish boosting his b18a1 in his 90 hatch. So far it's a stock b18a1 with a 14b, still using the internal gate and a custom (ugly) made manifold, and is now running off a vafc2 and dsm 450's. For some reason i can't seem to get the car to make more than 8psi at full boost. When we first put it together and had a straight line ran from the compressor housing to the wastegate, it only made 5 psi. It also didn't start making decent boost until close to 4700 rpm, which i thought was weird for a 14b on that size motor. I ended up putting a vacuum T in the wastegate line and left the one side open to atmosphere to bleed off some pressure to let the wastegate open later. After that we got 8psi, but he wants more. Tried out some weird deal with an air pressure regulator to try and see if we could use it like a MBC, but still only peaks at 8psi. It almost feels like the wastegate is being held open, but I've checked it a couple times and it does seem tight. I know we can put more boost on this motor, hell...even the afc settings aren't set past -38 at 8 psi, and coupled with his FPR set at 58psi of fuel pressure, it still runs close to a 10:1 AFR. Anybody have any ideas, cause i'm pretty much stumped, and we're both getting pretty frustrated with this :7

Re: weird boost issues on b18a1...
 

I don't know, you think the wastegate actuator could just be bad? Try running the vac line off of the intake mani for it and see if that helps...I have an actuator off a Dodge turbo that might work for you? I could put that in the mail for you if you pay shipping? I don't know, the other could be exhaut leaks or restrictive exhaust, try open dp and see if that makes a difference and check the mani for any black from exhaust gas passing throw, thoughs are good possibilities too, HTH....Matt

Re: weird boost issues on b18a1...
 

Well, this is the weird thing too...i built a 2.5" exhaust for him, from the downpipe on back and used a magnaflow turbo muffler for a little while. With that setup it was making almost 10 psi at times, but he didn't like how raspy it was so we swapped in a straight through magnaflow can style muffler. After that we dropped down to 8 psi again. I could try disconnecting the wastegate line for a quick pull and see if it'll go above 8, thought of doing that but my buddy kinda got a little scared at that idea lol. What psi does the dodge actuator open at? I might end up doing that if the wastegate is shot. I guess it's a possiblity that the wastegate might leak too. I'll check that tomorrow after work then.

Re: weird boost issues on b18a1...
 

Hmm...I believe it was from a turbo daytona but my guess is probably 5.5-6.5 it will atleast help you figure out what the problem is if the old one is bad, I might even have the mounting plate other odds and ends for it but you'll probably need to rig it for it to work but thats why this is HMT ;) My guess is it might be exhaust leaks, check between the mani and turbo, I had a bolt loosen there on the back side and couldn't see it when it was on the car

Re: weird boost issues on b18a1...
 

tell him not to be a ----- that will show you a lot. Just do a pull and watch you gauge closely and once it builds up to 10-12 punch in the clutch. Simple. If it doesn't build then you gotta narrow down the problems.

I personally like to hook WG lines up to the intake mani to avoid the pressure drop through the intercooler, not sure if you guys are runnin one or not.

Re: weird boost issues on b18a1...
 

Perhaps the housing around the wastegate has a nice crack in it.

Re: weird boost issues on b18a1...
 

this is VERY common for 14b mitsu turbos... trust me i've gone thru 2 of them in the past

Re: weird boost issues on b18a1...
 

Well, i know there's no exhaust leaks bewtween the manifold and the turbo. There is a possibility of the crack around the wastegate though. I'll try and check on that tonight too.It's possible that the FMIC he's got is creating a massive drop. It's a '04 or '05 Lancer evo8 FMIC (pretty much identical to the one i run and i never had any issues), so it probably is dropping quite a bit through it.

Re: weird boost issues on b18a1...
 

Update: Well, figured out one of the problems with boost kicking in late...wastegate arm was bent and it was holding it open almost a 1/4". I fixed that problem, and now it spools up too fast lol...right around 1700 so i'm gonna bend the arm back a little. Still can't figure out why it won't make over 8psi max though, right now it's making around 6.8 or 6.9 according to the afc after fixing the arm, and even with the bleeder T in it it still only gets up to 8 psi by 3000 rpm, and then falls flat on it's face by 4000...almost feels like it goes N/A.